■1*1- • - J m- v\ **- QSA > P363h 1857 K5'r«v. f. •:***'. ■*'^iSN^' :f ••" if ... ''^%aK£-#fctfte ^^»*, C ?™*m CL'i^lt.68 (i": ■/6 /t/y 7-JLJJ? ^ . deU.. 2fc / vi V NATIONAL LIBRARY OF MEDICINE Bethesda, Maryland v»a HUMAN HISTOLOGY IN ITS RELATIONS TO DESCRIPTIVE ANATOMY, PHYSIOLOGY, AND PATHOLOGY, Wafy 't***^ Entered according to the Act of Congress, in the year 1857, by BLANCHARD AND LEA in the Clerk's Office of the District Court of the United States in and for the Eastern District of Pennsylvania. PHILADELPHIA : T. K. AND P. 6, COLLINS, PRINTERS. R. D. MUSSEY, M.D., LL.D., WHOSE PROFESSIONAL SKILL, SCIENTIFIC ACCURACY, AND MORAL INTEGRITY, INCITED THE AUTHOR'S FIR.ST DESIRE TO ENTER THE MEDICAL PROFESSION, m »rk IS MOST RESPECTFULLY INSCRIBED. PREFACE. The plan of the following work was formed nine years ago; since which time the author's annual courses of lectures have been arranged in accordance with it. Meantime several works have appeared in Germany, France, and England, upon the subjects embraced in it; but no one including its entire aim, viz:— I. To give a connected view of the simple chemical elernents, of the immediate j^inciples, the simple structural elements, and the proper tissues, entering into the composition rf the fluids and the solids of the human body. II. To associate with the structural elements and the tissues, ifieir function ichile in health, and the changes they undergo in disease. In the prosecution of his object, the author has drawn more especially upon the work of Eobin and Terdeil in the first part; that of Lehmann in the division including the fluids; and on Kolliker's excellent work in the part on the tissues proper. He has not hesitated, indeed, sometimes to use the language of the latter, when sufficiently concise. He has not, however, embarrassed the text by references to the various authorities whence materials have been derived; except in instances where views varying from those of previous writers are advanced, as being, in the author's judgment, the most satisfactory at the present time. In regard to the dimensions of the minute structural elements, Kolliker has been more especially relied upon. And as this work is intended especially for those who use the English language, they are given in fractions of an inch, instead of a millimetre, or a Paris line, as has usually been done by translators of German and French works, both in England and in this country. vi PEEFACE. An experience of sixteen years as a public teacher of anatomy, physiology, and surgery, has confirmed the author's conviction that the only rational method of imparting a knowledge of function is by associating with the latter all that is known of the forms and relations of the structural elements, and of their chemical composi- tion, in each part and organ. Pathological anatomy, moreover, and therefore pathology, can be rationally understood only as we take the same point of departure. As the student should, however, study the last mentioned departments after acquiring a knowledge of the healthy structure and functions, the pathological conditions of the tissues are, in the present volume, specified in closer type; as intended to be more especially studied on a second reading of the work. The same remark also applies to the parts which con- cern the structure of the lower animals. Some typographical errors, overlooked in the pressure of other professional occupations, will be corrected at once by the intelligent reader; excepting, perhaps, those referred to at the end of the volume. Some portions compiled for it, relating to pathological and comparative histology, have also been omitted, to avoid render- ing it formidable, from its size, to medical students; to whom, and to the profession, it is submitted as the first American work on the subjects of which it treats. New York, October, 185T. TABLE OE CONTESTS. GENERiL REMARKS ...,.., PART I. STCECHIOLOGY. FIRST DIVISION. The simple chemical elements entering into the structure of the human body (15 in number)--practical remarks . . . . SECOND DIVISION. The immediate principles of which the tissues of the human body are composed (84) ....... Classification of the immediate principles . . . . Tabular arrangement of " " . . . . List of other substances sometimes regarded as immediate principles . 1st GROUP OF IMMEDIATE PRINCIPLES. Class First. IMMEDIATE PRINCIPLES OF MINERAL ORIGIN. Division I. Gaseous, or liquid principles, and those not saline (5) 1. Oxygen ...... 2. Hydrogen ..... 3. Nitrogen ...... 4. Carbonic acid ..... 5. Water, its amount, source, and use in the body Division II. The saline principles (salts, 19) General remarks ...... 1. Chloride of sodium .... 2. Chloride of potassium .... Vlll TABLE OF CONTENTS. 3. Fluoride of calcium 4. Hydrochlorate of ammonia 5. Carbonate of lime 6. Carbonate and bicarbonate of soda 7. Carbonate of potassa 8. Sulphate of soda . 9. Sulphates of potassa and lime 10. Basic phosphate of lime . 11. Phosphate of magnesia . 12. Ammonio-magnesian phosphate . 13. Neutral and acid phosphates of soda 14. Phosphate of potassium . 15. Carbonate of Magnesia . Class Second. IMMEDIATE PRINCIPLES FORMED WITHIN THE BODY BY DIS-ASSIMILATION. General remarks ..... Division I. Acid and saline principles of organic origin 1. Lactic acid & Uric acid and the urates . 3. Hippuric acid 4. Oxalate of lime . 5. Pneumic acid Division II. Neutral nitrogenized immediate principles 1. Creatine .... 2. Creatinine 3. Urea .... 4. Cystine .... Division III. Sugars (neutral non-nitrogenized principles) Remarks ..... 1. Hepatic or diabetic sugar (glucose) 2. Sugar of milk (lactose) . Division 1V. Fatty principles General remarks .... Origin of the fatty principles 1. Cholesterine 2. Oleine, margarine, and stearine . Uses of the fatty principles in the organism Practical remarks 2d GROUP OF IMMEDIATE PRINCIPLES. Class Third. ORGANIC SUBSTANCES, OR COAGULABLE PRINCIPLES. General remarks ...... Classification of the organic immediate principles . 80 83 TABLE OF CONTENTS. IX Division I. Those naturally in a fluid state . 1. Pancreatine 2. Ptyaline .... 3. Mucosine .... 4. Albumen ; its properties; its pathological relations—Origin and use of albumen—Practical remarks 5. Albuminose ..... 6. Caseine, its properties and uses . 7. Fibrine ; its properties ; origin ; uses in the organism Its coagulation as modified by various agents . Remarks ...... Division II. Solid or demi-solid organic immediate principles 1. Globuline 2. Crystalline 3. Musculine ; origin and uses—Remarks 4. Osteine ; origin and uses—Remarks 5. Cartilageine ; uses—Remarks 6. Elasticine .... 7. Keratine .... Division III. Coloring or colored organio substances 1. Urrosacine 2. Bile pigment 3. Haematine; origin; uses . Hsematoidine ; crystals of the blood 4. Melanine .... PAc: i: 83 83 83 84 84 89 89 92 96 96 96 97 98 99 100 100 101 101 101 102 102 103 > X TABLE OF CONTENTS. PART II. HISTOLOGY. PAGE Definitions—subdivisions, etc. ....•• 105 FIRST DIVISION. THE SIMPLE HISTOLOGICAL ELEMENTS. CHAPTER I. HOMOGENEOUS SUBSTANCE. Description—Two forms—Origin—Functions—Distribution—Its pathological states ......... 107 CHAPTER II. SIMPLE MEMBRANE. Two forms—Properties—Distribution—Basement-membrane ; its uses . 109 CHAPTER III. SIMPLE FIBRE. Description—Distribution—Uses . . . . . .112 CHAPTER IV. CYTOLOGY. Elements of the cell. 1. The cell-wall; 2. The contained fluid; 3. The granules ; 4. The nucleus. How affected by acetic acid—Free nuclei— Pathological developments of nuclei. 1. Tubercle, its chemical analy- sis ; 2. The glomerulus, or exudation-corpuscle. 5. The nucleolus ; not necessarily developed from fibrine, the latter not being the only plastic element of the blood . . . . . . .114 Cytogeny, or development of cells. I. Free cell-development; described. II. From pre-existing cells, a. Endogenous cell-development, b. De- velopment of cells by division—Physiology of cells : 1. Their growth; 2. The nature of the contents of cells; 3. Functions of cells—absorp- tion, secretion, and contraction ...... 120 Pathological changes in cells. 1. Fatty degeneration; 2. Pigmentary do. ■ 3. Dropsy; 4. Crystalline deposits ; 5. Atrophy . . . 129 The primordial cells. Schwann's discovery ...... 130 Isolated Cells.—I. Pigment cells.—Their structure—Distribution in the Ne- gro, and the Albino—Freckles—Peculiar forms of pigment cells, in the TABLE OF CONTENTS. XI PAGE choroid, sclerotica, &c.—Their distribution in the lower animals—Color of the hair and eyes—Pigment in sebaceous glands of the skin—De- velopment of pigment cells ; effects of solar light upon—Functions of pigment cells—Regeneration of do. ..... 131 Pathological formations qi pigment cells—'Melanosis, ephelis, moles, &c. . 136 II. Cancer cells.—Forms of cancer—Cancer nuclei — Their nucleoli — Six forms of cancer cells. 1. Polygonal; 2. Caudated; 3. Fusiform; 4. Concentric; 5. Compound or mother cell; 6. Agglomerated cell . 137 Elements liable to be mistaken for cancer. 1. Corpuscles of fibro-plastic tissue; 2. Fibro-plastic cells ; 3. Enchondromatous tumors ; 4. Pus- corpuscles ; 5. Tubercle-corpuscles; 6. Epithelial cells . . 142 The value of the microscope in the diagnosis of cancer . . . 143 SECOND DIVISION. HYGROLOGY.—THE FLUIDS OF THE HUMAN BODY. Cytoid corpuscles common to several of the fluids—Description of—Their chemical reactions—Development—Functions of cytoid corpuscles . 145 CHAPTER I. histological relations of the blood. {Lymph and Chyle.) I. Lymph.—1. The liquor lymphse. 2. Its histological elements—Its origin —Uses ......... 147 II. Chyle.—1. The liquor chyli. 2. Its histological elements. Its quan- tity—Origin—Uses ....... 149 III. The Blood.—Its physical properties—Its coagulation—The liquor san- guinis, and the blood-corpuscle ...... 151 1. The liquor sanguinis.—Chemical analysis—Its fibrine—Water— Albumen — Fat — Glucose—Other organic constituents—Mineral constituents ; chloride of sodium and potassium, carbonate of ammonia, etc.—Origin of the liquor sanguinis—Uses of its dif- ferent elements—Fibrine not the only plastic element of the blood —Albumen is so likewise—The latter is probably the plastic ele- ment of the blood—What then are the uses of fibrine . . 152 2. The blood-corpuscles. a. The colorless corpuscles.—Their cell-membrane—Their con- tents—Their size and origin—Uses—Vitality of the blood due to them, the fibrine, and the red corpuscles . . 159 3. The colored corpuscles.—Their size—Do. in the lower animals —Chemical analysis of do.—Cell-membrane—Contents— " Fibrinous flakes"—Tendency to sink, of the corpuscles— Their color as changed by different agents and circum- stances—Amount of corpuscles in the blood—Their num- ber—Analysis of the blood as a whole—Origin of the red corpuscles from the white—Function of red corpuscles— Duration of their existence . . . .162 Xll TABLE OF CONTENTS. pagp: Quantity of blood in the human body . . . 172 Variety in composition of the blood in different physiological conditions ; sex, pregnancy, age, during digestion, &c.— Do. in the lower animals—Different composition of the blood in different vessels : 1. Arteries and veins ; 2. Por- tal vein ; 3. Hepatic vein; 4. Placental vessels ; 5. Veins of extremities; 6. Menstrual blood . . . 173 Pathological states of blood—in inflammation ; fevers ; cholera ; dysentery; acute exanthemata ; puerperal fever; Bright's disease ; plethora; anae- mia ; chlorosis; leucaemia ; pyaemia ; carcinoma ; diabetes ; etheriza- tion—Diseases in which each of the elements of the blood is increased or diminished ........ 176 CHAPTER II. serous secretions, and transudations. Distinction between secretion, transudation, and exudation . . .179 1. The serous secretions.—Distinguished from others so called—Their normal quantity—Origin—Uses . . . . .180 2. Transudations.—Enumeration of—Pathological do.—Transudation results from a physical necessity in certain circumstances—Ex- plain them — Resemble blood-serum in chemical composition — Quantity of albumen in; do. of salts ; do. fibrine—Fat in them ; bile pigment, urea, &c.—Quantity of Transudations—Uses . 181 3. Exudations.—Definition of an exudation—How differing from transu- dation—Contain no histological elements at first—Their origin— Uses ......... 184 Varieties of exudations — Changes occurring in them ; absorption, or- ganization, and suppuration—Circumstances determining between organization and suppuration of exudations . . .186 Origin and character of pus.—1. Pus-serum ; 2. Pus-corpuscles; nuclei and contents of the latter—How long a time necessary for the formation of pus—Character of true pus.—" Sterile" cells—Uses of pus—Suppuration a destructive process—When desirable . . 189 CHAPTER III. THE MUCOUS AND THE GLANDULAR SECRETIONS. Section First.—Mucus. Mucus secreted by epithelial cells alone—The membrane, as such, having no special function—Mucus varies in composition . . .194 1. Liquor Muci.—2. Mucus corpuscles, so called . . 19G Quantity secreted by mucous membranes . . 197 Its origin ....... 197 Uses of mucus ...... 198 Three varieties of mucus ..... 198 Relations of synovia to mucus . . . .198 The gastric fluid.—Description—Chemical composition—Pepsin—Acids of the gastric juice—Its origin—Quantity in twenty-four hours—Uses . 198 TABLE OF CONTENTS. XU1 PAliE Intestinal fluid.—Description—Morphological elements—Fluid constituents— its quantity—Origin—Uses ...... 200 Section Second.—The Glandular Secretions. I. Milk.—Description—Colostrum—Milk-globules—Analysis of its fluid portion—Circumstances affecting the amount of caseine—of sugar— of salts and of fat—Quantity in twenty-four hours—Origin—Uses of milk—Milk of lower animals ..... 202 II. Semen.-—Description; 1. Liquor seminis ; 2. Spermatozoids—Semi- nal granules—Recognition of semen—Origin—Uses . . 206 III. Glandular Secretions discharged into the Alimentary Canal. 1. Saliva.—Description—Its characters as obtained from the dif- ferent glands — Origin — Uses — Does not normally convert starch into sugar ...... 20? 2. Bile.—Its properties, chemical analysis, -organic constituents, mineral constituents—Biliary concretions—Its amount—Origin —Fourfold function of the bile . . . .210 3. Pancreatic fluid.—Description—Its chemical analysis—Pan- creatine—Quantity in twenty-four hours—Origin and uses . 213 4. Urine.—Description—Normal morphological elements—abnor- mal elements—Chemical analysis—Urea, uric acid, creatine, and creatinine ; its mineral constituents—Substances passing unaltered into the urine—Abnormal organic constituents of urine—Sugar normally in it during pregnancy—Quantity of urine in twenty-four hours—Its origin and uses . . 214 Urinary deposits, list of—Urinary concretions, table of— Uric acid most frequently their nucleus . . 222 5. LachrymalJluid.—Description—Origin—Uses . . .. 225 CHAPTER IV. THE CUTANEOUS SECRETIONS. I. Sebaceous secretions.—Not all precisely Identical—How modified by in- flammation—Acarus folliculorum—Analysis of sebaceous fluid—Rela- tions of the sebaceous glands to the hair follicles—Vernix caseosa— Castoreum—Their origin—Uses . . . . . . . 225 II. Perspiration.—The sweat-glands—Analysis of sweat—Gases contained in it—Amount in twenty-four hours—Origin—Uses—Effects of " check of the perspiration" explained ...... 228 THIRD DIVISION. THE TISSUES. Classification of the Tissues. CHAPTER I. EPITHELIUM, NAILS, AND HAIR. Section First.—Epithelium. Definition—Form and contents of epithelial cells—Their size—Five va- rieties of epithelium ...... 235 XIV TABLE OF CONTENTS. 1. Scaly epithelium.—x. Simple scaly—Distribution—Peculiarities, b. Compound scaly—Distribution—Peculiarities—Its modifications in the lower animals . . • • • • .2,6a 2. Conoidal epithelium.—a. Simple conoidal—Distribution—Peculiari- ties, b. Compound conoidal—Distribution . • • 241 3. Ciliated epithelium.—Cilia described, their action and uses—Distri- bution of ciliated epithelium—Peculiarities . • • 243 Development of epithelium—Its reparation—Functions of the several kinds of epithelium—Action of various agents upon . . 244 Pathological conditions of epithelium—Epithelioma—Papillomata—Epi- thelial cancer—New formations of epithelium—Peculiar appear- ances of epithelium of the tongue in disease—Fungous growths upon—Oidium albicans ...... 247 Section Second.—The Nails. Are a modification of the epidermis—Bed of the nail—Divisions of the nail itself—Its structure—Growth of nails—Time necessary for their development—Regeneration—Uses .... 249 Pathological states of the nails ...... 252 Section Third—The Hairs. Subdivisions of a hair : 1. Shaft; fibrous substance ; its color ; cuticle ; the medullary substance. 2. Hair-sac ; root-sheath ; the papilla ; chemical composition of hair; physical properties; distribution and size of the hairs; number on a given surface—Development of the hair—Periodical shedding of—Uses and physiological rela- tions of the hair—Its sudden changes in color . . . 253 Pathological developments of hair ..... 267 CHAPTER II. YELLOW FIBROUS (ELASTIC) TISSUE. Its three varieties of form—Description of—Arranged in three principal modes in the various organs—Vessels of elastic tissue—Chemical composition —Not acted upon by acetic acid—Its properties and uses—Distribution of yellow fibrous tissue—Distribution in the lower animals . . 268 Development of elastic tissue—Nuclear fibres—Growth of elastic tissue—Is not regenerated . . . . . . . . 269 Pathological new formations of elastic tissue ..... 274 CHAPTER III. WHITE FIBROUS (COLLAGENOUS) TISSUE. Description—Contains no nerves or lymphatics—Its chemical composition— Its properties and uses—Distribution—Structure of tendons and liga- ments, and fibro-cartilages — Fibrous membranes — Structure of the cornea—Contains no vessels ...... 275 Distribution of white fibrous tissue in the lower animals—Development of white fibrous tissue—Its growth and reparation . . .282 Pathological states and new formations of collagenous tissue . . 283 TABLE OF CONTENTS. XV CHAPTER IV. AREOLAR TISSUE. PAGE Distinguished from connective tissue—Description—Its two fibrous elements, and its areolae—Contents of the latter ..... 284 Chemical composition and properties of areolar tissue—Its vessels—Uses— Distribution—Peculiarities . . . . . . 2S7 The subcutaneous areolar tissue—Description—Relations to it of fat-cells . 289 Development of areolar tissue: 1. In repair by granulation; 2. In union by adhesion—Mr. Paget's experiments—Its regeneration . . 291 Pathological states and new formations—Hypertrophy—CEdema—Dropsy— Pneumatosis—Subcutaneous areolar tissue the seat of fatty tumors . 293 CHAPTER V. ADIPOSE TISSUE. Adipose or fat-cells—Their peculiarities—Contents—Intercellular connect- ive tissue—Its peculiarities in the lower animals—Its chemical compo- sition ......... 295 Distribution of adipose tissue—Peculiarities in this respect; illustrated by epitaphs ......... 299 Circumstances modifying the deposit of fat . . . . . 302 Distribution of adipose tissue in the lower animals—Use of fat as a tissue— Its development, growth, and regeneration .... 303 Pathological states and new formations of adipose tissue—Atrophy—Hyper- trophy—Adipose tumors, or lipomata—Encysted tumors—Cholesteatoma 306 Fatty degeneration, or steaiosis: 1, of bone; 2, of heart; 3, of paralyzed muscles ; 4, of kidney; 5, of liver; 6, of arteries (atheroma)—Fat abounds in encephaloid ....... 309 CHAPTER VI. CARTILAGE. Varieties: 1. Simple cellular cartilage ; 2. Compound cartilage—Descrip- tion— Cartilage cells — Intercellular homogeneous substance — Peri- chondrium ........ 313 Chemical composition of cartilage—Its properties and uses—Its develop- ment ......... 315 Pathological states and new formations of cartilage—Ulceration—Loose car- tilage, so called, in joints—Enchondroma—Atrophy—Necrosis—Fatty degeneration . . . . . . . .319 CHAPTER VII. OSSEOUS TISSUE, AND THE BONES. Section First.—Osseous Tissue. Its ultimate granules—The lacunae and pores—The vascular canals of osseous tissue—1. Cancellated bone structure; thecancelli; their XVI TABLE OF CONTENTS. contents ; 2. Compact bone structure; its general lamellae ; special lamellae—Haversian rods—Various forms of lacunae and pores— Chemical composition of osseous tissue—Its changes in pregnancy —Its changes in various diseases—Sclerosis—Osteoporosis—Rachi- tis—Softening—Caries—Properties and uses of the osseous tissue —Its distribution—Its distribution in the lower animals . . 321 Section Second.—Structure of Bones. Their bloodvessels—Lymphatics do not exist—Nerves of the bones— The marrow—Its uses—Do. in birds—Periosteum—Articular car- tilages—Synovial membranes ; are not closed sacs—Interarticular fibro-cartilages—Connection of tendons and ligaments with bones— Structure of the diarthrodial articulations—The amphiarthroses or symphyses—The synarthroses—Properties of the bones—Their uses —Their strength as columns of support .... 336 Development of Bones : 1. Cancellated bone-structure—cancelli formed by absorption ....... 350 2. Development of the compact bone-substance—Pores formed by ab- sorption—Development of secondary bones—Remarks—Weight of bone formed in a day—Fractures—Growth of bone—Its reparation 356 Pathological conditions and new formations of bone—Hypertrophy— Atrophy—Osteostearosis—Necrosis—Osteoporosis—Cancerous and tuberculous deposits in bone—New formations of bone (true ossifi- cation) ........ 365 CHAPTER VIII. DENTAL TISSUE, AND THE TEETH. Section First.—Dental Tissue. Relations of dentine, enamel, and cementum : 1. Dentine—its inter- tubular substance ; its chemical analysis; the dentinal tubuli. 2. Enamel—description of its fibres, and chemical composition. 3. Cementum—chemical analysis of. Remarks . . . 367 Section Second.—Structure of the Teeth. 1. Cortical portion. 2. Dental pulp—its vessels and nerves; the gum ; periosteum of the alveolus. Properties, uses, and development of the teeth—Time of appearance of the different teeth . . 374 Pathological states of the teeth : Exostosis ; necrosis ; caries ; teeth co- lored in jaundice—developed in abnormal situations . . 382 CHAPTER IX. MUSCULAR (CONTRACTILE) TISSUE, AND THE MUSCLES. Section First.—Muscular Tissue. 1. Contractile fibre-cells, or smooth muscular fibre: Description—Chemi- cal composition—Their distribution—Peculiarities in the uterus— Their distribution in the lower animals—Functions of the con- tractile fibre-cells—Their development—Regeneration . . 383 Pathological conditions and new formations of contractile fibre-cells : Hypertrophy—Atrophy—Fatty degeneration . . . 391 TABLE OF CONTENTS. XV11 PAGE 2. Striated muscular tissue: Description of striated fibres—A. Myolem- ma ; b. Myoline. The fibrillae—Peculiarities in the heart—Chemi- cal composition, and physical properties of striated muscular tis- sue. 1. The " muscular juice ;" 2. The musculine. Analysis of muscular substance—Color of muscular fibres—their elasticity. Distribution of striated muscular fibres—their elasticity and pecu- liar forms in the lower animals. Development of striated muscu- lar fibre—Growth—Functions of do.—Modifications of contractility of do.—Spasm—Paralysis—The rigor mortis . . . 392 Pathological conditions and new formations of striated muscular fibre: Hypertrophy—Atrophy— Stearosis—Softening—Rupture—Concre- tions—Ossification—Parasites—New formations in testis and ova- rian tumors ........ 405 Section Second.—Structure of the 2Iuscles. Divisions of fusiform muscles—Aponeurosis — Tendon — Belly—the perimysium—Connection of the tendons with muscular fibres— Connection of do. with bones—Vessels of the muscles—Nerves— their final subdivision—Peculiarities of muscular nerves in lower animals ........ 408 Accessory organs of the muscles: 1. Muscular envelops, or fasciae. 2. Ligaments of the tendons. 3. Tendinous sheaths and synovial sacs. 4. Fibro-cartilages and sesamoid bones. Physical proper- ties of the muscles—Physiological remarks—Tonicity—Sensibility —Muscular sound—Heat developed by muscular contraction . 417 Development of the muscles—Do. tendons .... 421 Pathological states of muscles and accessories—Talipes—Ganglion__ Housemaid's knee ....... 422 CHAPTER X. NERVOUS tissue, and the structure of the NERVOUS SYSTEM. Section First.— The Nervous Tissue. 1. The fibrous or tubular nerve-tissue: Various sizes of nerve-fibres ; their structural elements ; the neurilemma; 'neurine; the axis- fibre ; the medulla or pulp. Fine nerve-fibres not peculiar to the sympathetic system—Fibres of Remak—Distribution of nerve- fibres—Chemical composition of do.—Functions of do. . 423 Development of nerve-fibres : 1. Those in nerve trunks ; 2. Peripheral terminations of nerve-fibres ; 3. Nerve-fibres in the central organs; growth of nerve-fibres ...... 431 Pathological states amd new formations of nerve-fibres : Atrophy—Divi- sion of fibres—Neuroma—New formations of, in pleuritic adhe- sions, &c. ........ 433 2. Nerve-cells: Various forms — Contents — Distribution. Chemical composition and physical properties—Functions of nerve-cells— development of do. ....... 434 Pathological states and new formations of nerve-cells . . . 437 2 xvm TABLE OF CONTENTS. Section Second.—Structure of the Nervous System. 1. Structure of the nerves ...... 438 Perineurium—Bloodvessels ...... 438 a. The spinal nerves ; their roots ; ganglion-cells and ganglion- fibres—Pacinian bodies ..... 439 B. Ganglionic nerves ; their ganglion-cells and ganglion-fibres— Distribution of the latter ..... 444 c. The encephalic nerves : 1. The fifth pair; 2. The motor nerves ; 3. Those of special sensation; first pair, and optic nerve; optic chiasma. Five layers of the retina; acoustic nerve. Distribution of vestibular and cochlear branches . . 446 2. Structure of the nervous centres. a. The spinal cord; longitudinal and horizontal fibres of its white matter ; fibres of its gray substance ; various forms of cells in latter ........ 455 Do the fibres of the cord ascend to the brain ? . . .458 B. Structure of the encephalon. 1. Medulla oblongata and pons Varolii. 2. Cerebellum; its gray matter ; peculiar cells in ferruginous layer. 3. The ganglion of the cerebrum; corpora quadrigemina; optic thalami; corpora striata. 4. Cerebral hemispheres ; their white substance ; their gray matter . . . 460 The membranes and vessels of the nervous centres. 1. Pia mater; plexus choroides ; ependyma ventriculorum. 2. Arachnoid. 3. Dura mater; vessels of preceding membranes ; lymphatics of do. ; nerves of do.; vessels of encephalon and cord. Chemical composition of the nervous centres ; quantity of fat in the brain ; do. of phosphorus . . . 468 Functions of the nervous system ..... 474 Pathological states of the nervous centres . . . . 475 CHAPTER XI. THE MEMBRANES. Typical forms of papillae, villi, and glands .... 475 I. The skin. a. The corium ; its structure ; the tactile papillae . . .476 B. Basement-membrane, c. Epithelium—Epidermis, and stratum Malpighianum—their -absolute and relative thickness. Che- mical composition, and physical properties of the skin—its bloodvessels, lymphatics, and nerves—Development of the skin—Regeneration of do. . ... . . 479 Appendages and accessary organs of the skin: 1. Subcutaneous bursae mucosae; 2. Sebaceous glands—Various forms—Minute structure —Development; 3. Sweat-glands—their number—Volume__Ag- gregate length—Minute structure—Ceruminous glands . 486 Functions of the skin ...... 492 Pathological states of the skin : 1. Of the epithelium ; 2. Of the corium • 3. Of the sebaceous glands ..... 493 TABLE OF CONTENTS. XIX II. Mucous Membranes : Variety and structure—their functions . Pathological states of the mucous membranes—Atrophy—Inflammatory exudations upon—Ulceration ..... III. Serous Membranes : Structure—are closed sacs—functions IV. False Membbanes : Usually confounded with coagulated exudations— Are organized exudations, with vessels—Prone to involution—New membranes ........ PAGE 495 495 496 497 CHAPTER XII. THE VASCULAR SYSTEM. I. The Heart : The pericardium—Muscular fibres of the heart—Endocar- dium—Valves—Vessels ...... II. The Bloodvessels : a. The arteries ; 1. External coat; 2. Middle coat; 3. Inner coat—Vasa vasorum—Nerves of the vessels, b. The ca- pillaries—Walls of simple membrane merely—Capillary plexus— " Vasa serosa" do not exist, c. The veins—Structure of smallest veins—Do. of medium size—Do. of largest—Veins presenting pe- culiarity of structure—Their valves III. Lymphatic Vessels and Glands : Capillary lymphatics—the largest do Thoracic duct—Their vessels and valves Structure of lymphatic glands—Degeneration of the latter Functions of the vascular system .... Development of the heart, arteries, and veins—Do. of capillaries Pathological conditions and new formations of vessels—Atheroma in arteries—Aneurism—Varicose veins—Fatty degeneration of capil- laries ........ New formations of vessels ...... 498 500 509 510 511 511 513 513 CHAPTER XIII. STRUCTURE OF ALIMENTARY CANAL AND ITS APPENDAGES--SUBDIVISIONS OF ALIMENTARY CANAL. a. Alimentary Canal. 1. Oral cavity.—Its mucous membrane ; corium of the latter; papillae of do.; papillae of the tongue, filiform, fungiform, and circumval- late ; their uses ....... 514 Pathological appearances of the tongue ..... 51S Glands of the oral cavity; 1. Mucous; 2. Simple follicular; 3. Com- pound follicular . . • • • • .519 Salivary glands . . . . •' • • .521 II. Pharynx.—Its mucous membrane; its glands; bloodvessels, lymphatics, and nerves ........ 522 III. (Esophagus.—Its structure . • • • ■ .522 IV. Structure of the stomach; gastric glands ; peptic cells ; bloodvessels of stomach; lymphatics, and nerves ..... 523 V. Structure of the small intestine. Jejunum—Ileum—The villi; size and structure; the lacteals; function XX TABLE OF CONTENTS. 531 of the villi; glands of the small intestines; 1. Lieberkuhn's glands ; 2. Brunner's glands ; 3. Closed follicles (Peyer's glands) ; Peyer's patches . . . . • • . ozo VI. Large Intestine—its glands : 1. Lieberkuhn's; 2. Peculiar closed folli- cles ; its bloodvessels .....•■ b. Appendages to the Alimentary Canal. 1. Liver.—No distinct lobules in man; relations of vessels in its islets 532 Capsule of Glisson—portal canals ; arrangement of hepatic cells in the islets ; their connection with the hepatic ducts; sacculi of the lat- ter ; capillary network of the islets. Chemical composition of the liver; its functions ; pathological conditions ; cirrhosis; jaundice 533 2. Pancreas—its structure ; function of pancreatic fluid . . 540 CHAPTER XIV. THE URINARY APPARATUS. 1. The urethra (of the female) ; its structure ; 2. The bladder; its muscu- lar layers; its mucous membrane; 3. The ureters and pelvis of the kidney; their fibrous coat; muscular do. ; mucous membrane ; 4. Structure of the kidneys; cortical and tubular portions : 1. Tubnli uriniferi; structure and arrangement; their contorted form in the cor- tical portion. 2. Other peculiarities of the latter ; Malpighian bodies ; their number ; vessels of the kidney ; nerves ; chemical analysis of the kidney; its function; development .... 541 Pathological states of the kidney ...... 549 CHAPTER XV. THE SEXUAL ORGANS. I. Sexual Apparatus of the Male. 1. The urethra; its corpus spongiosum—Muscular layers; mucous membrane; the penis; its corpora cavernosa; muscular fibres in their trabeculae ; its arteries, lymphatics, nerves—Prostate gland ; its muscular portion, glandular portion. 2 and 3. Vesiculae semi- nales, with the ejaculatory ducts and vasa deferentia; their struc- ture. 4. The testes ; their fibrous tunic—Lobules of parenchyma —Seminiferous tubes, their contents—The spermatozoids, their movements—Ejaculatio seminis ..... 550 II. Sexual Organs of the Female. 1. The vulva; mucous membrane ; numerous papillae — Sebaceous glands—Bartholini's glands . . . . 559 2. The vagina ; muscular layer; mucous membrane ; its papillae ; hy- men ....... 3. The uterus and oviducts; their muscular layers; mucous membrane of uterus; presents no papillae ; numerous glands—Mucous mem- brane of canal of cervix uteri; its rugae and glands—Mucous mem- brane of Fallopian tubes—Round ligaments—Broad ligaments__ Uterine sinuses ..... gpo 559 TABLE OF CONTENTS. XXI PAGE Changes of the uterus at the menstrual period and in pregnancy—Do. immediately after latter . . . . . .564 4. The ovaries ; structure ; ovisac ; its membrane; its contents ; mem- brana granulosa; germinal disk; ova ; vitelline membrane ; zona pellucida ; yolk; germinal vesicle ; germinal spot—Corpus luteum of menstruation—Do. of pregnancy—Function of female genitalia —Slight sensibility of the interior of the uterus . . .565 5. The lacteal gland ; its structure—Muscular fibres in the mammilla and areola—Terminal lactiferous ducts .... 569 CHAPTER XVI. RESPIRATORY ORGANS. Air passages: 1. Nasal passages and upper portion of pharynx; structure of mucous membrane; its glands. 2. Larynx and trachea; their struc- ture ; do. of mucous membrane; its glands; ciliated epithelium; bloodvessels ; lymphatics and nerves. 3. Lungs; Bronchi and their subdivisions ; muscular fibres of do. ; their mucous membrane—The pulmonary arteries—The bronchial arteries—interlobular connective tissue—pulmonary lobules ; their structure—Connection of the terminal air-tubes with the air-cells ; structure of the latter; their number— Capillary plexus of the lobules . . . . . .572 Function of the respiratory apparatus . . . . .580 Development of the lungs . . . . . . .580 Pathological states of the lungs—Emphysema—Deposits of pigment—Red and gray hepatization—Qlldema—Fatty degeneration—Tuberculous and cancerous deposits—Gangrene ...... 581 CHAPTER XVII. BLOOD-VASCULAR GLANDS. 1. Spleen, its serous and fibrous coat; its parenchyma—The trabeculae and pulp ; cells of the latter—The Malpighian bodies ; their structure—Ves- sels of the spleen ; lymphatics ; nerves ; its function ; development . 583 2. Thyroid gland; its structure; chemical analysis ; bloodvessels; lymph- atics ; nerves; function unknown ..... 583 Pathological enlargements of thyroid body ..... 589 3". Thymus gland; structure of its lobules ; their cells and nuclei; distribu- tion of arteries ; fluid inclosed in its cavities; its involution, commenc- ing at from twelve to twenty years ; function unknown . . 590 4. Supra-renal glands: 1. Cortical portion; the cortical cylinders. 2. Me- dullary substance ; its pale cells ; bloodvessels of these organs ; their nerves very numerous ; function unknown; have no physiological con- nection with the kidney . . . . . . .592 CHAPTER XVIII. ORGANS OF THE SENSES. 1. Organ of touch ........ 594 2. Of taste ......... 594 xxii TABLE OF CONTENTS. PAGE 3. Of smell.........594 4. Of hearing; the internal ear . . . • • .594 5. Eye: I. Its membranes; sclerotic coat; choroid coat; veins of the latter; ciliary zone and nerves ; the retina ; the cornea ; the iris ; arrangement of its muscular fibres ; its color . . . . . .594 II. The humors of the eye ; the aqueous humor ; the crystalline lens; composed of tubes ; their appearance ; capsule of the lens ; the latter not vascular; uses of the lens ; its growth; is some- times regenerated ; cataract—The vitreous body ; description ; use—The conjunctiva ; the eyelids ; the tarsi; appendages of the eye . . . . . . . . 600 LIST OF ILLUSTEATIONS. Part I.—STCECHIOLOGY. FIG. PAGE ' t Chloride of sodium ...••• 2.) . 49, 50 3. Carbonate of lime ...... 51 1 Phosphate of lime ...... . 54,55 6. Ammonio-magnesian phosphate . 57 7. Stellate crystals of do. . 57 8. Foliaceous crystals of do. . 57 9. Rosette crystals of do. . 57 10. Calculus of do. 57 11. Uric acid ..... 61 12." 13. 14. • Uric acid rhombs ...... . 61, 62 15. 16. Uric acid, hourglass form ..... 62 17. Uric acid from urine ■ . 62 18. Uric acid on hair ...•••• 62 19. Uric acid on a fibrinous cast of a uriniferous tube 62 i Uric acid calculus ...... 21.) 63 22. Urate of soda ...•••• 63 23. Urate of soda calculus ....•• 63 24. Urate of ammonia ...... 64 25. Hippuric acid crystals ...... 64 26. Oxalate of lime crystals . 65 27, X Oxalate of lime ...... 28.) 65 29. Oxalate of lime. Octah. dried . 65 30* I Oxalate of lime. Dumb-bell . 31.) 65 32. Calculus of lime (mulberry) . 66 33. Calculus of lime, section . 66 34. Alternating calculus . . • • • 66 35. Creatine ...••••• 67 XXIV LIST OF ILLUSTRATIONS. FIG. 36. Creatinine 37. Urea 38. Cystine . 39. The torula cerevisiae 40. Fat-globules 41. Cholesterine 42. Glomeruli, &c. . 43. Simple fibres 44. Crystals from human blood 45. Crystals from blood of guinea-pig PAGE 68 68 69 70 73 75 78 92 103 103 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. Part II.—CYTOLOGY. Homogeneous substance of cartilage Basement membrane Simple fibres in membrana, putaminis Simple fibres in inflammatory exudation Fibre-cells becoming fibres Nuclear fibres Simple fibres, &c. Typical cells Spermatozoids Germinal spot Tubercle from peritoneum Tubercle from lung Tubercle from mesentery Glomeruli and granular cells Endogenous cell-development Endogenous cell-growth in a meliceritious tumor Segmentation of vitellus Latter stage of do. Cells from encephaloid of tongue Development of secreting cells in the caeca of glands Blood-corpuscles multiplying by division Multiplication of cartilage cells . Vertical section of cuticle of negro Pigmentum nigrum of the eye Cells between choroid and sclerotic of sheep Cells on choroid of black and of white rabbit Pigment cells of the skin of lamprey Pigment cells in the tail of a tadpole Vertical section of the skin of nose Cancer cells in a fibrous stroma, &c. Simple and compound cancer cells Melanotic cancer Free cancer nuclei Polygonal cancer cells . Caudated cancer cells LIST OF ILLUSTRATIONS. XXV FIG. SI. Fusiform cancer cells . 82. Fusiform fibres of fibro-plastio tissue 83. Two concentric cancer cells 84. Compound cancer cells . 85. Agglomerated cancer nuclei 86. Spherical fibro-plastic cells S7. Tubercle corpuscles distinguished from 88. Young epithelial cells . 89. Tessellated epithelium . 90. Buccal epithelium 91. Ciliated epithelium from air-passages THE FLULDS. 92. Cytoid corpuscles .... 93. Pus-corpuscles changed by acetic acid 94. Fibres in fibrous tumors 95. White blood-corpuscles 96. White corpuscles, various phases of . 97. Colored blood-cells .... 98. Colored blood-cells, shrivelled by chemical agents 99. Nummular arrangement of do. . 100. Development of first set of red corpuscles 101. Phases of blood-corpuscles . . 102. Development of lymph and chyle corpuscles into red corpuscles 103. Fat globules in blood .... 104. Exudation globules and nucleated fibres in pus 105. Other elements mixed with pus 106. Pus-corpuscles ..... 107. Sterile cells, with pus-corpuscles 108. Sputa of acute pneumonitis 109. Mucus-corpuscles with epithelial cells, &c. 110. Gastric peptic glands .... 111. Gastric favuli ..... 112. Intestinal follicles, &c. .... 113. Milk globules and colostrum corpuscles 114. Termination of milk ducts 115. Ultimate follicles of lacteal gland 116. Human Spermatozoids .... 117. Phases of development of spermatozoids 118. Biliary ducts and parenchymal cells of liver . 119. Isolated cells of liver .... 120. Mucus-corpuscles and epithelial cells in urine 121. Pus-corpuscles in urine 122. Colored blood-corpuscles in urine 123. Fibrinous cast of uriniferous tube 124. Fibrinous cast, and epithelial cells containing fat globules 125. Large organic globules .... 126. Small organic globules ... XXVI LIST OF ILLUSTRATIONS. FIG. 127. The torula in urine 128. Fungoid growths in the urine . 129. Sarcina ventriculi 130. Structure of kidney 131. Two Malpighian tufts and their relations 132. Uriniferous tube and its epithelial lining 133. The lachrymal gland, &c. 134. Acarus folliculorum 135. Simple sebaceous follicles of skin 136. Meibomian gland 137. Ceruminous gland 138. Sweat gland and duct . THE TISSUES. 139. Pavement epithelium from uriniferous tubes 140. Scaly epithelium of serous membrane 141. Epithelium of arteries (horse) 142. Scaly epithelium of lymphatics 143. Scaly epithelium of left ventricle (horse) 144. Scaly epithelium of left auricle (horse) 145. Membrana granulosa 146. Vertical section of epidermis . 147. Epithelial plates 148. Simple conoidal epithelium 149. Simple conoidal epithelium of Lieberkuhn's follicles 150. Simple conoidal epithelium 151. Simple conoidal epithelium (ciliated) . 152. Compound conoidal epithelium (ciliated) 153. Epithelial condylomata 154. Epithelial cancer 155. Oidium albicans 156. Transverse section of nail 157. Transverse section of nail, its body and bed 158. Relations of nail to the cuticle 159. Structure of Hair 160. Plates of fibrous substance 161. Plates of cuticle of hair 162. Epithelium of root of hair 163. Cells of medulla of rodentia . .' 164. Hair of bat and squirrel 165. Cells of inner root-sheath 166. Rudiments of hair-sac . 167. Development of hair 168. Development of second eyelashes 169. Old hair falling out . 170. First and second forms of elastic tissue 171 ) 5- Third form of elastic tissue . 172. ) LIST OF ILLUSTRATIONS. XXV11 FIG. 173. 174. 175. 176. 177. 178. 179. 180. 181. 182. 183. 184. 185. 186. 187. 188. 189. 190. 191. 192. 193. 194. 195. 196. 197. 198. 199. 200. 201. 202. 203. 204. 205. 206. 207. 208. 209. 210. 211. 212. 213. 214. 215. 216. 217. 218. 219. 220. 221. Vessels of elastic tissue Formative cells of elastic tissue White fibrous tissue Vessels of tendons The fibrous tissue in the testis Tubular interspaces of the cornea Continuity of cornea into sclerotica Vessels of the sclerotica Yellow and white fibrous tissue, in the areolar tissue The areolae of areolar tissue Vessels of areolar tissue Formative cells of white fibrous tissue in indurations Normal isolated fat-cells Polyhedral fat-cells Fat-cells and connective areolar tissue Vessels of fat-cells Crystals of margaric acid in fat-cells Crystals of spermaceti in fat-cells of whale Fat-cell, showing nucleus I Atrophy of fat-cells Structure of lipoma Structure of cholesteatoma Fatty degeneration of bone Fatty degeneration of liver Atheroma in arteries Do. advanced stage Cells from chorda dorsalis of lamprey Cellular cartilage of mouse's ear Fibro-cartilage . Reticulated cartilage Groups of ceils in cartilage-cavities Vessels of articular cartilage (foetus) Do. do. after birth y Enchondroma. External structure . Do. Internal structure Ultimate granules of bone-tissue Lacunae and pores of bone Termination of pores on the surface of bone Vessels in the substance of the osseous tissue Spherical cancellus Structure of the cancelli while developing The general (fundamental) lamellae of bone Radiation of pores from the Haversian canals Various forms of lacunae and pores Interstitial osseous substance . Fibres of osteine in bone acted on by acid &c. PAGE 273 273 275 278 279 280 2S1 281 285 286 287 292 296 296 297 297 298 304 305 307 308 309 309 311 312 312 313 313 314 314 317 318 318 319 320 321 322 323 325 326 327 329 330 331 331 333 XXV111 LIST OF ILLUSTRATIONS. FIG. 222. Section of articular cartilage .... 223. Section of joint showing synovial membrane . 224. Union of bone and tendon .... 225. Linear arrangement of cartilage-cells in developing bone 226. Processes of new bone projecting between rows of cartilage cells 227. Formation of interrupted laminae 228. Vertical section of sub-periosteal layer of developing bone 229. Development of secondary bones 230. Relations of the dentine, enamel and cementum of a tooth 231. Tubes and intertubular substance of dentine . 232. The divisions of the dental tubuli, and the granular layer 233. The dentinal globules ..... 234. Transverse striae of enamel-fibres, and external surface (showing their hexagonal ends) .... 235. Transverse striae of young enamel-fibres, acted on by hydrochloric acid ....... 236. The cementum of old teeth, containing Haversian canals 237. The four stages of development of the teeth . . • 238. The closed sac in which the enamel is formed 239. The dental pulp, enamel-sac, and development of enamel 240. Cells with prolonged filaments forming the dentine 241. Transformation of enamel-pulp into enamel-fibres 242. Non-striated muscular fibres as usually described 243. Contractile fibre-cells (smooth muscular fibres) 244. Contractile fibre-cells in walls of the bloodvessels 245. Colossal contractile fibre-cell from impregnated uterus 246. Contractile fibre-cell with fringed margin 247. Minute vessels of smooth muscular tissue 248. Contractile fibre-cells in uterus three weeks after parturition 249. Hypertrophy of smooth muscular fibres of stomach . 250. Striated muscular fibres and fibrillae . 251. The myolemma of striated fibres 252. Anastomosing muscular fibres of human heart 253. Development of striated muscular fibres 254. Development, and effects of acetic acid 255. Contracted state of striated muscular fibre 256. Contracted state showing muscular fluid beneath myolemma 257. Hypertrophy of striated muscular fibres of the heart 258. Atrophy of striated muscular fibres of the heart 259. Fatty degeneration of muscular fibres of the heart 260. The three subdivisions of fusiform muscles 261. Transverse section of a tendon 262. Transverse section, showing elastic fibres 263. Section of muscle, showing internal and external perimysium 264. Union of muscular fibres with tendon 265. Union of muscular fibres at an acute angle 266. Minute vessels of the muscles .... 267. Minute vessels in the internal perimysia 268. Nerves of the muscles . .' . LIST OF ILLUSTRATIONS. XXIX FIG. 269. Divisions of the nerve-fibres in muscles 270. Multiple subdivisions of nerve-fibres in muscle of frog 271. Development of the tendons 272. Various sizes of nerve-fibres 273. The neurilemma and neurine of nerve-fibres 274. The axis-fibre of a nerve-fibre or tube 275. Changes in the medulla by various agents 276. Fibres of Remak 277. Development of nerve-fibres 278. Development of nerve-fibres at their peripheral extremities 279. Various forms of nerve-cells 280. Branching multipolar nerve-cells 281. Perineurium of ischiatic nerve 282. Anterior and posterior roots of spinal nerves, &c 283. Structure of ganglion on posterior root of spinal nerves 284. Ganglion-cells and their nucleated capsules 285. Ganglion-cells continuous with nerve-fibres 286. Pacinian bodies 287. Minute structure of Pacinian bodies 288. Structure of sympathetic ganglia 289. Ganglion-cells of sympathetic ganglia 290. Branches of olfactory nerve 291. Fibres of the olfactory nerve . 292. Distribution of olfactory nerves to the septum 293. The optic chiasma 294. Nerve-fibres of the optic nerve 295. Section of the retina, showing its five layers 296. Branched nerve-cells in gray layer of retina 297. Capillaries of gray layer 298. The rods and cones of the bacillar layer 299. Bacillar layer seenfrom without 300. Plexiform arrangement of cochlear nerve 301. Bipolar ganglion cells interrupting the cochlear nerve-fibres 302. Transverse section of spinal cord 303. Course of nerve-fibres in spinal cord . 304. Nerve-cells of central gray matter of the cord 305. Transverse section of medulla oblongata 306. Anterior view of medulla oblongata 307. Posterior view of medulla oblongata . 308. Cells of gray matter of cerebellum 309. Ganglia of the cerebrum 310. Nerve-cells of gray matter of the convolutions of cerebrum 311. Fine nerve-fibres of superficial white layer of cerebrum 312. The ependyma ventriculorum . 313. Minute vessels of the white and the gray cerebral substance 314. Divisions of terminal arteries on entering convolutions 315. Typical forms of cutaneous papillae and intestinal villi 316. Typical forms of simple and compound glands 317. Vertical section of the skin .... XXX lis't of illustrations. inner coat of arteries FIG. 318. Simple papillae of the palm 319. Compound papillae of surface of hand 320. Section of the epidermis 321. Under surface of the epidermis 322. Capillaries of the papillae 323. Nerves of papillae and axile corpuscles 324. Forms of sebaceous glands 325. Sebaceous glands of the nose . 326. Minute structure of sebaceous glands 327. Structure of the glandular coil of the sweat glands 328. Structure of excretory duct of coil of the sweat glands 329. Sebaceous and ceruminous glands 330. Anastomosing muscular fibres of heart 331. Elastic layer of semilunar valves 332. Section of artery showing three coats 333. Middle and inner coat of arteries 334. Internal elastic (fenestrated) layer of 335. External portion of fibrous layer 336. Epithelial cells of aorta 337. Structure of capillaries 338. Section of vein, showing three coats 339. Capillary lymphatics . 340. Section of walls of thoracic duct 341. Structure of lymphatics and lymphatic 342. Development of capillaries 343. Fatty degeneration of minute arteries 344. Filiform papillae of tongue 345. Nerves of filiform papillae 346. Fungiform papillae 347. Papilla circumvallata . 348. Racemose mucous glands of mouth 349. Simple follicular glands of mouth 350. Compound follicular glands (tonsil) 351. Section of walls of stomach, showing glands 352. Compound peptic and mucous glands . 553. Minute vessels of mucous membrane of large intestine 354. Section of wall of small intestine, showing villi 355. Minute vessels of villi, and Lieberkuhn's follicles 356. Villi with the contained lacteals 357. Structure of follicles of Lieberkiihn 358. Minute vessels of mucous follicles 359. Section of wall of small intestine and closed follicles 360. A solitary closed follicle with villi : 361. Peyer's patches with openings of follicles 362. Solitary closed follicles of large intestine 363. Section of hepatic lobules showing vessels 364. Transverse section of a portal canal 365. Human hepatic cells .... 366. Network of hepatic ducts glands and capillaries PAGE 478 478 479 481 483 4S4 486 487 488 490 491 492 499 499 500 501 502 502 503 504 507 509 510 510 512 513 516 517 517 518 519 520 521 524 525 526 526 527 527 529 529 530 530 531 531 532 533 533 534 LIST OF ILLUSTRATIONS. XXXI FIG. PAGE 367. Network of hepatic ducts, magnified .... 534 368. Hepatic islets with their radiating cells 535 369. The hepatic cells within tubes of simple membrane . 535 370. Communication of interlobular ducts with preceding 536 371. Narrowest portion of bile-duct, and its epithelium 537 372. Terminal portion of bile-duct, and its epithelium 537 373. Simple pouches of hepatic ducts .... 538 374. Compound pouches of hepatic ducts .... 538 375. Section of kidney, showing uriniferous tubes . 544 376. Stroma between tubes of kidney .... 545 377. Relations of Malpighian body to arteries and tubes of kidney 546 378. Minute vessels of kidney, and of Malpighian bodies . 547 379. Cast of a tubulus uriniferus ..... 549 380. Littre's glands from the/fossa Morgagnii 551 3S1. Minute arteries of corpus cavernosum penis . 552 3S2. Structure of vesiculae seminales .... 554 383. Arrangement of seminiferous tubes . 555 384. Caecal extremities of seminiferous tubes 555 385. Structure of the testis ...... 556 386. Structure of a spermatic tube ..... 557 387. Spermatophori and spermatozoids .... 558 388. Uterine mucous membrane soon after conception 561 3S9. Papillae of vagina and cervix uteri . . 562 390. Rugae of cervix uteri ...... 562 391. Rugae of cervix uteri, magnified .... 563 392. Section of a Graafian vesicle (ovisac) .... 566 393. Structure of the human ovum ..... 567 394. Ovary containing corpora lutea . 568 395. Corpora lutea of pregnancy 568 396. Structure of lacteal gland ..... 570 397. Smallest lobules of lacteal gland .... 570 398. Terminal caeca of lacteal gland .... 571 399. Lacteal gland of new-born infant .... 571 400. Ciliated epithelium of nasal passages .... 572 401. Smooth muscular fibre in bronchi .... 576 402. Lobular passages, and infundibula of lungs 577 403. Air-cells opening into the infundibula 577 404. Air-cells opening into the infundibula, seen in section 578 405. Structure of walls of air-cells ..... 578 406. Capillary plexus of the air-cells .... 579 407. Capillary plexus of small bronchial tubes 579 408. Tubercles in the air-cells ..... 581 409. Cretaceous transformation of tubercle .... 581 410. Peculiar fusiform fibres in the spleen .... 583 411. Cells, &c, of the pulp of the spleen .... 584 412. Malpighian bodies of the spleen .... 585 413. Structure of Malpighian bodies of the spleen . 586 414. Connection of a Malpighian body with the surrounding vessels 587 415. Structure of thyroid gland ..... 588 XXX11 LIST OF ILLUSTRATIONS. FIG. 416. Thyroid gland, vesicles filled with colloid 417. Structure of thymus gland 418. Minute vessels of thymus gland 419. Section of supra-renal gland 420. Cortical cylinders of supra-renal gland 421. Section of external, middle, and internal ear . 422. Membranous semicircular canals, &c. . 423. Termination of vestibular nerves 424. The labyrinth, laid open 425. Relations of labyrinth to external and middle ear 426. Section of the eyeball .... 427. Sclerotic and choroid coat of the eye . 428. The ciliary muscle and the chambers of the eye 429. Capillaries of the choroid coat 430. Ciliary processes of the choroid 431. Relations of crystalline lens and vitreous body 432. Cells and tubes of crystalline lens 433. Structure of tubes of crystalline lens . 434. The " star" of the crystalline lens HUMAN HISTOLOGY. GENERAL REMARKS. The human body, when fully developed, is composed of solids and fluids, in the proportion of one of the former by weight to at least eight or ten of the latter.1 All the solids are permeated to a greater or less extent by the fluids, of which, also, water is always the principal constituent. The mere descriptive anatomist regards the solids alone, as if isolated from the fluids which form an essen- tial part of them. But the chemical physiologist and the histologist must study the latter as well as the former. The isolated fluids, also, as the blood, chyle, milk, and other secretions, come within the domain of histology so far as they contain cells, granules, nu- clei, or other histological elements; and these, therefore, as well as the tissues, will be embraced in this work. Commencing, however, with an analysis of the human body as seen by the unaided eye, and omitting for the present the isolated fluids, we find that it is composed— 1. Of parts and organs. 2. That the organs are formed of combinations of tissues. 3. The tissues are composed of certain chemical compounds called immediate principles. 4. And the last are formed by a direct combination of a few of the simple chemical elements. Reversing this view, we perceive that— 1. The simple elements unite to form the immediate principles. 2. The last unite to form the tissues. 1 A mummy of a native of Teneriffe, presented to Blumenbach by Sir Joseph Banks, weighed but seven pounds and a half; probably not more than one-sixteenth of the weight of the same body during life. 3 31 GENERAL REMARKS. ' 3. And the tissues, separately and in combination, constitute the parts and organs of which the body consists. This work will, accordingly, consist of two parts— Part I., containing an account of the simple elements, and of the immediate principles of the tissues and the fluids, or Stcechiology. Part II., giving a description of all the tissues, and the fluids con- taining histological elements, or Histology. PART I. STCECHIOLOGY Stcechiology1 comprises the classification and description of the simple chemical elements, and of the immediate principles which enter into the composition of the tissues and fluids of which the human body is composed. FIRST DIVISION. THE SIMPLE CHEMICAL ELEMENTS ENTERING INTO THE STRUCTURE OF THE HUMAN BODY. Of the sixty-five simple bodies now (18572) known to chemists, it is not certain that more than fifteen are normal constituents of the human body. These are— 1. Oxygen. 6. Phosphorus. 11. Chlorine. 2. Hydrogen. 7. Calcium. 12. Fluorine. 3. Carbon. 8. Magnesium. 13. Silicum. 4. Nitrogen. 9. Sodium. 14. Iron. 5. Sulphur. 10. Potassium. 15. Manganesium. M. Millon announced that copper and lead also normally exist in the blood-corpuscles of man, and Orfila added arsenic as entering into the composition of the tissues. These observations have, how- 1 From i-rci^siov, an element, and Xoyo;, description. 2 Two or three others have just been announced, but their discovery has not been confirmed. 36 SIMPLE chemical elements. ever, not been confirmed; and either of these three substances, found in the human organism, must be regarded as accidentally present. Iodine and bromine enter into the composition of the lowest marine animals; but it is not yet proved, nor probable, that they normally form a part of the human body, though such an assertion has been made. The fifteen elements just mentioned unite variously to form the immediate principles of the tissues hereafter to be considered. The following is, however, a general account of the parts and the fluids in which each is found:— 1-4. The first four elements are found in all the tissues, and most of the fluids, except fat; the first three in all tissues and fluids, without exception. Of the first two water is constituted; whose abundance in the human organism has already been alluded to. 5, 6. Sulphur and phosphorus exist in the albuminous group of immediate principles (albumen, fibrine, &c), and in the tissues formed from them, and all animal cells. They also enter largely into the composition of the brain—about T45 of its weight being phospho- rus. { Von Bibra.) Sulphur is a constituent of hair and nails, which accounts for their odor during combustion. Both the sulphuric and the phosphoric acids exist in the urine, and the latter in bones also, in. combination Avith lime and magnesia. Treviramis believed that spontaneous combustion of the human body may be due to an ex- cess of phosphorus in it. 7, 8. Calcium and magnesium are found only in the state of oxides, i.e. as lime and magnesia; and combined with acids to form salts. The phosphate of lime constitutes about one-half the weight of human bone, and the carbonate about one-tenth; the phosphate of magnesia amounts to the one-hundredth part. Both these ele- ments also exist in milk, and other fluids. 9. Sodium, in combination with chlorine—i. e. forming common salt—exists in every solid and fluid in the body. In all other cases it is in the form of an oxide (soda), and, in combination with acids forms various salts in the different tissues and fluids. 10. Potassium also unites with chlorine to form the chloride of potassium, the latter being abundant in muscular tissue. Otherwise it is in the oxide state—potassa—and in combination with acids. It however, exists but sparingly in animals, in comparison with soda, while it abounds in plants. 11. Chlorine combines with hydrogen to form the hydrochloric REMARKS. 37 acid in the gastric fluid. In all other cases it is found as chloride of sodium (common salt), or of potassium. 12. Fluorine is combined with calcium, in small amount, in bones. 13. Silicum exists, oxidized (as silica), in small quantity in the hair, in wool and feathers, and in the urine. It abounds in plants. 14. Iron constitutes about ^^^ part, by weight, of the blood; it also exists in hair, muscle, milk, pigment-cells, and (a mere trace) in the gastric fluid. Iron always exists, also, in the feces, since solid and fluid articles of food contain more of it than is required in the organism. 15. The oxide of manganese is found in bone {Kane), and, some say, in the coloring matter of the hair. It is separated from the organism in the bile. RemarTcs.—1. Our food (and drink) must contain at least the fif- teen elements just specified, in order to secure and maintain the development of the body. No single article of food, except milk and eggs, perhaps, contains them all, and hence the necessity for variety of aliment. 2. The absurdity of the idea of some, that minerals should never be used as remedies, is at once apparent. Ten of the fifteen simple elements are minerals, and the rest, also, all enter into the compo- sition of various mineral substances. We must, therefore, take minerals in all our food, and this whether the latter be animal or vegetable; for all vegetable as well as animal tissues contain mine- ral substances. 3. Nor is the notion that no minerals except such as form a part of the body should be used as medicines, any more tenable, for the same objection would hold against all vegetable remedies, since not one of them (opium, lobelia, &c.) naturally enters into the compo- sition of the body; and thus the sole remedies remaining would be the fifteen elements above named; for if it be said that the active principles of vegetables, as morphia, quinia, &c, contain only the elements above mentioned (e. g. the four first mentioned), yet it is true that some of these compounds, as strychnia, hydrocyanic acid, &c, are more dangerous and destructive to animal life than any mineral substance known. SECOND DIVISION. THE IMMEDIATE PRINCIPLES OF WHICH THE TISSUES OF THE HUMAN BODY ARE COMPOSED. The immediate principles of the tissues, are the "last bodies con- stituting the organism to which the tissues can be reduced by mere anatomical analysis; and which admit of no further subdivision without chemical decomposition."1 Sugar, gum, starch, cellulose, water, &c, are immediate principles to a plant; and water, albu- men, fat, urea, &c, to an animal. The carbon, oxygen, hydrogen, &c, composing these are the simple elements, or the elementary (or mediate) principles of the plant, or the animal, respectively. The expression, " immediate principles," is borrowed from Chev- reul, who thus defends its use: "Some scientific writers think this expression objectionable, since it is not reasonable to apply the word principle to compound bodies. I do not participate in this opinion. For when we consider in a general way the composition of a salt, as established by Lavoisier, it is apparent that it is constituted by the union of an acid and an alkali, rather than by the elements of the acid with those of the alkali, since if these ele- ments are united in other proportions than such as constitute an acid and an alkaline body, they no longer give us the idea of a salt. Hence it seems proper to say that the acid and the alkali are the two immediate principles of the salts. It is the same with suo-ar, starch, gum, lignine, &c, in respect to a plant, and with fibrine, albumen, &c, in respect to an animal. These substances should be regarded as the immediate principles of the plant or of the animal to which they belong, while oxygen, nitrogen, carbon, and hydrogen 1 Robin and Verdeil's Anatomical and Physiological Chemistry; 3 vols. p. 1887 with, an Atlas. For an extended review of this work, and many of the facts intro- duced into this division, see the American Medical Monthly, for March 1855. CLASSIFICATION. 39 are their remote or elementary principles^1 It will appear that the three gases just mentioned are, however, also immediate principles in certain circumstances. Thus the study of the immediate principles of organized bodies is intermediate between mere organic chemistry on the one hand, and histology on the other, and must precede the latter. CLASSIFICATION OF THE IMMEDIATE PRINCIPLES IN THE HUMAN BODY. The number2 of immediate principles in the human body is not precisely determined; but the following classification, embracing 84, may be for the present adopted. These 84 substances, being all compound except oxygen, hydro- gen, and nitrogen, are divided into two groups:— I. The first group includes those principles which are crystal- lizable or volatile, without decomposition. These are di- vided into two classes:— 1st. Principles of mineral origin, 24 in number. 2d. Principles formed within the body by dis-assimila- tion,3 and therefore of organic origin, 42 in number. II. The second group includes those which are not crystalliza- ble, or not volatile, except in consequence of decomposition; only 18 in number. This group is not divided, and con-, stitutes the third class, organic substances. The three classes are divided as follows:— A. Of the first class—principles of mineral origin—there are two divisions. 1st. Gaseous or liquid, and not saline bodies, 5 in number. 2d. Saline bodies (salts), 19 in number. B. The second class—principles of organic origin—has four divisions:— 1st. Acid or saline principles, 23 in number. 2d. Neutral nitrogenized compounds, generally called nitrogenized alkaloids, 4 in number. 3d. Neutral non-nitrogenized compounds or sugars, 2 in number. 1 Recherches Chimiques sur les corps gras d'origine animale. Paris, 1823, p. 4-5. 2 Robin and Verdeil reckon 92 immediate principles in man and the mammiferce. 3 This word implies the same as the terms " waste" or " metamorphosis" of the tissues. 40 IMMEDIATE PRINCIPLES OF THE TISSUES. 4th. Fatty and saponaceous compounds, 13 in number. C. The third class—organic substances—has three divisions:— 1st. Substances naturally in a liquid state (7). 2d. Those naturally solid or demisolid (7). 3d. Pigmentary substances, also solid or demisolid (4). The following table indicates the particular compounds included in each of the classes and divisions just mentioned. Tabular Classification of the Immediate Principles. Group I.—Principles crystallizable or volatile, independ- ently OF DECOMPOSITION. First Class.—PRINCIPLES OF MINERAL ORIGIN (24). First Division. Gaseous and not Saline (5). Oxygen, Carbonic acid Hydrogen, Water. Nitrogen, Second Division. Salts (19). Chloride of Sodium, Sulphate of Soda, " Potassium, " Lime, Fluoride of Calcium, Basic Phosphate of Lime (Bones), Hydrochlorate of Ammonia, Acid Phosphate " Carbonate of Lime, Phosphate of Magnesia, Neutral Phosphate of Soda, Potassa, Acid " " " Soda, Phosphate of Potassa, Bicarbonate " Ammonio-Magnesian Phosphate. Sulphate of Potassa, Second Class.—PRINCIPLES OF ORGANIC ORIGIN FORMED WITHIN THE BODY BY DIS-ASSIMILATION (42). First Division. Acid or Saline Principles (23). Lactic Acid, Hippuric Acid, Lactate of Soda, Hippurate of Lime, " Potassa, " Soda, " Lime, " Potassa, Oxalate of Lime, Inosate of Potassa, Uric Acid, Pneumic Acid, Neutral Urate of Soda, Pneumate of Soda, Acid " " Taurocholate " Urate of Potassa, Hyocholinate " " Magnesia, , Glycocholate " " Lime, Lithofellic Acid. " Ammonia, TABULAR CLASSIFICATION. 41 Second Division. Neutral Nitrogenized Compounds (5). (Nitrogenized Alkaloids.) Creatine, Urea (and Chloro-sodate of Urea— Creatinine, Urea with marine salt), Cystine. Third Division. Neutral Non-nitrogenized Compounds. Sugars (2). Sugar from the Liver, Sugar of Milk. Fourth Division. Fatty and Saponaceous Compounds (13). Cholesterine, Caproate of Potass., Soda, &c, Oleic Acid, Oleine, Margaric Acid, Margarine, Stearic " Stearine, Oleate of Soda, Elaterine, Margarate " Stearerine. Stearate " Group II.—Principles non-crystallizable or non-volatile, INDEPENDENTLY OF DECOMPOSITION. Third Class.—ORGANIC SUBSTANCES, OR COAGULABLE PRINCIPLES (18). First Division. Those naturally Liquid (7). Fibrine, Pancreatine, Albumen, Mucosine, Albuminose, Ptyaline. Caseine, Second Division. The Solid and Demi-solid (7). Globuline, Cartilageine, Crystalline, Osteine, Musculine, Keratine. Elasticine, Third Division. Pigmentary Substances (4). Hsematine, or Haematosine, Melanine, Biliverdine, Urrosacine. In addition to the preceding, may be mentioned1— I. Certain immediate principles of probable or certain existence, though not well determined. 1. Of the first class—Silex, in hair, &c, p. 37. 2. Of the second class—Acetate of soda, leucine, xanthine, hypo- xanthine, lienine, two acids peculiar to human urine, haematoidine, butyrine, butyroline, phosphorized fatty matters of the brain, cere- bric acid, and cerebrate of soda. 3. Of the third class, the following are probable: Neurine, syno- 1 Robin and Verdeil, vol. iii. pp. 415 to 573. 42 IMMEDIATE PRINCIPLES OF THE TISSUES. vine, lachrymine, spermatine, organic substance peculiar to dropsi- cal effusions, paralbumine, pyine. II. Substances known to exist, but doubtful as immediate principles. 1. Of the first class; ammonio-sodaic phosphate; phosphate of ammonia ; ditto of iron ; chloride of calcium, of magnesium, and of iron ; arseniate of lime. 2. Of the second class ; tartrate of iron: benzoic acid, and ben- zoates of soda, potassa, lime, and ammonia; glycocol; hippurate and lactate of ammonia ; succinate of soda ; urostealite, xanthocys- tine, urate of iron, sulphocyanuret of potassium, and of sodium; formic acid; a peculiar crystallized principle in semen; butyric acid; uroglaucine; inosite. 3. Of the third class ; phymatine ; hydatidine; animal substance of calculi; fibralbumine ; cyanurine; melanurine ; coloring matter of blue suppurations. III. Certain simple bodies whose actual state of combination is unknown, or not generally indicated: iron, copper, lead, manganese, arsenic, sulphur, and the carbon of the lungs. These are also termed medicinal principles. IY. Certain natural and artificial chemical compounds which are not immediate principles. And V. Substances called immediate principles; but which either do not exist at all, or do so as mixtures or products of chemical changes.1 First Group. CLASS FIRST. IMMEDIATE PRINCIPLES OF MINERAL ORIGIN. All these principles have a definite chemical composition, the formula for which will be given with the rapid description of each of them which follows. 1 For these two lists, see Am. Med. Monthly for March, 1855. OXYGEN—HYDROGEN. 43 FIRST DIVISION. The gaseous or liquid immediate principles, and those which are not saline. 1. Oxygen. (0.) Oxygen is to be regarded as an immediate principle only when existing in a free state in the body, as in venous and arterial blood, in the air-cells and bronchial tubes, and sometimes in the stomach. The whole amount of free oxygen in the body averages about 77f- grains, and in the blood alone 61 grains. There are about 9| cubic inches of oxygen in the arterial blood, and 14^ inches in the venous. But the proportional amount is greater in the former than in the latter, in the ratio of 2.41 to 1, and sometimes even of 3 to 1.17; since there is but two-thirds as much blood in the arterial system as in the venous. {Robin and Verdeil.) Oxygen exists in the blood in a liquid state (in a state of solution), and.probably mostly in the corpuscles alone. The amount of oxygen received into the lungs of an inhabitant of Potosi, 13,000 feet above the level of the sea, however, equals only two-thirds of that consumed by an inhabitant of a maritime city. The theory of Liebig, adopted by French and German chemists generally, that in the case of the higher animals the oxygen consumed in respiration is destined to combine finally with the tissues and the calorific (respiratory) elements of the food (starch, sugar, fats, &c), thus forming carbonic acid, water, &c, for the purpose of producing and maintaining the animal heat, is evidently too narrow a view of this subject. Heat is the result of nutritive changes of all kinds, but not the direct object of them. It is in its action on the tissues of the body, as a vital stimulus, that the prime importance of oxy- gen consists; though the incidental development of heat, as above stated, is indispensable to the organism. The quantity of oxygen consumed in a year by an adult male is about 800 pounds. 2. Hydrogen. (H.) Free hydrogen exists normally in the stomach, colon, and caecum, forming, of all the contained gases, 3.55 per cent, in the first organ, from 5.4 to 11.6 per cent, in the colon, and 7.5 in the caecum. This • 44 IMMEDIATE PRINCIPLES OF THE TISSUES. gas is formed in the alimentary canal; but precisely how, is not ascertained. There is also a very small quantity of it in the gases expired in normal respiration. None has, however, yet been found in the blood, though the last fact might lead us to expect to find it there.1 3. Nitrogen. (N.) Free nitrogen is found in the air-cells of the lungs, in the blood, and the intestinal gases, both healthy and morbid. The whole amount in the lungs and the blood varies from 46.755 to 47.52 grains. In the blood it is dissolved and in a fluid state. It consti- tutes from one-tenth to one-sixth of all the gases in this fluid, and is more abundant in the arterial than in the venous blood (as 1.51 to 1). Animals suffering from emaciation inhale more nitrogen from the atmosphere than they return to it by expiration. 4. Carbonic Acid. (C0.2) This gas exists in the lungs, the alimentary canal, the blood, and the urine,2 it being in the two latter in a state of solution. The amount in the blood would, in its gaseous state, occupy from one- fifth to one-third of the space actually filled by the whole mass of blood. It is dissolved in both the serum of the blood and the cor- puscles, there being more in arterial than in venous blood (R. and V.), as is the case with oxygen and nitrogen. Oxygen is, however, dissolved principally in the corpuscles, as has been seen. The greater amount of carbonic acid gas in the arterial blood confirms the idea that it is set free in the lungs from the carbonates in the blood by the action upon the latter of pneumonic acid. (Robin and Verdeil.) That it is originally formed, however, by the action of 1 Carburetted and sulphuretted hydrogen are also included among the immediate principles by Robin and Verdeil. They are here omitted, since they are found only in the air-passages and the large intestine, and appear to be evolved in consequence of some abnormal chemical process. In the intestine the sulphuretted hydrogen is always in smaller quantity than the other gases. It is formed in the alimentary canal; but precisely how, is not ascertained. It is also disengaged from abscesses near a mucous membrane (e. g. near the anus), or by putrefaction of pus or of or- ganized tissue. Abscesses on the limbs, under the deltoid, or in the kidneys, have also been known to disengage it. 2 "All the tissues in the body contain a small quantity of dissolved gases, and carbonic acid can be detected in all the animal fluids, &c."—Todd and Bowman p. 730, Am. ed. WATER. 45 oxygen upon the tissues and the calorific elements of the food, may be regarded as established; and to prevent an undue accumulation of it in the blood from these sources is the principal object of the aerating process. 5. Protoxide of Hydrogen— Water. (HO.) Water enters into the composition of every, fluid and every tissue, however solid (even enamel), in the body, uniting in true binary combination, and forming one of its essential constituent parts. It is, therefore, one of the most important of the immediate principles, and exists in far greater amount than all the rest to- gether. The cubical mass of the human body is calculated by Eobin and Verdeil as varying from 62 to 70 litres1 in the male, and from 46 to 53 in the female—equal in the former to a cube 16 to 16.4 inches on a side. Of the preceding quantity, at least 42 or 43 litres are water, which equals a cubic mass 14.4 to 15.2 inches on a side. Thus nearly three-fourths of the body is water. Burdach estimated the water at two-thirds of its weight. Of course the proportion is still greater in infancy and childhood. A table is given by the authors just mentioned,2 showing the proportional amount of water in each fluid, and in each tissue and organ, in the body. With the exception of enamel, dried cuticle, teeth, bones, tendons, and elastic tissue, there is no tissue which is not more than one-half water. Enamel is only -g^ water (Senac); the substance of the testis, j8^ water. The human brain is T708090- water. (Denis.) But no tissue or fluid in the body has always pre- cisely the same amount of water, or of any other immediate principle. It varies constantly, though within narrow limits, from one-tenth to three-tenths, and the mean only is given in the table alluded to. But the other immediate principles vary with the variations in the water. Hence the error of those who would find the cause of diseases in one tissue or fluid alone, or who would cure them by the administration of water alone, or of any other immediate principle exclusively. In all the tissues and organs just mentioned, in which less than one-half is water, and in many cases where the water constitutes TYa (muscle) to T8D50 (cortical substance of calf's brain) of the whole, 1 A litre is very nearly a quart in measure. ' Op. cit., pp. 115-118. 46 IMMEDIATE PRINCIPLES OF THE TISSUES. the water is in a solid state, and entirely different from any condition in which it is found in the mineral kingdom. Hence muscle has more consistence than blood, and the cortical substance of the brain more than synovia; though these two fluids have less water than the solids compared with them. This water is, therefore, in chemical combination in the tissues, and not interposed between their elements. In the fluids the water is, of course, in a fluid state, and here holds solids in solution. In a single instance only—the halitus from the lungs—is the water in a gaseous state. Mere solution is chemical combination, but the feeblest known. Water combining with a solid in less amount than sufficient to dis- solve, is fixed in it, itself becoming solid; in increased quantity, it dissolves the other substance, that, on the other hand, becoming fluid. The organic substances (osteine, musculine, &c.) have the pe- culiar property of fixing an amount of water of far greater volume and weight than themselves, while they still remain, and also render the water demi-solid. Organs formed principally of these substances, however (and hence containing much water, as explained), alone live independently and on their own account—alone present the double vital phenomenon of composition and decomposition. But it is not, however, merely pure water—the mere protoxide of hydrogen—that is fixed and solidified by albumen, gelatine, &c, but a saline solution instead. Hence they swell when immersed in pure water, since an additional amount of the latter is thus gene- rally fixed. The muscle of the calf contains more water than that of the ox; but an equal weight of human bone (separate from the marrow), whether from the infant or the adult, contains the same amount of it. Tables are given of the diseases in which the blood contains an abnormal amount of water, whether in excess or diminution. Since, however, the blood is, in almost all cases, taken from the arm alone, while that of the vena portae, of the hepatic veins, and of the renal veins, is different, and cannot be examined in man, we need further investigation in regard to the blood in these latter vessels, in case of diseased animals, that we may thus infer its condition in the same vessels in cases of disease in the human body. Whence comes the water in the body?—for it both enters and leaves the body already formed, i. e. as protoxide of hydrogen. The water in the ovum and in the embryo during development is SALTS. 47 obtained from the body of the mother, first by imbibition from the mucus of the Fallopian tube by the vitelline membrane, then by the villi of the chorion, and when these become vascular, after the de- velopment of the allantois, they derive it from the mother's blood till birth. Subsequently it enters the blood from the alimentary canal, having entered the latter with the food, or as a beverage; accidentally entering, also (as in bathing), by the skin. The aggre- gate amount of water consumed as drink by an adult male in a year is about 1,500 pounds. M. Barral finds that more water leaves the body than enters it, and maintains that the surplus is formed in the body by the combination with hydrogen of the oxygen in the in- spired air, and the excess of oxygen over the hydrogen in our ali- ment. Uses of Water in the Body.—It gives to organic substances their mechanical properties, to fluids their fluidity, to demi-solid sub- stances their elasticity and particular consistence; and different properties to the hard parts—to cartilage its flexibility, to bone its tenacity. But in the last the water is more intimately united, and being once separated, will not unite again. Water gives to all parts the possibility of manifesting their chemical properties also, and hence that instability characteristic of organized tissues, and the constant acts of combination and decomposition. But it also, with these advantages, confers the liability to sudden changes in the blood, or in the organs, from putrid, purulent, or mephitic infec- tions, facilitates the transmission of poisons, procures the aptitude to decomposition, and hence, in many cases, induces sudden death.1 The water makes its exit from the body by the kidneys and the skin, in the feces, and from the pulmonary mucous membrane. About 1,900 pounds escape annually through these outlets, the urine alone containing 900 pounds. The fact that 400 pounds more of water are excreted than are ingested as drink is accounted for, in part, by M. Barral, as already stated; while it must be recollected that our food, also, always contains more or less water. SECOND DIVISION. The Saline Principles—Salts. (19.) The salts contained in each tissue are represented by the ashes resulting from its combustion pretty nearly, but not precisely, since 1 Robin and Verdeil. 48 IMMEDIATE PRINCIPLES OF THE TISSUES. the carbonic acid of the carbonates is set free by too elevated a tem- perature, and then merely the base remains in the ashes. Salts enter into the composition of every organized tissue, though sometimes in the slightest degree. The salts in the fluids and tissues are merely dissolved^ in water; on being dissolved, they then serve as solvents for other immediate principles—e. g. solutions of salts with alkaline bases (soda ^ and potassa) in the serum of the blood, dissolve certain fatty principles there. None of the salts combine with-the principles of the second class (those formed by dis-assimilation) except common salt, which unites with urea, forming the chloro-sodate of urea. It is, indeed, in this combination with soda that urea exists in the blood, in the vitreous humor of the eye, and, in part, also, in the urine. (R. and V.) Some of the salts, especially several of the phosphates, in con- nection with water, combine directly with some of the organic sub- stances (third class), and thus result certain organized substances, or tissues. E. g. the phosphate of lime combines directly with the osteine in bone, to form the tissue of the latter. Besides, the earthy salts especially, by their union with the or- ganic substances, manifest a power in aid of assimilation; and common salt, the phosphates of lime and magnesia, and the neutral phosphate of soda, are found in every tissue and every fluid in the body. Hence the salts are indispensable in our food. They also aid in dis-assimilation by yielding their bases, while still forming a part of the tissues, to acids of organic origin, as the uric and hip- puric. By these latter combinations, also, the animal heat is in part produced. Moreover, their presence with the principles of the second class alone enables several of the latter to combine with oxygen, and even to displace it from metallic oxides. Liebig discovered, in respect to this class, that the phosphates and carbonates of soda may replace each other in the blood without detriment. Hence, if the food contains only phosphates, without carbonates—e. g. bread and meat—the blood contains no carbonates; if potatoes be added to the preceding, the blood contains some car- bonates; and if the diet be of fruits alone, the blood acquires the character and the composition of that of the ox or sheep. The urine also contains alkaline phosphates in the first case, and alka- line carbonates in the latter. The observations of Bence Jones, to the effect that, in chorea and CHLORIDE OF SODIUM. 49 delirium tremens, the sulphates and urea are increased in the urine, while the phosphates are diminished, and that in encephalitis the phosphates and the sulphates are considerably increased, are ex- plained by a reference to the chemical composition of the muscles and of the brain respectively, and to the substances resulting from their dis-assimilation. 1. Chloride of Sodium, or Marine Salt. (NaCl.) Common salt is contained in every fluid and every solid in the body, except that it has not yet been found in enamel. The urine of those in articulo-mortis is almost entirely deprived of it. It is the most abundant of the principles of inorganic origin, and is found during the whole period of existence, even in the ovule. Its whole amount in the body of the male is about 277.05 grs. " " " female " 234.9 " In human blood the marine salt amounts to 0.31 to 0.37 per cent., and bears to all the other salts taken together the proportion of 2.4 (even 3) to 1; and the proportion is very similar in the blood of other animals. Muscular tissue contains very little of it, and Bra- connot found none at all in the heart of the ox. There is more of it in saliva, gastric juice, mucus, pus, and inflammatory exudations,(?) than in the blood. Indeed, it always abounds where cells are form- ing in fluids. It exists in a liquid state in every part except the bones, teeth, and cartilages. It is always dissolved in water, and never chemi- cally combined in any tissue with the peculiar elements of the latter. Thus, also, it is never found in the organism in an isolated state. There is three or four times as much common Fig. l. salt in the blood as in the muscles, and still more . in the urine than in the blood. The proportion in the urine,however, varies with the nature of ^°^ V * ----------,------, *^» OrA the aliment; that in the blood does not. There £^ ^ is a large amount of chloride of potassium in P ^ HI the muscles; and this salt has very generally *> tp o ^ been confounded with the chloride of sodium chloride of sodium ot>- in analyses of the different organs and tissues. ^a^t^T^ciS The forms of the crystals found in the urine, of acid»and siowiy evaporat- common salt, are represented by Figs. 1 and 2. The presence of common salt in the blood is a condition essential to the endosmosis from the alimentary canal into the blood, of ali- 4 , 50 IMMEDIATE PRINCIPLES OF THE TISSUES. mentary substances dissolved in water, and of the solution of albu- men, and perhaps of the fatty principles. In connection with albumen, it prevents the solution of the blood-cor- puscles in the serum. It is also a condition of the acts of assimilation and cfe-assi- milation; hence the suppres- sion of it in food produces chlorosis (even in man), lan- guor, weakness, and pale- ness, and even oedema. It produces a more abundant secretion both of saliva and of gastric fluid, and thus fa- cilitates digestion. Hence it is needed most if the food Chloride of sodium from slow evaporation of healthy "qq principally Vegetable, Or urine. . u i 1 • in case of herbivorous ani- mals, since this kind of food contains very little of this salt. More marine salt than is actually required in the organism enters the stomach in the food and drink. The average daily amount con- sumed is, according to M. Barral, 4.75 grains in the food, and 109.2 grains added as condiment; more than this amount, however, being used in the latter way during winter. It leaves the body in the urine, the feces, the sweat, and mucus. 2. Chloride of Potassium. (KC1.) This is found in milk, the muscles, the liver, cerebro-spinal fluid, the blood, nasal mucus, saliva, bile, gastric fluid, and the urine. It exists, also, in the fluid rejected in choleras, and in that of dropsies. In the preceding alone has it thus far been found. It constitutes from 0.4 to 1 part in 100 of muscle, and only .03 to 100 in human milk. In blood the quantity has not yet been specified. It is always dissolved in water,- like common salt. And since in human blood the phosphate of potassa is always accompanied by chloride of sodium, and these two salts may become mutually de- composed into chloride of potassium and phosphate of soda, the salt under consideration may thus be formed in the body, as well as be introduced in muscle or milk used as food. CARBONATE OF LIME. 51 3. Fluoride of Calcium. (CaFl.) This is found only in bones and teeth (both the enamel and den- tine). Marchand finds 1 per cent, of it in human bone; the quan- tity in human teeth has not been determined. Berzelius found in the ox 4 per cent, of this salt in the enamel, and 5 per cent, in the dentine. It is not known from what alimentary substances it is derived, how it leaves the body, nor the part it acts therein, except by reason of its hardness.1 4. Hydrochlorate (and Carbonate and Bicarbonate) of Ammonia. (NH3HC1.) Nothing is known of the functions of these, and it is not demon- strated that the last two are immediate principles. The first exists in the tears, the saliva, and the urine. Whether formed in the body, or derived from the food, is unknown. 5. Carbonate (and Bicarbonate) of lime. (CaOC02.) The presence of the latter is only accidental in the human body. The carbonate of lime exists in bones, teeth, cartilages, and the blood. Otoconites are formed almost entirely of it. Traces are found in the ashes of the lungs. It is also found in the concretions (incorrectly called ossifications) of the muscles, arteries, valves of the heart, in false membranes, around fibrous tumors of the uterus, in the dura mater, and in the pineal body. Preputial, salivary, ton- sillary, lachrymal, and certain pulmonary concretions, tubercles (cre- taceous and the common form), and certain urinary, biliary, and arthritic calculi, contain this salt. In all cases it is combined with the phosphate of lime. It is sometimes also found in alkaline human urine. A rare form in the urine is shown by Fig. 3; it usually being an amorphous powder like the phos- phate of lime. Landerer has also found it in the crystalline lens affected with cata- ract. This salt is found in most of the tissues 1 n . ■, . t .A rare form of carbonate of lime, and fluids in an amorphous state—e.g. m found in aikaiine m-ine. Fig. 3. 1 Dr. G. Wilson has demonstrated the existence of fluorine in the blood and in milk; and the fluoride of calcium exists in many mineral waters, and in plauts growing in micaceous soils. 52 IMMEDIATE PRINCIPLES OF THE TISSUES'. the pineal gland, on the plexus choroides, &c.; but otoconites are formed entirely of carbonate of lime, in crystals of the rhomboidal form, which is peculiar to it. It is, doubtless, in a solid state in bones, teeth", and cartilage, and in the concretions before mentioned. It is certainly in a liquid state in the blood, but not in direct solution, since water very slightly dissolves it. The chloride of potassium and the carbonic acid there may aid in its solution, since both the former and also a fluid con- taining the latter acid dissolve it in a slight degree. In bone and cartilage the carbonate is doubtless united with the phosphate of lime before being combined (in company with it) with the organic bases (osteine and cartilageine) to form the fundamental organized substance of these two tissues. It is derived, in the organism, from spring water holding carbonic acid in solution, and also from the other salts of lime in the food. Finally, much of the carbonate of lime found by calcination of tissues, &c, whence it is derived, may be formed by this process itself; since all the salts of lime which have a combustible acid (e. g. the lactic) are thus converted into the carbonate of lime. 6. Carbonate and Bicarbonate of Soda. (NaO.C02 & Na0.2C02 + HO.) The first of these salts is found in the blood, feces, saliva; in the urine, when alkaline, without being ammoniacal; and in osteosar- coma. Valentin also found about one-third of one per cent, of it in the compact tissue of healthy bone. It is always, in the organ- ism, dissolved in water, and therefore liquid or solid, as may be the case with the water itself. In blood it constitutes 0.1628 per cent., and in feces .08 per cent. To it is due the alkaline reaction of the blood, the saliva, and the cerebro-spinal fluid. It is combined with, and dissolves, the albumen of the blood; and even prevents the fibrin from coagulating, if the blood drawn from a vein falls into a vessel containing a solution of this salt. It maintains the elasticity and the firmness of the blood-globules, conditions without which haematosis cannot be secured. (Robin and Verdeil.) A very little of this salt is derived from water and food; it is almost wholly formed in the body. The malates, citrates, tartrates, and lactates of soda and of potassa, contained in fruits taken as food, are all converted into the carbonate of these two salts respect- ively, and thus appear in the urine. The hydrogen lost by these acids, on being converted into the carbonic, is said to have been SULPHATES OF SODA AND POTASSA. 53 withdrawn by combination with the atmospheric oxygen, to form water and produce animal heat; a proposition, however, which ad- mits of doubt. The salt leaves the body in the urine,, and a portion is also decomposed in the lungs, by the pneumic acid, into the pneu- mate of soda. The bicarbonate of soda exists nowhere else than in the blood, and there its existence is very probable, rather than demonstrated. It is formed by the action of the carbonic acid in the blood upon the carbonate of soda. Its function is too nearly identical with that of the latter salt to need further notice here. 7. Carbonate (and Bicarbonate) of Potassa. (K0C02.) The latter of these two salts is found in the urine of the herbivorar but not in the human body at all. The carbonate of potassa exists in the blood of the herbivora, and of man and the dog, when they consume vegetable food. It does not, however, in the former, equal more than one-third or one-half of the carbonate of soda. It is formed, like the latter salt, from the malate, citrate, tartrate, lactate, &c, of potassa. Its function appears to be very similar to that of carbonate of soda. 8. Sulphate of Soda. (NaOSO3+10HO.) This principle exists in very small quantity in the body, but in almost every part and fluid, except the milk, bile, and gastric fluid. It may be found in milk when administered medicinally. Poggiale found 0.44 in 1,000 of human blood. It everywhere exists in a fluid state, dissolved in water, and conduces to preserve the elasticity of the blood-corpuscles, and to dissolve and keep-in a liquid state the fibrin of the blood. It is derived, probably, from food and drink, and is evacuated in the urine. This sulphate, and that of potassa, increase in the urine in in- flammatory diseases, while both diminish in chlorosis and chronic maladies. 9. Sulphate of Potassa and of Lime. (KOS03 and CaOS03.) The first of these is found wherever the sulphate of soda is, they being both dissolved in water, and mixed. Simon found 3 parts in 1,000 of urine. Its functions appear to be like those of the pre- ceding salt. The sulphate of lime is said to exist in the feces, in blood, and in 54 IMMEDIATE PRINCIPLES OF THE TISSUES. rachitic bones; but this is not yet certain. It is probably held in solution by the alkaline salts, already described. It is obtained from the water drunk. It is, perhaps, evacuated in small quantity in the urine; or is decomposed into some other salt of lime, and one of the sulphates just mentioned. 10. Subphosphate or Basic Phosphate of Lime. (Phosphate of Lime of the Bones—8Ca0.3POs.)1 The ashes of every tissue and fluid in the body of man and the mammiferae contain this salt, while some of them have it for their principal constituent, so far as the mass is concerned. It consists of eight parts of the base combined with three parts of the acid. All calcareous deposits, as well as many urinary calculi, and phos- phatic gravel, contain this salt. We have seen that in all cases this exists where the carbonate of lime does. It is the phosphate of lime which forms most of the calculi around foreign bodies intro- duced into the bladder, and those of the prepuce, and which is deposited on instruments left for a time in the bladder. It forms, often by itself, or with the ammonio-magne- sian phosphates, the urinary sand; and pros- tatic calculi are formed of it alone. Uterine and vaginal concretions consist of this, with a little animal matter around some nucleus introduced from without. A calculus of this Phosphate of lime calculus.from gah; is shown bv Pi0' 4 the bladder. . J °" ' The quantity of phosphate of lime varies in different parts. In bones there is 48 to 59, and in enamel even 88J, per cent.; in dry muscular fibre, .93 to 1 per cent.; in coagu- lated albumen (from the blood), 1.8 per cent.; and in fibrine (from venous blood), .69 per cent. It is also a constituent of caseine, globuline, and cartilageine; and of osteine in the white fibrous tissue, as well as in bone. In the ashes of urine are 2.57 per cent., and of solid feces 12.78 per cent. But the more a part is submitted to mechanical influences, the more phosphate of lime is deposited. Thus there is more in the bones of the lower than the upper ex- tremities (in the same weight), and less, than in either in the more passive ribs. The eburnation of bone is generally said to be an illustration of the same principle; though Lehmann found less than the normal amount of this salt in this condition. But when this 1 Heintz finds the formula to be 3CaO,PO, PHOSPHATES OF LIME AND MAGNESIA. 55 salt increases in the various bones, the others, except the phosphate of magnesia, diminish in proportion, and vice versa; the proportion of the principles of mineral origin remaining constantly the same at all periods of life, and both in the compact and the cancellated tissue. The salt just excepted, however, increases or diminishes with the increase or diminution of the phosphate of lime. (R.and V.) This salt is in a solid state in bone, teeth, nails, and hair. Though insoluble in water, it is in a liquid state in the blood and all the other animal fluids, whether in its free state or combined with albu- minous matters. When free^it is in solution by the aid of the free carbonic acid in the blood, of the bicarbonates, or by the chloride of sodium. In bone it is combined with their peculiar organic substance (osteine), and doubtless with the other earthy salts. It is also combined with albumen and Fig- 5- fibrine in the blood, as has been seen. In the urine it is held in solution by the acid phos- phate of lime and of soda, and the other salts of these two bases; also by the carbonic acid in the urine. Its appearance as a urinary de- posit is shown by Fig. 5. This principle gives to several tissues their physical properties of resistance and solidity, Phosphate of lime in amor- upon which their uses principally depend. ^^"^1^^* This is most apparent in the osseous tissue. Liebig also ascribes to it the insolubility of certain tissues, as the muscular and the areolar. It is derived from milk and other animal, and still more from vegetable, diet. The phosphate of lime of bones—i. e. the basic phosphate—exists in nature. It is evacuated in the urine. That in the feces is the overplus in the aliment which had not left the alimentary canal by absorption. A part is, however, changed into the acid phosphate of lime, and then aids in the decomposition of the tissues. The acid phosphate or biphosphate of lime exists in urine (and in gastric juice?), and is formed, probably, from the basic phosphate. 11. The Phosphate of Magnesia. (MgOP05.) This is found in all the tissues and fluids in the bodies of the mammiferae, but in all cases in small quantity. It is more abundant in muscle, however, than the phosphate of lime. 56 IMMEDIATE PRINCIPLES OF THE TISSUES. It is found, in a crystallized form, in the pus of abscesses of dif- ferent organs, in the serosity of ovarian and other cysts, in that of the pus of the pleura and peritoneum, and on the surface of carious and necrosed bones. Ovarian calculi are sometimes composed mainly of it, and a small quantity, at least, exists in all urinary calculi. In human bone it constitutes 1.16 per cent.; in that of the herbi- vora it is more abundant (2.05 per cent, in the ox). In the varying physiological and pathological conditions it increases or diminishes with the phosphate of lime. Of enamel it constitutes 1.5 per cent.; of dentine, 1 per cent.; of muscle, .023 per cent. Cartilage contains a large amount—even 6.9 per cent.; and blood, .137 per cent. Hu- man milk contains .05 per cent. In bone, nails, and teeth it is probably in a solid state, and com- bined (as is always the case) with the phosphate of lime. Though slightly soluble, it is doubtless directly dissolved in water. In bone, &c, these two salts, first united together, combine with the plasma to form the organic principle, or osteine. It is obtained, in the organism, from vegetable food; carnivorous animals deriving it from the bones of the herbivora. It is excreted principally in the urine; the feces also containing any amount not absorbed from the food, as well as that contained in the intestinal and pancreatic fluids. The formation in the organism of ammonia causes a part of this salt to pass into the state of ammonio-magne- sian phosphate—as in the feces, in cases of typhus and dysentery. The function of the phosphate of magnesia in aid of endosmosis, and of assimilation and cfos-assimilation, may be associated with that of phosphate of lime. 12. Ammonio-Magnesian Phosphate. (MgO.NH04.HO.P05.) This is formed, as just explained, in the feces in disease, and in the urine after standing twenty-four hours or less; and sometimes when first excreted, if the latter is alkaline. It may form in any alkaline fluid containing the phosphate of magnesia^ It is found in vesical calculi, gravel, and sand, and still oftener in renal calculi; and in intestinal, salivary, uterine, and biliary calculi. In all cal- culi it is habitually united to the phosphate of lime. It exists in the fluid form only in acid urine, being but slightly soluble in warm water and in solutions of other salts. A prolonged use of phosphate of magnesia (or mineral water containing it), has produced a vesical calculus, and in one instance even in two weeks. PHOSPHATE OF SODA. 57 It escapes from the body in the fluid (or feces) in which it is formed. For the various forms of its crystals, as found in the urine, consult Figs. 6 to 10. Fig. 6. ' Fig. 7. Crystals of ammonio-magnesian (triple) phosphate, with Stellate crystals of triple phosphate. mucous corpuscles, from catarrh of the bladder. Fig. 8. Fig. 9. Fig. 10. Foliaceous crystals of triple Rosettes of triple phosphate. Calculus of triple phos- phosphate phate. 13. The Neutral and Acid Phosphates of Soda. (Na0.2HO.P05+2HO.) The neutral phosphate is found in all the fluids and solids in the body. Urine normally contains both it and the acid phosphate, the former constituting 2.41 parts in 1,000. (Simon.) In cartilage it constitutes .92, and in woman's milk .04 per 1,000. It is always, in the body, in a state of solution in water; and this solution be- comes a solvent of the insoluble phosphates and the nitrogenized substances. Thus it has properties analogous to the sulphate of soda. It may also replace the carbonate of soda in the blood, and does so in case of a substitution of animal for vegetable food. It escapes in the urine and the feces, but in the former is con- 58 IMMEDIATE PRINCIPLES OF THE TISSUES. verted previously into the acid phosphate, or into the forms of phos- phate of lime, of magnesia, or the ammonio-magnesian phosphate. The acid phosphate of soda has hitherto been found only in the urine. We have seen how it may be formed from the neutral phos- phate ; the basic phosphate may also exist in the economy, and be converted by the union of carbonic acid into the neutral phosphate and carbonate of soda. The acidity of the urine is probably due to this salt. There is no free acid in fresh urine, except the uric, and this in very small quantity. The constantly changing reactions of this secretion are owing to the instability of the phosphate of soda. (Robin and Verdeil) 14. The Phosphate of Potassa. (KOPOs.) This very much resembles, in all its relations, the salts just men- tioned. Like the chloride of potassium, it is unfavorable to the exchange of oxygen and carbonic acid, since it destroys the con- sistence and elasticity of the blood-corpuscles, and, like it, is also much more abundant in the muscles than in the blood. Precisely the reverse is true of the phosphate of soda. In the muscles of the calf it is more than four times as abundant as all the other phos- phates taken together. (Robin and Verdeil) It is derived from vege- table aliments mainly. It has not been found in the urine; but, as, if meeting the chloride of sodium, the phosphate of soda and the chloride of potassium will be formed, it probably leaves the body in the form of these two salts. 15. Carbonate of Magnesia. (MgOC02.) This salt exists rarely in the bones and in concretions, and is therefore included by Lehmann among the accidental mineral con- stituents of the body. It is often quite abundant in the urine of herbivorous animals. CLASS SECOND. IMMEDIATE PRINCIPLES OF ORGANIC ORIGIN, FORMED WITHIN THE BODY BY DIS-ASSIMILATION. The principles of this class are sometimes termed "secondary organic compounds." They all have a definite chemical composi- tion, are formed within organized bodies, vegetable and animal, and exist only in them. Being, however, formed (except the fatty prin- PRINCIPLES OF ORGANIC ORIGIN. 59 ciples, as hereafter explained) by dis-assimilation, they constitute a part of the organized substance of the body only in an accessory manner, and not as original constituents of the tissues. Hence they are rejected from the body (except fat) almost as soon as formed, mostly in the bile and urine.1 Their accumulation, indeed, is inju- rious, and, as in the case of urea and others, may prove fatal. Even fat, accumulating in the epithelial cells of the kidney or the liver, and in other cases of fatty degeneration, produces death. Very corpulent persons do not attain to an advanced age. These principles (except the fatty, so far as they enter into the formation of adipose tissue) are not alimentary,, not assimilable. Only the first and the third classes are so. Hence our food must contain these last, while it does not contain the principles under consideration. The fatty compounds, however, are required in the food for the development of adipose tissue; and sugar is usually taken in the food, though it may be formed in the body from starch, in case none is thus taken. But no tissue is nourished by it. In any tissue, therefore, except the adipose, in which these principles are found (as lactic acid, creatine, &c, in muscle), they are the result of the waste of the tissue itself. Though so numerous (forty-two in all), the principles of the second class constitute a much smaller part of the body than those of the other two classes, since they generally exist in small quanti- ties. Indeed, about two-thirds of them all are contained in the blood, and the urine is next in order in this respect. The bile contains several, also, which the urine does not. All these compounds are in the liquid state in the body, except (sometimes) stearine and margarine; and perhaps the cholesterine of the brain. Some of them may, however, accidentally become solid, and form concretions, as uric acid, cystine, &c. Generally they are liquid by direct solution in water. Stearine and marga- rine, however, when liquid, are dissolved in oleine. But nine simple elements are found in this class—sodium, potas- sium, calcium, magnesium, sulphur, carbon, oxygen, hydrogen, and nitrogen. Preparatory to their exit from the body, these principles gene- rally pass into the state of carbonates, and then of carbonic acid; or are rejected in the urine, either unchanged or after isomeric cata- 1 This class, therefore, includes all the " urinary deposits," except the organized (as mucus, pus, and blood), and some of the salts just mentioned. 60 IMMEDIATE PRINCIPLES OF THE TISSUES. lysis. Some of them, however, are previously converted into lactic, uric, hippuric, or pneumic acid. Since the tissues are formed mainly from the immediate princi- ples of the third class, and those of the second class result from the waste of the tissues, it follows that the last-mentioned principles represent the amount of chemical elements of the third class which have ceased to be a part of the living organism. Hence, though very important to the physiologist, they need not occupy much space in a work on histology. The most important alone will, therefore, be particularly mentioned, and these as briefly as possible. FIRST DIVISION. Acid or Saline Immediate Principles of Organic Origin. For the twenty-three compounds in this division, the reader is referred to the table, page 40. They are found in a notable quan- tity only in the excrementitious fluids, or in the urine alone, or in morbid products, except the inosate of potassa and the lactic and pneumic acids. Only these two acids, together with the uric and hippuric, and the oxalate of lime, will be here described.1 1. Lactic Acid. (C6Hs05.HO.) In its most concentrated state, lactic acid is a colorless, inodorous, thick, syrupy fluid, not solidifiable by the most intense cold. It exists in sour milk, resulting from the fermentation of its sugar. In the human body it is always found in the urine when the oxalate of lime is, and while one is living on a strictly animal diet; as it is in all circumstances in the urine of carnivorous animals. It is also abundant in the "muscular juice;" so much so, indeed, as to be more than sufficient, Liebig asserts, to saturate the alkali of all the alkaline fluids in the body. Lehmann has also found that lactic acid and the lactates exist in the human gastric juice and in the small intestines. Origin.—The lactic acid in the stomach and small intestines pro- ceeds partly from the gastric fluid, and partly from the starch and sugar in the food, by fermentation. It enters the urine, of course, from the blood; and the latter from the alimentary canal on the one hand, and from the muscular juice on the other. 1 The last four salts of soda in this class (see the table), are peculiar to the bile. URIC ACID. 61 Uses.—Lactic acid in the gastric juice (with the hydrochloric) is essential to the digestion of the nitrogenized elements of our food. • Moreover, as the alkaline lactates are absorbed into the blood, they undergo rapid combustion (being thus converted into alkaline car- bonates), and thus become the most efficient supporters of animal heat. The lactic acid in the muscular juice is doubtless a resultant of the use and efts-assimilation of the muscular tissue. Hence, as Berzelius asserted, it increases in proportion to the extent to which they have been exercised. Liebig's hypothesis, that an electric ten- sion influencing the function of the muscles is established by the acid muscular juice and the alkaline blood in the capillaries, is simply ingenious. The lactates of soda, potassa, and lime are also among the imme- diate principles of this class. 2. Uric Acid. (C9HN202.HO.) Uric acid always constitutes about 1 part in 1,000 of the urine of healthy men. It is usually far less abundant in carnivorous animals. Fig. 11. Fig. 12. Uric acid crystals—artificial. Uric acid—rhombs. Fig. 13. Fig. 14. Uric acid—thicker rhombs. Uric acid—modified rhombs. 62 IMMEDIATE PRINCIPLES OF THE TISSUES. Its crystals are usually tinged with a yellowish hue by the coloring , matter of the urine, and their various forms are represented by Figs. 11 to 19. Fig. 15. Fig. 16. Uric acid—rhombs replaced by square form. Uric acid—hour-glass crystals. More uric acid is found in the urine during disturbed digestion, the urea being at the same time diminished. (Lehmann) It is in- Fig. 17. Fig. 18. Uric acid from urine. Uric acid as sometimes found crystallized on a hair. Fig. 19. creased by any obstruction of the circulation producing deficient aeration of the blood; hence it increases during fever, in heart diseases, and en- largements of the liver; also very much in acute articular rheumatism. It dimi- nishes, however, in gout. In the urine, when discharged, it nor- mally exists in combination with soda, and is found in its free state an hour or more afterwards. In some pathological states, however, and in cases especially of uric Uric acid crystallized on a fibrin- . , . . J ous cast of a uriniferous tube, acid calculus (Figs. 20 and 21), it may be URIC ACID. 63 found free in urine just discharged. It often constitutes the nucleus of the various forms of urinary calculi. (See "Urinary Concretions," Part II.) Fig. 20. Fig. 21. Uric acid calculus. Uric acid calculus, showing internal concentric layers. It is demonstrated that the urinary deposit described by Dr. Golding Bird as the urate of ammonia is the urate of soda. (Fig. Fig. 22. Fig. 23. Urate of soda. Urate of soda calculus. 22.) This salt normally exists in the urine, forming, when abun- dant, the "lateritious sediment," or the "amorphous yellow and impalpable sediment" (Prout) so common in febrile states. It also forms calculi (Fig. 23), and concretions in the joints. Indeed, the urate of ammonia (Fig. 24), very seldom occurs as a urinary de- posit. (Lehmann) 64 IMMEDIATE PRINCIPLES OF THE TISSUES. Urate of ammonia. Fig- 24- Uric acid also exists in the blood, the precise amount being not yet determined. It is, however, always increased in it in acute gout, and often in Bright's disease. It is not increased in acute rheumatism. From .004 to .0175 per cent, has been found in the blood of gouty patients. (Garrod) Origin.—Though uric acid is doubtless a result of waste of the tissues, it is not certain from what substance nor in what locality it is first formed. It appears to stand "one degree higher in the scale of the descending metamorphosis of matter than urea" (Lehmann)—i. e. it is converted into urea (and oxalic acid) by a partial oxidation. Hence, when aeration, and consequently oxy- genation, is imperfect, more uric acid and oxalate of lime, and less urea, appear in the urine. 3. Hippuric Acid. (C^HgNOj.HO.) Hippuric (or uro-benzoic) acid is present in the urine during the use of a vegetable or a mixed Fig. 25. Crystals of hippuric acid from human urine. diet. It occurs in large quan- tity in acid febrile urine, what- ever the variety of febrile ex- citement, and in diabetic urine. (Fig. 25.) The hippuric has no ascer- tained relationship to the uric acid, nor is any thing certainly known of its origin. It is doubtless formed from the effete tissues, and has no special use in the organism. The hippurate of lime, soda, and potassa are also immediate principles. 4. Oxalate of Lime. (CaO.C203.) This salt is frequently present in very small amount in normal urine; much increased, it indicates a pathological condition. The forms of its crystals are indicated by Figs. 26 to 29. OXALATE OF LIME. 65 The dumb-bell crystals of oxalate of lime, so called, are probably the oxaluret of lime—Figs. 30 and 31. (Bird) Fig. 26. Octohedral crystals of oxalate of lime. Fig. 28. Oxalate of lime. Fig. 30. Oxaluret of lime—dumb-bell crystals. Fig. 27. Oxalate of lime. Fig. 29. Oxalate of lime—octohedral crystals, dried. Fig. 31. Oxaluret of lime—dumb-bell crystals. The oxalate of lime increases in the urine after the use of vege- table food; and of beer which contains much carbonic acid gas, and the alkaline bicarbonates and vegetable acid salts. It often appears in the urine of pregnant women, and very constantly on the mucous membrane of the pregnant uterus. Lehmann finds that it increases 5 66 IMMEDIATE PRINCIPLES OF THE TISSUES. if the aerating process is in any way disturbed, and is common in pulmonary emphysema and chronic bronchial catarrh, and in con- valescence from severe diseases—as typhus. It is always accompa- nied in the urine by lactic acid. The mulberry calculus (Figs. 32 and 33) consists mostly of the oxalate of lime, and the latter enters in small quantity into almost Fig. 32. Fig. 33. Oxalate of lime (mulberry) calculus. Section of mulberry calculus. all the varieties of calculi. It often forms alternate layers with uric acid (Fig. 34), a fact disproving the notion of the "uric acid diathesis." In some cases of gout, the oxalate of lime exists in the blood. (Garrod) Origin.—Oxalic acid (C203) in the organ- ism is normally converted into carbonic acid by oxidation—C203 becoming C204, or 2(C02). Any cause preventing this ox- idation, therefore, causes an accumulation Alternating caicuius of oxalate of f oxalic acid, which, combining with lime, lime and uric acid. ' ' o ' forms the salt under consideration. Oxa- late of lime, therefore, proceeds—1. From the oxalate in vegetable food. 2. It accumulates if there be an excess of carbonic acid gas in the organism (as from beer, &c). 3. Impeded aeration, producing diminished oxidation, may increase it; and hence debility of the nervous system may do so indirectly, by diminishing the respira- tory movements. 4. Finally, oxalic acid may be produced by the oxidation of uric acid and several other substances in the organism; and hence diminished oxidation may produce more uric acid and less oxalate of lime, so far as this source of the latter is concerned Fig. 34. CREATINE. 67 and vice versa. Hence, also, alternate layers of these two substances may be found in the same calculus, and the idea of the "oxalic diathesis" must, moreover, be regarded as a fiction. s 5. Pneumic Acid. Pneumic acid was discovered by Verdeil in 1851. It exists in the organized substance of the parenchyma of the lung, and at all ages of life. It has the same relation to the lungs that creatine has to muscle, being a result, probably, of their metamorphosis. It decomposes the carbonates in the blood, and thus sets free their carbonic acid, which accounts for its greater proportional amount in arterial than in venous blood (p. 44). The pneumate of soda is also found in the lungs, and in the blood in them; but it subsequently disappears, not being found in any of the secretions. SECOND DIVISION. Neutral Nitrogenized Immediate Principles. (4.) 1. Creatine. (C8H9N304.) Creatine forms transparent and very brilliant crystals (Fig. 35), and is found in muscular tissue (both the striated and the smooth fibre), in the blood, and in the urine. Lean meat contains more than fat meat, and the heart most of all. It constitutes about .067 per cent, of human muscle. (Schloss- berger) The flesh of fowls con- tains the largest quantity; that of fresh water fishes the smallest. It is always in a liquid state, dis- solved in water. Origin.—Creatine in the mus- cular tissue is a constituent of the "muscular juice,"hereafter to be described; but, from the readi- ness with which it is decomposed into creatinine and urea, there is , ■, n i , . i , •, • Creatine crystallized from hot water. no reasonable doubt that it is derived from the decomposition of the muscular tissue, and is de>- 68 IMMEDIATE PRINCIPLES OF THE TISSUES. Fig. 36. composed into these and similar substances in the living body, and thus expelled in the urine. 2. Creatinine. (C8H7N302.) The crystals of creatinine are shown by Fig. 36. It is found only in the muscles and the urine, and always in company with creatine. The liquor amnii also probably contains it. (Scherer) In the muscles it is far less abun- dant than creatine; in the urine it is far more so. Origin.—Creatinine is pretty certainly produced in the organ- ism from creatine, being one de- gree lower than the latter in the descending metamorphosis of the tissues. It differs from creatine merely in containing two equi- valents less of water, or is crea- Creatinine crystallized from hot water. tine minUS 2(HO). 3. Urea. (C2H4N202.) Urea is the most highly nitrogenized compound in the body. It crystallizes, if slowly, in flat, Fig. 37. Urea slowly crystallized from aqueous solution. dropsical transudations. serous fluids, and sometimes in the saliva colorless, four-sided prisms (Fig. 37); if rapidly, in white, silky, glistening needles. It is found in the urine, the blood, and the vitreous and aqueous humors of the eye. It exists in combina- tion with common salt (i. e. as chloro-sodate of urea), in the blood and the vitreous humor, and partly so, also, in the urine. (Robin and Verdeil.) Urea does not exist in the muscular juice. (Grohe) It sometimes exists in milk (Rees), and very often in In Bright's disease it is found in all the SUGARS. 69 Urea normally constitutes about 13 parts in 1,000 of urine. (Bird) The amount is increased by a nitrogenized diet, and by muscular exercises. Origin.—It is decided that urea is formed in the blood, and it is doubtless formed from creatine, uric acid, and probably inosic acid also, by the action of the alkalies, and of free oxygen. (Lehmann) And since creatine is produced by the waste of muscular tissue, strong muscular exercise increases the urea in the urine. Thus, also, in delirium tremens, and all states attended by intense muscu- lar actions (convulsions, &c), a similar increase occurs. But urea probably also results from the decomposition of any tissue containing nitrogen, and not from that of the muscles alone. Moreover, if an excess of nitrogenized food is absorbed into the blood, it is excreted in the form of urea, this substance being the last and lowest step in the descending scale of the metamorphosis of the tissues, while the lactic, uric, and oxalic acids, creatine, and creatinine constitute the preceding grades. The idea of a "urea diathesis" is thus seen to be un- tenable. Fig- 38. 4. Cystine. (C6H6N04S2.) Cystine occurs in colorless, transparent, hexagonal plates and prisms (Fig. 38), and only in the urine, and in pathological states. It is richer in sulphur (it constituting 25 per cent.) than any other organic substance, except taurine. It sometimes forms calculi. Nothing is known of the con- ditions Of the formation Of CyS- Cystine from urinary calculus, recrystallized from tine in the organism. ammonia. THIRD DIVISION. Sugars, or Neutral Non-nitrogenized Immediate Principles. But two kinds of sugar are found in animals—sugar of the liver, and sugar of milk. In vegetables there are several kinds; and grape sugar, or glucose, has the same composition as hepatic sugar. 70 IMMEDIATE PRINCIPLES OF THE TISSUES. Hence grape sugar, glucose, hepatic sugar, and diabetic sugar, are all synonymous terms, and are all expressed by the formula C12H14014. Cane sugar is C12HnOn; and hence grape sugar is formed in the organism (though in small quantity) from the latter, by the addition of three atoms of water 3(HO). Hepatic sugar (or diabetic) possesses great physiological import- ance, and is an immediate principle of the liver; and milk sugar is normally an element of that fluid. That either results, however, from the dis-assimilation of the organ producing it, is scarcely pro- bable, though they are included in this class by Kobin and Verdeil. 1. Hepatic Sugar. (C12H14014.) Synonyms: Diabetio Sugar; Grape Sugar; Glucose. Hepatic sugar exists normally in the parenchyma of the liver, in the hepatic veins, and the portion between them and the heart, of the inferior vena cava, in the blood of the right heart and the pul- monary artery. During fasting, little or none is found in the pul- monary veins, the left heart, and the aorta and its branches; but during digestion it may be found in all these parts, in small amount, and sometimes in the veins generally also. A very little may be found in the vena portae during digestion, but never at any other time, unless it be introduced in the food; though it will still be found in the hepatic veins. It never exists in bile, in the normal state. It is found from the fourth or fifth month of intra-uterine life to the most advanced age. The urine of the foetus in utero normally contains it, this fluid being at that epoch normally diabetic. In diabetes, glucose exists in the urine, the kidney, the saliva, the serosity of the pericardium, and that produced by a blister, in the semen (of a dog), in matters vomited, and in the perspiration. Others add the feces also.1 But none is found in the brain or spinal cord, 1 The existence of the yeast fungus (torula cerevisiae) in urine has been regarded as a proof of the presence and the fermentation of sugar. (Fig. 39.) Fungi of a Fig. 39. Torula cerevisise. Successive stages of ceU-multiplication. HEPATIC SUGAR. 71 the pancreas, nor the spleen. There is much less sugar in reptiles than in birds and mammals, and none at all in the liver of the ray. Glucose exists in a fluid state in the blood, dissolved directly in water. The contact of organic substances in that fluid rapidly (in twenty-four hours or less) converts it, by catalysis, into lactic acid. In the urine it normally combines with common salt, and thus loses the taste of sugar. In the liver of the higher animals the sweetish taste is owing to its presence. In some diseases no sugar at all is formed in the body for a short time before death. An excess of it is one of the signs of a deep general lesion. Origin.—Normally, the grape sugar is formed in the liver, from the principles of the organism itself. The parenchyma, and the blood in the hepatic veins, contain it, though none exist in the food. (Bernard) But cane sugar also, entering the vena portaa by endos- mosis from the intestines, becomes grape sugar in the hepatic veins by fixing three equivalents of water. Perhaps the sugar of milk is converted in a similar manner. Glucose itself also exists in some articles of food (in cooked starchy substances, grapes, &c), and then, of course, appears first in the blood of the vena portae; though most of such substances pass merely into the state of dextrine (C12H10O10), and which probably becomes glucose in the liver by assuming/owr equivalents of water. The glucose actually formed in the liver (not derived from food, &c.) is formed in its parenchyma, and not in the blood,1 since in ani- mals bled to death it still remains in its substance. Anything in- creasing the activity of the circulation through the liver increases the quantity of sugar, and vice versa. Hence, probably, the fact that the condition of the nervous system modifies the amount of sugar (Bernard), since this modifies the circulation. Irritation of the me- dulla oblongata, at the origin of the pneumogastric nerve, was, therefore, found by Bernard to increase the quantity of sugar; and precisely similar shape may, however, be developed in normal urine, after standing for some time at a high temperature, and sometimes even if the urine still pre- serves an acid reaction. But they have generally only about one-half the diameter of the yeast-cells, and are probably developed from the mucus. For an illustration of the forms of vegetation in urine, see Figs. 127 and 128. 1 Dr. C. Hanfield Jones has recently maintained that the sugar is formed by the cells of the liver, while the bile is secreted by the epithelial cells of the hepatic ducts alone. Neither of these proportions, however, is probably correct. See '• Liver," Chap. XIII. 72 IMMEDIATE PRINCIPLES OF THE TISSUES. irritation of its extremities in the lung, by inhalations of ether or chlorine, produces the same effect, by a reflex action to the liver. Hence we may infer that in diseases of the lungs or medulla ob- longata, diabetes might occur. The changes necessary to convert the cane sugar and the dextrine of the food into glucose in the liver have already been stated. Moreover, Bernard has shown that this change is effected by the pancreatic juice in the duodenum. But all thus formed passes from the vena portae into the hepatic vein, while in the preceding circum- stances it is formed by and in the substance of the liver itself. The glucose disappears from the blood by being converted, cata- lytically, into lactic acid (C6H505.HO), which decomposes the car- bonates, and combines with their bases in the blood. But they are soon reconverted into carbonates, and in this form are evacuated in the urine. If there be an excess of sugar in the blood, it will pass off as such in the urine, and perhaps also appear in other secretions already specified. 2. Sugar of Milk. (C24H24024.) Synonyms: Lactine; Lactose. This is found only in milk, and in that of all the mammalia. It exists only from some point of time after puberty, continues only a few months at a time, and ceases a few months after the last preg- nancy. In woman's milk it forms 3.2 to 6.4 per cent.; the colostrum containing even 7 per cent. It diminishes in quantity the further the date from the previous delivery; being 5.5 per cent, a few days after delivery, it had fallen to 4.6 per cent, five months from this time. It becomes glucose (as does cane sugar) in the liver, and then is finally converted, as before explained, into lactic acid.1 If this latter change occurs in the milk itself, it becomes acid spontaneously. Origin.—The parenchyma of the mammary gland fabricates the lactine, as that of the liver does the glucose; from what elements is not precisely known. The longer the milk remains in the breast, the less sugar and other solid principles, and the more water, it con- tains. The kidneys and the lungs are merely eliminators, and not fabricators. Taken into the stomach of the infant, the lactine may be con- 1 Four atoms of lactic acid equal one of lactine. FATTY PRINCIPLES. 73 verted into glucose by mere addition of water, or by the action of the pancreatic fluid in the duodenum. Or if not thus, this con- version occurs in the liver. Its subsequent disposal has already been explained. FOURTH DIVISION. Fatty Principles (Fatty Acids and Soaps). All the immediate principles of this class exist in a fluid state, except that cholesterine, margarine, and perhaps stearine, are some- times, in morbid conditions, found solid. They are also composed of carbon, hydrogen, and oxygen alone, and in definite proportions, and are found in both vegetable and animal organisms. There is, however, no proof that they are the result of dis-assimilation, though included in this class by Robin and Verdeil. The fatty principles exist in the tissues and fluids of the human body in three entirely different conditions:— 1. Inclosed in cells, which constitute the fatty or adipose tissue. This will be described in connection with the other tissues. 2. They exist in chemical combination with other elements, and hence can be detected only by chemical analysis. This is the case with the fat in the organic matter of epithelium, nails, horn, and hair. 3. They form minute oil-drops, or "fat-globules," without any en- velop, and in this form naturally enter into almost all the tissues, except teeth and bones,1 and into many of the fluids. They are very minute, though of varying size, and possess a high refractive power. (Fig. 40.) Flg* 40- Thus the fatty principles are completely iso- ^^^r^ lated from all others, though they exist with others in the same tissue or fluid. The- drops are, however, themselves always made up of several of the fatty principles united together, molecule to molecule ; and the l»- same is true of the fat in the cells of adi- Fat-giobuies. pose tissue. The only exceptions are the fatty elements of the brain, cholesterine in the blood, and certain 1 Bones inclose fat in their cavities, but here it is contained in cells. 74 IMMEDIATE PRINCIPLES OF THE TISSUES. fatty acids, each of which may be found in a state of isolation from other fatty elements. Though several of the tissues contain the fat-globules under con- sideration, they are most abundant in the corpus luteum. They also abound in cancerous (encephaloid), atheromatous, and other morbid growths; and when they replace the normal tissues in or- gans, or become abnormally abundant in them, they produce the "fatty degeneration," or Stearosis, and in this way may produce fatal results. The organs most liable to this change will be speci- fied in the chapter on "Adipose Tissue." The fat-globules exist in the fluids in a state of suspension or emulsion. The smallest of all are those of the chyle. They are twice or thrice as large in the blood during digestion, and are still larger in milk, constituting the cream. Fat-globules also normally exist in urine, semen, prostatic fluid, saliva, nasal mucus, synovia, and bile, and in the serosity of the pleura, of the peritoneum, and that produced by a blister. Blood-serum contains fat even when mixed with other fluids (as urine), and pus also contains it in notable amount. The fatty immediate principles exist in the ovum, and through life. In the adult they constitute about 5 per cent., or ^ of the weight of the body. Of the entire brain, fat constitutes at least 10 per cent.; of the muscles, 1J to 4 per cent.; and of the blood, 0.14 to 0.33 per cent. The globules alone of the blood contain 0.331 per cent.; the serum alone, 0.175; and the fibrine (when dry), 2.6 per cent. Origin.—The fatty principles in the body are mostly taken into the organism, already formed, in the food, and, being converted into an emulsion in the duodenum and jejunum by the action of the pancreatic fluid (Bernard), are then absorbed mainly by the lacteals, and enter the venous current from the thoracic duct. But it is also extremely probable that the fatty principles may be, to some extent, formed in the human organism; and Liebig's idea that they are formed in the alimentary canal, from the metamorphosis of certain nitrogenized elements in our food, is the most plausible. At least, the amount of fat in the blood does not vary much, whether the food contains very much fat, or is deficient in it (Boussingault); and both the amylaceous and the nitrogenized compounds in our food cer- tainly afford the elements for the formation of the fatty principles. The fact sometimes cited to prove that carnivorous animals form fat within their own organisms—viz., that their milk contains fat— CHOLESTERINE. 75 proves nothing, since most of the tissues of the animals on which they prey also contain it. It is also very certain that the human liver has the power to form fat directly, to some extent, as well as sugar (p. 71). It is not, however, probable that the adipose tissue is nourished by fat formed elsewhere in the organism, but that the fatty materials for its nutri- tion are contained in the food, or, in default thereof, may be elabo- rated by the fat-cells themselves out of the other elements brought to them in the blood. But that almost all the fatty principles in the body are, under all ordinary circumstances, introduced in the food, hardly admits of a reasonable doubt. Of the fatty principles which enter the blood, a portion is appro- priated to the nutrition of the adipose tissue, and others normally inclosing "fat-globules," and for the secretions which contain the latter; the remainder is burned up by combination with oxygen to maintain the animal heat, and leaves the body in the form of car- bonic acid and water. Though the fatty principles possess great physiological import- ance, only oleine, margarine, and stearine are especially important to the histologist. These, therefore, and cholesterine, will alone be here considered. "Seroline" has been shown by Lehmann to con- sist of the crystallizable parts of several fats blended together. 1. Cholesterine. (C37H320.) Cholesterine (or bile-fat) crystallizes in very thin rhombic tablets. (Fig. 41.) It is normally dissolved in the bile, and is found in the blood, bile, liver, brain, nerves, feces, cerumen, the crystalline lens, and in many pathological productions. Gall-stones are composed almost entirely of it. The blood contains about .088 parts of cholesterine in 1,000. It increases in old age, and in most acute diseases; especially in inflammations, and in icterus. It also occurs in pus, and often in dropsical transudations, creta- ceous tubercles, old echinococ- CUS CyStS, encysted tumors, de- Tablets of cholesterine. 76 IMMEDIATE PRINCIPLES OF THE TISSUES. generated ovaries and testes, and carcinomatous growths. It has not, thus far, been found in the urine. Cholesterine is found only in animals, and must be formed in the organism—by the liver, probably. It is not, however, known from what elements it is formed, nor what office it performs in the organ- ism ; nor how it makes its exit therefrom, except so far as it is con- tained in the feces. It is, however, to be regarded as an excre- mentitious product, and probably is a result of dis-assimilation of the liver itself. 2. Oleine, Margarine, and Stearine. These three immediate principles are combined together to form the contents of the cells of adipose tissue, and the fat-globules in various tissues and fluids. Each of them is composed of a fatty acid in combination with a compound radical—the oxide of lipyl. (C3H20.) From the latter glycerine is formed. 1. Oleine (C39H3605) is compounded of the oxide just mentioned and oleic acid. (C36H3303.HO.) It is, therefore, the oleate of the oxide of lipyl. When isolated, it maintains its fluidity at any tem- perature above zero of Fahrenheit, and in it are the margarine and stearine in the tissues, dissolved. 2. Margarine is a compound of margaric acid (C34H3303.HO) with the oxide of lipyl, or is a margarate of this oxide. It becomes solid at a temperature of 118° Fahr. It forms a much greater pro- portion of human fat than oleine. 3. Stearine exists in human fat, but in very small quantity. It is a compound of stearic acid (C68H6605.2HO) and the oxide of lipyl, and is the stearate of this oxide. Stearine does not exist in vege- tables, but is the main constituent of all solid animal fats, as sperma- ceti, suet, and tallow. Butter contains margarine and oleine, but no stearine. The last may, however, be formed in the organism from the other two prin- ciples. In a dog taking butter alone for sixty-eight days, the liver contained a large quantity of stearine, and very little if any oleine. (Magendie) It will be seen that two equivalents of margarine pre- cisely correspond to one of stearine, with the addition of one atom of oxygen. These three principles together will not, however, by themselves nourish an animal, while adipose tissue will do so for a time. Soaps are formed by boiling either margarine or oleine with USES OF THE FATTY PRINCIPLES. 77 potassa or soda. Some of the fatty principles are, however, not thus decomposed by alkalies, nor by the oxide of lead, and are, therefore, called non-saponifiable fats. Cholesterine and seroline are of this class. It is probable that potassa decomposes fat in the body as well as out of it; hence the liquor potassae is the most reliable remedy for excessive corpulence.1 Uses of the Fatty Principles in the Organism.—These have been generally stated on a previous page (p. 75). Certain further par- ticulars should find a place here. 1. The use of fat in the adipose tissue, or rather of adipose tissue itself, will be specified further on. 2. The fat in the blood is partly appropriated to the nutrition of the adipose tissue, and partly appears in the form of "oil-drops" in the tissues and in several secretions (p. 75). A portion also enters into organic combination in the structure of the brain; and, finally, the overplus of the fat is burned up, and thus becomes a calorific material, being converted into carbonic acid gas and water, and thus leaving the body. But it is also quite probable that the bile is formed, in part at least, from the fat in the blood. Lehmann, however, considers it doubtful if the cholesterine is derived from this source. But the blood of the vena portae contains more fat than that of any other bloodvessel in the body; besides, it is of a darker brown color, con- tains more oleine, and is therefore more greasy than the fat in other veins. The fact that there is much less fat in the hepatic veins points to the inference that the bile is formed in part from that in the vena portae; and this is confirmed by the fact—first, that the secretion of bile continues free during starvation, and while ema- ciation is progressing; secondly, that the blood contains more fat in icterus than in any other disease; and, thirdly, that a disease of the liver producing diminished secretion of bile also produces obesity, as that occurring in drunkards from nutmeg liver and other diseases of that organ. In acute diseases, also, emaciation first becomes mani- fest in connection with a free discharge of bile from the alimentary canal. (Lehmann) Lehmann expresses the opinion that fat also co-operates in the formation of the blood-pigment, or haematine. See the chapter on "Adipose Tissue." 78 IMMEDIATE PRINCIPLES OF THE TISSUES. It is an interesting fact that in tuberculosis the saponified fats are far more diminished in the blood than in any other fluid. (Becquerel and Rodier) Solid tubercle itself also contains but little fat; and it is not an unphilosophical idea that the principal predisposing cause of tuberculosis is this same diminution of fat in the blood, and that it is for this reason that fatty compounds—and, above all, cod-liver oil—are found so efficient to prevent or arrest it. 3. Why fat exists in some of the secretions—as semen, mucus, &c.—is not understood. Of pus, Guterbock found fat sometimes to constitute even 5 per cent.; about 3 J per cent, being contained in the corpuscles. But it follows that an excessive secretion of these fluids must produce emaciation, as results from profuse suppuration and from venereal excesses. The fat in milk is essential to the development of the young mammal. It constitutes 2| to 4 per cent, of woman's milk, and exists both within cells and in the form of oil-drops. In the colos- trum it forms the peculiar granular cells, or "colostrum-corpuscles;" and which, being also seen in inflammatory exudations, in the sputa of chronic catarrh, in old apoplectic cysts, &c, have been termed "glomeruli" and "inflammation-globules." (Fig. 42.) Not a single primordial cell, indeed, can be formed in the embryo without fat an *ncn m thickness. It is nourished by vessels lying near or under it, but is never penetrated by any vessel, *nerve, or, indeed, by any other tissue whatever. It is entirely imperforate at every part, the highest powers of the microscope never revealing any pores, or openings of any kind. Forming, therefore, a complete barrier between the structures on its opposite sides, it has, in some parts, been termed a limitary membrane. The posterior layer of the capsule of the crystalline lens affords an excellent illustration of this kind of tissue. Being structureless and transparent, it can, how- ever, only be seen when accidental folds or other irregularities are formed. (Queckett, p. 116.) In some case, however, granules also appear in simple membrane; and in a third form of it dis- tinct spots appear, which have been regarded as nuclei; and it may be broken up into separate portions, each containing one of these. (Fig. 47.) If the simplest form is solidified albumen or plasma, the second is probably the same sub- Basement membrane of intra-glandular lympha- tics. HO SIMPLE HISTOLOGICAL ELEMENTS. stance, containing granules in it; and the third form is an instance of the development of scales from germinal points, or nuclei, as cells are normally developed (Chap. IV.), and which scales coalesce at their borders to form the continuous layer. In all these cases, how- ever, it is organized, and manifests vital properties. Simple membrane is found only in two conditions, except when an element of the compound tissues, viz., in the form of a mem- branous expansion, to constitute— 1. Basement membrane, which will be described at the end of this chapter. 2. As constituting the walls of cells, whether secreting, absorbing, or primordial, &c. &c. Properties of Simple Membrane.—Though the simplest of the histo- logical elements, it manifests important vital properties. Since it forms the walls of cells (secreting and otherwise), simple membrane is the direct agent of secretion in all cases. It is also, in many in- stances, of absorption. These are, therefore, its two vital properties. The physical property of endosmosis also inheres in it in a re- markable degree.1 Distribution of Simple Membrane.—The basement membrane of the skin, and of serous and mucous membranes, is formed of this element. It therefore enters the lobes and follicles of all glands. It forms the capsule of the crystalline lens, and the posterior layer of the cornea. It lines the bloodvessels and the lymphatic vessels, in the form of epithelium, if not of a basement membrane also. It forms the walls of all cells, whether blood-corpuscles, secreting cells, fat-cells, &c. &c.2 As an element of compound tissues, it also constitutes the myo- lemma of the muscular fibres, and the neurilemma of the nerve- fibres or tubes. Simple membrane will, therefore, constantly recur in the descrip- 1 By endosmosis is meant the property inherent in animal membranes, of trans- mitting fluids through them. If two fluids of different specific gravity are placed on opposite sides of them, they are transmitted in opposite directions, and thus mixed—one current being termed endosmosis, and the other exosmosis. 2 Simple membrane also forms the walls of the cells from which the tissues of vegetables are developed; it being identical in them, it is said, with cellulose, C24H2102„ or Cb4-Aqua7. It is an interesting fact, if verified by future investiga- tions, that the vegetable cell is lined by a "primary utricle" or cell, identical in composition with proteine—i. e. it is an albuminous compound, as is the animal cell-wall. SIMPLE MEMBRANE. Ill tion of cells and of the various tissues; and, in connection with these, its important vital relations will be particularly indicated. Basement Membrane. A basement membrane is a mere expansion of simple membrane entering into the structure of the skin, and all mucous and serous membranes, and lying directly upon the corium of these structures respectively. It is itself covered, in turn, by the epithelium of the serous and mucous membranes, and the epidermis of the skin. Its thickness is often not more than 2T5£oo- 0I> an incn- Kolliker does not mention the basement membrane at all as an element of the three tissues just mentioned. There is, however, no doubt of its existence in many parts of them. It has been shown that simple membrane presents three forms; and Queckett asserts V the probability that in one or another of these, basement membrane exists in every part of the three membranes just mentioned. Uses.—The basement membrane is a complete barrier between the vessels and nerves of the corium on the one hand, and the epithelium on the other, being never perforated by any structures whatever. It thus rises over and covers the villi of the small in- testine, and the papillae of the skin. It also dips down into and lines all the sebaceous follicles and sweat ducts of the latter, and the mucous follicles of the former. Thus it forms everywhere the basis of the epidermis and of epithelium. Whether it secretes from the vessels under it the plasma from which the epithelial cells are de- veloped, is uncertain. This has been supposed to be the fact; but this supposition is, at least, quite improbable. A basement membrane is said by some to exist as a distinct structure in the lining membrane of the bloodvessels also. This assertion still needs confirmation, though the presence of a kind of epithelium there suggests the idea of its presence also from analogy. Kolliker asserts the contrary. 112 SIMPLE HISTOLOGICAL ELEMENTS. CHAPTER III. SIMPLE FIBRE. Fig. 48. Fibres enter into the composition of some of the compound tissues; and two of the simple tissues—the white and the yellow fibrous tissues—are formed of them exclusively. Simple fibre is, however, something entirely different from these, and sustains to them no higher comparative rank than do the lower forms of ho- mogeneous substance in comparison with osteine. An example of simple fibre, always , easy to obtain for illustration, is found in the membrane lining an egg-shell (membrana putaminis), which consists of several layers, each formed by the interlacement of simple fibres. (Fig. 48.) Pure coagulated fibrine also consists merelv of a network of simple fibres (p. 92). Simple fibre appears always to consist of mere threads of coagu- lated fibrine. In other words, it Simple fibres of membrane lining the egg-shell. Fig. 49. Simple fibres in inflammatory exudation from peritoneum. appears to be merely the result of the fibrillation of fibrine already described (p. 93). These threads average about g^^ of an inch in diameter. Of course they are less perfectly developed in the cir- cumstances in which coagulation is less perfect (p. 95). On the other hand, they are most per- fectly developed in inflammatory exudations. The human chorion appears to SIMPLE FIBRE. 113 be formed at first exclusively of simple fibres. These, however, subsequently disappear, as its development proceeds. There is reason to believe that simple fibres constitute the matrix in which the tissues generally are developed during embryonic life, as well as the nidus in which repair takes place after solutions of continuity with or without loss of substance (p. 91). Uses.—Simple fibre is, therefore, not a permanent constituent of the human body. It must be regarded as a merely temporary element, laid down as a framework on which higher histological elements may be developed, and which then becpmes absorbed and disappears. In this way, however, its relations to the tissues are all-important. Since, also, coagulated fibrine consists of a network of similar fibres, they become the medium for the spontaneous arrest of hemorrhage, as before explained (p. 91).1 In pathological epigeneses four kinds of fibres are found: 1. Cleavage fibres, by far the most common of all, which occur in in- flammatory exudations after coagula- tion ; 2. Fibres of coagulation, i.e. formed by fibrillation of fibrine, as occurs in colloid; 3. Cell-fibres, those formed in cells (Fig. 50); 4. Nuclear fibres, those r. formed of elongated nuclei (Figs. 51 ( and 174). The first two forms seem identical with simple fibres. Nuclear fibres are the embryonic form of the yellow fibrous tissue. Fig. 50. r^v^- & .■*" ^ Fibre-cells passing into fibres. Fig. 51. Fig. 52. Nuclear fibres. Simple fibres and nuclei in false membrane. 1 The elastic spiral fibre in the tracheae of insects is probably mere simple fibre; and the fibre found in the air-vessels of plants presents a similar appearance, though of different chemical composition. 8 114 SIMPLE HISTOLOGICAL ELEMENTS. That fibres of any kind are ever formed by the mere conjunction of nuclei, must be, for the present, regarded as very improbable. Simple fibres are found as a permanent development in some false membranes, so called, as shown by Fig. 52. CHAPTER IV, CYTOLOGY.—CELLS. The description of the cells (and their development and function), from which the tissues are originally formed, constitutes the depart- ment of histology termed Cytology.1 These are closed vesicles, usually of a globular form, varying from y^ to g^oo or% an incn in diameter, and consist of the five following structural elements:— 1. The cell-wall. 2. A contained fluid. 3. Granules floating in the fluid. 4. A nucleus. 5. A nucleolus. Fig. 53. Cells showing the cell-membrane, the contained granules, the nucleus, and the nucleolus. 1 and 2. The typical spherical form. The rest as changed by pressure. 1. The cell-wall is formed of simple membrane, and, of course, is an albuminous compound, but is not fibrine. Though varying much in thickness in different instances, it presents nothing peculiar. It is generally soluble by acetic acid. The walls of epithelial cells, however, are not thus dissolved after they become corneous, though 1 From jcutoj, a cavity or cell, and \oyoj, description. CYTOLOGY —CELLS. 115 they are while young; and the same is true of most pathological cells. The wall of the colored blood-corpuscle is not dissolved by acetic acid; but most observers regard these bodies as nuclei, and not as cells. 2. The fluid contained in the cells is almost invariably trans- parent, or nearly so. In the blood-corpuscles, however, it is of a bright red color. In chemical composition it varies extremely, being usually an albuminous compound—in part, at least. It is not so, however, in the epithelial cells of glands; and in the cells of adipose tissue it consists of margarine and stearine dissolved in oleine (p. 76.) The cells of the epidermis, and of nails, horn, and hoofs, contain keratine and fat; and those of the epithelium on mucous membranes generally contain mucosine, but no albumen. 3. The granules floating in the fluid contained in the cells are often in immense number; are rounded corpuscles, so minute as hardly to admit of being measured; and, in most instances, have no investing membrane. This is the case with the fatty granules in many cells and glandular secretions,1 they being merely fat-glo bules. The granules giving the color to the pigment-cells have also no investing membrane. In other cases the granules have an investment, and are termed elementary vesicles (more properly called free nuclei); e. g. milk- globules are originally such granules of fat, with an .investment of caseine in the form of a simple membrane (p. 89), and contained within the secreting cells; and the molecules floating in chyle and blood are mere fat-granules with an albuminous investment. (Mul- ler.2) T. Wharton Jones regards the colored blood-corpuscles of man and the mammalia as elementary vesicles, or free nuclei, except while in the parent cells (the colorless corpuscles of the blood) in which they were formed. Neither of these two kinds of floating granules just mentioned (milk-globules and blood-corpuscles) in- crease in size when once formed, nor do they multiply by subdir 1 As the granular precipitates of the coloring matter of the bile. Add to these. also, the albuminous granules in certain portions of the gray substance of the cerebro-spinal centre, and of the retina. 2 Ascherson discovered, in 1840, that whenever fluid fat and fluid albumen are shaken together, the fat-globules thus formed are always surrounded by an albu- minous coat. He termed this the haptogen membrane. It is the result of mere chemical action, and exhibits no vital endowment whatever.. 116 SIMPLE HISTOLOGICAL ELEMENTS. vision or by endogenous development. (Kolliker, p. 12.) Thus they incline towards merely inorganic forms, as produced by crystal- lization. It should be added that in some cells no granules exist, but only a clear fluid, as in case of the fat-cells and the colored blood-cor- puscles. 4. The nucleus is a globular or lenticular body, measuring from ssuu to ooo" 0I> an inch.1 It is attached to, or imbedded in, the wall of the cell, except in case of the free nuclei already mentioned, which have escaped from the parent cell, and have no nucleoli; and is transparent and of a yellowish color. All nuclei are themselves vesicles. The contents are, besides a nucleolus usually present, almost invariably a yellowish or transparent fluid; and in this both water and acetic acid precipitate the same dark granules which are found floating in the cells. Acetic acid, however, renders the nucleus more visible, while it dissolves the cell-wall. But the pus-corpuscle, which Gluge incor- rectly regards as a mere nucleus, is dissolved by this acid. Sometimes this vesicle (the nucleus) contains formed granules, as the spermatic filaments (spermatozoids) in semen (Fig. 54), and peculiar granules (germinal spots) in ova (Fig. 55). The germinal spot is actually a nucleolus within the germinal vesicle, the latter being the nucleus of the ovum. Spermatozoids. 1 to 4. Their variety Germinal spot, &c, of ovum. 1. Stroma of the ovary. 2 and in form. 5. Seminal grannies, 3. External and internal tunics of the Graafian vesicle, i. Cavity of the latter. 5. Thick tunic of the ovum, or yolk-sac. 6. The yolk. 7. The germinal vesicle. 8. The germinal spot. 1 It sometimes measures even from'-^ to ^ of an inch, as in ganglion-cells and ova. NUCLEI. 117 The membranous wall of the nuclei is certainly an albuminous compound, and probably but little, if at all, different from the younger cell-membranes. Generally the granules within it are mere globules of fat, like those floating in the cell. Nuclei are found in all cells of embryos, and in adults also while the cells are still young; though in some cases, as in the fat-cell, they subsequently disappear. Generally but a single nucleus exists in each cell; but when a cell is multiplying, as many nuclei arise as there are new cells to be formed. In some cases, however, several nuclei naturally exist; four, ten, twenty, or even more, nuclei being found in the same cell. This is especially the case with cancerous and other rapidly developed ma- lignant growths. Free nuclei also take part in the formation of certain tissues—as in the rusVcolored layer of the cerebellum, and in the granular layer of the retina. Thus a nucleus is, histologically, an embryo cell. Pathological Developments of Nuclei. 1. The characteristic structure of tubercle—tubercle-corpuscles— consists of mere nuclei inclosing nucleoli, there being no cells in this deposit. The other element of tubercle is an amorphous, semi-solid hyaline substance, which, in the opaque or yellow variety, but not in the gray or transparent tubercle, contains granules also (p. 108). The nuclear bodies of tubercle are usually oblong, polyhedral, averaging -ggVi OI> an inca l°ng> and 4573 of an inch wide. They consist (1) of a delicate transparent membrane, with (2) a transpa- rent, colorless, or faintly ambreous fluid, containing (3) granules, and Fig. 56. Fig. 57. Fig. 58. Fig. 56. Tubercle-corpuscles from peritoneum. Those at the right show the effects of acetic acid. Fig. 57. Tubercle-corpuscles and granular homogeneous substance from lung. Fig. 58. Tubercle- eorpuscles from meienteric gland. Free oil-globules are seen at the right in Fig. 57. 118 SIMPLE HISTOLOGICAL ELEMENTS. (4) two or three to a dozen scattered, globular, transparent nucleoli. (Figs. 56, 57, and 58.) Tubercle-corpuscles are distinguished from those of pus, from being smaller, less granular, and not having their nucleoli aggre- gated. Acetic acid also slightly affects their nucleoli; while it must often be applied to the nucleoli of pus-corpuscles, to render them visible. The peculiar nuclei of cancer are distinguished from those of tubercle by being larger, regularly oval, or not unfrequently spherical, and from containing only one or two nucleoli. As seen under the microscope, typhous and scrofulous deposits are not to be distinguished from tubercle. Chemical analysis of the solid matter of tubercle gives the follow- ing result. (Preuss) Scherer, however, finds that tubercle varies much in composition in different cases. 1. Matters soluble in hot alcohol. Cholesterine......4.94 2. Matters soluble in cold alcohol, but not in water. Oleate of soda......18.50 3. Matters soluble in dilute alcohol. A peculiar substance ) Lactate and sulphate of soda >• . . . 8.46 Chloride of sodium ) 4. Matters soluble in water. Caseine1 ) Sulphate and phosphate of soda >- . . 7.90 Chloride of sodium ) 5. Matters insoluble in cold water and alcohol. Caseine1 altered by heat ) Phosphate and carbonate of lime v . 65.11 Oxide of iron, magnesia, and sulphur ) 99.91 In cretaceous transformation of tubercles, the salts of lime espe- cially become increased. The small amount of fat existing in tu- bercle has already been alluded to (p. 78). In a gray, well-dried tubercular mass, Lehmann found but 3.54 per cent, of fat. The cholesterine should not be regarded as fat. 2. The exudation-corpuscle (inflammation-corpuscle of Gluge) con: sists of a group of ten to forty or more granules, held together by a coagulated albuminous matter, soluble in acetic acid. These mul- berry-like bodies are also called granule-cells and glomeruli. They measure from ^q-q to 5gIJ of an inch in diameter. They £n albuminous compound, but not caseine. (Lehmann.) NUCLEOLI. 119 are, however, not peculiar to inflammation, but appear in the colos- trum and in the egg. They are regarded as free nuclei, and are represented by Fig. 59. Fig. 59. 2 06 T Glomeruli and granular cells. The dark cells are the glomeruli. 1. From inflamed lung. 2. From inflamed pia mater. 3. From tubercular meningitis. 5. The nucleolus is a round, sharply defined, fat-like granule, generally of a dark color, and measuring T3^5 to g^^ of an inch1 in diameter. It is inferred that they are vesicular, from their sharply defined form, from their similarity to free nuclei, and from the fact that, when large, a cavity filled with fluid frequently be- comes developed in them. Acetic acid does not dissolve them. They are believed to be constituted of fat, with an albuminous compound for the investing membrane. Nucleoli are generally found in nuclei while still young, and in many during their whole existence. Still, they cannot be regarded as an essential constituent of the cell, like the nucleus, since they cannot always be with certainty recognized in the latter. Cells without nuclei, of course, have no nucleoli. Usually but one nucleolus is found in a nucleus, but frequently there are two; and in solitary cases four or five may be found, which then are either eccentric, or lie free in the nucleus. A nucleolus is, therefore, histologically, an undeveloped nucleus; and since both nucleoli and nuclei contain fat, and the free granules in cells consist of it usually, in part at least, fat is always indis- pensable in the plasma from which cells are developed. On the other hand, there is no evidence that fibrine exists in the cell-wall or the contained fluid. All agree that the former is an albuminous substance. That fibrine, therefore, is the only plastic element in the blood, is highly improbable. The remark of Gluge, that " the formation of fibres and cells from fibrine is a matter of direct observation,"2 1 In ganglion-cells, and in the germinal spots of ova, they sometimes measure *oVi' Multiplication of cartilage-cells by division. The Physiology of Cells. Under this head will be considered— A. The growth of cells. B. Their physiology proper, including the nature of their contents, and the processes performed by them. A. The Growth of Cells. Growth, doubtless, occurs in all cells, to some extent. It is, how- ever, most manifest in cases when the cell-membrane is formed physiology of cells. 127 directly around the nucleus. But cells which from the first have contents (the cell-membrane in these cases forming around masses investing the nucleus), increase very slightly in size. The nucleus, and nucleolus also, usually increase in size with the cell; but the nucleoli always retain their globular form, except when dividing fissiparously. In cell-growth there is an increase either of the surface or of the thickness of the cell-wall, and this increase may be either general or partial. It is general when the cell grows larger without change of form;1 partial when the cell changes its form by extending itself at two or more points. Carpenter thinks this extension takes place in the direction of the least resistance; but its cause is not demon- strated. In some cases the cell becomes narrower as it elongates; and here we must admit that absorption occurs in one direction while deposition goes on in the other. The power of growth does not appear to be simply innate in every organic membrane, and therefore manifesting itself whenever formative material is presented, but it requires certain conditions which the cell-membrane alone affords. The nuclei, when free, never grow to any considerable extent, and especially not in one particular direction.2 B. The Nature of the Contents, and the Functions of Cells. Usually the contents of a cell may be regarded as a "moderately concentrated solution of albuminous elements with alkaline and earthy salts, and dissolved or suspended fatty particles." Different cells, however, differ greatly in this respect; some one of these con- stituents greatly predominating in some, while in others altogether different substances may be found. The nerve-cells abound in albu- minous elements; adipose cells, and those of the sebaceous follicles and of milk-glands, in fat; while in certain other cells, hasmatine, melanine, or biliary or urinary constituents, abound. The functions performed by cells, as inferred from the phenomena manifested by their contents, may be specified under the heads of 1 According to Schwann, the cell-membrane exerts an attractive influence upon the surrounding fluid, and causes the deposition of newly formed particles in its substance ; and partial growth occurs when the molecules do not all attract equally, but only, or more particularly, at certain points. 2 The nuclei in the hair-pulp, tooth-pulp, areolar tissue, and smooth muscular fibre, however, grow in one direction, to a considerable extent, these not being free. 128 SIMPLE HISTOLOGICAL ELEMENTS. absorption, secretion, and contraction. These vital actions depend much on physical and chemical conditions, and may, to a great extent, be subjected to microscopic investigation. 1. Absorption must be distinguished from mere endosmosis, since the nutrition of the cell (a vital and not a mere physical process), depends on the former, and some of the constituents of the sur- rounding fluid are introduced through the cell-membrane, while the rest are rejected. Thus the contents of all cells are chemically different from the surrounding cytoblastema. For instance, the blood-corpuscles contain more potassa than the liquor sanguinis. Doubtless the chemical composition of the cell-contents and the surrounding fluid, and the thickness of the cell-membrane, also exert an influence on this process; nor must endosmosis be entirely overlooked in this connection, since cells are known to dilate in diluted, and to contract in concentrated solutions. The vital processes in cells produce changes both in their walls and in their contents. The membranes generally become denser, and of a different chemical constitution, with age; though whether the membrane itself changes chemically, or an incrustation of salts occurs within, or a deposit on the exterior, are points not con- clusively settled. The changes in the cell-contents are various. The primordial cells of the embryo, at first distended with the elements of the yolk, especially with oil, gradually acquire more fluid and homogeneous contents, the granules becoming dissolved. Then, as development proceeds, various new formations appear in the cells, as hasmatine, melanine, fat, &c. But changes in cell-contents occur in adult ani- mals also. Fat-cells, in great deficiency of their nutritive elements, may lose their proper contents, and contain mere serum; or, in case of a superfluity of nutriment, they may even burst from fulness.1 The lymph-corpuscles also develop the coloring matter of the blood and the colored corpuscles, within them; and the cells which secrete the bile undergo marked changes in their contents. (Kolliker) Changes in the form of the cells accompany the preceding altera- 1 Donders has ascertained that the cell-membranes are elastic, and the contents will suffer a greater or a less pressure, according to their amount. This elasticity may conduce to the maintenance of a regular interchange of substances in the ex- cretive and absorptive processes. And the greater density of the cell-contents than of the surrounding cytoblastema may be due to the fact that they are always under greater pressure. PHYSIOLOGY OF CELLS. 129 tions in the contents, such as thickening of the membrane with laminated depositions, as in cartilage, and with the formation of minute canals; while within, also, the granules may be precipitated, fat-drops, elementary vesicles, concretions, crystals, or nuclei may be formed, and molecular movements may occur. The nuclei rarely participate in these changes, though they some- times become clear in consequence of the liquefaction of their viscid contents. Very rarely granules are developed in them; and in cer- tain animals, "urticating threads" and spermatozoids are developed in nuclei.1 2. The process of secretion is manifested by cells in two ways:— First. Their contents consist of substances received from with- out, unaltered, or slightly so; as in case of epithelium-cells, espe- cially of serous membranes, and the cells of those glands which simply separate certain substances from the blood—e. g. the lachry- mal glands and the kidneys. (Kolliker) Secondly. The cell-contents include substances prepared within the cell; as the colored blood-corpuscles, fat-cells, the bile-cells in the liver, and those (secreting the gastric fluid) of the gastric glands. 3. Contraction is sometimes manifested by cell-membranes and by the cell-contents. Contractile cell-membranes occur in many, if not all, of the Protozoa, in the yolk-cells of the Planariae, in the heart- cells of many embryos, &c. Some consider that the colorless cor- puscles of man, the frog, and the skate, mucus-corpuscles, and the cells in the meshes of the areolar tissue of the disk of the medusa, are contractile cells.2 Contractile cell-contents are found in the fibre-cells of smooth muscle, in the stellate cells of the skin of the embryo Umax, and in striped muscular fibre. Certain important changes in the cell-contents occur in patholo- gical conditions. Besides those already specified, the following may be noted here:— 1. Fatty degeneration is the most common change in cell-contents, more or less fat-drops accumulating in the cell. But it must be borne in mind that the cells in certain parts and organs normally contain a few fat-globules. 1 Thus it is very certain that the molecular and chemical changes of the cell- membrane and the nucleus are independent of each other. * Donders, however, maintains that the cell-contents only (and not the cell- membrane) are contractile. 9 130 SIMPLE HISTOLOGICAL ELEMENTS. 2. The fatty degeneration may pass into the pigmentary; which may also occur spontaneously. Here the coloring matter generally passes from deep yellow to brownish black. 3. Dropsy of cells occurs if the blood contains an undue amount of water. (Wedl) 4. Crystals form in cells from the absorption of the watery por- tion of the cell-contents. 5. Atrophy or involution (Wedl) of cells may occur, in conse- quence of a diminished supply of nutrient fluid. Primordial Cells. Schwann discovered that all the tissues of animals,1 as well as of plants, are developed originally from nucleated cells; and to these the name of primordial cells has been given. They present nothing peculiar in their microscopic appearance, however; containing the five elements already mentioned as usually characterizing a cell (p. 114). We find in the embryo a mass of cells, for instance, which are to develop bone; another to form muscle; a third, fibrous tissue, &c. But though the microscope does not enable us to detect any original difference in them, their vital properties must differ, as the developmental result demonstrates. Schwann's assertion, however, applies only to the tissues proper, and not to the simple histological elements already described. Simple fibre and simple membrane are, for example, lower develop- ments than cells, and are not formed from the latter. On the con- trary, cells have their walls formed of simple membrane, as has been shown. The primordial cells, therefore, need no further notice here, since it is in respect to their functions, and not as mere histological ele- ments, that they are peculiar. Besides, the manner in which each tissue is developed from its primordial, cells, and the peculiarities of the latter in each case, will be explained in the division of this work upon the "Tissues proper." Before proceeding to speak of the fluids, however, certain cells which are either found isolated, or, at least, do not coalesce to form tissues, will be described. 1 This discovery was announced in 1839. Schleiden had previously shown that the tissues of plants are formed from cells. PIGMENT-CELLS. 131 Isolated Cells : Cells not coalescing to form Tissues. Under the head of isolated cells, Carpenter includes the white and the colored blood-corpuscles, epidermis and epithelium, the cells containing the spermatozoids of the semen, and absorbing and secreting cells. Epidermis and epithelium, however, perform their functions as a distinct tissue, and will therefore be included in the classification of the tissues proper. Secreting cells will be described in connection with the various glands containing them; and the blood-cells of both kinds, and the spermatophori, will be considered in connection with the fluids of which they respectively constitute a part. The only kind of cells to be considered here, as being normally scattered in the interstices of the tissues, and not forming a tissue by themselves, is the pigment-cell; after which the various forms of cancer-cells will be described, as constituting one of the most im- portant of the pathological developments. The isolated cells in the nervous centres will be described in the chapter on "Nerve-tissue." I. Pigment-cells. Pigment-cells derive their peculiarities from the fact that the granules they contain are colored, consisting of the immediate prin- ciple melanine, described on page 103. As this principle abounds in carbon, neither chlorine nor strong acids remove the color of the granules. The latter are often found lying among the cells, as well as within them. They are also among the minutest objects in nature, being often less than 33^ of an inch in diameter. It has been shown that melanine is probably derived from haema- tine, and, like the latter, has iron associated with it; the pigment of the choroid coat of the eye containing .254 per cent, of this metal. Distribution of Pigment cells. In the human body, the distribution of pigment-cells is quite limited. In the eye, they are found on the inner surface of the choroid membrane, on the ciliary processes and the iris (uvei), and between the choroid and the sclerotica. They also exist in the skin of the perineum and of the genital organs, especially of the scrotum, and in the areola of the mammary gland. Pigment-granules also 132 simple histological elements. give the gray color to the cells of the cortical substance of the cerebrum and cerebellum, and the central part of each half of the spinal cord; and pigment-cells are also found in the cervical pia mater and the membranous labyrinth. In negroes, the skin also contains a layer of pigment-cells over the whole surface of the body; and to this its blackness is due. This is the last formed and deepest layer, consisting of cells lying directly on the basement membrane of the skin. Similar cells, darker than the rest, also exist in this layer of the skin of Eu- ropeans, but their pigment is of a lighter color. In fact, the differ- ence in amount and color of pigment in this layer of cells gives rise to all the varieties of color presented by the different races of men. Fig. 68 repre- sents the appearance of the several layers of cells in the cuticle of the Section of the cuticle of the negro. neffr0# Jn ^q outer layers, which are a. Deep cells, loaded with pigment, b. ° # . Ceiis at a higher level, paier and more flattened into scales, the pigment is flattened c Cells at the surface, scaly tirel abgent jf the cuticle of fae and colorless, as in the white races. J negro be removed by a blister, the pigment-cells on its inner surface will be found clustered together around circular spots of a bright color where the cells are wanting. The spots correspond to the depressions in the under surface of the cuticle into which the papillae of the skin projected. On the other hand, in albinoes1 no pigment-granules are found in the epidermis at all. Freckles upon the skin of the white races, whether congenital or otherwise, are also due to a development of pigment-cells in the layer next underneath the epidermis—the Malpighian stratum. The pigment in the lungs of man and the lower animals, both under the pleura and in the parenchyma, is in the form of granules; but which are not contained within cells. They are probably mere particles of carbon. In the lower animals, a single lobe is some- times quite black, while the rest remains unchanged; though a section of it shows that its function is not essentially, if at all, im- paired by the deposit. So called from albus, white. PIGMENT-CELLS. 133 Peculiarities of Form of Pigment-cells. Generally, pigment-cells present no« peculiarities of form; but those (the pigmentum nigrum) of the choroid membrane of the eye are of a hexagonal- form, resembling pavement epithelium. (Fig. 69.) Those between the choroid and the sclerotica are somewhat Fig. 69. Fig. 70. Pigmentum nigrum of adult human subject, a. Cells forming epithelium of the choroid, b. Irregular cells from substance of choroid. Nuclei visible at a; pig- ment granules, b. Cells between the choroid and sclerotic of the sheep. (Queckett.) Fig. 71. fusiform, and sometimes have bifid extremities. Their appearance, as found in the sheep, is shown by Fig. 70. In both these figures the nuclei are seen to be white. In albinoes there are no pigment-granules in the cells on the choroid, and hence they are not pigment-cells. Fig. 71 shows the appearance of the cells of the pigmentum nigrum of a black rab- bit at A, and of the white (albino) rab- bit at B. In the human foetus, also, the granules are less numerous than in the adult. The pigment-cells of the human skin also often present the hexagonal form; they being here, in fact, epithelial (epidermic) cells. A. Cells on choroid of black rabbit. b. Cells on choroid of white rabbit, des- titute of pigment granules. (Queckett.) Distribution of Pigment-cells in the Lower Animals. In the lower animals, pigment-cells present a variety of forms. In the skin of the lamprey they resemble the lacunae and pores of bone. (Fig. 72.) In the skin of the frog, and some other reptiles, they are of a more stellate form. (Fig. 73.) In the iris of the tiger 134 SIMPLE HISTOLOGICAL ELEMENTS. Fig. 72. Fig. 73. S8^ll§i§8 Pigment-cells of the skin of the lamprey. (Queckett.) boa (Python tigris), white pigment-cells are found. (Queckett.) The red spots on the skin of the plaice are produced by minute, irregular cells. Pigment-cells are often found in the peritoneum of fishes and reptiles; and the pigment se- creted in its ink-bag, so called, by the cuttle-fish, is used by artists under the name of "sepia." Pigment-cells in tail of the tadpole. The transparent ones are the young cells, in which the pigment granules have not yet appeared. Color of the Hair and Eyes. In connection with the color of the skin, that of the hair and eyes should be alluded to; though the coloring matter may be otherwise than black in case of either, and therefore is not always melanine. The pigment coloring the hair is found generally both in the cortical and in the medullary portions of the shaft; and since hair is an epithelial appendage, as will be shown, we might expect that its color will correspond, within certain limits, with that of the skin. Spots of black hair are found (as in the hog) to grow on patches of skin of the same color. In the albino, on the other hand, the hair is colorless. For the particulars,.however, consult the section on "The Hair." The color of the eye is determined by that of the iris, as is ex- plained in the last chapter of this work. It is blue, hazel, and, in some cases, nearly jet black. The conformity of color with that of the skin (or the complexion) is not so rigid as is that of the hair; and yet the disparity ranges within certain limits. The irides of albinoes are of a pink color; since, not being covered with pigment- cells, the numerous very minute bloodvessels of the iris are visible, PIGMENT-CELLS. 135 The sebaceous follicles of the skin being Fig- 74. in close relation with the hair-bulbs, are sometimes found distended with pigment. This is especially the case in acne, a dis- ease essentially consisting of an enlarge- ment and suppuration of the sebaceous follicles, and in which masses of black matter may be pressed from them. Fig. 74 shows a section of the skin of the nose having a stratum of black pigment , .. . . Section of skin of the nose, showing in the deepest portion of the cuticle, pigment. (Queckett.) which also dips down into the sebaceous follicles, seen on each side of the two hairs growing from the corium. Development of Pigment-cells. The stimulus of solar light doubtless exerts an influence on the development of the pigment-granules. In many persons a strong sunlight produces freckles; and exposure for several years to a tropical climate renders the fairest complexion sallow. The Dutch who have for several generations resided in Africa, have at length become so black as to be distinguished from the natives by their features only, and not by their color. The natives of the torrid zone almost invariably have black hair and eyes. The infant negro is scarcely darker than the white during the first few days after birth.1 The genital organs become colored on the third day, and the whole body on the fifth and sixth. The stimulus of solar light is essential to the development of the green pigment (chlorophyl) of plants, which also consists, in great part, of carbon; and with this fact the preceding may be naturally associated. Functions of Pigment-cells. The pigment-cells in the pigmentum nigrum of the eye are im- portant principally in the way of interrupting or absorbing light, and thus contributing to the perfection of vision. Hence albinoes cannot see well in the full light of a sunny day. In the substance and on the posterior surface of the iris, however, the pigment-cells 1 Some writers maintain that the different varieties of the human race are due to climatic influences, exerted through a long succession of generations. If color alone were to be taken into the account, this idea would be more plausible. 136 SIMPLE HISTOLOGICAL ELEMENTS. seem to be intended, at the same time, for ornament also—giving the peculiar color to the eye. The variously colored cells on the surface of the lower animals apparently subserve the latter object alone. We cannot, however, remark the same in regard to the colored spots on the peritoneum of some of them. The presence of pigment-cells in the epithelium of the skin of man bears some relation to the degree of solar light and heat to which it is exposed; but which is not well understood. Pigment-cells abound, as has been stated, in the human brain and spinal cord. That the function of these organs, or of even the cells, does not depend on the color of the contained granules, may be inferred from the fact that in the spinal cord of the frog the cells contain colorless, instead of colored, granules. The fact that the pigment-granules in the epidermic cells of the areolae around the mammilla of the human female are increased in pregnancy, is well known, and its darker color is regarded as one of the signs of that condition. We can only associate this fact with the development of the whole mammary gland at the same time, in consequence of the sympathy existing between it and the uterus. It may also be added that an increased tendency to develop pigment-granules is often manifested in other parts of the body during the last weeks of pregnancy, in the form of freckles, espe- cially of the face, neck, and upper part of the chest. Regeneration of Pigment-cells. In the case of a young man who had a congenital black spot on the skin just below the angle of the mouth, a blister was applied to remove the epidermis, and then the nitrate of silver till the corium was completely abraded. Still, the pigment-cells were reproduced as abundantly as before. In case of ephelis hepatica affecting the forehead, cheek, or back of the neck, the same experiment has been followed by the same result. After such failure, however, the pig- ment has sometimes spontaneously disappeared. In negroes, if a portion of the skin be lost, that which replaces it, for a long time, is deficient in pigment-cells. In some cases, however, the new skin, after many years, becomes as black as the original integument. Pathological Formation of Pigment-cells. The abnormal development of pigment-cells or granules in the tissues constitutes melanosis. The latter is not, therefore, itself ma- CANCER-CELLS. 137 lignant, but it often forms a part of cancerous and other malignant growths. Pigment-cells developed on patches of skin (most fre- quently of the forehead or other part of the face) constitute the disease called ephelis hepatica; it being usually associated with disease, often merely functional, of the liver. A different form of deposit of pigment on the skin is also mentioned by Queckett, in which it could be brushed off from the surface with a camel's-hair pencil. It is believed that the face only is liable to this form of deposit; and its actual existence is to be distinguished from some other pigment purposely applied by the patient (usually a female) to deceive the medical attendant. Moles and freckles, when congenital, are due to a deposit of pig- ment-cells, from a cause not understood. The deposit of pigment sometimes occurring in cases of acne has already been mentioned. II. Cancer-cells. Cancerous masses consist of the four following elements, in addi- tion to bloodvessels:— 1. A matrix of homogeneous substance, either hyaline or gran- ular. 2. Fibres more or less approaching those of white fibrous tissue in appearance. 3. A great variety of cells and nuclei, some of which are gene- rally regarded as peculiar to cancer. 4. A peculiar cream-like fluid, termed the "cancer-juice." These elements vary extremely in their proportion in the different forms of cancer, of which three are usually designated:— 1. Scirrhus, or fibrous cancer, in which the homogeneous matrix and the fibres, one or both, predominate. (Fig. 75.) 2. Encephaloid, or cellular cancer, being constituted mainly of cells. (Fig. 76.) 3. Colloid cancer, in which there is a predominance of a peculiar ge- latinous fluid. These three forms are often found coexisting in the same cancerous mass. Melanotic cancer is distin- guished merely from having pig- ment-cells added to the cancer ele- ments. (Fig. 77.) Neither the homogeneous matrix Cancer-cells in a fibrous stroma. 138 SIMPLE HISTOLOGICAL ELEMENTS. nor the fibres can be regarded as peculiar to cancer. Only the cells and the cancer-fluid are so. But, in encephaloid cancer, the fluid is Fig. 76 Fig. 77. Encephaloid. Simple and compound cancer-cells, Melanotic cancer. (Bennett.) not always found. The cells alone will be here described; and the investigations of Dr. F. Donaldson, of Baltimore, will be quoted, as the most explicit account hitherto given of their various forms.1 With a power of 555 diameters, Dr. D. found that the cells, the nuclei, and the nucleoli existing in cancer are all peculiar to it. A. The cancer-nuclei (Fig. 78), whether inclosed in a cell or free, are, in their form and appearance, the most constant and unva- rying of all the cancer ele- 78. ments. They are generally round or ovoid in shape, with a length of from %■£$■$ to i^g 5 of an inch. Their contour is dark and well defined, the interior con- taining minute granules. In width they measure from 33>2? to ^vs of an inch. It is noticeable that while in other cells the nucleus is generally found near the centre, in cancer no rule in this respect is observed. Two or more nuclei, with their nucleoli, both of great size in pro- portion to the diameter of Cancer nuclei, a. Type form. b. The same, with a piece nicked out of the side accidentally, c. Shows a free nu- cleus in which the molecular granules are very minute, often met with in perfectly fresh specimens, d. A nucleus in which larger grannies have commenced to form. e. The characteristic nucleolus, with its dark contour and bright centre, h. Fine molecular granules, i. The second va- riety of granules, or gray granulations, j. Fat-granules. 1 American Journal of the Medical Sciences, vol. xxv. p. 43. CANCER-CELLS. 139 the cell, are often seen in all the varieties of cancer-cells; while other cells, as the epithelial, rarely have more than one. B. The nucleoli are of a yellowish tinge and peculiar brightness, and average 72575(5 of an inch in diameter. Sometimes two or three are found in the same cell. For the perfect exhibition of these cha- racteristics of cancer-nucleoli, it is necessary that the specimen be fresh. M. Robin notices the action of acetic acid upon cancer-nuclei and their nucleoli as peculiar, since it renders the nucleus and cell gra- dually paler, though destroying neither, while the nucleolus is en- tirely unaffected by it (p. 116). C. Cells.—Cancer-cells present a considerable diversity of form. Dr. Donaldson mentions the following varieties:— 1. The polygonal or more or less spherical and ovoid cell. 2. The caudated cell. 3. The fusiform cell. 4. The concentric cell. 5. The compound or mother cell. 6. Agglomerated nuclei connected by granular homogeneous substance. 1. The polygonal cell (Fig. 79) may be regarded as the type in cancer. Thus, in hard tumors the cells are found irregular, and sometimes almost triangular in form. In medullary (encephaloid) cancer, cells of an ovoid or spherical shape are oftenest met with. Fig. 79. Polygonal cancer-cells, g. Spherical cells, a. Dark contour of inclosed nucleus, e. The nucle- olus, k. A nucleus with its contour pressed out of shape. I. A form of cell frequently seen, where there is a deficiency of part of the wall. /. From pressure rendered triangular, 140 SIMPLE HISTOLOGICAL ELEMENTS. Perfectly round cells are rarely seen; though cells approaching this form, of variable diameter, are often discovered. 2. Caudated Cells.—This form is invariably found in the bladder, and was formerly considered the cancer-cell. It is of irregular form, Fig. 80. Caudated cancer-cells, m. The most usual forms, n. Cells containing double nuclei. Cancer of the bladder invariably contains this variety. having Fig. 81. from two to five prolongations or poles branching off from the body of the cell. (Fig. 80.) 3. Fusiform Cancer-cell (Fig. 81). —This shape is caused by a swelling in the centre, the' ends being point- ed so as to form an acute angle. M. Robin has invariably found it when- ever cancer has attacked the bones. These cells somewhat resemble the fusiform fibres of fibro-plastic tissue1 (Fig. 82), but may be distinguished from them by their greater width and length, the presence of the clear, bright centre, and the greater size of the nuclei. Fusiform cancer-cells, o. The nucleus, which in this variety of cell is almost constantly ovoid. The transverse diameter of the cell, and the size of the nucleus in proportion to the cell, together with the characteristic nucleolus, distinguish this variety from the fusiform fibro-plastic element. ~ 1 And have been mistaken for them by some observers. CANCER-CELLS. 141 Fig. 82. Fig. 83. Fusiform fibres of fibro-plastic tissue. 4. The narrow Two concentric cancer-cells, a. The and long fusiform cell, containing a nucleus (5) with a cancer-nucleus, the size of which is al- small dot in its centre for a nucleolus. Average length ways in proportion to the innermost cir- of cell, l-300th of an inch. cle. e. The trilliant nncieolus. 4. The concentric cancer-cell is formed of an ovoid or spherical body, surrounded by concentric rings, increasing in size as they go further out. This variety Fl8- 84, never forms the basis of a Compound cancer-cells, a. Nucleus : when there are more Agglomerated cancer-nuclei, a. than one nucleus within a cell, they are smaller than the sin- Nucleus, p. Granular homogene- gle nucleus, o. From Lebert. ous matrix. authors, of their splitting up into smaller segments, and multiplying by division. They are of variable form, and often contain three, four, or more cancer-nuclei. (Figs. 84 and 64.) 6. Agglomerated nuclei are also rarely met with, which seem to be held together by the granular homogeneous substance in which they are generated. They seem to have no cell-wall about them, and may be recognized by the bulk of their envelop. (Fig. 85.) 142 SIMPLE HISTOLOGICAL ELEMENTS. Elements liable to be mistaken for Cancer-cells. It is important, in this connection, to specify the histological ele- ments which may be mistaken by the microscopist for the cancer- cells just described; though, with the exception of the first two, the distinction is easily made at a glance. 1. The fusiform corpuscles of fibroblastic tissue1 are often as much as ^i„ to =1^ of an inch long. Their comparative narrowness, the smallness of their nuclei, the nucleolus, and, indeed, their whole aspect, distin- guish them from cancer-cells; They have already been shown by Fig. 82. 2. The fibro-plastic cells and their free nuclei (Fig. 86) may be mistaken for cancer-cells by a superficial observer. These cells are ovoid, sometimes poly- gonal, and vary from z^ to yg1^ of an inch in diameter. The nucleus and nucleolus, however, appear different from those of cancer, and the granules they contain are very much finer and of more uniform size. The free nuclei are so much smaller as to be at once recognized. Both of the fibro-plastic elements just mentioned are found in the brain, blad- der, ovaries, mammary gland, uterus, &c, and in the healthy state as well as in inflammatory products. These will also be found with cancer-cells, if inflam- mation has existed in a cancerous de- posit. 3. Mr. Bennett thinks that the cells escaping from the cavities of enchondro- matous tumors, while they are softening, may be mistaken for cancer-cells. Dr. Donaldson does not accept this as pro- bable. 4. Nor can pus-corpuscles be mis- taken for cancer-cells, though often found mixed with the latter. 5. The appearance of tubercle-corpus- cles, as contrasted with cancer-cells, is shown in Fig. 87. The former were, however, magnified 833 times, the cancer-cells but 555 times. 6. The contrast between epithelial cells in different stages of de- 1 This is a phrase applied to the fibres, cells, &c, developed in exuded plasma, generally in case of inflammation. 4 O U I I O Spherical fibro-plastic cells. 6. Well- marked cell. 7 and 8. Nuclei inclosed in cells or floating free ; transverse dia- meter, l-5000th inch. Fig. 87. Tubercle-corpuscles (nuclei) distin- guishedfrom cancer. 1. Corpuscles found in softened tubercular matter; small, irregularly formed, globular bodies with many nucleoli. 2. Nucleoli and inte- rior granules. 3. Free, loose granules. CANCER-CELLS. 143 velopment, and of the various kinds, and cancer-cells, is seen in the four next figures (Figs. 88 to 91). Fig. 88. Fig. 89. Young epithelial cells filled with few and small granules, w. Cell-wall. x. The nu- cleus, very small in proportion to cell, and containing no nucleolus. (Lebert.) Cells from the epidermis, y. Nucleus without nucle- olus, diminutive in proportion to cell. i. The cell, with homogeneous minute granulations filling up the cen- tre. Diameter of the cell, when taken from the skin, l-250th inch. Fig. 91. Buccal epithelial scales. 11. Irregularly poly- Ciliated epithelium from air-passages. 9. gonal contour. 12. The characteristic nucleus Hair-like appendages (cilia), which, during without any appearance of a nucleolus; which is life, are constantly in motion. 10. Nucleus clear rarely met with in epidermic cells, or in those com- in the centre. ing from the buccal surface. Since crystals of cholesterine, of ammonio-magnesian phosphate, and of margarine, fat-globules, filaments, and pus, may be found mixed with cancer-cells, Dr. Donaldson insists upon the examination of every part of a mass supposed to be cancerous, before deciding that it is not so. "If but one cancer-cell be found, it is conclusive," says Dr. Donaldson; a proposition, however, which should not be practically adopted, as will appear. "Out of the body, cancer elements change more rapidly than any others; nor can they be preserved in any fluid;" therefore they should be examined at once. Within the first day they may become degenerated by the appearance of fatty granules, which often hide their distinctive characteristics. Epithelial cancer will be spoken of in connection with " Epithe- lium." Much discussion has arisen, of late, in regard to the value of the microscope in the diagnosis of cancer; one party contending that this instrument is totally unreliable in this respect, while the oppo- 144 SIMPLE HISTOLOGICAL ELEMENTS. site would rely upon it alone. The following is believed to be the only tenable view of this subject:— 1. In all cases of well-developed cancerous formation, the micro- scope, in the hands of one skilled in its use, will alone demonstrate the true character of the growth, unaided by any knowledge of its appearance to the naked eye, of its tactile properties, or of the his- tory of the case. This - it will do by detecting one or more of the peculiar forms of cell or nucleus already described. Here, therefore, the diagnosis may be positively expressed in the affirmative. 2. But there are all possible grades of development, from the en- cephaloid, as the most strongly pronounced form of cancer, to the fibrous cancer, and onward to the simple, innocent sarcoma. There will, therefore, be a corresponding shading-off of the peculiarities of the minute cancer elements (cells, nuclei, &c.) into the normal elements of the tissues. Besides, when cancer-cells are still young, they do not present the peculiarities before mentioned.1 In the imperfect or early development of cancer, therefore, the cancer-cell may so nearly resemble the fibro-plastic or some other cell, that a microscopic discrimination is impossible. Here, then, the microscopic diagnosis must be guarded, and the history of the case and the other sensible properties of the growth must decide. 3. The cancer elements may exist in small amount in a mass sup- posed to be cancerous, and in the midst of a variety of other minute elements, and therefore escape detection. If so, the microscopic diagnosis is inferentially negative, but not unqualifiedly so. The unaided eye, the sense of touch, and the history of the case may, however, together, decide the diagnosis unqualifiedly, either in the affirmative or the negative. 4. In cases of well-developed cancer, therefore, the microscope, since it alone may decide the diagnosis, is in the highest degree reliable. In the other two cases mentioned, it is less reliable than the other means alluded to; but here, also, it may prove of the highest value, by confirming or opposing the diagnosis suggested by them. It is the absurd assumption that the microscope can de- cide in every possible case, which has brought the instrument into disrepute. It merely enables us to see what would be invisible without it; and gives, so far as the minute elements are concerned, an advantage over those who refuse to use it, like that which one who has perfect sight enjoys in respect to things visible to the naked eye, as compared with the purblind. But as the unaided sight alone is almost never expected to decide, in case of suspected cancer, without regard to the tactile properties and the history of the case; so the sight, when aided by the microscope—for it is mere sight still—must not, except in a single class of cases, be relied upon alone. In these it should be recognized as an arbiter in the diagnosis of cancer; in all other cases it is merely a valuable aid. 1 All pathological newly-formed cells have no especial character peculiar to them. (Wedl, p. 66.) SECOND DIVISION. THE FLUIDS OF THE HUMAN BODY (HYGROLOGY1). In their histological relations, the fluids may be considered under the four following chapters:— I. The blood, including lymph and chyle. II. Serous secretions and transudations (effusions), and exudations. III. Mucous and glandular secretions. IV. The cutaneous secretions. There is, however, one histological element which is common to no less than six of the fluids about to be considered, and this will be described before entering upon the fluids individually. This element is the "cytoid corpuscle"2 (Henle), and which has been variously termed the lymph-corpuscle, the chyle-corpuscle, the co- lorless blood-corpuscle, the mucus, the pus, and the exudation-cor- puscle, accordingly as it has been found in these six fluids respect- ively. Cytoid corpuscles (Fig. 92) have a granular investing membrane or cell-wall, and contain either a single round and occasionally oval or reniform nucleus, or several nuclei heaped one upon another. They are not perfectly spherical. Flg" 92, Their diameter varies with the specific gravity of the i||^ fluid containing them, since they are highly endos- , 3 motic. Hence they are larger in saliva than in pus. (©) ^) The addition of water to any fluid containing them, J . . Cytoid corpuscles causes them to enlarge, and their investing mem- of wood. 1. Nam- brane to appear less folded and smoother. Their ^^l™™ £ diameter varies, therefore, even in the same fluid, dilute acetic acid. 1 From 'vypic, wet, fluid, and xoyo;. The term Phlegmatology has also been used ; but its derivation being founded on the obsolete notions of the ancients respecting phlegm, it should be discarded. 2 /. e. cell-resembling corpuscle, L'om xJxsf, cell, and s.'h;, resemblance. 10 146 THE FLUIDS. with variations in its composition. It usually ranges between 2^UTS and 2^ou °f aQ incn in tne s^ fluids before named. Bowman re- marks that these corpuscles are usually smaller in mucus than in pus, and that they are also less distinctly granular; and Hassall asserts that they are smaller in chyle than in lymph. In the blood they are specifically lighter than the colored corpuscles, since they both contain more fat, and are also deficient in the ferruginous haematine. Cytoid corpuscles are also easily acted upon by extremely dilute mineral acids, or moderately dilute solutions of organic acids (uric, lactic, &c); all of which render the nuclear matter more perceptible. And since pus easily passes into the acid fermentation, on exposure to the air, its previously invisible nuclei are at once thus rendered apparent. Hence the "pus-corpuscle," so called, when observed,has been generally found to be more gran- ular than the "mucus-corpuscle;" and the original simple nucleus is seen to have divided into two, three, or more vesicles, in which one or two granules may be distinguished. (Fig. 93.) But the peculiar modifications un- dergone by the cytoid corpuscle, in the fluids just mentioned, will be more particularly adverted to in connection with each in detail. Development of Cytoid Corpuscles. The lymph, chyle, and colorless blood-corpuscles are uniformly regard- ed as instances of free cell-develop- ment (p. 120). It is probable that the cytoid corpuscle is always so; in pus, mucus, and exudations, as well as in the three fluids just mentioned. It appears to be a general law that cytoid corpuscles are developed in any fluid approximating, nearly in composition to the blood- plasma, since such a fluid contains their nutritive elements. The latter, of course, exist in exudations; and the relations to these of pus, which will be pointed out in the following chapter, demonstrate their presence in pus also. In mucus, the .cytoid corpuscles are also Fig. 93. Pus-corpuscles changed by acetic acid. s. The irregular contour of the corpuscle freed from the granules, leaving the nuclei clear, t. Characteristic nucleus without any nucleolus, u. Free nuclei, the walls having been destroyed, v. Remnant of contour. LYMPH. 147 probably developed in the liquor muci, the latter containing their nutritive elements; and are not secreted by the epithelial cells of the mucous membrane, as is often asserted. The idea of Gluge, that pus-corpuscles are merely free nuclei, can be adopted only by such as still maintain that there is a wide distinction between them and the mucus-corpuscle (p. 116). Functions of Cytoid Corpuscles. The colorless corpuscles of the blood are, with very valid reasons, regarded, by T. Wharton Jones, as the parent cells of the red cor- puscles ; and those of lymph and chyle are formed in these fluids preliminarily to entering the blood. In the lymphatics of the spleen, and in the thoracic duct, however, the cytoid corpuscles appear already to have developed red blood-corpuscles, and which enter the blood with the lymph and chyle. In exudations, the cytoid corpuscles constitute the basis of new tissue, as is generally understood; while in mucus and pus they appear to be developed in accordance with the law announced above, but do not advance to any higher degree of organization. CHAPTER I. THE HISTOLOGICAL EELATIONS OF THE BLOOD, INCLUDING LYMPH AND CHYLE. Since lymph and chyle are, in a physiological point of view, to be regarded as blood in its primary stages of development, some remarks on these fluids may appropriately precede the description of the blood itself. I. Lymph. Lymph, as obtained from the lymphatic vessels, is a colorless or slightly yellowish and somewhat opalescent fluid, of a saltish, insi- pid taste, with an alkaline reaction. It coagulates in from four to twenty minutes after being exposed to the air, forming a gelatinous. colorless coagulum. 148 the fluids. Seen under the microscope, lymph consists of two portions: 1. The fluid portion, or liquor lymphoz; 2. Certain morphological ele- ments. 1. The liquor lymphoz is similar in chemical composition to the liquor sanguinis, as might be expected; there being, however, more water, with less albumen and fibrine. The saline and extractive matters are, however, proportionably more abundant. It is, in fact, a dilute liquor sanguinis. The albumen varies from 4.34 (Mar- chand) to 60.02 (DHeritier) in 1,000 parts, and the fibrine from .32 to .52. Fat constitutes .264, and water 924.36 to 969.26 parts. Of the liquor sanguinis about 903 parts in 1,000 are water. Contrary to what has been asserted, the albumen and fibrine of the lymph appear to be identical with those of the blood. 2. The histological elements of lymph are—1. Cytoid corpuscles (lymph-corpuscles); 2. Fat-drops; and 3. Nucleus-like formations. 1. The cytoid corpuscles have already been described (p. .145). They average about ^fo-Q of an inch (5^-q to 225$) in diameter in this fluid (2525? Hassall). 2. The fat-globules present nothing peculiar. (See p. 73.) 3. The nucleus-like bodies are probably the still undeveloped cytoid corpuscles. It should also be added that in the lymph obtained from the lymphatics of the spleen, red corpuscles, identical with those of the blood, are found. They have also been found in the lymph of starving animals. The explanation of this fact has already been given (p. 147), though it has also been suggested that they are ob- tained from bloodvessels opened in the search for them. Origin.—Lymph is derived mainly from the overplus of the plasma exuded from the capillaries, into the parenchyma of organs for their nutrition, or for the formation of secretions. It, more- I over, contains some of the immediate principles resulting from the I dis-assimilation of the tissues. It is impossible to calculate, with any approximation to accuracy, the quantity of lymph in the human body. Bidder believes that about 28.6 pounds pass from the thoracic duct into the subclavian vein in twenty-four hours—6.6 pounds being true chyle, and 22 pounds being lymph. Few will object to the last estimate as not being sufficiently high. Uses.—Lymph, though derived from the blood, is to enter it a second time. It is, therefore, to be regarded as blood in its primary chyle. 149 stage of formation. As it traverses the lymphatic glands, and is elaborated by them, it approximates more and more nearly to the blood itself, till it is at last mingled with the latter from the thoracic and the great right lymphatic ducts. In the lowest animals the blood itself is scarcely a higher development than mere lymph, and in none of the invertebrata do lymphatic vessels exist. In the lowest vertebrata, also, no lymphatic glands are found, but lymph- atic vessels merely, and the lymph is poured directly from these into the nearest veins. II. Chyle. Chyle is the fluid obtained from the lacteals (lymphatics of the small intestine) and the thoracic duct; where it is, however, of course, mixed with lymph. It results from the digestion of certain elements of the food; and the experiments of Bernard would prove that it is derived from the fatty alone. It differs in appearance with the part of the chyliferous system from which it is obtained, and with the state of the animal as to having been lately fed or not. Indeed, lymph,alone exists in the lacteals and thoracic duct during fasting. Chyle also varies in different species of animals. Human chyle is generally a milky, opalescent, yellowish white or pale reddish fluid, with a saline and mawkish taste, and an alka- line reaction. It coagulates into a very soft, friable coagulum, in about ten minutes after its removal from the vessels. Under the microscope, the chyle shows—1. The liquor chyli; 2. The morphological elements. 1. The liquor chyli (intercellular fluid—Lehmann) is very similar to the liquor sanguinis, especially if the former be taken for exa- mination from the thoracic duct. The amount of fibrine in human chyle is not yet precisely ascertained, but it augments while the chyle is passing through the mesenteric glands. Subtracting this element from the liquor chyli, the remainder is called the chyle- serum. This resembles the blood-serum in composition, being, how- ever, poorer in albumen, while it is richer in water, fat, extractive matters, alkalies, and salts—especially the chlorides of sodium and potassium. Whether it is, like blood-serum, free from iron, is not yet positively decided. It becomes more turbid and milky if more fat is taken in the food, but not otherwise, whether animal or vege- table food be taken. The fat, however, diminishes while the fluid is passing through the mesenteric glands; partly, doubtless, from 150 THE FLUIDS. the fact that it is required for the development of the cytoid cor- puscles. 2. The histological elements of the chyle are—1. Extremely minute granules; 2. Coarse granules; 3. Distinct nuclei with nucleoli; and 4. Cytoid corpuscles. It is only during digestion, however, that these elements appear in a marked degree. 1. The granules cover the field of view like a minute veil. They constitute what Mr. Gulliver termed the molecular base of the chyle. Miiller found them to be fat-granules surrounded by a proteine-like (albuminous?) substance. Probably no true fat-globules normally exist in the chyle. To this molecular base of the chyle its turbidity and milky appearance are due. It is more abundant in proportion as the food contains more fat. 2. The coarse granules are grouped together, and appear to be held in contact by a hyaline substance. (Mutter) 3. The nuclei are sharply defined, contain nucleoli, and are some- times covered with individual granules. (Kolliker) 4. The cytoid corpuscles are identical with those of lymph (p. 148). It is, however, an interesting fact, that, while they are often 211515 0I" an inch in diameter in the lacteals, they are seldom more than f^n to 3 0^5 in the thoracic duct. . Colored blood-corpuscles are also always found in the chyle from the thoracic duct, these being either developed there from the cytoid corpuscles, or being derived from the lymphatics of the spleen, as already explained (p. 147). The quantity of the chyle entering the blood in twenty-four hours is not satisfactorily settled. Vierordt estimates it at 5| pounds; Bidder at 6.6 pounds, as already stated (p. 148). Origin.—Bernard concludes that chyle is formed by the digestion of the fat alone in the food. If this be true, chyle is scarcely other- wise than mere lymph, with an addition of fat. It is, however, very certain that not all the fat in the food is converted into chyle and absorbed by the lacteals, since the blood of the vena portae is almost twice as rich in fat during the process of digestion as during fast- ing. And, on the other hand, it is probable that the other elements of food, besides fat, are not entirely excluded from absorption by the lacteals, since the albuminous matters of the chyle are more likely to have been admitted with the fat than to have been deve- loped from the latter by the addition of nitrogen from the blood in the mesenteric glands, as has been suggested. Since, however, the THE BLOOD. 151 albumen and fibrine of the chyle may have existed in the lymph, or have been absorbed directly from the bloodvessels, it is not yet necessary to controvert the conclusion of Bernard, that the fat alone of the food is directly absorbed by the lacteals to form the chyle. The uses of the chyle need not be enlarged upon after the pre- ceding remarks upon lymph. Its abundance of fat, however, ren- ders it more prolific than the latter in the development of the cytoid corpuscles, which are to constitute an important element of the blood; and its other elements also are developed in it, as prepara- tory to their admission into the latter fluid. III. The Blood. The histological relations of the blood are all-important, since the elements for the development of the tissues, and for the forma- tion of the fluids, except chyle, are derived from it. Blood is distinguished from all other animal fluids by its bright cherry-red color, which, however, undergoes certain variations in circumstances anon to be specified. It is a thick, slightly trans- lucent fluid, with an alkaline reaction. Its specific gravity is from 1045 to 1075—averaging 1055; being less in women than in men, in children than in adults, and in pregnant women than in those not so. Normal blood solidifies or coagulates after its withdrawal from the vessels, a change depending on its fibrine, and whose properties have been specified on page 90. This process includes three pe- riods: 1. The blood becomes viscid and gelatinous in from two to four minutes after its withdrawal. 2. After seven to fourteen minutes it has become a consistent jelly. 3. The fibrine contracts and pours out from its fibrillated network a thin, colorless, or pale yellow fluid, the serum, which rises to the surface. This increases in quantity in proportion as the other part, the clot, contracts, its contraction continuing for a time varying from twelve to forty hours. The particulars respecting the fibrillation of the fibrine in the clot have been stated on page 92, and the microscopical appear- ances have been represented by Fig. 43. The clot consists of the fibrine of the blood, together with the blood-corpuscles, both red and colorless; and its lower part is of a darker, and the upper part of a brighter red than the original blood. Arterial blood coagu- lates more rapidly than venous; and the blood of women more rapidly and less firmly than that of men. 152 THE FLUIDS. Seen under the microscope, while circulating, the blood consists (1) of a fluid portion—the liquor sanguinis—containing (2) histo- logical elements of two kinds, viz., the white and the red corpuscles. Of 1,000 parts of blood, 510 to 520 are corpuscles, and from 490 to 480 are liquor sanguinis. 1. The Liquor Sanguinis. The fluid portion of the blood, called the liquor sanguinis, blood- plasma, and the intercellular fluid (Lehmann), consists of the serum already mentioned and the fibrine. Its specific gravity varies but little from 1028. It contains all the elements necessary for the de- velopment of the tissues, viz., those of the first class, fat, and the albuminous compounds of the third class. It also contains many of the principles of the second class resulting from the metamor- phosis or dis-assimilation of the tissues, as urea, creatine, &c. It may, indeed, be regarded as a solution, in 903 parts of water, of 97 parts of the principles just mentioned; for, though not all of the latter are directly soluble in water, it has been shown that all are actually in solution in the blood (pp. 55 and 48). The following is an analysis of 1,000 parts of liquor sanguinis, by Lehmann, the specific gravity being 1028:— Water .... . 902.90 1 Solid constituents . 97.10 Fibrine .... . 4.05 Albumen , . 78.84 to 98 Fat .... , , . 1.72 Extractive matters . • . 3.94 Mineral Substanct '•s (8.55). Chlorine .... . 3.644^ Sulphuric acid . . 0.115 Phosphoric acid . 0.191 Potassium . 0.323 - 8.55 Sodium .... . 3.341 Oxygen .... . 0.403 Phosphate of lime . . 0.311 Phosphate of magnesia . 0.222. The fibrine constitutes 4.05 in 1,000 of the plasma alone, and from 2 to 2.2 (about 3—Lehmann) in 1,000 of the whole blood. Arterial THE BLOOD. 153 c contains more than venous blood. There is but little in the portal vein, less in the splenic, and a mere trace or none at all in the he- patic. We shall recur (p. 158) to its uses in the blood, and its rela- tions to the tissues, after speaking of the other elements in the plasma. The serum is best obtained, in its isolated state, from coagulated blood, after the contraction of the clot has ceased. It is sometimes seen to contain a quantity of undissolved particles in suspension, which give it a milky appearance, and which consist of fat-globules, granules of precipitated albumen, or of colorless (cytoid) blood- corpuscles. The amount of water in the serum is generally directly propor- tioned to that in the whole blood, and inversely to the number of the blood-corpuscles. A very watery serum, however, necessitates an increase of water in the individual blood-corpuscles, from endos- mosis. In the serum of the blood of adult males it averages 90.5 per cent.; in that of females, especially during pregnancy, somewhat more. Arterial blood contains more water than that of the veins; that of the portal vein, however, contains the most water of all of the latter, especially during digestion, and the blood of the hepatic vein less than that of any other vessel. The serum becomes more watery in most diseases, except in the first stages of typhus fever, measles, scarlet fever, and cholera. The blood of the amphibia contains more water, and that of birds less, than the blood of the mammalia. The principal constituent of the blood-serum is albumen, of which there is from 7.9 to 9.8 per cent.; and from 63 to 70 parts1 in 1,000 of blood. (Becquerel and Rodier) Arterial blood contains less albu- men than venous; in the horse, as 9.2 to 11.4. (Lehmann) The blood of the hepatic vein is very rich in it, while the portal vein has still less than the arteries. The quantity of albumen in the blood of the veins increases considerably during digestion. Human blood contains, on an average, more albumen than that of most mammalia. In most diseases the amount of albumen is diminished, it having been found increased only in plethora, intermittent fever, and cholera. It is not yet satisfactorily demonstrated that caseine exists in the 1 This includes about 4 parts of albuminose. (Robin and Verdeil.) Lehmann's analysis would, however, give only about 44 in 1,000 parts of blood, which is pro- bably nearer the fact. 154 THE FLUIDS. blood-serum even of pregnant women, and of the placental vessels. The "serum-caseine" may be merely albumen deficient in alkali and salts. (Lehmann) The fats of the serum consist principally of stearic, ohsic, and margaric acids, and cholesterine. What has been called "seroline" is a mixture of the crystallizable part of these fats; these prepon- derating in the serum, while the more oily and yellow-colored are found in the red corpuscles. Phosphoretted substances soluble in ether do not exist in the serum, though they do in the corpuscles. The amount of fat in the serum is not precisely determined, but it is constantly increased during digestion. It is, on the average, more abundant in the serum of women than in that of men. The blood of the veins contains more fat than that of the arteries, and the portal vein the most of all (p. 77). In diseases, the ordinary fats appear to diminish, while the cholesterine increases. Glucose, or grape sugar (p. 70), is also a constituent of the blood- serum, though in extremely small quantity. After the use of amy- laceous or saccharine food it may be increased to 0.5 per cent. The blood of the hepatic vein abounds in sugar, while that of the portal vein contains only traces of it. Bernard has found that the glucose is formed in the substance of the liver, and, sometimes at least, from a nitrogenized material. M. Figuier's statement, that the sugar is formed in the portal vein and stored up in the liver, has not yet been confirmed. Urea, hippuric acid, creatine, and creatinine exist in serum, but in quantity too small to be determined. A peculiar yellow coloring matter has also been supposed to exist in it, but this is not decided. Formic, acetic, and lactic acids may also exist in the serum, since the first is formed in the perspiration, and the last in the muscles; but they have been detected only in the blood of the splenic vein. Hypoxanthine has been found in the blood of the spleen. It occurs also in case of leucaemia; as do the three acids just mentioned, and glutin. Biliary coloring matter and acids occur only in diseased blood, and sometimes when there is no decided lesion of the liver. Uric acid has been found, with certainty, only in diseased blood, especially in arthritis. Of the mineral constituents of the serum, the chloride of sodium is the most abundant, averaging 61 per cent, of the ash. Next is carbonate of soda, 28.9 per cent. Chloride of potassium varies THE BLOOD. 155 much, but averages about 4 per cent, of the ash; the phosphate of soda about 3 per cent.; while the sulphate of potassa depends mostly on the manner of incineration. The salts together average about .85 per cent, of the serum. They are more abundant in the blood of men and of adults than in that of women and children. There are more salts in arterial than in venous blood, except that of the portal blood, which contains more than that of the arteries. In case of repeated bleedings, more salts are found in the blood last drawn than in the first. The serum salts are much diminished in violent inflammations, and still more so in cholera; while they are consi- derably increased in acute exanthemata, typhus, dysentery, Bright's disease, and especially in dropsy. The carbonate of ammonia is found in the blood only in severe diseases, and especially in uraemia; and almost always in the blood of cholera patients. Origin.—The liquor sanguinis is derived from the lymph and the chyle, principally from the latter. The sources from which its mineral constituents are originally derived have been specified in connection with each of the imme- diate principles, in the first part of this work. The fats are almost entirely taken in the food. The albumen is derived directly from albuminose; the latter being formed in the small intestine, as has been shown (p. 87), from the digestion of the albuminous sub- stances (albumen, caseine, and fibrine) and the peculiar organized immediate principles (osteine, musculine, elasticine, &c.) of the food. The fibrine is also formed at once from the albuminose, or from the albumen in the blood. Uses.—From the liquor sanguinis all the tissues and the fluids, except chyle, are formed, unless the blood-corpuscles also have_, some part in the development of the former; which will be shown to be improbable when the functions of the corpuscles are discussed. Nor is it difficult to decide what is the precise function of each of the elements of the liquor sanguinis, excepting the albumen and the fibrine. The water is indispensable, both as a solvent of, and as a vehicle for carrying, the blood constituents to the capillaries; and it also enters into the composition of all the solids and fluids of the body (p. 45). The salts are essential constituents of the tissues and the fluids, and the use of each is specified in the first part of this work. E. g. common salt aids in the assimilation and the dis-assimilation of the tissues, and prevents the solution of the 156 THE FLUIDS. blood-corpuscles in the serum (p. 50). The phosphate of lime is indispensable for the formation of bone. The fats are also required for the development of adipose tissue, and the formation of all the fluids containing fat (p. 77); while the other principles of the second class, as urea, creatine, creatinine, &c, result from the dis- assimilation of the tissues, and are to be eliminated from the blood, in the excretions, as effete materials. In regard to the uses of albumen and fibrine, it is generally asserted by authors that the former exists in the blood principally as the material from which the fibrine is formed, though it also becomes solidified in certain organs (especially the nervous centres), and forms a part of the serous secretions and the transudations; while the fibrine is the only plastic or organizable element in the liquor sanguinis, and, therefore, the one from which all the tissues are formed. But in the first place, it is impossible that any single immediate principle can be the source' of all the tissues, since all of the latter consist of several of these principles combined. The phosphate and carbonate of lime are as indispensable in the formation of bone as is the organic substance which unites with them, whether it be formed from fibrine or albumen. Hence, also, both albumen and fibrine naturally have these salts and some others always associated with them (pp. 84 and 90). So far as this point is concerned, therefore, albumen may be a plastic element as well as fibrine; and it occurs at once as improbable that all the tissues can be developed and nourished from an element constituting only about g|7 part (Leh- mann) of the blood, while another similar immediate principle ex- ists in at least twenty times ("nearly twenty times'1—Lehmann) that amount. But we proceed to examine the grounds of the view usually entertained. 1. The tissues are said to be developed and nourished from fibrine only, because all plastic exudations contain fibrine. If this were true, we might also remember that they also contain albumen. But Lehmann asserts that plastic exudations are sometimes entirely deficient in fibrine.1 Fibrine, therefore, cannot be the only organ- izable element in the liquor sanguinis, at any rate; albumen must be organizable in exudations containing no fibrine. And if so in such cases, it is probably in all, for we find no exudations not 1 Physiological Chemistry, vol. ii. p. 290. THE BLOOD. 157 containing albumen. Gluge's assertion, that "the organization of fibrine into fibres and cells is a matter of direct observation," has already been quoted (p. 119). We know that it is developed into fibres by mere coagulation, but have shown that there is no proof of cells being developed from fibrine. On the other hand, they are probably never developed from fibrine, but from albumen rather; fibrine never rising to a higher organization than mere simple fibre. 2. It is asserted that false membranes are at first formed from organized fibrine alone, and that this is subsequently converted into a higher tissue, usually some modification of the areolar. It is true that the future new membrane is at first shadowed forth by the fibrillated fibrine. The latter is, however, either ultimately reab- sorbed and replaced by other permanent tissues; Flg* 94, or the fibres themselves remain, and present the appearance represented by Fig. 94. The fibril- lated fibrine constitutes the matrix or nidus in which the cells and other histological elements (if any) are developed from the albumen and other immediate principles, as there is every reason to believe; and, having per- formed this temporary function, the fibrine usually disappears. If, however, no other his- tological elements are formed in it, it sometimes remains. The fact is undoubted that it is the fibrine which is organized into the fibres, and this alone shows that it cannot be also organized into higher elements and tissues; for every histological element has its own identity and independent vitality. Hence fibres are never converted into cells, nor any one tissue into another (p. 82). It must, there- fore, be something else that is converted into cells and tissues, and we can assign no other element than the albumen. In respect to the tissues, therefore, albumen, and not fibrine, is the plastic element of the blood-plasma. Ordinarily, however, the coagulated fibrine © 6 A. Fibres in flbro-cystic tumor, b. After addition of acetic acid. 158 THE FLUIDS. must shadow forth the future tissue as its matrix, and hence it is almost always present in the plastic exudations. The histological relations of the fibrine in the liquor sanguinis are, therefore, it is believed, comprised in the following paragraphs (pp. 91 and 95):— 1. Fibrine is the primum organizatum of the liquor sanguinis, the element first organized in the plasma. It therefore becomes the matrix or nidus in which other and more permanent tissues are de- veloped. This is also the fact, whether the original development of the tissues, or the formation of pathological new growths, or the normal reparative process, be in question. Hence the blood of pregnant women contains an increase of fibrine (to 4.4 parts in 1,000) during the last two or three months of pregnancy, while the tissues of the foetus (and its blood, also) are being most rapidly developed (p. 91). 2. But fibrine has also a not less important relation to the blood itself The blood, as well as the tissues, has its own vitality to maintain; and without its power of coagulation, depending on its fibrine, the spontaneous arrest of hemorrhage would be impossible. Nor, indeed, could art long restrain it, were even the smallest vessel divided, without the aid of the clot invariably formed (p. 91). When we use pressure to arrest hemorrhage, or apply a ligature, it does so merely till the clot is formed and sufficiently organized to allow of the removal of the artificial appliances. 3. Fibrine is, therefore, a peculiar and indispensable element of the blood, merely as such; and it is surprising that so small a propor- tional amount (?^ to 3^3), has the power to secure the temporary solidification of all the blood effused in hemorrhages. Hence it may be said, indeed, that fibrine exists first and especially for the advan- tage of the blood alone; and secondly, for the benefit of the tissues. Thus, also, it appears that the vitality of the blood inheres in the fibrine; though in part only, as will appear in the sections upon the blood-corpuscles. Mr. Simon maintained that fibrine is an excremen- titious matter. Difficult, however, as it may be to account for its increase in the blood in certain pathological states, we are obliged to reject at once the idea that the blood owes its vitality, in part, and its power of self-preservation, to an effete substance floating in it. On the other hand, albumen is the great histogenetic element of the blood, since from it all the tissues are directly formed. Thus it is, indeed, directly the pabulum of the tissues. It is also, pro- THE BLOOD. 159 bably, the source of the fibrine in the plasma; both the latter and the tissues assimilating it to'themselves (p. 86). 2. The Blood-corpuscles. The blood of the lowest animals consists of a fluid merely, the analogue of the liquor sanguinis already described. As we ascend in the scale, we first find colorless corpuscles added to this por- tion; and, in the vertebrate animals, still a third element, also, the colored corpuscles. A. The Colorless Corpuscles of the Blood. The colorless corpuscles of the blood (lymph-corpuscles—Figs. 95 and 96) are the cytoid corpuscles already described (p. 145) as existing in lymph, chyle, and exuda- tions. They are far less numerous Fis- 95- than colored corpuscles (1 to 346, or even 400 in adults1), are more globu- lar, though not perfectly spherical, and are not elastic. They average ^■j1^ of an inch in diameter. They have a granular cell-membrane, or • capsule, and either a single round or colorless wood-corpuscies. (Magnified400 ._ , in diameters.) reniform nucleus, or several small nu- clei heaped upon each other. They are lighter than the red cor- puscles, since they contain a larger amount of fat, and are also de- ficient in the iron contained in the latter. The capsule is so viscid, that they possess a well-marked tendency to conglomerate into larger or smaller groups. Hence, while circulating in the capillary vessels, they are seen rolling slowly along upon the internal surface, while the red corpuscles move rapidly on in the central portion of the blood-column. Their quantitative analysis has not been attempted. The cell-membrane, or capsule, is probably an albuminous sub- stance. The contents of the cytoid corpuscles consist of an albuminous solution, containing extremely fine granules in suspension, most of which are formed, doubtless, of fat. A distinct molecular motion is produced in them by the endosmotic action of water. 1 Moleschott finds the proportion in children 2£ to 12 years old, as 1 to 226 ; at 22 years, 1 to 330 ; 30 to 50 years, 1 to 346 ; 60 to 80 years, 1 to 381; women when menstruating, 1 to 247 ; not menstruating, 1 to 389 ; in pregnancy, 1 to 281. 160 THE FLUIDS. The nuclei are single, double, triple, or multiple. They are ren- dered more visible by the action of water, but dilute acetic acid exposes them by dissolving the cell-wall. The size of the colorless corpuscles is varied by the endosmotic action of the fluid portion of the blood; hence the richer the blood is in water, the larger they are, and vice versa (p. 145). The cytoid corpuscles of the blood are more abundant in young animals, and after venesection; and in the blood of pregnant women during the last months of pregnancy. They are also more abun- dant in venous blood. (Kolliker) An abnormal development of them constitutes leucaemia. Pyaemia, also, is scarcely distinguish- able from the latter, since the pus-corpuscle is not to be distin- guished from that under consideration, as will be shown under the head of "Pus." Origin.—The colorless blood-corpuscles, like all other cytoid cor- puscles (p. 146), are originally developed, by free cell-development, in the lymph, the chyle, and perhaps also the liquor sanguinis. Secondarily, however, new cells may, doubtless, be developed from pre-existing ones, and thus their multiplication seems actually to occur. Lehmann states that they are, "under certain conditions, doubtless formed in the liver; but their formation, or, at all events, their development and growth, are not confined to any one definite locality, but proceed in the vessels of very different organs." Kol- liker maintains that the cytoid cor- puscles of the chyle originate in the minutest lacteals. He there found nu- clei, either free or surrounded by gran- ules, and very fragile young cells, with walls almost touching the nucleus, and states that they increase in size on their way to the thoracic duct. In the latter he found none of these nuclei, but two kinds (larger and smaller) of lymph-granules; and maintains that the smaller only are converted into the red blood-corpuscles, while the larger are gradually dissolved in the blood. The various phases of their development are shown in Fig. 96. Uses.—Histologically, the cytoid cor- Fig. 96. Colorless blood-corpuscles in various phases, a, a. Stellate form occasionally seen after escape of their contents, b, b. Free nuclei, c. A nucleus surrounded by a few granules, d, e. Small cells, some with a distinct nucleus. /, g. Larger cells, one with a visible nucleus, h. Similar cell after addition of water, i. Similar cell after addition of acetic acid. THE BLOOD. 161 puscles of the blood (especially the smaller) may be regarded as merely a transitional stage of development of the red corpuscles. The idea of Kolliker, however, that they are not all converted into the colored corpuscles in the human body, is confirmed by com- parative histology; since in all the white-blooded animals they are arrested in their development, and -form no colored corpuscles, though they are in some animals quite abundant. The manner in which the red corpuscles are developed from those under consideration will be specified in the following section (p. 168). But it should be here added that even in the white-blooded animals they cannot, during their development and their metamor- phosis, be without influence on the composition of the blood, and thus, directly or indirectly, on the development and the metamor- phosis of the tissues. Besides, they will incidentally secure a patulous condition of the minute vessels, and thus subserve the circulation of the liquor sanguinis in these species. The former remark may also be applied to the human cytoid corpuscles, since they are living cells manifesting an active interchange of matter with the blood-plasma. To them, therefore, as well as to the fibrine, the blood owes its vitality. Those who maintain that fibrine is the pabulum of all the tissues, have suggested that the colorless corpuscles elaborate fibrine from the albumen in the blood. This is quite improbable; for though the amount of fibrine and the number of colorless corpuscles are sometimes simultaneously increased (as in inflammation), there are no grounds for the opinion that these cells contain any fibrine at all.1 In leucaemia, also, the cells are abnormally numerous (even one to three red blood-corpuscles), while the fibrine is not increased; and the same is also true of the blood of young and growing animals. They are, therefore, to be regarded as entirely independent, histologically, of fibrine, and their increase or dimi- nution must be attributed to causes acting independently upon them. Wherever growth is going on, cytoid corpuscles appear— e. g. in new formations, reparative or otherwise, or in the original development of the tissues—and it might be expected that they would be developed rapidly in the blood also of young animals, as one of its normal constituents; its metamorphosis being rapid, as 1 An increase of fibrine in the blood is perhaps always attended by an increase of white corpuscles, but the converse of this does not hold. 11 162 THE FLUIDS. well as that of the tissues. On the other hand, in leucaemia there appears to be rather a general arrest of development of the white corpuscles, and thus a great proportional diminution of the colored ones. That the cytoid corpuscles of the blood are also liable to dis- ease, especially to fatty degeneration, is a fact recently established by the investigations of Wedl and others. Fig. 97. Colored blood-corpuscles. (Magnified 400 diameters.) B. The Colored Blood-corpuscles. The colored blood-corpuscles (red corpuscles, blood-cells, blood- disks—Fig. 97), which, in their natural or moist state, constitute 510 to 520 parts in 1,000 of blood, and about one-half of its mass, are thick, circular, slightly biconcave disks,' ave- raging Wsu of an incn (Wtjo- t0 st*™ Hassall) in diameter. Their thickness at the circumference is about one-fifth of their diameter. Their specific gra- vity is 1088.5 to 1088.9 in men, and 1086 to 1088 in women. They consist of a colorless cell-membrane, with red, or, by transmitted light, yellow viscid contents. Some of them are also originally found to contain one or more amorphous granules, but none ever contain a nucleus. The corpuscles of the embryo are somewhat larger than they are after birth. All the mammalia have circular and discoid blood-corpuscles, except the camel, the dromedary, and the lama, in which they are elliptical and biconvex. In birds the corpuscles are long and oval, elevated in the centre, and thick at the margin; in the amphibia they are oval and very convex. Those of most mammalia are smaller than those of man, while those of the amphibia are far larger—in some cases (the pro- teus) ^3 of an inch in diameter. The following are the mean dimensions of the blood-corpuscles of several of the lower animals, compared with man (Schmidt):— Man Dog . Eabbit Rat . Pig . __i _ 3333 3T5TJO" 3TSB Mouse Ox . Cat . Horse Sheep 4T55 4BS3 i 5SUT5 ** u Elephant .3^5 Siren Proteus i 4~35 35ZF 570 0' It is evident that the blood-corpuscles and their viscid contents must have a different composition from the intercellular fluid, or THE BLOOD. 163 liquor sanguinis, in which they float. The following is Lehmann's analysis of 1,000 parts of corpuscles, the specific gravity being 1088.5, the water being to the solids as 2.14 to 1, and the or- ganic to the inorganic constituents as 40 to 1. One thousand parts of blood-corpuscles contain— Water..... . 688.00 Solids..... . 312.00 f Haematine .... . 16.75 Globuline and cell-membranes . 282.22 Fat..... 2.31 Extractive matters 2.60 Mineral substances without iron (8.12). Chlorine .... 1.686 •> Sulphuric acid 0.066 Phosphoric acid . 1.134 Potassium .... 3.328 - 8.12 Sodium .... 1.052 Oxygen .... .667 Phosphate of lime .114 Phosphate of magnesia .073 , The cell-membranes, once erroneously believed to be fibrine, when isolated, form, in the moist state, a whitish-gray adhesive mass, which has not a fixed composition. (Lehmann.) In the hepatic veins the cell-membranes are distinguished from those of all other vessels in not being made entirely to disappear by the addition of water. They are, probably, an albuminous substance; but not fibrine, nor the deutoxide of protein, as has also been stated. The viscid contents of the blood-corpuscles have been said to con- sist principally of the coloring matter called haematine, held in solu- tion by the globuline. Lehmann, however, terms it, as a whole hcemato-crystalline. We prefer the term hozmato-globuline (p. 96). There is from 18 to 26 per cent, of dry haemato-globuline in the moist corpuscles; in the whole blood, from 9 to 12 per cent. But the haematine and globuline do not stand in a definite numerical relation to each other. The insoluble ferruginous substance called haematine does not exist as such in the blood, but is a product of the transformation of the actual blood-pigment (p. 103). In the blood the latter is soluble, and it is calculated to constitute 16 to 17 164 THE FLUIDS. per cent, of the contents of the blood-corpuscles of an adult man. The iron in the ash of the corpuscles belongs to the haematine alone, and varies with it—constituting 6.64 per cent, of the haema- tine, and 4.348 per cent, of the dry corpuscles. (Schmidt}) But a considerable part of the fats of the blood is also contained in the red corpuscles—their quantity amounting to .2 or .3 per cent, of the moist cells. It appears that more fat is found in the cells of venous than of arterial blood. The so-called extractive matters also exist in the blood-corpuscles; of which, however, neither the amount nor their precise composition is known. Of the mineral constitu- ents of the blood-corpuscles, the phosphates and the combinations of potassa are in great excess over the chlorine and the sodium combinations. The common salt is confined almost entirely to the serum of the blood, as already shown. The cells of arterial blood always contain more salts than those of venous blood; but those of the hepatic vein are especially rich in them. Finally, the gases of the blood are especially contained in the corpuscles. These are carbonic acid gas, oxygen, and nitrogen. Whipped blood absorbs 1^ times its volume of carbonic acid gas, and only 15 per cent, of its volume of oxgen. Nitrogen is not more largely absorbed by blood than by water, and about equal quantities are found in arte- rial and venous blood.2 There is only more oxygen relatively to carbonic acid in arterial than venous blood; the proportions being in the former as 6 to 16, and in the latter as 4 to 16. That these gases exist in great part in the blood, and especially in the cor- puscles, in a chemical combination, though a loose one, is no longer doubtful (Lehmann)', there being from 11 to 14 times the amount that could be taken up by mere mechanical absorption. The hae- mato-globuline manifests a remarkable affinity for them. There are other gases, however, as carbonic oxide and several carbo-hydro- gens, which combine with the corpuscles so energetically as to blacken or even to destroy them. It has already been stated that the gases in the blood are in a fluid state (pp. 43, 44). 1 The metallic iron constitutes 1 part to 230 of dry corpuscles, 1 to 229 in women, 1 to 248 in pneumonitis, 1 to 269 in chlorosis, and 1 to 249 in pregnancy; in the first stage of typhus, 1 to 220. The blood-cells in the hepatic veins con- tain but two-thirds as much iron as those in the vena portae. In hydrasmia the cells contain an excess of peroxide of iron; the globuline being diminished, and thus the haematine relatively increased. (Schmidt.) Berzelius found less iron than Schmidt in the dry corpuscles. (See p. 102.) 2 Robin and Verdeil say 1£ times as much in arterial as in venous blood. THE BLOOD. 165 Fig. 98. Whipped blood also contains certain morphological elements called fibrinous flakes. They do not, however, consist of fibrine, but are more allied, chemically, to horny substances; consisting of epithelial cells, partly from the inner coat of the vessels, and partly of fragments from the cuticle of the observer, as Briich suggests, which have fallen into the blood. The fragments of destroyed cell- membranes have also been mistaken for them. I he cell-membrane of the blood-corpuscles being powerfully en- dosmotic, the latter undergo changes of form from currents between their contents and the intercellular fluid, and hence, also, changes in specific gravity. The latter, of course, increases when water is abstracted from them, and vice versa. Evaporation, or the addition to the blood of small quantities of neutral alkahne salts, sugar, or gum, may remove a part of the water; when they may present the shrivelled appearance represented by Fig. 98. Repeated bleedings also in- crease the specific gravity of the blood- corpuscles. (Lehmann) On the other hand, an increase of water in the corpuscles diminishes their specific gravity, and may distend them till they become almost spherical, or even burst. Hence their lower specific gravity in anaemia. They are also lighter when they contain an excess of fatty granules. These changes in the weight and the form of the blood-cells affect both their tendency to sink in the plasma (and thus modify the ap- pearance of the clot), and also modify the color of the blood. 1. The "tendency to sink" is increased by an increased specific gravity of the corpuscles; and, apparently, also by an excess of car- bonic acid in the corpuscles, and a diminished quantity of albumen in the serum. At least, the blood in inflammations manifests the pecu- liarities of composition just mentioned; and in this state, also, the corpuscles sink more rapidly than those of healthy blood. The effect of this peculiarity on the color of the clot has been alluded to (p. 93). The aggregation of the Biood-corpuscies in num- corpuscles into nummular roUs (Fig. 99) seems m*ar ™"a- Surface9 en; 1 \ o / tirely adherent at o, and to be a consequence, rather than a cause, of this partially at b. Blood-corpuscles shriveUed by chemical Fig. 99. 166 THE FLUIDS. increased tendency to sink, since, on sinking, they necessarily apply their broad sides to each other. 2. The precise color of the blood, as a whole, depends very much on the shape of the blood-corpuscles, and therefore indirectly upon physical conditions, some of which have been already mentioned. While the corpuscles retain the biconcave form, their color is lighter; when distended by endosmosis so as to become biconvex, they disperse the light more, and thus render the blood, as a whole, darker. Hence all substances abstracting water from the blood-cells without decomposing them, and thus rendering their central de- pression more distinct, produce in it a bright red to a vermilion color—as all neutral alkaline salts, solutions of sugar, &c; while those agents which render them more nearly spherical—as water, ether, and dilute organic acids—give to the blood a dark bluish-red color. Still, the form alone does not always determine the color; for the blood-cells of the amphibia are naturally biconvex, and can- not become biconcave, and yet they are colored bright red by the solutions of sugar and of the salts mentioned above. The following salts produce a vermilion color in the blood of the mammalia, of birds, and of the amphibia: sulphates of potash and soda, nitrates of potash and soda, chloride of potassium, phosphate of soda, car- bonate and bicarbonate of soda, ferro-cyanide of potassium, borax, iodide of potassium, sulpho-cyanide of potassium, sal ammoniac, sulphate of magnesia, &c. But the thickness of the cell-membranes, and their amount of folding, must also influence the color of the blood. If the cells are collapsed, the membrane is thicker and folded; if distended, they are thinner and smooth. In the latter case, the coloring matter shines through in its natural hue, which is a very dark red; as in a thin milk-glass a dark red fluid still appears so, but in a thick one, light red. Hence the darker color, usually, of venous blood, and the fact that all sub- stances which corrugate the cell-membranes render the blood dark red, as acetic acid, the alkalies, &c. The above-mentioned salts, when found experimentally to give a brighter color to the blood of the amphibia, are seen to wrinkle the large blood-cells. According to some, oxygen also contracts, and carbonic acid gas expands the cor- puscles ; and herein is another cause of the bright color of arterial, and the darker hue of venous blood. It is also found that if even colorless solid substances strongly reflecting light are mixed among the corpuscles, they give to the mass of blood a brighter red tinge. THE BLOOD. 167 Hence the bright color of the fatty blood of drunkards; and the blood in leucaemia is also bright red, since the cytoid corpuscles, in which it abounds, strongly reflect the light. Thirdly, it must be admitted that chemical combinations with the blood-pigment, especially of oxygen and carbonic acid, affect the color of the blood; the former rendering it lighter, and the latter darker colored. Indeed, all the salts which at first contract the blood-cells, and render the blood lighter colored, entirely dissolve them when in a more concentrated solution, and then give to the blood a deep dark-red hue. The proportional amount of the moist corpuscles has already been generally stated at 510 to 520 in 1,000; the extremes in adults being 472 and 542, and the average 512. The blood of women, bow- ever, especially in pregnancy, contains a smaller proportion of them, which is also diminished by repeated losses of blood and other fluids. Of the lower animals, the blood of swine contains the greatest amount of corpuscles; that of the amphibia comparatively few of them. The enumeration of the blood-cells has been recently attempted by Yierordt and Welcker, and it is found that from 42,700,000 to 45,500,000 corpuscles exist in a single cubic line of healthy human blood! (Lehmann) Assuming the whole amount of blood to be 20 pounds, their whole number is about 65 billions and 570,000 millions. They are more numerous in venous blood. (Kolliker) In former analyses, the blood-corpuscles were previously dried, and were then found to constitute about 140 parts out of 1,000 of blood. The following is the analysis of Becquerel and Rodier, showing the elements in the liquor sanguinis and corpuscles, taken together; the mean being given for both men and women:— Man. Woman. Water . 779.0 ) 221.0 J 791.1 Solid constituents . 208.9 Fibrine..... 2.2 2.2 Corpuscles . 141.1 127.2 Albumen1 . 69.4 70.5 Fat2..... 1.6 1.6 Extractive and salts of serum . 6.8 7.4 1 This is too high an estimate for the albumen. (See note, page 153.) 2 The amount of fat in the blood is not sensibly affected by its amount in the food. 168 THE FLUIDS. Origin.—The blood-cells first formed in the embryo appear to have their origin in the primordial cells of the germinal structure; some of these developing tissues, and others becoming isolated and metamorphosed into blood-cells. These also are multiplied by bipartite division (p. 126). But in the human embryo the first brood of corpuscles disappears entirely by the end of the second month, when the lymph and chyle begin to be poured into the blood, and when they are superseded by those developed from the lymph and chyle-corpuscles. (Paget.) The first blood-cells are larger than the subsequent ones; being about ^ijm OI> an incn m diameter, and nucleated. The nucleus is -gfa^ of an inch in diame- ter, central, circular, very little prominent on the surface of the cell, Development of first set of red corpuscles (mammalian embryo), a. Dotted nucleated and nucle- olated embryo cell. b. Same with a dividing nucleus; the division being complete at c. At d, the cell also is dividing, e. Cell still containing a few granules, p. Perfect blood-corpuscle. Fig. 101. Phases of the red blood- corpuscle (man), a and 6. Colorless corpuscles or gran- ale-cells in the coarsely and the finely granular state, e and d. Nucleated cells with- out and with color, e. Free cellseform nucleus, or perfect red corpuscle. and slightly granular or tuberculated. Fig. 100 shows the several stages of their develop- ment. The doctrine that the continued development of the red corpuscles occurs from the colorless corpuscles of the blood, is the most plausible, though open to some objections. Mr. Whar- ton Jones has shown that in the whole animal kingdom five forms of blood-corpuscle are to be met with (which are represented by Fig. 101), viz: 1. Coarse granule-cells (a); 2. Fine granule-cells (b); 3. Colorless nucleated cells (c); 4. Colored nucleated cells (d); 5. Colored non-nucleated cells (e), or perfect red cor- puscles of man and the mammalia. These THE BLOOD. 169 five forms are believed to correspond to as many stages of develop- ment. The third form (the colorless nucleated cell) is, however, the highest stage of development in the white blood of the invertebrate animals. The "colored nucleated cell" (fourth stage) is the highest form in the oviparous mammalia; while the "colored non-nucleated cell" is the perfect blood-cell of the mammalia. It does not, how- ever, follow that the human blood-cell passes through the five stages mentioned by Mr. Jones, nor that any stage corresponds precisely with one of these. There is, however, a general correspondence not without interest. The following account of their development is extracted from Mr. Paget's lectures,1 and which may be accepted as the most reliable hitherto. Fig. 102 represents the five stages of Fig. 102. Development of the red from the colorless corpuscles of the blood, a. Cytoid corpuscle, b. Same, being converted into a red corpuscle, c. Cytoid corpuscle with its membrane raised by the action of water, d. Same, having lost most of its granules, e. Same, acquiring color; a single granule remaining like a nucleus, f. Perfect red corpuscle. development of the colorless into the colored cell; though the im- probability has already been remarked that all the cytoid corpuscles are thus transformed (p. 161):— "The white corpuscle, at first tuberculated, containing many gran- ules, and darkly shaded (a), becomes smoother, paler, less granular, and more dimly shaded or nebulous (b). In these stages the cell-wall may be easily raised from its contents by the contact and penetration of acetic acid, or by the longer action of water (c); and, according to the stage of development, so are the various appear- ances which the contents of the cell thus acted on present. In the regular progress of development, it becomes at length impossible to raise the cell-wall from its contents (d). Then the corpuscles 1 On the Life of the Blood. 1848. 170 THE FLUIDS. acquire a pale tinge of blood color, and this always coincides with the softening of the shadows which before made them look nebu- lous, and with the final vanishing of all the granules, with the ex- ception sometimes of one, which remains some time longer like a shining particle in the corpuscle, and has probably been often mis- taken for a nucleus (e). The blood color now deepens, and at the same rate the corpuscles become smooth and uniform*; biconcave, having previously changed the nearly spherical form for a lenticular or flattened one; smaller, apparently by condensation of their sub- stance, for at the same time they become less amenable to the influ- ence of water; more liable to corrugation and to collect in clusters; and heavier, so that the smallest and fullest colored corpuscles always lie deepest in the field (f). Thus the most developed state of the mammalian red corpuscles appears to be that in which they are full-colored, circular, biconcave, small, uniform, and heavy. This is the state in which they appear to live the longer and the most active part of their lives."1 It will be observed that Mr. Paget regards the mature blood-cor- puscles not as mere free nuclei, as some observers have done (p. 115), but as non-nucleated cells. The blood-cells of the amphibia are, however, always nucleated. The idea maintained by Weber and others, that the liver is the special agent in the development of the blood-cells in the embryo, appears to be applicable to oviparous animals, but not to the mam- malia. The fact, however, that ,the blood of the hepatic vein in man contains a much greater amount of blood-cells than does that of the vena portae, indicates that they are developed with peculiar activity in that organ. This, however, may be a mere consequence of the fact that the blood of this vein is also rich in colorless cor- puscles, and which undergo their development while in the hepatic vessels, independently of any peculiar action of the liver itself. Thus the life of the blood is seen to inhere in the red corpuscles, the colorless corpuscles, and the fibrine (pp. 158 and 161). Function.—The view which ascribes to the red corpuscles the function of absorbing oxygen while in the lungs, and giving it par- tially off in the capillaries, while they also absorb carbonic acid in the capillaries, and give it off in the air expired from the lungs, 1 The necessity of fatty elements in aid of the development of the blood-cells is inferred from their composition, already stated. Hence, also, their rapid formation from the use of cod-liver oil, as observed by Popp. THE BLOOD. 171 has been controverted by the observations of Hannover (p. 103) and Marchand; though Lehmann regards it as "completely proved." The fact that chlorotic persons exhale as much carbonic acid as those in health, may be explained by the supposition that, there being a certain amount to be removed, each corpuscle absorbs more than in health; and the fact that the liquor sanguinis always ab- sorbs a part of this gas. It is also very certain that a part of the oxygen taken up by the blood-cells is only mechanically absorbed, while a part (and probably the greater portion) acts chemically upon their constituents. Lehmann found that after the inspiration of oxygen the mineral substances and the haematine in the blood-cor- puscles increased, while the organic substances, and more especially the fats, were considerably diminished; the latter being destroyed by oxidation, and their effete products being transferred to the intercellular fluid, or, at all events, undergoing a considerable loss of weight by the formation of carbonic acid and water. Heat is also evolved in connection with the formation of the latter. The blood-cells, therefore, have a direct relation to the function of respiration (aeration), and to the rapidity of the metamorphosis and repair of the tissues. Hence, in the different species of animals, we find a direct ratio between the normal amount of the blood-cells in the blood, the activity of the aerating process, the waste of the tissues and their repair (and, of course, the amount of food required), and the natural (or organic) heat of the organism. But the oxygen merely mechanically contained, in the blood-cells also leaves the latter in the capillaries and combines with the tissues, thus securing their metamorphosis also, and again developing heat. ' At present, therefore, we must regard the blood-cells as the great agents for effecting the dis-assimilation of the tissues, and of the blood itself. And since vital phenomena are impossible without a constant metamorphosis of the molecules of the tissues manifesting them, the blood-cells are indispensable in all the more active species of the animal kingdom, and incidentally the natural temperature of each is proportioned to their activity. Still, the corpuscles are only the special, but not the sole carriers of oxygen; the blood-plasma also, to some extent, possessing that power. Hence the slow dis- assimilation and low temperature of the invertebrata may be secured without them. In some of the latter, also, which possess a high degree of activity (as the insects), the corpuscles are not required, since oxygen is brought into direct contact with all their tissues 172 THE FLUIDS. through the ramifications of the tracheae, which open upon the sur- face of their bodies. Lehmann's idea, that the blood-cells are laboratories in which the individual constituents of the plasma are prepared for the higher function of aiding in the formation and reproduction of the tissues, is scarcely tenable, since the nutrition of the tissues is equally per- fect, so far as can be perceived, in animals whose blood is destitute of this histological element. Indeed, that the red corpuscles have any direct relation to the formation of the tissues, is very impro- bable; cfo's-assimilation and the consequent development of vital force being, it is believed, their special function. We have no certain knowledge of the length of time the blood- cells exist. Since the cells of the same blood differ in the length of time during which they resist chemical agents, it is probable that the more easily decomposed, and which are usually of a deeper color, are the older; while the paler and less easily acted upon, and which present in their granules the rudiments of a nucleus, are of more recent origin. That their regeneration is not very rapidly effected is probable, from the fact that the blood is poor in corpuscles for several days after a moderate venesection, and exhibits a great deficiency of them for a prolonged period after repeated bleedings; and since there is a copious supply of colorless corpuscles after severe losses of blood. If, however, they are slowly regenerated, they cannot have a very short existence, since otherwise the num- ber of the colored cells would not so far exceed that of the colorless corpuscles. (Lehmann) Whether the blood-cells are disintegrated in one particular part or organ, is not yet satisfactorily decided. Schult designated the liver, and Kolliker the spleen, as the organ where this process is effected. On the other hand, Gerlach and Schaffner regard the spleen as the organ in which the corpuscles are formed. Scherer's investigations confirm the idea of Kolliker. If there be a particu- lar organ in which the corpuscles are formed, and another in which they are disintegrated and dissolved—which is still very doubtful, however—we should mention the liver as the former, and the spleen as the latter (p. 170). Quantity of Blood in the Human Body. Very different estimates of the whole amount of blood have been THE BLOOD. 173 made,1 it being usually stated that its weight constitutes one-fifth of that of the whole body. Ed. Weber has, however, recently insti- tuted some experiments, according to which only one-eighth of the weight of the body is blood, or 18 pounds for a man weighing 144 pounds. Lehmann calculates that the whole amount of blood in a young man is 17J to 19 pounds. The estimate of Weber appears to be the most accurate hitherto made. It is calculated that only one-third of the whole blood can be lost rapidly without fatal con- sequences. But much more than this may be ultimately lost by frequently recurring hemorrhages, the vessels thus having time to adapt themselves to the diminished amount of their contents, so that the circulation is still maintained. Varieties in the Composition of the Blood in different Physiological Conditions. 1. Sexual varieties. The blood of women is of a lighter red color than that of men, is specifically lighter, contains more water, and evolves a less intense odor of perspiration when treated with 1^ times its volume of sulphuric acid. It generally contains less cor- puscles, but the same amount of fibrine (Lehmann); and some more serum in proportion to the clot. It usually contains more albumen and salts (especially the soluble), and less fat and extractive matters. 2. In pregnancy the blood is darker than usually, is richer in water and poorer in corpuscles and albumen, and therefore speci- fically lighter. There are no certain data respecting the fats and salts; but the fibrine is relatively increased in the last months, and the clot is generally very small, with a superficial stratum of fibrine frequently resting upon it (p. 158). 3. Varieties depending on age. The blood of new-born infants abounds in solid constituents, especially blood-corpuscles and iron, while it is poor in fibrine and salts. It contains about the same amount of fat and albumen as in the adult, and a much larger pro- portion of extractive matters. In advanced life, and in the female after the cessation of the catamenia, the blood is poorer in corpuscles, and the serum loses in some of its constituents, but the cholesterine increases. 4. During digestion, both the plasma and the cells become richer in solid constituents; though the latter experience a relative loss 1 Blumenbach estimates it at 8£ to 10 pounds ; Reil at even 44 pounds. 174 THE FLUIDS. in haematine. The fibrine coagulates more slowly, and is richer in fat; the serum is denser, sometimes even exhibiting a milky tur- bidity from an abundance of fat-globules (Fig. Fig. 103. 103) and cytoid corpuscles. The fat, albumen, extractive matters, and the salts of the serum are also pretty uniformly augmented. 5. Among the lower animals, the blood of the omnivora (hog, &c.) is the most abundant in corpuscles (and therefore in soluble phos- phates of iron); birds are next in order; then Fat-giobuies in blood. the carnivora and the herbivora. Of fibrine, the blood of birds contains the most; then that of the omnivora, herbivora, and the carnivora. Of fat, the blood of- birds also contains most; then the carnivora and the herbivora. The blood of the mammalia contains more albumen than that of birds. The solid constituents of the serum also preponderate in the omnivora. In the cold-blooded vertebrata (fishes and amphibia), the blood is poorer in corpuscles and richer in water than in the warm- blooded. Normal Differences in Composition of the Blood in different Vessels. A. In arterial blood the red corpuscles are less numerous than in venous blood (Kolliker), and contain more water and less solid con- stituents; though they have relatively more haematine and salts, but far less fat. The white corpuscles are also less numerous. (Kol- liker) The intercellular fluid of the arteries is richer in fibrine than that of venous blood, and its serum contains somewhat more water and less albumen1 and fats; while their extractive matters are slightly increased, and the salts still more so. Arterial blood also contains more oxygen, but only relatively to its carbonic acid gas (p. 164). It absolutely contains more of both these gases than venous blood, and about the same amount of nitrogen (pp.44,164). B. The blood of certain veins is peculiar. 1. The portal vein. During digestion, if sufficient drink has been taken with the food, the portal blood is rich in intercellular fluid and in water, and the number of blood-cells is therefore small. The fibrine is slightly, and the fat considerably, increased; while the albumen, extractive matters, and salts are moderately so. Compared with the blood of the jugular vein, the portal blood is poor in cells 1 In the solid constituents alone of the serum, an equal quantity of albumen is found in arterial and venous blood. (Lehmann.) THE BLOOD. 175 and in solids generally. The cells are also partly flocculent, easily distorted, and soon become jagged after their removal from the body, are richer in haematine and poorer in globuline, and contain twice as much fat. The intercellular fluid contains a less quantity of a fatty fibrine; while the serum contains less solid constituents generally (especially albumen), but more fat and extractive matters and more salts than any other vessel. Biliary substances have not been found in portal blood, and sugar only seldom occurs. 2. The blood of the hepatic vein differs much from that of any other vessel. Compared with the portal vein, it is poor in water; as 3 to 4 during digestion, and as 5 to 12 after it. Its clot is volu- minous, and easily falls to pieces; and it contains less serum, in the proportion of 15 to 34. It is far richer in both cytoid and colored corpuscles, the former presenting every variety of size and form, and the latter forming heaps of a purplish-red color. The cell-walls of the latter are also less easily destroyed than those of the blood generally (p. 163), and the proportional amount of moist blood-cells in the blood of the hepatic and the portal veins is as 317 to 141. The latter are, however, poorer in fat and richer in salts, and espe- cially poor in haematine, or at least in iron (two-thirds as much as in the vena portae), but somewhat richer in extractive matters. Still, they have a greater specific gravity, though lighter in relation to the serum, since the intercellular fluid is far more dense, and con- tains much more of the solid constituents (as 11.8 to 8.4). The latter is, however, either wholly deficient in fibrine, or only con- tains a scarcely perceptible trace of it; and contains less albumen1 and fat, and much less salts, with considerably more extractive matter, including sugar. 3. The blood of the splenic vein has been analyzed in horses by Mr. Gray.2 Compared with that of the jugular vein, it contains more water, iron and fat, and more albumen and fibrine. There is also less solid residue in the serum, which always presents a dark- reddish tinge, and the corpuscles are very much diminished. c. The blood of the placental vessels contains but little albumen 1 The serum of the blood of the hepatic vein contains but two-thirds as much albumen as is found in the portal vein. The remaining one-third received from the portal vein has probably been assimilated in the development of the blood- cells which abound in the blood of the hepatio vein. 2 On the Structure and Use of the Spleen. London, 1854. 176 THE FLUIDS. and fibrine (Stas), but a large amount of serum-caseine. Stas also found urea in this blood. D. Zimmerman n found the serum of the blood of the veins of the lower extremities poorer in water than that of the upper extremities. E. The menstrual fluid is to be regarded, histologically, merely as a hemorrhage1 periodically recurring from the interior of the uterus, and therefore as pure blood. It is, however, discharged per vaginam in a state of admixture with the mucus of the cervix uteri and the vagina, and therefore contains epithelial cells and cytoid corpuscles. (Fig. 109.) Jul. Yogel states that menstrual blood contains no fibrine. On the other hand, E. H. Weber found coagulated blood on the mu- cous membrane of a young girl who had committed suicide during the catamenial period. The fact that in ordinary circumstances the menstrual fluid does not coagulate, has generally been attributed to the action of the acid mucus of the vagina, and not to the absence of fibrine, the former holding the latter in solution. Certain it is, that where the menstrual flow is so increased as to constitute a pa- thological condition (menorrhagia), there is no deficiency either of fibrine or of coagula. Pathological States of the Blood in certain Diseases. 1. Inflammation. The changes in the intercellular fluid in inflam- mation are these: 1. In all inflammations accompanied by a febrile reaction there is an increase of fibrine (hyperinosis), it ranging from 4.7 to 10.5 parts in 1,000 of the blood. The highest increase occurs in acute rheumatism and pneumonitis. It may be considerable when the inflammation is not extensive, as in erysipelas; but in each particular disease it is proportioned to the degree and duration of the inflammation. It is independent of the strength of the pa- tient, and of the increase or decrease of the other solid constituents of the blood, occurring in the most decided anaemia or hydraemia, and as abundantly in meningitis and other acute cerebral diseases as in inflammation of other parts. 2. The albumen is somewhat dimi- nished in inflammatory blood. The serum also frequently becomes turbid from the presence of separated albumen. (Scherer) 3. There is less chloride of sodium in inflammatory than in normal blood, but the sulphate of soda and of potassa are increased. The red corpuscles are diminished in violent inflammation (rheu- matism and pneumonitis), but not in any marked degree unless other pathological conditions coexist to induce a simultaneous dimi- 1 Those who maintain that this fluid is an exudation, or an effusion, overlook the fact that the blood-corpuscles can leave the vessels only after a rupture of their walls. See next chapter, on "Effusions" and "Exudations." THE BLOOD. 177 nution of the whole mass of blood-cells. In some cases scarcely any diminution is observed. Still, the carbonic acid in the red cor- puscles is increased in inflammatory blood, as are also the colorless corpuscles; and the former manifest an increased tendency to sink. The diminution of the solid constituents of the blood is usually proportioned to the violence of the inflammation and the quantity of exudation thrown off If there be but a small amount of the latter, they may, indeed, be rather augmented than diminished. Finally, inflammatory blood coagulates slowly, and the clot usually presents the buffy coat (p. 93), and often the "cupped" appearance also. 2. Fever. Becquerel and Rodier found the blood in fever to be generally somewhat richer in water than in the normal state, and the phosphorized fats and cholesterine to be especially increased: while the phosphates are also considerably so. The blood-corpuscles are slightly diminished in number. Fibrine, extractive matters, and soluble salts occur in the normal amount. In simple ephemeral and remittent fever, however, the albumen, as well as the cholesterine, was increased. In slight intermittent fever they found the fibrine usually diminished, while Zimmermann found it usually normal. In marsh fevers the fibrine, albumen, and fats are diminished, and the blood- corpuscles are increased. In typhus (also including typhoid) the blood exhibits no changes warranting us in regarding it as a dyscrasia. From the fifth to the eighth day it is very similar to that of plethora. From the ninth day it undergoes a great change, being specifically lighter, chiefly from a diminution of the corpuscles; though the solid constituents of the serum also diminish daily through the disease, with a rapidity pro- portioned to the intestinal affection. The salts and extractive mat- ters are relatively increased, rather than absolutely diminished. 3. Cholera. In this disease the whole blood is especially dense and viscid. The fibrine is unchanged; the serum is denser, and poorer in water and salts. Relatively, however, it is richer in salts, and very rich in albumen. But it contains more>potash salts, and phosphates than normal serum, with some urea, and an extractive substance which rapidly converts urea into carbonate of ammonia. The blood-corpuscles are augmented—from 513 to 559 in 1,000 in men, and from 400 to 464 in women. (Schmidt) This increase is, however, relative, since many blood-cells are actually destroyed. They are also poorer in salts, and their proportional amount of water is diminished (2.14 to 1.77). The proportion of organic to inorganic constituents is, however, increased—from 44.1 to 58.1. The specific gravity of the corpuscles is increased in men to 1102.6. 4. Dysentery. In this disease the corpuscles are fewer and lighter, their specific gravity being but 1085.5. The fibrine is usually in- creased, the solids of the serum decreased, especially the albumen, and the salts considerably increased. 12 178 THE FLUIDS. 5. In the acute exanthemata there is a diminution of the blood- cells, and increase of the intercellular fluid. The serum is denser than usual, and its salts more augmented than the organic substances. 6. In puerperal fever there is considerable diminution of the co- lored corpuscles; the fibrine is increased, is soft and gelatinous, and almost always forms a crust. In most cases the solid constituents are considerably diminished, though sometimes increased. Bile- pigment is occasionally, and free lactic acid not unfrequently, met with; the blood sometimes also having an acid reaction. 7. Bright'1 s disease. The blood-cells and the constituents of the serum are diminished. The specific gravity of the former is often reduced to 1084.5. Cholesterine and the salts of the serum are, however, increased. On an average, there is more fibrine than in normal blood. 8. In plethora the blood-cells are rather more numerous, and the albumen is somewhat increased. In other respects the blood is nearly or quite normal. 9. Hydrcemic blood is very much attenuated, pale, watery, and forms a loose, infiltrated, gelatinous clot. 10. Anozmia. The character of the blood depends much on the cause of the anaemia. In respect to the diminution of the blood- cells, it corresponds with the blood of hydraemia and chlorosis. 11. In chlorosis the blood forms a solid clot, covered with a buffy coat, and floating in a large quantity of serum. The corpuscles and iron are both diminished, in a small or an excessive degree, without any relation to the intensity of the disease. The fibrine is nearly normal; the albumen is increased only relatively to the cells. 12. In leucozmia the blood is pale red, often marked with whitish streaks, is rich in colorless blood-corpuscles (even one of these to three colored cells), and has an alkaline reaction, though the fluid filtered from the clot is acid. It contains true glutin, a body which ranks between glutin and albumen, hypoxanthine, and, finally, formic, acetic, and lactic acids. 13. In pyozmia the fibrine is diminished, and the colorless blood- cells augmented. This state is difficult to distinguish from leu- caemia. 14. In carcinoma there is an increase of fibrine. The blood-cells are slightly diminished. 15. In diabetes there is simply an increase of sugar in the blood. 16. Etherization. The immediate effect of the inhalation of ether seems to be to make the blood richer in water and fat, and poorer in blood-corpuscles. Finally, in regard to variations in the amount of particular ele- ments of the blood in different diseases, the following may be re- garded as established:— 1. The fibrine is increased (hyperinosis) in all inflammations and in carcinoma. An increase also occurs during the last months of SEKOUS SECRETIONS. 179 pregnancy. It is diminished (hypinosis) slightly in intermittent and marsh fevers, and in pyaemia. 2. The albumen of the blood is increased in plethora, in intermit- tent fevers, after drastic purgatives, and in cholera. It is diminished in simple ephemeral fevers (slightly), in severe inflammations, in the later stages of typhus, in scurvy, malaria, puerperal fever, dysentery, Bright's disease, and dropsy from organic affections. 3. The extractive matters are increased in puerperal fever and scurvy. 4. The salts of the serum (and especially the chloride of sodium) are increased in all cases in which the albumen is diminished (Schmidt); hence in dysentery, acute exanthemata, Bright's disease, typhus, and especially in dropsy. They are diminished in inflammation, and still more so in cholera. 5. The colorless corpuscles are increased in inflammation, leucae- mia, and pyaemia, and after repeated losses of blood. 6. The colored corpuscles are increased in plethora, in cholera, in the first stages of heart-disease and the first eight or ten days of typhus, and in marsh fever. They are diminished in violent in- flammations, in dysentery, anaemia, the last stages of typhus, in hydraemia, chlorosis, puerperal fever, acute exanthemata, Bright's disease, carcinoma, and scurvy. Their specific gravity is increased in cholera (to 1102.6), and diminished in albuminuria (to 1084.5) and dropsy (to 1081.19). The number of the red corpuscles is also diminished by prolonged fasting, and extreme losses of blood or of other fluids; while the plasma becomes poorer in albumen and other organic constituents, but richer in salts; the whole blood becoming much the same as in anaemia. Similar results are, moreover, produced by substances interfering with digestion, or the formation of blood, especially the preparations of lead, acids, kc. CHAPTER II. SEROUS SECRETIONS, TRANSUDATIONS, AND EXUDATIONS. Secretion implies a separation of certain elements from the blood by the direct action of cells. It is, therefore, a vital action, and not dependent on mere physical agencies. In the case of se- creting membranes, the secreting cells always constitute an epithe- lium upon its free surface. By the bursting of the secreting cells, v 180 THE FLUIDS. the contained fluid is set free, and is then recognized as the proper secretion of the surface on which it is found. Transudation, on the other hand, is merely a physical phenome- non, dependent upon the permeability of membranes, by certain elements of the blood contained in their vessels; and must not be confounded with the vital process before defined. The word effu- sion is sometimes used to express the same phenomenon. Exudation is also a vital process, as will appear. I. The Serous Secretions. Lehmann has included all the serous secretions under the head of transudations. This is, however, incorrect, since it has been proved that the normal serous secretions are separated from the blood by the epithelial cells of the serous membranes. The serous surfaces are, however, very liable to transudations also; and in all cases where an excessive amount of fluid is accumulated in a serous cavity, a transudation (or an exudation, which consists of the blood- plasma very nearly), directly from the blood, has occurred, and be- come mixed with the proper secretion; e. g. in ascites from pressure of abdominal tumors, the accumulation is almost exclusively from transudation, and very slightly from the natural secretion. The proper serous secretions are, therefore, the fluids normally found upon the various serous membranes, viz., on the pleura, peri- toneum, pericardium, the cerebral layer of the arachnoid, and the membrane lining the ventricles of the brain. To these may also be added the aqueous humor of the eye, the liquor Cotunnii, and the endolymph of the internal ear. The liquor amnii is a serous secretion; but, apparently, to a still greater extent, also a transuda- tion. The synovial are incorrectly termed serous membranes, and their secretion is intermediate between the serous and the mucous secretions. None of the serous secretions contain histological elements, ex- cepting fragments of the epithelial cells (or still perfect ones) which secreted them. Molecular granules or cytoid corpuscles are merely accidental constituents, when present. In fact, the serous are the simplest of all secretions. They ap- proximate more or less nearly to the serum of the blood; while other secretions contain elements peculiar to themselves, which they have formed from the blood-plasma. It is, indeed, for this reason that physicists would regard them as mere transudations. Still, TRANSUDATIONS. 181 they are not identical in composition on all the serous membranes, but vary to suit the requirements of each; e. g. the fluid of the ventricles of the brain contains the least albumen of all (0.5 per cent.), that of the peritoneum 1 per cent., and that of the pleura the most of all (1.8 per cent.). Albumen is entirely wanting in the aqueous humor, and in the liquor amnii during the last months of pregnancy. (Lehmann) But to the physiologist the idea that this adaptation of the fluid to the requirements of the surface is dele- gated to a mere physical force, is, d priori, in the highest degree improbable, were there no facts to. disprove it. It is impossible to ascertain the normal quantity of the serous secretions, their amount is so small. Much of the fluid found after death in the serous cavities is a mere transudation, doubtless, occur- ring during the last moments of life. Origin.—From the epithelial ceils of the serous membranes, as already described. Uses.—The serous secretions are merely for the prevention of friction of the opposed surfaces of the serous membranes. In the eye and the ear they evidently conduce to the perfection of the senses of sight and hearing. II. Transudations. It has been already stated that mere transudations are very liable to occur on serous surfaces, and these also are very similar in com- position to blood-serum. Indeed, the true serous secretions being normally in so small amount that enough for analysis can hardly be obtained, the analyses of serous secretions (so called) are usually those of transudations, mixed with a very small amount of the former. In all cases when the secretion is abundant we may as- sume that the major part is a transudation merely. And, except in a few instances, transudations are to be regarded as pathological, while the serous secretion is physiological. The transudations which may be regarded as physiological are the serous fluid in the areolae of areolar tissue, the halitus from the lungs, and a certain amount of fluid also given out on the skin, in- dependently of the true perspiration. The pathological transudations include all cases of simple oedema, and of dropsy (ascites, anasarca, hydrothorax, hydrocephalus, hy- drocele, hydrops articuli, ovarian dropsy, &c). Colliquative sweats, diarrhoeas, and the discharges in cholera must be also referred to 182 THE FLUIDS. this head; and the hydragogue effects (so called) of certain cathar- tics.1 Transudation results, as a physical necessity, whenever bloodvessels are exposed very near to a surface in contact with the air, as is the case with the air-passages and the skin. But the state of fulness of the vessels, and the rapidity of the circulation through them, as well as the physical and chemical character of the blood itself, also exert a controlling influence on the amount of fluid transuded. The fuller the vessels, and the slower the motion of the blood-current, the greater is its amount. Hence congestion of the vessels of a part is a common cause of transudations; e. g. diarrhoea from portal congestion. And since congestion is often produced by pressure on venous trunks, the latter is commonly accompanied by oedema, anasarca, or ascites; as, in case of the last, from abdominal tumors, ovarian or otherwise. That the accumulation in such cases is not secretion merely, is evidenced by the fact that it amounts in some instances to 2 or even 3 pounds per day. Transudations, like serous secretions, very nearly resemble the blood-serum in chemical composition, and, like them, they also nor- mally contain no fibrine. But since animal membranes are more easily penetrated by water than by the other constituents of the blood-serum, next by the extractive matter and soluble salts, and then by albumen, it follows that transudations will contain more water proportionally to the solids than blood-serum does, and more salts in proportion to their albumen. The quantity of albumen in transudations varies exceedingly. Lehmann states that it mainly depends on the following circum- stances :— 1. Certain systems of capillaries transude more than others; e.g. those of the pleura most of all, and those of the ventricles of the brain least of all. 2. The slower the blood-current in the capillaries, the richer in albumen is the transudation; e. g. more albumen is found in peri- toneal transudations (ascites) when dependent on pressure from large tumors than when caused by less disturbance of the circula- tion, as by cirrhosis of the liver. 3. The poorer the blood is in albumen, the less appears in transu- 1 Lehmann also adds hydatids, and vesicular eruptions on the skin from any cause, to this list. TRANSUDATIONS. 183 dations. Hence they contain little albumen in Bright's disease of the kidney. The salts in the transudations are most abundant when the blood is richer in water; though they are always less, proportionally, than in the blood-serum, except in some cases of Bright's disease. The chlorine and potassium compounds predominate over the other solu- ble salts, in the transudations as well as in the blood-serum. In cho- lera, or after the administration of drastic purgatives, the quantity of salts is five or even seven times as great as that of the albumen; these transudations being, at the same time, richer in water than any other fluid in the organism. Fibrine is said by Lehmann to be present in some morbid transu- dations, and which are termed fibrinous transudations by Jul. Yogel. We should, however, term a fluid containing fibrine in the circum- stances supposed, an exudation, and not a mere transudation. If blood-corpuscles appear in a transudation, laceration of the minute vessels must also have occurred. But little of the neutral and saponifiable fats is found in the transudations. The non-saponifiable fats (cholesterine and seroline) are far more abundant. The former, especially, is often very abun- dant in the fluid of ovarian dropsy and of hydrocele. It often abounds, also, in those from the ventricles of the brain, and from the peritoneum and pleura. Bile-pigment and urea are also found in transudations; and sugar, in cases of diabetes. The quantity of the transuded fluids varies greatly in pathological conditions, between the least perceptible increase of the normal transudation or secretion and the highest extremes. In a case re- ported by the author, 103 pounds of transuded fluid were removed from the peritoneal cavity; the patient (a female) being 63 inches in circumference.1 Uses.—The normal transudation in the areolar tissue gives it its required fulness and suppleness; while the halitus of the lungs and the transudation of the skin aid incidentally in preserving a moist condition of the pulmonary mucous membrane and the external integument. The rest are merely pathological phenomena. 1 American Journal of the Medical Sciences, Jan. 1856. 184 THE FLUIDS, III. Exudations. Exudation has been very often confounded—and especially by chemists—with mere transudation; from which, however, it is widely different, both histologically and physiologically. Leh- mann, however, admits that while transudation is the result of mere physical agencies, as has been explained (p. 182), exudation is due to vital power. But he limits exudations to inflammation as their producing cause, and admits that their organizability distinguishes them from mere transudations. We cannot restrict the idea of exudation to the inflammatory process alone, however. We equally find organizable elements separated from the blood in cases where there is no inflammation; and we cannot apply to such cases the term transudation, any more than we can in case of inflammatory exudations. Any organizable fluid spontaneously separated from the bloodvessels, without rupture of their walls, is an exudation, whether it be in the case of repair (in wounds, &c.) without inflammation, or in cases of actual inflam- mation. Exudations differ from transudations—-first, in regard to the cir- cumstances in which they are formed; and, secondly, in respect to their constituents. 1. Transudations are the result of physical agencies merely, and occur upon the natural free surfaces more especially, and while their epithelium is still in a normal state, and in the areolae of the areolar tissue'(p. 181); escaping, also, as Wedl suggests, through the walls of the veins. Exudations occur in consequence of some modified action of the vital force, and directly from the capillaries; and if upon natural free surfaces, in consequence usually of inflammation or irritation of the same. They also elevate and detach the epi- thelium, as is seen in case of vesicular diseases of the skin. But exudations also occur—and not transudations—upon free surfaces artificially produced; as in case of wounds, with or without loss of substance. In all cases, indeed, in which repair takes place, or in which new formations (false membranes, indurations, &c.) are pro- duced, exudations occur; and it is by their organization that the repair or the formation of the new tissue is secured. Moreover, in normal nutrition an exudation of the plastic elements of the blood occurs in the substance of the tissues, and from which the latter are nourished. But this topic is included under the subject of nutrition; EXUDATIONS. 185 though the fact shows that stasis of the blood is not necessary to exudation, as some have maintained. 2. It follows, therefore, that exudations differ from transudations in their constituents, since the latter are not organizable, and there- fore cannot become the medium of the reparative process, nor be converted into adventitious growths in cases of inflammation. In exudations a considerable amount of fibrine is almost always pre- sent;1 an element always wanting, we believe, in mere transudations (p. 183). There is also far more albumen in exudations, and the phosphates and potassium compounds are more abundant. Blood- corpuscles, more or less altered, are also often found in fresh exuda- tions ; but they are not an essential constituent, and depend upon a rupture of the minute vessels of the part. Sometimes, also, the exuded fluid, in case of inflammation, is stained by the haematine which has been dissolved out of the blood-corpuscles stagnant in the inflamed part. Exudations, indeed, approximate more nearly to the blood-plasma, and transudations to the blood-serum merely. But the latter are never precisely identical with the serum; and exudations abound far more in water and in the phosphates than does the liquor sanguinis, while they contain less fibrine. Thus it appears that no histological elements exist in pure exu- dations when first separated from the blood, though the former are soon, developed in them, unless the exudation is promptly reab- sorbed, as will appear. Origin.—Exudations are poured directly from the bloodvessels of the part; and as they normally contain no blood-corpuscles, no rupture of the vessels is required for their effusion, any more than in the case of transudations. The exudation in an incised wound is entirely free from blood-corpuscles, and occurs after all hemor- rhage ceases. Exudation is not, therefore, a modification of secre- tion, no cell (epithelial or otherwise) nor other special structure being required for their production. In inflammatory exudations, blood-corpuscles are frequently also found, since rupture of the ves- sels, and consequent hemorrhage, is a very common concomitant of inflammation. It is in accordance with a vital law of the organism that ivhere new material for repair is required, or wherever an inflam- mation occurs, an exudation is poured out from the vessels of the part. 1 Lehmann states, however, that plastic exudations sometimes occur without fibrine (vol. ii. p. 290). Non-plastic exudations also contain it. 186 THE FLUIDS. Uses.—The use of the normal exudations is explained in the preceding sentence, since they alone afford the materials for the reparative process. Inflammatory exudations are, however, to be regarded as pathological, and are almost always productive of only mischief. Varieties of Exudations. Exudations differ much in different circumstances, in respect to the properties of their chemical constituents; but the only varie- ties necessary to be mentioned here are the euplastic, or highly organizable, and the cacoplastic, or imperfectly organizable. In- flammatory exudations are always cacoplastic; and non-inflamma- tory exudations are so also in unfavorable circumstances, especially when the blood is impoverished. In favorable circumstances, and in which exudations are required—as in incised wounds—the latter are euplastic. Plastic exudations contain more fat than those not so. Mr. Paget's division into the fibrinous and the corpuscular exuda- tions has reference to the forms of organization occurring in them, and which may or may not be due to original differences in their constituents, as will appear under the next head. All pure exuda- tions at first manifest the transparency and other physical properties of the liquor sanguinis, as has been already stated. The physio- logical and histological differences between the inflammatory and non-inflammatory exudations, as shown by their subsequent or- ganization, will next be explained. Changes occurring in Exudations. Exudations, whether inflammatory or not, generally become co- agulated soon after their separation from the vessels, and then promptly present the fibrillated appearance already described. (Fig. 49.) They may subsequently be (1) reabsorbed, or (2) may be or- ganized into a new tissue; or (3) may be converted into pus. 1. Absorption of an exudation may occur either before or after coagulation. In almost all cases it is desirable that inflammatory exudations be reabsorbed as soon as possible, since only swelling of the part and other mischiefs result from their presence. The ex- ceptions to this proposition are very few, and will be insisted upon by those only who still maintain the doctrine—never sustained by proof of any kind—that inflammation and the reparative process are identical. E. g. it is never desirable that the plasma exuded in EXUDATIONS. 187 the cavity of the pleura, or the pericardium, or in the substance of the lungs, or in pleuritis, peritonitis, or pneumonitis, should remain ; the sooner it is reabsorbed, the better. In case of non-inflammatory exudations, however, it is usually desirable that they remain and become organized into new tissue, since they alone afford the ma- terials for repair. We should receive the idea of J. Vogel, that a coagulated exudation is dissolved, before reabsorption, by another exudation, called the "solvent," with doubt. 2. Either inflammatory or non-inflammatory exudations may be- come organized; the latter into tissues more nearly resembling the normal, since they, when normal in composition, are euplastic. In case of the inflammatory exudations (which have been most studied), coagulation of the fibrine is always the first step towards organiza- tion, the fibrillation becoming more distinct than it is in the normal coagulation of healthy blood; and exudation-cells and glomeruli (Fig. 59) being subsequently developed among them, if permanent new tissues are to be formed. Thus indurations, false membranes, &c, are produced as sequelae of inflammations. On the other hand, euplastic (non-inflammatory) exudations are organized into tissues more nearly resembling the original, as in the healing of wounds by adhesion or "first intention." This form of organization is, therefore, to be regarded as an ascending metamorphosis of the exudation. It, however, when occurring on mucous membranes, proceeds no further than fibrillation, and to the subsequent develop- ment of cells, perhaps. The false membrane (so called) in croup never becomes vascular; and therefore, since it has no constant supply of nourishment from the blood, is always spontaneously detached if the patient's life is prolonged. But in case of inflam- mation on serous membranes, well-organized false membranes are frequently found, as will appear. (Ch. XL Sect. IY.) 3. Both kinds of exudations are liable to become converted into corpuscles, instead of fibres, and then into pus. Especially is this the case if they are exposed to the action of the atmosphere. In this case, exudation- or pus-corpuscles are usually developed in the exudation, without any previous coagulation; and hence Paget terms it the corpuscular, and Rokitansky the croupous exudation. It usually contains more fat, and the fluid part is mostly absorbed after the corpuscles are formed. The formation of pus in an exu- dation is sometimes said to be characteristic of the "suppurative inflammation." It is, in fact, mere suppuration—i. e. the production 188 THE FLUIDS. of pus—and not inflammation itself, nor necessarily dependent on inflammation in any sense. The corpuscles first formed are some- times called "exudation-corpuscles," as if peculiar to exudations. They are, however, merely the cytoid corpuscles already described (p. 145), and are developed in accordance with a law stated on page 146. That they are also here histologically (though not phy- siologically) identical with pus-corpuscles, will be shown under the characteristics of pus. Whether an inflammatory exudation is to become organized into fibres and tissues, or into corpuscles (pus) merely, depends mainly upon three circumstances (Paget):— 1. The condition of the blood, and therefore the composition of the exudation itself. Hence empyema is more common as a result of pleuritis in scrofulous and other debilitated subjects, and adhesions in the more robust, (p. 94.) 2. The seat of the inflammation. If this be on serous membranes (as the pleura), fibrillation and false membrane are common; if the tissue of the lung itself is attacked (pneumonitis), the exudation first coagulates (forming the red hepatization, as it is improperly called), and is then converted into pus, which, by an equal misnomer, is termed the "gray hepatization." In true croup, the exudation first fibrillates, and subsequently, if sufficient time is given, is developed into pus, the fibres being previously dissolved. Hence, in an abscess containing pus, fibres are also frequently found intermixed, espe- cially in the portions of pus first formed. 3. The intensity of the inflammatory process affects the organization of the exudation by modifying its plasticity. The more intense the former, the more liable is the latter to be developed into pus. While the organization of exudations into tissues is an ascending metamorphosis of the former, their conversion into pus must be re- garded as an abortive attempt at the same. The pus-corpuscle is, histologically, identical with the exudation-corpuscle, and not a de- generation of the latter, as has been asserted. It is merely an arrest of development of the exudation-corpuscle. Exudation-corpuscles nor- mally form cell-walls around them, and then develop the higher tissues; and hence the exudation (cytoid) corpuscles become, in fact, the nuclei of exudation-cells, of which less notice has been taken. Hence Gluge regards pus-corpuscles as nuclei, " because in granu- lations and the formation of cicatrices it is readily and directly conclusive that cells form upon pus-corpuscles; for the nuclei of young cicatrix-cells, in appearance and chemical relations, are per- fectly identical with the latter."1 We would say, exudation -cells form upon exudation-corpuscles, the latter being the nuclei of the former; while the pus-corpuscles are merely the exudation-cor- puscles, arrested in their development, and destined not to rise to 1 Pathological Histology, p. 45. CHARACTERS OF PUS. 189 any higher organization. Pus is totally aplastic, and its corpuscles possess a very low vitality. Origin and Characteristics of Pus. Thus pus is not a secretion, but is a changed exudation; the change being due to various causes, among which the action of the atmo- sphere is one of the most prominent. In granulating wounds, there- fore, we find a pure exudation constantly appearing on the surface of the living tissues, with exudation-corpuscles and cells forming in it; while the external portion of the exudation has become true pus. All the intervening grades of development between these two ex- tremes will, of course, present themselves. Flakes or fibrillae of coagulated fibrine will also be often found mixed with the pus first formed in an abscess; these having been formed by simple fibril- lation as the initiatory step, and before the pus-corpuscles are developed. It is also certain that pus may be formed from a solid mass of fibrine after its coagulation. (Vogel) Thus, also, it appears that pus is formed from an exudation by a "retrogressive metamorphosis." (Wedl) Characters of Pus. Pus, when perfectly formed—genuine pus—is a yellowish, creamy, thick fluid, of a specific gravity of 1030 to 1033 (Gluge). and a feeble alkaline reaction. Exposed to the air, however, it soon undergoes transformations; passing into the acid fermentation, or the alkaline, or into putrefaction. In cases of phthisis, pus is sometimes acid when expectorated. The whole amount of solid constituents in pus is 140 to 160 parts in 1,000, of which only 5 to 6 per cent, consists of mineral sub- stances. Of the last, the soluble salts predominate, being propor- tioned to the insoluble as 7 or even 9 to 1. It also contains the oxide of iron. Seen under the microscope, pus consists of (1) a fluid portion, containing (2) histological elements—the pus (cytoid) corpuscles. An analysis of pus, as compared with that of the blood, shows the former to contain far less albumen, no fibrine at all, far more fat, and about three times as much chloride of sodium, the latter being confined almost exclusively to the pus-serum. Fibrine, whether coagulated or not, is sometimes found mixed with pus, however; a portion of the exudation still remaining unchanged. " Connective tissue-cells" (nucleated fibres), may also be found in pus, from a higher organization of a part of the exudation. (Fig. 104.) 1. The fluid portion (pus serum, or liquor puris) is perfectly clear, colorless or slightly yellowish, has a feeble alkaline reaction, and coagulates, on being heated, into a dense white mass. Its main con- stituent is albumen, which constitutes from 12 to 37 parts in 1,000. Some of the fat in pus also belongs to the serum, and about 1 per cent, of cholesterine. 190 THE FLUIDS. Mucosine (pyine), and caseine, are only abnormal constitu- ents of pus-serum (Lehmann), as are also bile-pigment, resin- ous bile acids, urea, and sugar. It is the mucosine which forms the filaments seen in Fig. 107. It was called pyine by Giiter- bock. 2. Accidentally, blood-cor- puscles, epithelial cells, exu- dation-cells, and fragments of tissues (Fig. 105) may be found in pus; but the only normal histological element is the cy- toid (pus) corpuscle, except occasionally minute fat-glo- bules. Pus-corpuscles (Fig. 106) have already been described under the head of cytoid corpuscles (p. 146), they being vesicles consisting of a cell-membrane often appearing granular, with a nu- cleus adhering to it, and viscid hyaline contents. They average ® ®9& ©<§>#© © d Exudation-cells and nucleated fibres in pus. a. Large granulous exudation-cells. 6. Pus-corpus- cles, c. Nucleated fibres, d. Pus-corpuscles, their nuclei being brought out by acetic acid. a'. Granu- lar exudation-cells after action on their nuclei of water. Fig. 105. Fig. 106. wo q® i_ Fig. 105. Other histological elements, in pus, in an incipient state of fatty degeneration. The granular corpuscles (a) are pus-corpuscles ; the open rings (J) with borders are red blood-corpuscles ; the sharply-defined circles are fat-globules. Two epidermic cells (c), with an oval nucleus are also seen, and a coagulated mass with molecules (d). (Wedl.) Fig. 106. Pus-corpuscles, a. Natural appearance, b. After acetic acid. from axj1^ to 2ii}J5 0I" an in°h iQ diameter, being usually larger than the cytoid corpuscles of the blood, and smaller than those of saliva. They, however, vary in different circumstances, being all small in an abscess, and all large in a wound. (Vogel.) They also vary in appearance in different states of the organism—as in phthi- sis, in typhus, and in the cancerous dyscrasia. (Lehmann) Besides, CHARACTERS OF PUS. 191 their size varies, on account of their endosmotic properties, with the specific gravity of the pus-serum, they being contracted and smaller as the latter increases, and vice versa (p. 145). The investing membrane—sometimes wanting in the smaller cor- puscles ( Wedl)—is an albuminous ("proteine") compound, but is not fibrine. (Lehmann) The nuclei of pus-corpuscles are ^gg to ^gV? 0I" an iQCn m dia- meter (Wedl), and also appear to be an albuminous substance. If they had been originally visible, they are usually of a lenticular form, and these are probably the mature corpuscles. In case they are invisible at first, they are subsequently found to be tripartite, and of a sharply-defined outline. This latter appearance, usually produced by a change in the chemical reaction of the pus after its formation, has been thought to be characteristic of pus-corpuscles. It has, however, been already explained (p. 146). The contents of the pus-corpuscles are also principally albuminous compounds. (Lehmann) The fat of pus (20 to 60 parts in 1,000) is contained, in great part (about two-thirds), in the corpuscles; and the granules are probably composed of it, in part at least. In regard to the precise manner in which pus-corpuscles are formed, nothing special need be remarked here, they being deve- loped from minute granules into larger corpuscles—the nuclei—as Vogel has shown, and around which the cell-wall subsequently ap- pears; it being at first transparent, and afterwards granular. They, like all other cytoid corpuscles, are first formed by free cell-develop- ment. But they may, doubtless, be subsequently developed from the pre-existing corpuscles, and thus pus propagates itself. Hence the importance of seasonably evacuating a cavity containing pus; or of destroying the pus-corpuscles, as by the application of caustic, &c, as in the treatment of ophthalmia and blennorrhcea. It is a practically important question, How long a time is neces- sary for the development of pus in a fresh exudation? Lehmann states that in exudations "not perfectly fresh, obtained from subcu- taneous wounds with loss of substance," in the lower animals, granules and nuclei, constituting the beginning of the suppurative process, appear in "about half an hour." Gluge says that in "twelve hours after a blister is applied to the surface of the human body, the exudation has become slightly turbid from the presence of pus- corpuscles, many of which already have a clear border to one-half of their circumference, which is the future cell-wall in the course of development." The process of development still continues, even if the exudation be removed from its contact with the body. In- deed, in the clear exudation, when removed from the surface, "per- fectly spherical cells with nuclei were developed after several hours" (p. 46). Helbert had before asserted that cells may form in a plastic liquid removed from the body. In the case of a blister, we may, therefore, conclude that true pus may be formed in less than twenty-four hours. A longer time, 192 THE FLUIDS. however, than forty-eight hours is required for its development in case of wounds; and more frequently at least' seventy-two to ninety- six hours elapse before suppuration is established in case of surgical operations in adults. It is, however, more promptly established in children, and in the warmer season of the year. Genuine pus is a bland fluid, and does not dissolve the tissues in contact with it; but only destroys their vitality, if at all, by pressure. It is thus that the articular cartilages may die in case of suppuration in bone in contact with them. Morbid pus, however (sanies, &c), is highly corrosive, and rapidly'dissolves the tissues. Decomposed pus may also produce the same effect. It is not necessary here to speak of the pathological conditions of pus, any further than to remark that the pus-corpuscles (like all other cytoid corpuscles) are liable to fatty degeneration; strongly- defined fat-globules appearing within them, as in Fig. 105. The serum also then contains more fat than usual; and finally the cha- racters of the pus-corpuscles are lost, only scattered molecules re- maining in their stead. In connection with pus, Wedl mentions a peculiar histological element, occurring most frequently and in the greatest abundance in the sputa of pneumonitis. It is a finely-granular globule, yg1^ to g^no- 0I" an incn in diameter, with a sharply-defined cell-wall of a yellowish or yellowish-brown color, sometimes containing scat- tered pigment-granules, and entirely destitute of a nucleus. Fig. 107 shows four of these bodies, mixed with pus-corpuscles and Fig. 107. Granular globules (sterile cells), without nuclei, in the grayish-yellow sputa of pneumonitis. The smaller cells are pus-corpuscles, and the lines represent filaments of mucosine. The sterile cells are filled with occasionally pigmented contents. (Magnified 350 diameters.) (Wedl.) filaments formed by the mucosine from the sputa above mentioned. They may perhaps be abortive glomeruli or granule-masses, and hence Wedl terms them "sterile cells." Another form of sputa in Fig. 108. Sputa of acute pneumonitis, containing fibrinous casts of the minute bronchial tubes, large cells filled with oil-globules, and finely-granular cells resemblingpus- corpuscles. USES OF PUS. 193 acute pneumonitis, containing casts of the tubes and cells filled with oil-globules, is shown by Fig. 108. Finally, pus cannot be absorbed from a part without disintegra- tion of the corpuscles, and then reappear in another part, as some still maintain. It may enter the blood through openings in the vessels (as in stumps, &c), but in no other way.1 Uses of Pus. 1. Pus, being a bland fluid, is incidentally useful when formed upon granulating surfaces, in protecting the subjacent layer of the exuda- tion from the action of the air, and thus enabling it to be organized into tissue instead of pus. The granulations themselves also would be reabsorbed, and the reparative process arrested, if the air were not thus kept from them. It follows, therefore, that whenever it is impossible to exclude the air from a granulating surface by artificial means, the pus should not be entirely removed when the dressings are renewed; but only any excess, or any portion which has under- gone or may soon undergo decomposition. Here, then, pus is inci- dentally useful; though its formation—i. e. suppuration—is not de- sirable, were it possible to secure the organization of the whole of the exudation into new tissue. 2. Again, when an exudation has become coagulated in a part, or on a mucous membrane, it is sometimes better that it should be organized into pus than into tissue, provided it cannot be reab- sorbed ; for then it may be removed from the part. E. g. in pneu- monitis the exudation had better become developed into pus-cor- puscles and fatty molecules (gray hepatization), and be removed in the sputa, than become organized into an indurated mass, destroying the pulmonary structure. And if the exudation in true croup is converted principally into pus and removed by the act of coughing, instead of taking the form of a tough false membrane, so much the better for the patient. In such cases, therefore, the formation of pus is an advantage; in other terms, suppuration is an advantage, though the pus itself is of no use in the organism. 3. On the other hand, suppuration is always directly destructive of the exuded plasma—i. e. it prevents the latter from being organized into tissue. Hence profuse suppuration produces a powerful exhaust- ing effect upon the organism, unless neutralized by an abundance of nutritious food. The emaciation which it also produces is easily ex- plained by the abundance of fat in pus, there being, on an average, at least ten to fifteen times as much, proportionally, as in the blood. Hence the use of cod-liver oil seems to be indicated here as well as in scrofula and phthisis. It also follows that in all cases of repair 1 Vogel mentions a case of empyema in which a thick creamy fluid escaped in the urine when the thoracic effusion subsided. The microscope, however, showed that the urinary admixture consisted entirely of epithelial debris. 13 194 THE FLUIDS. by granulation we should, by excluding the air by appropriate dressings, and by all other possible means, reduce the amount of pus to the minimum. The preceding is believed to be the view of the subject of transu- dations, exudations, and the formation of pus, which the present state of science demands. In regard to the first two subjects, it must, however, be admitted that much still remains to be ascertained and settled. Only well-marked transudations on the one hand, and exu- dations on the other, have been here discussed. But all possible transitional forms between the two are found to exist; there being sometimes a transudation with a small amount of exudation added to it, and at others precisely the reverse. We may also have a trans- udation, as well as an exudation, mixed with pus; and herein lies the essential difficulty in investigating these subjects. In conclusion, we must confess, therefore, with Wedl, that "our present doctrine with respect to exudation [and transudation] is but a very poor crutch, upon which we must hobble for a time, in order, in some degree, to obtain a measure of the field we have to survey" (p. 38). CHAPTER III. THE MUCOUS AND THE GLANDULAR SECRETIONS. The glandular are here associated with the mucous secretions from the fact that the ducts of all true glands are lined by a mucous membrane, which secretes some of the varieties of mucus in a part of its extent, while its epithelial cells in the smallest subdivisions of the ducts elaborate the secretion characteristic of the gland. It consequently results that all the true glandular secretions contain an admixture of mucus, to a greater or less amount; and hence the mucous secretions will be first described, under the head of "Mucus." SECTION I. MUCUS. It has been supposed to be a sufficiently accurate statement that mucus is the fluid normally secreted upon the mucous membranes. While, however, we have a definite idea of a mucous membrane as MUCUS. 195 always containing the same histological elements, it is by no means true that precisely the same secretion is afforded by them all. The ultimate ramifications of the ducts of all true glands (salivary glands, kidneys, &c.) are lined by a mucous membrane, though their secretions widely differ from each other, and are in no case true mucus. It is more accurate to say that the epithelial cells alone of the membrane secrete. But here again we must exclude the epithelial cells of the minutest gland-ducts in specifying the structure concerned in elaborating mucus. Where, however, we find a mucous membrane, in other circum- stances, is expanded as a protective structure (as in the alimentary canal, air-passages, &c), we also find minute cavities sunk into its substance and opening upon its surface, and the epithelial cells of these are the actual secretors of true mucus. Doubtless, also, the epithelial cells upon the general level of the mucous membrane secrete mucus, but in a less degree.1 Mucus may therefore be defined to be the fluid secreted by the epithelial cells of the follicles and of the general surface of mucous membranes, except where they form the lining of minute gland- ducts. It is, however, not true that mucus is always, in composition, the same fluid, even when restricted to these limits. It contains an immediate principle called mucosine; but it has already been stated (p. 84) that at least three varieties of this substance exist, to which as many different forms of mucus correspond. Indeed, it is clear that the same fluid would not answer the requirements on the dif- ferent mucous membranes, or on all parts of the same one; hence the mucus of the mouth is very different from that of the nasal passages, and that of the cervix uteri from that of the uterine ca- vity and of the vagina. A more discriminating investigation of the different fluids termed mucus, because found on mucous mem- branes, is therefore demanded. Physiologically, mucous membrane has no specific character, so far as it is secretive, but only so far as it is protective. Mucus is described as a viscid mass, capable of being drawn into threads, and consisting (1) of a pellucid, cohesive fluid, con- taining (2) a variety of morphological elements, principally epi- thelial cells. 1 Synovial bursa (so called) also belong to this category, and secrete mucus. 196 THE FLUIDS. 1. The fluid portion alone of mucus is peculiar, and this alone is to be regarded as a secretion. Its chemical reaction varies; being alkaline, for instance, in mucus from the cervix uteri, while it is acid in that from the vagina. It contains only from 4.4 to 11.8 per cent, of solid matter, of which 0.7 per cent, consists of salts, the chloride of sodium being the most abundant. 2. The morphological elements are to be regarded as distinct developments, either formed or merely inclosed in the fluid portion. The epithelial cells belong to the latter category; the cytoid (mucus) corpuscles are developed in the true mucus, after its secretion from the blood, upon the mucous membrane (p. 147). The morphological elements, however, usually form a large portion of the whole mass. The epithelial cells are conoidal or otherwise in form, according to the particular membrane or part from which they are derived. The cilia usually become detached if the epithelia were ciliated. Albumen does not exist normally in mucus, but occurs whenever the mucous membrane becomes inflamed. (Julius Vogel) It may also occur in mere congestion; but in both of these cases results from transudation. Fat is abundant in catarrhal affections, in the form of vesicles or granules; there being, however, but very little in normal mucus. Molecular granules are most abundant in the white sputa of typhus. Coagula of fibrine and colored blood-cor- puscles are often found on mucous membranes when inflamed (e. g. in croup); but here true mucus Fig. 109. Mucus-corpuscles, epithelial cells, and blood-disks, in vaginal mucus. The epithelial cells are recog- nized by their comparatively very large size. is no longer secreted, but an exudation has occurred instead. These coagula often form tubes lining the bronchia in bronchi- tis and pneumonitis. A mixture of mucus and blood-corpuscles and epithelial cells is shown by Fig. 109. Granular masses and cells— inflammation-globules (p. 119), are also found, especially in case of inflammation of the air-pas- sages. Some discover pus-cor- puscles, also, in case of inflam- mation of the mucous mem- branes ; but it has been already MUCUS. 197 shown that the latter are not to be distinguished, in their natural state, from the normal cytoid corpuscles in mucus (p. 146). Vibri- ones and microscopic fungoid growths must be considered as of incidental occurrence. It should also be added that a fluid possessing all the characters ascribed to mucus is sometimes secreted in certain cysts. The quantity secreted by the mucous membranes cannot be ascer- tained with accuracy. Valentin believed the amount to be exceed- ingly small, or even absolutely nothing, in the normal state. Cer- tainly it is only in irritative congestion, or inflammation, that the amount becomes considerable; but then there is a transudation or exudation, or both, mixed with the true mucus. Origin.—It has been stated that true mucus (i. e. the fluid portion) is secreted by the epithelial cells of the follicles or of the general surface of mucous membranes, except when they line the ducts of glands; while the epithelial cells of the latter secrete saliva, urine, &c., according to the gland in which they exist. It is, therefore, the epithelial, cells on a mucous membrane, and not the mucous mem- brane merely as such, which manifest specific vital properties and specific secretory functions (p. 195). It has been suggested that the true mucus is derived from a sort of decomposition or partial disintegration of the epithelial cells. Though this chemical view may be correct so far as it implies that mucus as found is different from the same while still inclosed within the epithelial cells, there are sufficient physiological grounds for the belief that mucus is, at any rate, originally elaborated within the epithelial cells, from the plasma of the blood. It might be antici- pated that the form of the epithelium, whether scaly or conoidal, would correspond with a difference in the fluid secreted. The cytoid (mucus) corpuscles are, by some, said not to be present in normal mucus. Kolliker maintains that they "are abnormal, but almost constantly present," in the mucus of the oral cavity; being a "kind of exudation or pus-corpuscle, with which they have the closest possible resemblance in structure" (p. 466). Lehmann seems rather to indorse the idea that the mucus-corpuscles, so called, are merely abortive epithelial cells. While we agree with Kolliker that the cytoid corpuscles consti- tute no part of the true mucus, we cannot regard them as abnormal products; nor admit, on the other hand, that they have any deve- lopmental relation to the epithelial cells. We believe them to be 198 THE FLUIDS. developed in the true mucus (probably from the mucosine espe- cially), in accordance with the law specified on page 146. Hence, in case of irritation, congestion, or inflammation of the membrane, these corpuscles increase; since not only mucus is secreted, but (from the consequent transudation or exudation upon the mem- brane) albumen or fibrine (or both) is blended with it. Uses.—True mucus is merely protective to the parts with which it is brought in contact. Some of its modifications, however—as the gastric and intestinal fluids—perform an important function in aid of digestion, as will appear (pp. 200 and 201). From the relations of the mucous membrane to the true glands, which have been specified, it must follow that all the glandular secretions must contain an admixture with them, to a greater or less extent, of true mucus and mucus-corpuscles. Varieties.—Three varieties of mucus have already been men- tioned, viz:— 1. The mucus from the nares and bronchial tubes, the large in- testine, and the interior of the uterus. 2. That from the neck of the uterus. This has an alkaline reac- tion, while that from the vagina is acid. 3. The mucus in the urine. Other varieties still might be added, which differ not only in appearance, but also in the characters of the mucosine they contain. Synovia, in its chemical composition, approaches nearer to the mucous than to the serous secretions. Tildanus always found mu- cosine in it, as well as albumen. The synovial bursae also contain true mucus rather than synovia, and were by Bichat not inappro- priately termed "bursas mucosae." The remaining modifications of mucus, which require a particular description, are the gastric and the intestinal fluids. The Gastric Fluid. Pure gastric fluid is clear, liquid, colorless or slightly yellowish, of a peculiar feeble smell, a slightly saltish taste, and of a very acid reaction. It is a little heavier than water, and for a long time resists decomposition. No morphological elements belong to it, though the epithelial cells of the gastric follicles (favuli) and their nuclei, and a fine molecular matter, are found floating in it. Gastric fluid, when filtered, contains only 1.05 to 1.48 per cent. of solid elements; of which 63 per cent, are organic, and 37 per cent, are inorganic matters. THE GASTRIC FLUID. 199 The organic substance to which the gastric fluid mainly owes its property in aid of digestion, is called pepsin. It is closely allied to the albumi- nous compounds. The free i • • ij bottom of which the glands open. epithelial cells of the peptic gastric glands They are ^ooth of an inch deep, (Fig. 110), as mUCUS is by the epithelial and l-250th of an inch broad; the ^ ° '" -i sePta bein8 l-1000th of an inch cells of other mucous membranes, as al- wide. Gastric peptic glands. a. Common trunk, b, b. Its chief branches, c, c. Terminal coeca, with spheroidal gland-cells. Chemical Physiology, p. 168. 200 THE FLUIDS. ready explained. The gastric favuli, into which these glands open, are shown by Fig. 111. Function.—It is by the agency of the gastric fluid that the albu- minous compounds in the food are dissolved1 and converted into uncoagulable substances, soluble in water and dilute alcohol, and which Lehmann has termed peptones. Mialhe first termed these substances albuminose (p. 87). It is probable that the acids are principally efficient in dissolving these compounds; while the pep- sin, acting by catalysis, enables them to exert a vastly greater sol- vent power than they would without it. From 3 to 5 grains of coagulated albumen may be dissolved in 100 grains of recent gas- tric juice. It has no effect at all on the fats and other non-nitro- genized elements of the food, these passing through the stomach unchanged by it. Other strong mineral acids (but not the organic) may partially supply the place of the hydrochloric and lactic. Its digestive power is also increased by the addition of fat. Bile en- tirely suspends its digestive power, and saliva diminishes it. The gastric fluid, however, is not sufficient to dissolve all the albuminous compounds necessary to nourish an animal.2 (Lehmann) Besides, it loses its digestive power in the duodenum, where its acid reaction is overcome by the alkaline bile and pancreatic fluid. Another fluid must therefore flow into the intestine, below the duodenum, which exerts a similar effect, and which will be next described. The Intestinal Fluid. Frerichs has ascertained that the glandulae aggregatae (Peyer's patches) contribute but very slightly3 to the formation of the intes- tinal fluid—they being closed sacs—and that its true secreting or- gans are the pouch-like follicles of the small intestine (Lieberkuhn's follicles), and the similar larger and very numerous follicles of the large intestine. In chemical composition, the fluids of the small and the large intestine are found to be perfectly identical. The intestinal fluid is a glassy, transparent, colorless, tenacious 1 Bernard proves that while white fibrous tissue is dissolved, muscular fibre is merely softened, as if it had been boiled. Starch, sugar, and fat are not affected at all by the gastric fluid. 2 This assertion is doubtless correct in itself, but not at all consistent with Leh- mann's estimate of its quantity, mentioned on page 199. 3 Not in the least, as will appear in the chapter on "The Alimentary Canal." THE INTESTINAL FLUID. 201 mass, with a strong alkaline reaction. (Frerichs) Of course there must be more or less true mucus, in all cases, in combination with the secretion of the follicles. The morphological elements found in this fluid are conoidal epithelium-cells (these having secreted it), nuclei from the same probably, granular cells, and here and there a little fat. This fluid averages 3.2 per cent, of solid constituents, .195 per cent, being fat. The quantity of the intestinal fluid cannot be accurately ascer- tained. Bidder and Schmidt calculate that about 9| ounces are secreted in twenty-four hours by a man weighing 140 pounds. It is secreted in greatest abundance four or five hours after a meal, and is increased by drinks. Origin.—The intestinal fluid is secreted by the epithelial cells of the follicles of the small and of the large intestine. (Fig. 112.) Fig. 112. Uses.—This fluid is proved, by the experiments of Bidder and Schmidt, to unite in itself the powers of both the gastric and the pancreatic fluids—i. e. it at the same time digests flesh and all albu- minous substances, and also changes starch and prepares it for absorption. It has been seen that the gastric fluid loses its power as a digestive agent on arriving in the duodenum; and the pan- 202 THE FLUIDS. creatic fluid is reabsorbed, and therefore disappears, by the time it reaches the middle of the small intestine. Other agencies are there- fore required to complete the processes these two fluids have com- menced, as the food passes lower down the canal; and these are apparently supplied by the intestinal fluid alone. It appears, moreover, that while bile suspends and the pancreatic fluid impedes the digestion of the albuminous compounds by the gastric juice, they do not at all interfere with that by the intestinal fluid. SECTION II. THE GLANDULAR SECRETIONS. By the glandular secretions are meant those of the true or com- pound racemose glands, and whose ducts are lined by a prolonga- tion from a mucous membrane. They, of course, all contain some admixture of mucus, and will be described in the following order:— I. Milk. II. Semen. III. Glandular secretions discharged into the alimentary canal (saliva, bile, &c). IV. Urine. V. The lachrymal fluid. I. Milk. Human milk is white, slightly translucent, colorless, of a weak sweetish taste, and of an alkaline reaction. Its specific gravity is between 1030 and 1034. After standing at rest for a time, a yel- low layer abounding in fat (the cream) forms on the surface, while the fluid below becomes specifically heavier, and of a bluish tinge. It is not coagulated by boiling, but forms on its surface a film of coagulated caseine mixed with fat-globules. Rennet (i. e. the mu- cous membrane of the calf's stomach) coagulates it, as has already been explained in connection with the properties of caseine (p. 88). Exposed to a temperature somewhat above the mean, an acid is developed in it, and which precipitates the caseine, constituting the acid fermentation or "souring" of the milk. The milk secreted for the first three or four days after parturition has peculiar characters, and is called colostrum. This is a turbid, yellowish fluid, resembling soap and water, viscid, and strongly alkaline in reaction. It contains more solid constituents than nor- mal milk, and passes more rapidly into the acid fermentation. This MILK. 203 increase principally affects the sugar (to 70 parts in 1,000) in wo- man's milk, and the caseine in that of the cow. It also contains more fat than normal milk (even 50 parts in 1,000), this proceeding probably from the colostrum- Fig. 113. 0^)00^o^oo° Milk-globules and colostrum-corpuscles, latter being the largest. the corpuscles; and twice or thrice the amount of salts. Under the microscope, milk shows an immense number of fat-globules suspended in a clear fluid, and which are called the milk-globules. (Fig. 113.) For a short time after parturition it also contains the colostrum-cor- puscles, some of which are also shown in the accompanying figure. 1. The milk-globules are from Wo-u to segg (Hassal says ^^ to 450o) °f an mcn m diameter, being fat-globules surrounded by a special membrane of caseine, as already stated (p. 89). The colostrum-corpuscles (granular cells) are irregular conglome- rations of fat-granules, held together by an amorphous albuminous substance (homogeneous substance), being s^Du to nearly ^^ of an inch in diameter, having no nucleus nor cell-wall. They occur not only in the colostrum (up to the third or fourth day after partu- rition, and sometimes even up to the twentieth), but always also when the milk-secretion is disturbed by any pathological condition. Precisely similar bodies also occur in inflammatory exudations, and are then called "glomeruli" and "inflammation-globules." (See Figs. 42 and 59.) Epithelial cells often appear in milk; cytoid (mucus) corpuscles rarely—and in pathological states of the mammary glands. Fibrin- ous clots and blood-corpuscles, of course, occur only when hemor- rhage into the lactiferous ducts has taken place. Infusoria (vibrio bacillus and byssus), as in the blue milk of cows, are very rarely observed. 2. The fluid portion of milk consists, on an average, of water 883.6 parts (Simon) to 1,000 of milk, holding in solution the fol- lowing substances, and in the following proportions:— 204 THE FLUIDS. Water........883.6 1. Caseine ........ 34.3 2. Sugar of milk (lactine) and extractive matters . 48.2 3. Fixed salts.......2.3 4. The butter (fat) is derived from the milk-globules, and, makes up the remaining 25.3 parts in 1,000. 1. The amount of caseine in woman's milk is greater after animal than after vegetable food. It is, however, less abundant than in cow's milk, the latter containing 41.6 (Playfair) in 1,000. The coagulum is also less dense, and therefore more easily digested by the infant. L'Heritier found over 50 per cent, more caseine in the milk of the brunette than in that of the blonde. 2. "Woman's milk contains more sugar than that of the cow; the latter containing 34 to 43 in 1,000. L'Heritier also found that the milk of the brunette contains more sugar than that of the blonde, in the proportion of 7 to 5.85. It is increased by a vegetable diet. (Dumas and Bensch) Diseases—especially syphilis—do not appear to modify its amount, nor does either an abundant or an insuffi- cient diet. 3. The salts are less than one-half as abundant in woman's milk as in that of the cow; the latter containing 5.5 to 8.5 in 1,000. The difference, however, more especially affects the insoluble salts be- longing to the caseine, and which are diminished with its diminu- tion. The principal salts are the chlorides of sodium and potassium, and phosphates of the alkalies, lime, and magnesia, besides the alkali combined with the caseine. 4. The fat (butter) of woman's milk is supposed to be richer in oleine than that of cow's milk. It is increased by fatty food. The whole amount of fat is much less than in cow's milk (the latter containing 45 in 1,000), and remains nearly the same through the entire period of lactation. The milk first drawn from the breasts is poorer in fat than that flowing afterwards. The fat also dimin- ishes in diseases. Albumen has been detected in milk in case of inflammation of the lacteal gland. But doubtless mere congestion may cause it to appear, a transudation being thus mixed with the normal secretion. Urea may occur in the milk in Bright's disease of the kidney. Iodide of potassium may also pass into the milk, but it has not been proved that other medicinal substances can. The quantity of milk secreted by a healthy nursing-woman, from MILK. 205 both breasts, in twenty-four hours, averages about 2 pounds and 14 ounces, or 22 grains for every 1,000 grains of her weight. A cow secretes only 10.4 grains to 1,000, or 13 pounds and 4 ounces in all.1 (Lehmann) Origin.—Milk is secreted by the epithelial cells of the ultimate follicles or cceca of the lacteal glands. It is not to be, hence, in- ferred, however, that its constituents exist preformed in the blood; for true secretion (the urine alone, perhaps, excepted) always implies that the fluid secreted is formed in the cells from the elements in the plasma of the blood, and therefore contains elements not to be found in the latter. It has already been stated that the sugar is formed in the mammary gland (p. 72); and the assertion of Mialhe, that caseine exists in the blood, though probable, has not been fully confirmed (p. 88). The caseine of the milk is pretty certainly derived from the albumen in the blood. The ducts and terminal follicles of the lacteal gland are shown by Figs. 114 and 115. Fig. 114. Fig. 115. Milk-ducts terminating in clusters of follicles. Terminal coeca (follicles) of lacteal gland, with their secreting cells (a, a); nuclei (6, b). The epithelial cells lining the follicles (Fig. 115) may be seen to contain the milk-globules, and are therefore proved to be the real agents in this secretion. On bursting, they set the globules free in the follicles, which, communicating with the ducts (Fig. 114), pour the milk into the latter. Uses.—Milk is the normal food of all the mammalia during the first period after birth. It therefore combines all the elements ne- cessary for perfect nutrition and rapid growth. A discussion of all its important physiological relations would, however, be out of place here. The caseine is its nutritive element (p. 89). If, however, milk is the proper nourishment for the infant, while 1 More than double the quantity here mentioned by Lehmann is very generally secreted by the cow, in this country. 206 THE FLUIDS. growth and development are rapid, it cannot be so for the aged. Seizures simulating apoplexy are sometimes produced by milk in aged persons not accustomed to its use. Woman's milk usually becomes suddenly deficient in caseine at the end of a year after parturition. This may be accepted as an indication that lactation should not, as a general rule, be prolonged beyond this period. Up to this time it becomes more and more nutritious, in proportion to the increased size and strength of the infant. It frequently becomes necessary to substitute the milk of one of the lower animals for that of woman, and the following facts are of interest on this subject:— 1. Cow's milk contains a small amount more of solid constituents than woman's milk, in the proportion (average) of 140 to 120 in 1,000 of milk. It contains more caseine (41.6 : 34.3), more fat (45 : 25.3), and far more salts (7 : 2.3). On the other hand, it con- tains less sugar (38.5 : 48.2). Consequently, if from 1,000 parts of cow's milk nearly one-half (|) of the cream is first removed, and then 186 parts of water and 10 parts of sugar be added, the result will, in composition, very nearly resemble woman's milk, except that the salts will still be too abundant. The following formula will, therefore, answer, for prac- tical purposes, as nourishment for an infant:— R.—Cow's milk . .16 ounces (1 pint). (Remove one-half the cream.) Water ... 3 ounces (6 tablespoonfuls). Sugar £ ounce (a large teaspoonful). 2. Goafs milk is sometimes substituted for that of woman. It contains 132 to 145 of solid constituents, of which 40.2 to 60.3 are caseine, 33.2 to 42.5 are fat, and from 40 to 53 are sugar, in 1,000 parts. 3. The milk of the ass has less (only 91.6 to 95.3) of solid con- stituents, there being only 16 to 19 of caseine, from 12.1 to 12.9 of butter, and 62.9 to 68 of sugar. It is the richest of all in sugar, but poor in caseine and butter. 4. Mare's milk contains 162 in 1,000 of solid residue, but little caseine (17), a large amount of fat (69.5), and the most sugar of all (87.5). 5. Sheep's milk contains 143.8 of solid constituents, 40.2 being caseine, 42 fat, 50 sugar, and 6.8 salts. A formula may be easily deduced from the preceding data, if it be desirable to sustain the human infant on the milk of either of the four animals last mentioned. SEMEN. 207 The only carnivorous animal whose milk has been analyzed is the bitch. Her milk has an acid reaction (when she is fed on animal food), and contains 274.6 to 224.8 in 1,000 of solid constituents. Of these, 80 to 110 are caseine, from 68.4 to 109.5 are butter, while the quantity of sugar of milk is very small. The last and the butter are increased by mixed food. The great amount of caseine and of fat deserves especial notice, in a physiological point of view. II. Semen. Semen, as usually observed, is mixed with the prostatic fluid and that secreted by Cowper's glands and the vesiculae seminales. It can be obtained in its pure state only from the vasa deferentia and the testes of animals in heat. When mixed as just stated, it is a mucous, viscid, colorless fluid, considerably heavier than water, and of a neutral or slightly alkaline reaction. 1. The liquor seminis, a great part of which is derived from Cow- per's glands, the prostate, and the vesiculae seminales, gelatinizes after emission; the gelatinizing substance (spermatine) resembling mucus more than fibrine. The salts most abundant in it are the phosphates of lime and magnesia. The fat (p. 78) exists principally in the cells hereafter to be described. Yauquelin found 10 per cent, of solid constituents in the semen—viz., 6 per cent, of organic matter, 3 of earthy phos- phates, and 1 of soda. 2. The peculiar histologi- cal element of the semen, the spermaJtozoiaW (spermatic filaments), are the most sin- gular developments in the organism. They occur in the semen of all animals, and are analogous in form in all, though distinguish- able in each species, as a general rule; consisting of a round, oval, or pyriform body, to which a long fila- ment or tail, gradually ta- pering to a point, is attached. Fig. 116. Human spermatozoids. A. From the vas deferens: 1 to 4, their variety of character; S, seminal granules, b. From testis: 1, large cell; 2, same, containing three granular bodies, from which the spermatozoids are developed ; 3, a bundle of spermatozoids still grouped together. From o-7ref>fAa, semen, (£»>?, animal, and eTio;, resemblance. 208 THE FLUIDS. (Fig. 116.) In the human spermatozoid the body is from gg'gg to 5^5 of an inch long, and from T7|jnu to Wuu OI> an incn iQ width, and the filament is from ggg to s^ 0I> an incn l°ng- They were formerly regarded as infusorial animalculae, on account of their active motions, the tail striking rapidly from side to side, and pro- pelling the body in a zigzag direction. This motion may be re- tained a long time if the semen is prevented from evaporation, or if placed in tepid serum, saliva, or mucus. If double its quantity of water is added to the semen, the power of motion is lost. Urine very soon stops the movements. In the interior of the female sexual organs they continue longer than elsewhere. Motion is also destroyed by a solution of opium, by alcohol, by strychnia, and by the electric spark, though not by galvanism. Concentrated solu- tions of sugar, albumen, urea, and various salts re-excite the motions again. If destroyed by strychnia, the tail remains extended. The spermatozoids are not readily destroyed by putrefaction, and may be kept for years as microscopical objects, in the dried state. The seminal granules are also peculiar to semen, and within them the spermatozoids are developed. Hence they are also called sperma- tophori. These are finely-granular, pale, sharply-outlined corpuscles, from ^^^ to iVo-is °f an iQCn m diameter. Fig. 117 shows the development within them of the spermatozoids. We also find in semen scattered epithelial cells, cytoid (mucus) cor- puscles, and minute fat-granules; nei- ther of which presents any peculiarity. The recognition of semen is often a matter of great medico-legal import- ance. A microscopic examination will at once detect the spermatozoids, their form is so characteristic. Urine con- taining semen very readily becomes alkaline. Seminal spots (as on linen) have been shown by Schmidt to differ from all others. The glistening surface of the spot will decide on which side of the linen it is, and here only can spermatozoids be found. He found that seminal spots became of a pale yellow color when kept near the fire for an hour or two, while the form of the spermatozoids is not Fig. 117. Phases of development of spermato- zoids. a. Original nucleated cells, b. The same enlarged, showing spermato- zoids. c. The latter nearly perfect, but still inclosed within the cell. SALIVA. 209 changed. Other substances, treated in this way, are colored green (as vaginal mucus), or are not changed in color. Origin and Uses.—The spermatozoids are developed within the spermatophori, as already stated, and are the part of the semen indispensable to impregnation. The spermatophori are probably developed from the spermatine, as cytoid corpuscles are in plasma, as described on page 146. Their relation to the seminiferous tubes of the testis will be explained in the chapter on "The Sexual Organs." III. Glandular Secretions discharged into the Alimentary Canal. 1. Saliva. Saliva, as obtained from the oral cavity, is a mixture of the secretions from the three salivary glands with the mucus of the mouth. It is a cloudy, viscid, slightly opalescent fluid, without taste or smell, and of alkaline reaction. Its specific gravity varies from 1004 to 1006, and its solid constituents from 0.35 to 1 per cent. The only histological elements in saliva are epithelial cells and cytoid (mucus) corpuscles; neither of which are, of course, peculiar to it. The pure saliva varies with the gland secreting it, whether the parotid, submaxillary, or sublingual. The secretion of the parotid gland has a specific gravity of 1006 to 1008.8, is clear as water, and without color, taste, or odor; and contains 1.4 to 1.6 per cent, of solid constituents. It contains much chloride of sodium and of potassium. The secretion of the submaxillary gland resembles the preceding, but is more viscid, less strongly alkaline, and has a less specific gravity (1004) and less solid residue (0.855 per cent.); and that of the sublingual gland is the most viscid of the three. All of these secretions contain a peculiar organic substance—salivine, or ptyaline (p. 83). Recent experiments give 3 pounds and 6£ ounces (avoirdupois) as the average quantity of saliva secreted by adults in twenty-four hours. (Lehmann) The quantity is increased by the mastication of dry and hard alimentary substances, and by movements of the jaw, whether in chewing, speaking, or singing. Acid, aromatic, and pungent substances have the same effect. 14 210 THE FLUIDS. Iodide of potassium is always found in saliva after the use of iodine, and mercury enters it in case of mercurial salivation. It is also acid in certain abnormal states, and usually so during fasting. Origin.—Saliva is secreted by the epithelial cells of the minute subdivisions of the ducts in the three salivary glands. Uses.—The mechanical functions of saliva are fivefold:— 1. It conduces to phonation and articulation, by securing a proper degree of moisture of the tongue and oral cavity. 2. It aids the sense of taste. 3. It cleanses the mucous membrane of the oral cavity. 4. To a certain extent it quenches, or rather prevents, thirst. 5. It aids in mastication and deglutition, and carries air into the stomach, the latter being inclosed in the form of bubbles during mastication. Bernard has shown, however, that it is the parotid secretion which prevents thirst, while that of the sublingual is sub- servient to deglutition, and that of the submaxillary conduces to the perfection of taste. An important chemical agency has also been attributed to saliva; the power of changing the starch of the food into sugar. Bernard has, however, proved that only mixed saliva has this effect, and only when in a state of incipient decomposition. In fact, the influence of saliva upon starch has been much overrated; the pancreatic and intestinal fluids being the principal agents for the conversion of the amylacea into sugar. It normally only hydrates the starch after it arrives in the stomach. 2. Bile. Bile, as obtained from the gall-bladder, is a viscid fluid, capable of being drawn into threads; of a green or brown color, a bitter taste, and a peculiar odor (often resembling musk). Its specific gravity is about 1020, and it is usually alkaline, often neutral, and very rarely acid, even in disease. When it contains much mucus, it putrefies very readily; when nearly free from it, with difficulty, or not at all. It doubtless always contains some of this element, and to its presence the viscidity of the bile is due. Pure bile has not yet been analyzed. The only morphological element in bile is the conoidal epithelial cell of the gall-bladder and biliary ducts. Bile, as usually obtained for examination, contains, on the average, 14 per cent. (10.2 to 17.3) of solid constituents; 90 per cent, of these BILE. 211 being organic matters, and 10 per cent, mineral substances. It be- comes more concentrated by a prolonged stay in the gall-bladder. The organic matters in bile are—1. The bile-pigment (the brown and the green) already described (p. 101); 2. Cholesterine (see p. 75); and which, with fat and fat-acids, form 27 to 30 per cent, of the solid residue. Among the mineral constituents of bile, the chloride of sodium preponderates. There are also found some phosphate and carbonate of soda, phosphate of lime and magnesia, and traces of iron and magnesium. The amount of bile secreted in twenty-four hours is unknown. Bidder and Schmidt's experiments on the lower animals would lead to the conclusion that it is not less than 23 ounces1 in the case of an adult man weighing 140 pounds. It is increased by animal food, in quantity, and at the same time in density. Fat, taken in abundance, increases it also. On the other hand, it is considerably diminished by the carbonate of soila, and by febrile diseases. Calomel increases it; but only so far as the water is con- cerned—the solid constituents remaining the same. The bile is constantly secreted; but increases about three hours after the reception of food, and so continues for some hours after- wards. After prolonged abstinence it is reduced to one-fourth the quantity of the secretion afforded in the twenty-fourth hour after the last meal. If an animal is fed exclusively on fat, no more bile is secreted than during fasting. The gall-bladder empties itself in two and a half to three hours after taking food. Origin.—There can be no doubt that the bile is formed in the liver.2 Not one of its constituents exists preformed in the blood of the portal vein; and icterus does not occur in any disease which attacks the parenchyma of the liver, and thus entirely suppresses the secretion of bile. The epithelial cells lining the terminal sub- divisions of the hepatic ducts are the immediate agents of the biliary secretion. Fig. 118 shows Kolliker's idea of the relations of these cells to the "parenchymal cells" of the liver itself; the ducts directly abutting upon the latter, as he believes; and Fig. 119, the secreting cells when isolated. The actual structure is, 1 Todd and Bowman estimate the quantity at 54 ounces, containing 2 ounces of solid constituents (pt. iv. p. 480). 2 Except, perhaps, the pigment. (See p. 101.) 212 THE FLUIDS. however, shown by Fig. 370, and explained in the section upon the liver. Fig. 118. Fig. 119. A FH V: -r ■ ■ Isolated cells of the liver. a. Nucleus. 6. Nucleolus, c. Oil-parti- cles. zzz^tmmmmmmm^^^ a Diagram of the arrangement of the cellular parenchyma (6 6) of the human liver, with reference to the radicals of the interlobular ducts (a a), and the vascular spaces (c c). The sugar formed by the liver is not an element of the bile (p. 70). It is found in the "parenchyma" of the liver, and is greatly increased in diabetes. Function.—Several dis- tinct functions have been ascribed to the bile:— 1. It neutralizes the acids of the gastric fluid, when the contents of the stomach enter the duodenum. The latter always react acid; but it is to the quickly decomposing acids of the bile that the acidity is due. It also precipitates the substances dissolved by the gastric fluid, and hardens those softened by it. (Bernard.) 2. It prevents the putrefactive decomposition of the contents of the intestine; holding them, as it were, in statu quo till the pan- creatic fluid exerts its peculiar action upon them. 3. The power attributed to bile in dissolving fat has been over- rated ; though it cannot be wholly denied. It is a well known fact that bile removes greasy stains; and it has been shown that fat passes much more easily through membranes saturated with bile than through those moistened with water. It is also found that 2J times less fat is absorbed from the intestine when the access of bile is prevented. The influence of bile, therefore, in aid of the absorption of fat is undoubted. 4. Finally, bile aids in securing a regularity of defecation, from its stimulating effects upon the muscular coat of the alimentary canal. Pathological States of the Bile. Albumen is found in the bile in the embryonic state, some- times in fatty liver, in Bright's disease, and in cases of abscess of PANCREATIC FLUID. 213 the liver. The albumen is, in these last cases, probably due to transudation. Urea occurs in the bile in urasmia, and therefore principally in cholera and Bright's disease. The solid constituents are usually increased in the bile in cases of cardiac affections and abdominal diseases which produce con- gestion in the large veins; and in cholera, in which disease all the fluids become more dense from the loss of water. On the other hand, the bile is more watery after violent inflam- mations, in dropsical affections, typhus, tuberculosis, and diabetes. In these conditions the amount of water in the bile seems always to be in a certain proportion to that in the blood. Biliary concretions (chololithi) are of three kinds: 1. Of choles- terine, inclosing a nucleus of pigment; 2. Of the chalky pigment alone; 3. Of pigment with lime; of a dark green or black color, and almost free from cholesterine. The regurgitation of bile into the stomach at once arrests the action of the gastric juice (p. 200). 3. The Pancreatic Fluid. This secretion is colorless, clear, slightly viscid, tasteless, and odorless, and presents a tolerably strong alkaline reaction. It co- agulates on being heated. Its specific gravity is variable; the con- centration standing in inverse ratio to the quantity of secretion afforded in a given time. The pancreatic fluid transforms starch into sugar in a few mi- nutes, and decomposes the neutral fats into glycerine and the cor- responding fat-acids. About seventy-eight per cent, of the solid residue of this fluid is the organic substance peculiar to it—pancreatine (p. 83). The mineral constituents of this fluid are, principally, chloride of sodium, phosphates of the alkalies and earths, sulphates of the alkalies, and carbonate of lime. The quantity of the pancreatic fluid is not accurately known. Experiments indicate that it varies not far from 4f ounces in twenty- four hours in an adult man. (Bidder and Schmidt) It is independ- ent of the volume of the pancreas, and attains its height during the period of digestion. Ingestion of solid food, and also especially of drinks, augments it. Origin.—The pancreatic fluid is secreted by the epithelial cells of the ultimate subdivision of the duct of ( Wirsung), the pancreas. Function.—The pancreatic fluid changes starch into glucose, the albuminous elements of the food into albuminose, and the fatty into 214 THE FLUIDS. an emulsion (Bernard); the last being absorbed partly by the lac- teals and partly by the bloodvessels of the villi, and the first two by these vessels alone. It cannot, however, be the main agent in changing the fatty elements below the jejunum; since it is changed or reabsorbed before it reaches the middle of the small intestine. The intestinal fluid supplies its place in this respect, through the remaining portions of the alimentary canal (p. 201). Fig. 120. Mucus-corpuscles and epithelial cells in urine. IV. Urine. The urine is of a lighter or deeper amber color, and has a bitter saline taste; being, while still of the temperature of the body, per- fectly clear and transparent, and of a pe- culiar faintly aromatic odor, and acid re- action. Its specific gravity never, in the normal state, rises above 1030 (Lehmann), and averages not more than 1020. The only morphological elements nor- mally found in urine are epithelial cellsi and more or less cytoid (mucus) corpus- cles (Fig. 120); these being accidentally present, as they are in the other glandu- lar secretions, and presenting nothing peculiar. But in pathological conditions, a variety of histological elements may be found. Of these, the spermatozoids, pus- (cytoid) corpus- cles, blood-corpuscles, and fibrinous casts of the tubuli uriniferi, are the most common; to which may be added cells and fibrinous casts containing fat-globules, as occurring in Bright's disease; and the large and small organic globules. 1. Spermatozoids (Fig. 116) are found most abundantly in the urine after pollutions and sexual inter- course, and are not to be referred to a pathological state except in some cases of spermatorrhoea. 2. Pus occurs in urine (Fig. 121) in cases of inflammation of the bladder; but the pus-corpuscle not being distin- guishable histologically from the mucus corpuscles (p. 146), needs not a distinct notice here. Cytoid-corpuscles abound in the urine in case also of inflammation of the kidney and the prostate; and in vesical catarrh, so called. 3. Blood-corpuscles appear in inflammation of the kidney, &c; in consequence of hemorrhage from any part of the urinary passages. Fig. 121. Pus-corpuscles in urine. URINE. 215 Their form is changed by the action of the fluid in which they are found, they most frequently resembling transparent rings. (Fig. 122.) 4. The casts of the tubuli uriniferi are bot- tle-shaped or cylindrical in form, and resem- ble fine hairs. They are from less than T^ to g1^ inch long, and j^^ inch in diameter; and present three varieties: 1. Those consist- ing of the epithelial coat alone of the urini- ferous tubes. These are observed in the com- mencement of Bright's disease, and in the desquamative stage of erysipelas and scarla- tina. 2. Those consisting of recent exuda- tion; generally granular, and containing more or less blood and pus-corpuscles. 3. Those consisting of pure coagulated fibrin; resem- bling hyaline tubes, and often hard to recognize on account of their transparency.1 5. Fibrinous casts and cells, containing fat-globules, are found in Bright's disease. Figs. 123, 124, and 379 represent these casts and cells. Fig. 122. & I i® Colored blood-corpuscles in ® ® ,3) ® ® ®® r.,0 > G> Fig. 123. Fig. 124. Fibrinous cast of uriniferous tube. Fibrinous cast containing epithelium and fat-globules. a. Cells containing fat drops, b. A fibrinous cast. 6. The large organic globules (Fig. 125), are not unfrequently met with in the urine of pregnant women. They appear to be merely Fig. 125. Fig. 126. O o 0° o u 0 0 o o o o 0 o c o c c Small organic globules. Large organic globules (400 diameters). 1 Dr. J. H. Bennet adds, the " waxy casts"—the detached basement-membrane alone of the tubes. 216 THE FLUIDS. a larger kind of cytoid corpuscle than those of mucus or pus. They are, moreover, not attended by the viscid and the albuminous fluid which respectively characterize mucus and pus. (J. E. Bow- man) The small organic globules (Fig. 126) are far more rarely found. They are spherical, smooth externally, and not granular within; are unaffected by acetic acid, and are much smaller than the pre- ceding. To these histological elements maybe added a thread-like fungus (confervoid), called the torula. (Fig. 127.) These threads are made up of cells s^g-Q to sssts of an inch in diameter. It occurs in de- composed urine, whether, as in vesical catarrh, decomposition corn- Fig. 127. Fig. 128. The torula in urine; crystals of uric acid Fungoid growths in the urine. and two epithelial cells. mences in the bladder, or after its emission. Another kind of fun- goid vegetation occurring in urine is seen in Fig. 128, in connection with crystals of oxalate of lime. Vibriones and monads also appear in decomposed urine; and the Fig. 129. Sarcina ventriculi. sarcina ventriculi of Goodsir has frequently been found in it 129.) URINE. 217 In chemical composition 1000 parts of urine consist of 933 to 972 parts of water, holding 67 to 28 parts of solid matters in solution. The following analyses by Lehmann and Becquerel, present the proportions of each element:— Lehmann. Water 937.682 (Solid constituents 62 .318) Urea 31.450 Uric acid . 1.021 Lactic acid 1.496 Extractive matters 10.680 Lactates . 1.897 Chlorides of sodium and ammonium 3.646 Alkaline sulphates . 7.314 Phosphate of soda . 3.765 Phosphates of lime and magnesia 1.132 Mucus 0.112 Becquerel. 971.935 (28.066) Other organic matters f Chlorine . ho a a o o Sulphuric acid . Phosphoric acid Potash Soda, lime, and magnesia 12.102 0.398 8.647 0.502 0.855 0.317 1.300 3.944 It will be noticed that Lehmann found nearly twice the amount of solids obtained by Becquerel, and about 2J times as much urea and uric acid. Berzelius and Marchand agree in all these respects very nearly with the former, and Simon and Dr. Miller with the latter. Of course the composition of the urine varies with its spe- cific gravity, and to this fact the disparity is doubtless due. Dr. Christison constructed a table showing the amount of solid con- stituents in urine of different specific gravities, which proves that the former increase very rapidly with slight increments of the latter. E. g. with a specific gravity of 1012, the solids are 27.96 in 1,000; while, if the former be increased to 1030, the latter are 69.90. If we look at the urea alone, we also find a rapid aug- mentation as the specific gravity increases. If the specific gravity is 1013.5, only 15 parts in 1,000 are urea; while, if the former be 1027, there will be 37.5 of urea—or just 2J times as much. (Leh- mann) To reconcile the analyses of Lehmann and Becquerel, we have therefore only to suppose that, while the specific weight in the latter was actually 1017.01, in the former it must have been at least 1025. But the results obtained by Becquerel are the more valuable 218 THE FLUIDS. in practice, since the specific gravity averages not more than 1020, and is generally rather less than this, according to most writers. Of all the constituents in solution in the urine, urea is the most important. Its proportional as well as its absolute amount varies extremely, the kind of food having a great influence in this respect (p. 69). An increased secretion of water is also accompanied by £n increased amount of urea, in the twenty-four hours. E. g. if 1,000 grains of urine be secreted in twenty-four hours, 33 grains are urea; if 2,000 grains, about 42 grains of urea; and if 3,000 grains of urine, about 50 of urea. Of course the specific gravity will be lowest in the last case, so that the amount of urea in one thousand parts of urine will be least of all. It has been seen that the urea is derived directly from the nitrogenized elements of the food and of the decomposed tissues (p. 69). Of uric acid, from 7.7 to 13.9 grains are excreted in the urine, by an adult, in twenty-four hours. Its amount depends less on the kind of food taken than on the internal conditions of the organism (p. 64). Creatine and creatinine (pp. 67, 68) are normal constituents of the urine, but their amount has not been determined. Formic acid is sometimes found in healthy urine, in very small quantities. Hippuric acid is hardly more abundant than the uric. Lactic acid is not found in normal urine, but at once occurs in those states of the organism in which the process of oxidation is interfered with (pp. 60, 66). The chlorides of sodium and potassium are very abundant in urine. An adult secretes about 162 grains of chlorine in twenty- four hours. They greatly diminish, or even entirely disappear, in diseases accompanied by copious exudations—as in acute dropsy, acute Bright's disease, acute tuberculosis, in violent diarrhoeas, cho- lera, typhus, and pneumonitis. The sulphates are found in variable quantities. An adult ave- rages 31.4 grains of sulphuric acid in twenty-four hours. They are increased only by violent bodily exercise (as in convulsions and delirium tremens), and in high mental excitement. The acid phosphate of soda (p. 57) is the principal source of the acid reaction of the urine. The phosphates of lime and magnesia are also found in considerable amount, and in the proportion, on an average, of 15 to 7. An adult discharges, on an average, 49.4 to 80.2 grains of phosphoric acid in twenty-four hours, and 15.4 grains URINE. 219 of earthy phosphates. The phosphates increase after taking nitro- genized food, and in acute affections of the nervous substance—e. g. in encephalitis (p. 49). It sometimes occurs, in the last months of pregnancy, that no lime at all is secreted in the urine; there being little or none in the blood also, as will be shown (Chap. VII). Traces of iron and silicic acid are usually found in urine; and gases are also dissolved in it, especially carbonic acid and a little nitrogen. Some substances—alimentary or medicinal—pass unaltered into the urine. These are such as are easily soluble in water, and do not form insoluble compounds with the constituents of the body; and which are, moreover, not readily oxidizable or decomposable. Thus the nitrates, carbonates, chlorates, borates, and silicates of the alkalies, and the chlorides, bromides, and iodides of potassium and sodium, pass unaltered into the urine; while sulphuret of potassium is oxidized, and appears in the urine as sulphate of potassa. All the salts of the metals pass into the urine unchanged, only when taken in large quantities; since they form insoluble compounds with animal matters, especially with albumen. Mannite, quinine, &c, are fully oxidized into carbonic acid and water. Most of the organic acids, as well as sulphocyanide and ferrocyanide of potas- sium, reappear in the urine unchanged. Tannic acid is, however, converted into gallic, benzoic and cinnamic into hippuric, uric acid into urea, and oxalic acid into carbonic acid and water. The neu- tral salts of the alkalies, with the vegetable acids, reappear in the urine as carbonates; and hence the urine speedily becomes alkaline after their reception. Urea passes unchanged into the urine. Co- loring or odoriferous matters generally pass unchanged or slightly modified>yThe following, however, do not reappear, viz: camphor, resin, inflammable oil, musk, alcohol, ether, cochineal, litmus, chlo- rophyl, and the coloring principle of alkanet. The rapidity with which different substances appear in the urine varies much. Iodide of potassium often appears after four to ten minutes. The following abnormal constituents may appear in the urine in pathological conditions, viz: albumen, fibrine, caseine(?), fat, sugar, abnormal pigments, biliary acids, bile-pigment, xanthine, cystine, carbonate of ammonia, sulphuretted hydrogen, butyric acid, and ammoniacal salts. 220 THE FLUIDS. Sugar is, however, normally present in the urine during preg- nancy, and of nursing women; always in the latter, and in one-half the cases of the former. Its amount varies from 1 to 12 grains in 1,000 of urine; it being more abundant as the milk is more abundant and rich. (M. Blot) Albumen may appear in the urine in any case in which there is congestion of the kidney, or a too watery condition of the blood; its presence being due, doubtless, to a mere transudation, and not to a modified action of the secreting cells. Hence albuminuria is by no means peculiar to Bright's disease, but occurs also in the course of fevers, in renal catarrh, in cases of disease of the heart or lungs, or tumors of the abdomen, and frequently in dropsy. Fat appears in the urine after taking fatty food, though rarely. Isolated fat- globules are sometimes seen in cases of rapid emaciation; also, either free or in the tubular casts, in Bright's disease. Ammonia salts are found in the acid, and especially in the alkaline fermentation of the urine. In acid pathological urine the occurrence of ammonia is not unusual—as in typhus, measles, and scarlatina. Ammonia is almost always contained in alkaline urine; for the alkaline reaction depends either primarily on ammonia formed by the decomposition of urea (especially in vesical catarrh), or upon carbonates of the alkalies, which soon decompose the urea. The quantity of urine secreted in twenty-four hours varies ex- tremely, the two most important factors bearing on it being the mechanical conditions for the passage of urine through the kidneys, and the condition of the blood. (Lehmann.) An adult male excretes from 17f ounces to 112^ ounces in twenty-four hours; averaging between 38J ounces and 48£ ounces. The adult averages 40.13 grains to 1,000 grains of his weight; a child, 72.5 grains. The dif- ferent proportions of water account in great part for the variations above mentioned in the quantity of urine; but the solid constituents are also liable to considerable variation, an adult discharging from 1J ounces to 2f ounces in twenty-four hours. They are increased by exercise, and diminished by sedentary habits. Moreover, if the blood is poor in albumen and abundant in salts (as in Bright's dis- ease), the solid constituents are diminished. The mineral constitu- ents also vary greatly; between 108 and 355 grains in twenty-four hours—averaging 231.5 grains, or nearly half an ounce. The urine of women is richer in water and poorer in salts than that of men; and especially during pregnancy. Hence the formation, in the latter condition, of the pellicle improperly called kiesteine, in the manner already explained (p. 89). Origin.—Urine is directly eliminated from the blood by the epi- URINE. 221 A great part of the water, Fig. 130. thelial cells of the uriniferous tubes however, is doubtless obtained by mere trans- udation into the urini- ferous tubes from the vessels which form the Malpighian tufts or bo- dies. Hence increased pressure of blood in the finer renal vessels causes increased separation of water and of the solids, especially the salts. If, on the other hand, the arterial and capillary tension is diminished, the secretion is also di- minished. It, however, by no means follows, as Lehmann implies, that the secretion of urine is a mere physical pheno- menon, dependent upon the fact that the blood undergoes compression while in the vessels of the Malpighian tufts. The more characteristic elements of the urine are separated by a vital action of the epithelial cells, and hence their amount in twenty-four hours is more nearly constant in health; while a great part of the water, and of the salts proba- blv when in PXPW* in Structure of the kidney. 1. Ccccal extremity of a tubulus uiy, wucu m CA^ess m nrinifems. 2,2. Recurrent loops of tubuli. 3,3. Bifurcations the blood, are Separated of tubuli. 4, 5,6. Tubuli converging towards the papilla. 7,7, P .-i 1 . . i 7, 7. Corpora Malpighiana seen to consist of plexuses of blood- iTOm tne latter Dy trans- vessels, connected with a capillary network. 8. Arterial trunk. 222 THE FLUIDS. udation merely. Fig. 130 shows the relations of the uriniferous tubes, arterial branches, and Malpighian tufts in a section of the kidney ; and Fig. 131 shows two tufts, with their afferent and effe- Fig. 131. Fig. 132. Fig. 131. Relation of Malpighian tufts to the vessels, a. Branch of the renal artery, af. Afferent vessel, m, m. Malpighian tufts, ef, ef. Efferent vessels, p. Vascular plexus surrounding the tubes, st. Straight tube. ct. Convoluted tube. (Magnified about 30 diameters.) Fig. 132. Uriniferous tube and its epithelial lining, a. Portion of a secreting tube from the cor- tical substance of the kidney, b. The epithelium or gland-cells, more highly magnified (700 times). c. Portion of a tube from the medullary substance of the kidney. At one part the basement mem- brane has no epithelium lining it. rent arteries. Fig. 132 shows a uriniferous tube with its epithelial lining, and, at B, a few cells, derived from its interior, of the scaly epithelium by which the true urine is secreted. Uses.—Urine is merely an excretion, i. e. it consists essentially either of effete elements resulting from the disassimilation of the tissues, or of others existing in the blood in excess—the incessant removal of which is essential to the health of the organism. Urinary Deposits. Though normal urine is perfectly clear and transparent when first emitted from the bladder, solid matters soon appear in it, form- ing a pellicle on its surface, or a sediment; and which are called urinary deposits. These are quite numerous, as found in various normal and abnormal conditions, and may be divided into two classes: 1, histological elements; 2, crystalline substances of mine- ral and organic origin. I. The histological elements have been specified at the commence- ment of this section, these being of course all suspended in the urine while it is still in the bladder, viz:— URINE. 223 1. Scaly epithelium. (Fig. 132.) 2. Mucus and-pus (cytoid), corpuscles. (Figs. 120 and 121.) 3. Blood-corpuscles. (Fig. 123.) 4. Albumen. Heat and nitric acid solidify it, and make it appa- rent (p. 86). 5. Fibrinous casts (three forms), together with fat-globules. (Figs. 123, 124, and 379.) 6. Organic globules (two kinds). (Figs. 125 and 126.) 7. Spermatozoids. (Fig. 116.) 8. Fungi (two kinds). (Figs. 127, 128.) 9. Sarcina ventriculi. (Fig. 129.) II. The crystalline (except carbonate of lime) deposits of mineral origin:— 1. Chloride of sodium. (Figs. 1 and 2.) 2. Triple phosphate. (Figs. 6 to 9.) 3. Carbonate of lime (usually amorphous). (Fig. 3.) Those of organic origin, and their compounds with mineral sub- stances, are:— 1. Urea. (Fig. 37.) 2. Uric acid (various forms). (Figs. 11 to 19.) 3. Urate of soda. (Fig. 22.) 4. Cystine. (Fig. 38.) 5. Hippuric acid. (Fig. 25.) 6. Oxalate of lime (various forms). (Figs. 26 to 31.) Urinary Concretions. (Vesical and Renal Calculi) Calculi in the bladder and kidneys are formed by precipitation of the solids in solution in the urine, around a nucleus, so called. This is sometimes a foreign body introduced into the bladder from without; and sometimes a particle of mucus or other animal sub- stance (and still oftener uric acid), formed within it. In either case, as soon as the nucleus is formed, the mineral constituents of the urine may be precipitated around it, and thus a calculus is con- centrically formed. The composition of the calculus will, of course, depend upon the constituents precipitated; and very frequently it happens that the concentric layers are formed of different sub- stances. Such are termed alternating calculi; and they alone de- monstrate the incorrectness of the doctrine of diatheses—as the uric acid diathesis, the phosphatic diathesis, &c. (Fig. 34.) Calculi found in the bladder may be first formed in the substance of the kidney. Calculi are also formed in the prostate gland (p. 54); but these are, of course, not concretions from the urine. The following abstract shows the composition of 353 calculi in Guy's Hospital; and of 78 in the Museum of the Transylvania University; the last having been examined by Dr. Peter.1 Bird on Urinary Deposits, pp. 321-23. 224 THE FLUIDS. Nuclei of uric acid " urate of soda " " lime " uric oxide " cystine " oxalate of lime !lime triple mixed 19 " foreign substances Mixed calculi The bodies were composed of— Uric acid (Figs. 20, 21) in Urates of soda, &c. (Fig. 23.) Cystine..... Oxalate of lime. (Figs. 32, 33.) Triple phosphate. (Fig. 10.) . Phosphate of lime Fusible mixed phosphates Carbonate of line The crust was composed principally of- Uric acid in Urate of soda .... Cystine..... Oxalate of lime Triple phosphates Phosphates of lime . Fusible mixture of phosphates Carbonate of lime Trans. Univ. 32 26 47 186 12 26 14 12 (mixed) 41 1 40 11 11 11 14 19 27 1 (mixed do.) 4 78 34 2 2 16 4 66 with ) phosphates j 34 2 9 2 37 The frequent occurrence of uric acid as a nucleus in the preced- ing calculi is remarkable (p. 63); and Lehmann states that a trace of uric acid, if nothing more, may always be detected in the nu- cleus of the concretion (Yol. II. p. 124). Scherer maintains that it is an acid fermentation of the mucus in the urine, which leads to the first precipitation of the uric acid, and therefore mucus must be first present and form a part of the nucleus. Mere irritation of the bladder may produce an abnormal mucus, and thus become the first step towards the foundation of the nucleus. An alkaline fer- mentation of the urine, on the other hand, leads to the deposition of the phosphates (as in paralysis of the bladder, &c.); and hence calculi may present the alternating layers (Fig. 34), already de- scribed. SEBACEOUS SECRETION. 225 Fig. 133. Y. The Lachrymal Fluid. The lachrymal fluid is a clear, transparent fluid, the principal elements of which are water, common salt, and an organic com- pound called by some chemists lachrymine. Any mucus-corpus- cles or epithelial cells in it come from the mucous mem- brane of the eyelids. Origin.—This fluid is se- creted by the epithelial cells of the cceca of the lachrymal gland. (Fig. 133.) Use.—The lachrymal fluid lubricates the eyeball, and thus diminishes friction be- tween it and the eyelid. In case of copious weeping, much of the fluid is merely a transudation, mixed With Conjunctival or inner surface of eyelid. I. Lachry- mal gland, d. Orifices of its 7 ducts on the conjunctiva. the Secretion Of the lachry- • The Meibomian glands are seen running towards the 1 -j j edges of the lids, o, o. Orbicularis muscle beyond the mai giana. lids {8ammering^ CHAPTER IV THE CUTANEOUS SECRETIONS. The secretions of the skin are two; the sebaceous secretion and the perspiratory. I. The Sebaceous Secretion. This is secreted by the sebaceous follicles (glands), situated in the substance of the corium of the skin. The Meibomian and the ceruminous glands also belong to this class. The secretions of all these glands are by no means precisely identical. In all of them, epithelial cells may be found as a mor- phological element; the scaly cells of the skin often predominating 15 226 THE FLUIDS. over the conoidal ones from the interior of the follicles. In the Meibomian secretion and the cerumen, peculiar oval, angular, or roundish cells are found, from ^^-^ to yg'g^ of an inch in diameter, containing a pale nucleus and nucleoli, with minute dark, sharply defined granules, and a few fat-globules. When in a state of inflammation, the sebaceous follicles, like the mucous, produce (cytoid) pus corpuscles. Mere irritation may also give rise to them. They Flg'134, are best seen in cases of inflammation of the exter- nal auditory passage, and of the Meibomian glands, in balanitis, and in acne; there being, in these cases, also an exudation in which the cytoid corpuscles are developed. The parasite called acarus folliculorum is often found in the nor- mal secretion of the seba- ceous follicles. (Fig. 134.) The fluid portion of these secretions contains an albu- minous substance not yet accurately recognized. But fat and lipoids constitute the principal part of them. It constitutes 47.5 per cent, of the vernix caseosa of the full grown foetus (Lehmann), and 52.8 per cent, of the smegma of the human prepuce.1 It has been ascertained that the liquor amnii contains most fat at the end of pregnancy; it being derived from the sebaceous follicles of the foetus. In the vernix caseosa many hairs are always to be found; this tissue being intimately associated with the sebaceous follicles, as will be shown. The mar- garates and oleates of potash, soda, and ammonia are also elements of these secretions. Cholesterine is found in the smegma prseputii, and a substance very similar to it, but not crystallizable, in vernix caseosa. Berzelius found a peculiar fatty substance in the ce- rumen. The sebaceous follicles are always situated close, or very near, to Entozoa from the sebaceous follicles, a. Two seen in their ordinary position in the orifice of one of the seba- ceous follicles of the scalp, b. Short variety, c. Long varietv. 1 Kolliker asserts that the smegma praeputii is formed almost exclusively of the epithelial cells of the prepuce. (See Chapter X.) • SEBACEOUS SECRETION. 227 the hair follicles, and often open into them; except that on the nymphse and the glans penis, and on the inner surface of the pre- puce, these follicles exist while hairs do not. (Fig. 135.) Yauquelin examined the fat of human hair, and found it oleaginous, colored, and containing sulphur. The mineral constituents of these secretions are, a little chloride of sodium and hydrochlorate of ammonia, with phosphate of am- monia and soda. Earthy phosphates are, however, more abundant; the vernix caseosa contains 6.5 per cent, and the smegma praeputii 9.7 per cent. Of water, the vernix caseosa contains from 66.98 to 77.87 per cent. In the sebaceous secretions after birth it must be constantly varying with the hygrometric and thermometric states of the sur- rounding air. The castoreum used as an antispasmodic is merely the smegma from the preputial folds of the penis and the clitoris of the beaver Canadian castor contains 5.8 per cent, of albuminous matter, 8.249 of fatty matters, and 41.34 of resinous constituents. (Lehmann) Origin.—The sebaceous secretions are secreted by the epithelial cells of the various forms of sebaceous glands. Figs. 135,136, and Fig. 135. Sebaceous follicles of skin in their relation to the hairs. 137 show the forms of the simple sebaceous follicles of the skin, and the Meibomian, and the ceruminous glands. 228 THE FLUIDS. Fig. 136. Fig. 137. Meibomian gland, a. Basement mem- Ceruminous gland, highly magnified. 1,1. Tube form- brane. b. Epithelial cells, c. Duct ing the gland. 2. The excretory duct. 3. Vascular trunk and its ramifications. Functions.—The sebaceous secretion diminishes the tendency to evaporation from the hair and the epidermis; and thus prevents the drying up of the deeper layers of the epidermis, and consequently of the corium. The Meibomian fluid prevents the lachrymal fluid from flowing directly over the lids, from the conjunctiva; and the cerumen both secures a proper moisture of the auditory passage, and, by its nau- seous odor, deters insects from entering it. II. Perspiration. True perspiration (sweat) is the fluid secreted by the perspiratory glands, which are situated beneath the skin, in the subcutaneous areolar tissue. They are delicate tubes, forming twisted coils at their commencement, from which they pass in a vertical direction through the corium of the skin, and in a spiral or cork-screw man- ner through the epidermis, to open upon the surface of the latter with a somewhat contracted mouth. Fig. 138 represents one of these glandular coils, with a part of its duct. Sweat, as collected on the skin, is a colorless, very watery fluid, PERSPIRATION. 229 Sweat-gland and part of its duct. a. Venous radicle. 6. Capillary plexus separated from the gland, and rising from arteries which also anastomose. with a saltish taste and more or Fig. 138. less intense odor, and generally presenting a weak acid reaction. The sweat from the axillse and the feet is, however, often found to be alkaline. There are no morphological ele- ments in sweat, except the scaly epithelial cells of the skin, which are accidentally present. The solid constituents of sweat probably do not exceed 1.25 per cent.; Favre says .443 per cent. only. Of the solid constituents, chloride of sodium is the most abundant. The salts of ammonia are also present in it. Earthy phosphates and a little peroxide of iron are also present, but these are probably derived from the epi- thelial cells in the fluid. The fat in the sweat may probably be, in great part, derived from the sebaceous follicles. But Krause has found that the sweat-glands also secrete fat, to some extent. Lehmann has proved that it con- tains butyric acid. Sweat also contains the acetic and formic acids (Schottin), and the lactic (Favre), and a sulphurous matter (Lehmann). Urea is also a normal constituent. (Favre) The thin bluish layer sometimes found on the bodies of persons who have died of cholera is a fine powder, composed, for the most part, of urea. Certain pigments sometimes occur in sweat, especially that of the bile in cases of icterus. It has also been demonstrated that gases, especially carbonic acid and nitrogen, are given off in the liquid secretion of the sudoripa- rous glands, and these must not be overlooked in determining the functions of the skin. The carbonic acid predominates in case of a vegetable, and the nitrogen of an animal, diet. But less gas is, on the whole, given off when the perspiration is active, as after brisk exercise. The amount of perspiration, in twenty-four hours, averages, in case of an adult man, not far from 25J ounces. ( Valentin) Krause calculated 25T7g ounces of water, ^ ounce of organic and volatile 230 THE FLUIDS. matters, and 38 grains of mineral substances. An adult man, in a Vapor-bath, loses f ounce of sweat in a minute. (Lehmann) About 412 cubic inches of carbonic acid gas are excreted from the skin of a full-grown man, in twenty-four hours, and a little less than one-half as much nitrogen. (Aberneihy) Origin.—It has already been shown (p. 181) that a transudation is constantly occurring upon the surface of the skin, as a mere phy- sical necessity; and doubtless very much of the fluid collectively called the sweat is produced in this way. The precise proportion of the true sweat, however, cannot be ascertained. Certainly, when the amount of perspiration is very suddenly augmented, as in a vapor-bath, it cannot be due to secretion wholly nor principally. But while secretion is probably thus increased, transudation is in- creased to a much greater proportional extent. In cases of colli- quative sweats, and the cold sweat so common in articulo mortis, it is certainly not increased secretion, but mere transudation, which produces the excess of fluid. Besides, it is probable that the gases escaping by the skin do so as a mere physical phenomenon, whether termed exhalation or otherwise. So far, therefore, as the sweat is actually a secretion, it is doubtless secreted by the epithelial cells lining the tubes forming the per- spiratory glands. But the portion elaborated by them constitutes the insensible rather than the sensible perspiration; and though it is highly probable that it contains all the substances mentioned as more characteristic of the sweat—as lactic, formic, and butyric acids—nothing positive is known on this point. Uses.—One use of the sweat is, doubtless, to regulate the tem- perature of the animal body; an excess of perspiration, and its evaporation, being a cooling process. But the main object of the perspiration is the elimination, it is said, of certain deleterious elements from the blood, it being one of the excretions. When we consider that more than 99J per cent, of the sweat is water (Favre), it hardly appears possible that this ex- creting power of the perspiratory glands has not been overrated. Yet all physicians are aware of the serious consequence resulting from a sudden "check of the perspiration," so called. We doubt not that the perspiratory glands do eliminate excre- mentitious substances, and that their function is therefore important. But it is probable that the gases and volatile substances which PERSPIRATION. 231 escape from the surface of the skin by mere exhalation and trans- udation are far more important as excretions than the actual ele- ments of the perspiration. It is, therefore, probably because the action of the skin as an exhaling and transuding surface is suddenly checked, and not that of the perspiratory glands alone, that such serious consequences ensue from such sudden changes. It is far more because carbonic acid and nitrogen gases, and water also, cease to be given off, than because the perspiratory elements and the minute amounts of the acids of the sweat are still retained in the blood, that the mischief results. And it is not singular that the pulmonary surface, or that of the alimentary canal, or of the urini- ferous tubes, should manifest a higher amount of power as a trans- uding surface when this physical process is suddenly checked on the skin; and that catarrhs, diarrhoeas, or diuresis should result therefrom. THIED DIVISION. THE TISSUES. CLASSIFICATION OF THE TISSUES. No classification of the tissues is possible which is not liable to some objections; but the following is proposed as the most simple, for the use of the student in histology. All tissues in which the microscope detects but one of the simple histological elements— whether cells, fibres, or membrane—are termed simple tissues; while if two or more elements are seen—as cells and fibres, or cells, fibres, and homogeneous substance—such are termed compound tissues. And the latter are termed binary or ternary, if constituted respect- ively of two or three elements. In any classification, the distinction between mere tissues, and organs consisting in great part of those tissues, must be kept in mind. E. g. white fibrous tissue constitutes a great part of the ligaments and tendons; but mere white fibrous tissue is one thing, while a tendon or a ligament is another—the latter containing bloodvessels and areolar tissue, together with much of the tissue in question. So bone-tissue, or osseous tissue, is a simple tissue; but a bone is a compound organ, consisting of osseous tissue, vessels, nerves, lymphatics, &c. We must also distinguish, in a classification, the tissue itself, from mere cavities which are found in it. Even though the latter may be peculiar to the tissue, and characteristic, they constitute no part of it whatever, and must exert no influence in deciding to what class the tissue belongs. These remarks apply more espe- cially to osseous tissue, this being a simple tissue; though the cavities (lacunse and pores) are more characteristic of bone, as seen under the microscope, than is even the solid substance itself. Dental tissue is here associated with the osseous, though the enamel is more nearly allied, in its method of development, to epi- CLASSIFICATION OF THE TISSUES. 233 thelium. The nails and the hair are classed with epithelium also; though the latter is often classed with teeth, and is, at the same time, a compound tissue. Only the highest form of muscular tissue (the striated) is strictly compound; but there is an obvious advantage in arranging and describing the two forms in connection. The fat-cells are a simple tissue; but adipose tissue is not so, and hence it is placed in the second class. It would be in accordance with analogy to term the fat-cells alone fatty tissue, and, when con- nected together with their vessels by areolar tissue, to apply the term fat—as we speak of osseous tissue and bone, of muscular tissue and muscle. In that case the term adipose tissue might be dropped, or adipose tissue and adipose might be used. For the pre- sent, however, it appears necessary to retain, as correlative terms, fat-cells and adipose tissue. It will be hereafter seen that the mucous and serous membranes, and the skin, are composed of the same histological elements; and they are, therefore, here classed together. The vessels and the heart present no peculiar histological elements; but they are sepa- rately described on account of their great physiological importance. For a similar reason, distinct chapters are devoted to the alimentary canal, the urinary, the sexual, and the respiratory apparatus, the ductless glands, and the sensory organs. Classification of the Tissues. First Class.—SIMPLE TISSUES. 1. Epithelium. Hair and Nails. 2. Yellow Fibrous (Elastic) Tissue. 3. White Fibrous (Collagenous) Tissue. 4. Osseous Tissue, including Teeth. Second Class.—COMPOUND TISSUES. 1. Areolar Tissue. 2. Adipose Tissue. 3. Cartilage and Fibro-Cartilage. 4. Contractile or Muscular Tissue (two forms). 5. Nervous Tissue—Vesicular and Fibrous. i Cutaneous (Skin.) 6. The Membranes -j Mucous. I Serous. 7. The Vessels. 8. Alimentary Canal and Appendages. 9. Urinary Apparatus. 234 THE TISSUES. 10. Sexual Organs. 11. Respiratory Organs. ( The Spleen. 12. Ductless Glands The Thyroid Body. The Thymus Body. The Supra-Renal Capsules. 13. The Organs of the Senses. In order, however, to avoid repetitions as far as possible, and to proceed at the same time in the most intelligible manner, the first seven tissues will be described in the following order; after which muscular tissue and the rest will follow in the order already given. 1. Epithelium and its modifications. 2. Yellow fibrous tissue. 3. White fibrous tissue. 4. Areolar tissue. 5. Adipose tissue. 6. Cartilage and Fibro-Cartilage. 7. Osseous tissue and the Bones; Dental tissues, and the Teeth. 8. Contractile or Muscular tissue, &c &c. CHAPTEE I. EPITHELIUM—NAILS AND HAIR. The epidermis and the nails have been by some authors termed the horny tissues; since, like the claws, horns, and hoofs of the lower animals, and whalebone, so called, and tortoise-shell—they contain the immediate principle called Keratine (p. 100). Both these, how- ever, and the epithelia of mucous and serous membranes, are histo- logically so similar, that they will be described under the head of epithelium; and the hair, next in order, as being an epithelial appendage. All epithelial developments are destined to fall off, and thus be lost to the organism, after accomplishing their proper functions; and they all consist of cells of various forms which have, in a mea- EPITHELIUM — EPIDERMIS, ETC. 235 sure, dried up if externally situated, and which are agglutinated to each other by an intercellular substance difficult of detection. Be- sides this last "problematical substance'' (Lehmann), there are three distinct elements of the cells: 1, the substance of the cell-mem- branes, which constitutes the principal portion of all these tissues: and, which is almost insoluble in alkalies; 2, the cell-contents, which, with the nucleus, are more readily soluble in alkalies; and 3, the granular matters which are wholly insoluble in alkali. The last remain after the entire solution of some of these tissues, and by no means consist entirely of fat. They all contain a considerable amount of unoxidized sulphur, and usually about one per cent, of mineral substances in all. SECTION I. EPITHELIUM (EPIDERMIS, ETC.). Every free surface of the body is covered by one or more layers of cells, constituting an epithelium.1 Epithelium, therefore, enters into the structure at every point of the skin, and of serous and mucous membranes, forming the outermost (i. e. farthest from the vessels), of the three layers of which they are alike composed. The next layer underneath the epithelium is the basement-mem- brane, already described (p. Ill), and the innermost, the corium. A^iewed in its histological relations, therefore, epithelium may be defined to be a continuous expansion of cells; consisting of one or more strata developed upon and completely covering a basement-membrane. A single layer of cells constitutes a simple, and two or more layers a compound epithelium. The epithelium of the skin is usually called epidermis or cuticle. These terms, however, include only the outer layers of the cuta- neous epithelium, as will be shown. The epithelia of the skin and of mucous membrane, are of course continuous where these mem- branes are so; as at the mouth, nostrils, anus, &c. Epithelial cells present no original peculiarities of form and con- tents. They consist of cell-wall, contained fluid, granules, nuclei, and nucleoli (p. 114). On some portions of the mucous membrane, how- ever, they assume a conoidal or elongated (cylindrical) form; while on serous membranes the contact of the opposed surfaces gives them a very flat form, allowing but a small amount of fluid con- 1 From \trl upon, and 8r,\h the nipple—it being very apparent on this part. 236 THE TISSUES. tents; and on the skin the outer strata of cells become dried and collapsed into solid horny scales. In the first instance, the epithe- lium is termed a conoidal (or cylinder), and in the latter case, a scaly epithelium. Between the conoidal and the flattened cell, many varieties are found; the globular and the polyhedral form predo- minating. Again, the conoidal cells are sometimes found surmounted by cilia,1 so called; in which case we have a ciliated epithelium. The conoidal (or cylinder) and the ciliated epithelium are found only on the mucous membrane, in the adult human body; the scaly variety exists everywhere on the skin and serous membranes, and also on certain parts of the mucous membranes, hereafter to be specified. The granules are more numerous in epithelial cells in proportion as the latter are smaller and younger, and in these also the circular or oval nuclei are more apparent. Acetic acid fenders them very distinct. Indeed, the granular appearance and the distinctness of the nuclei seem to measure the functional activity of the cells, and when both disappear the cells become detached or desquamated. The size of epithelial cells varies according to their form, and also in different parts of the body, and in the different layers in the same part. The conoidal cells of the epithelium of the small in- testine are jj2s to v^ of an inch in length, and 37515 *° Wos 0I" an inch broad. The cells in the most superficial layer of the conoidal epithelium of the larynx are 7^ to 5^ of an inch long, and 45*0-3 to ^g1^ of an inch broad. In the very lowest layers of the epithelium of the mouth, when the cells are arranged nearly perpendicular to the basement-membrane, they are T5Vo" t° 1*1515 0I" an inch long; in the middle layers they;are og1^ to 2^515 OI> an incn broad, having become somewhat flattened; while the most super- ficial cells are large flattened plates, called epithelial plates, by Kol- liker—g£o to even 3^ of an inch across. (Fig. 147.) The thickness of the epithelium must depend on the size of the cells and the number of layers. The small intestine, having but a single layer, will have an epithelium yy1^ to -g}2-g of an inch thick, as has been shown. The compound epithelium of the mouth is Ti 2 to ¥5 °f an incn thick; and that of the larynx is ?£H to ^^ of an inch thick. From " Cilium," an eyelash; since they resemble fine hairs. EPITHELIUM. 237 Fig. 139. Varieties of Epithelium. Both the scaly and the conoidal epithelium present two varieties, the simple and the compound. The conoidal epithelium is also in some parts ciliated, whether simple or compound. Thus we find— I. The simple scaly epithelium. II. The compound scaly epithelium. III. The simple conoidal epithelium. IY. The compound conoidal epithelium. Y. Either of the two preceding may be ciliated. Frequently the cells of a scaly epithelium (as on serous mem- branes) are matched together in such a way that its free surface re- sembles mosaic or a pavement, when seen under the microscope, the cells being polygonal and mostly hexagonal. This appearance has given rise to the expression "pavement or tessellated" epithelium. But the free surface of a conoidal epithe- lium often presents the same appearance; and since it depends not on the size of the cells, nor even their form, except so far as their free surface is concerned, there is no sufficient reason for making this appearance a distin- guishing characteristic. It is indicated in Fig. 139. Todd and Bowman have described the epithelium lining the minute ducts of the true glands as Consisting of globular Cells, Tessellated (scaly) epithelium n. 1-//11-I -I-I11) °fa tubulus uriniferus. and hence term this "globular or glandular epithelium. They suppose that the secretion of the gland is secreted by these cells alone. Since, however, all epithelial cells secrete in proportion to their size and fluid contents, this distinction is unne- cessary. Besides, these cells are not by any means uniformly glo- bular. There are all intermediate phases, so far as the form of the cells is concerned, between the flattened or scaly and the conoidal or cylindrical. It will appear that different functions are assigned to these differ- ent varieties of epithelium, now to be described. 233 THE TISSUES. I. Scaly Epithelium. a. The simple scaly or squamous epithelium consists of a single layer of flattened cells, of a polygonal outline. Fig. 140 shows the epithelium of a serous membrane. Distribution.—This kind of epithe- lium is found covering all true serous (but not synovial) surfaces. It also lines all lymphatics and bloodvessels throughout, and all mucous follicles, the air-cells of the lungs, and the ulti- mate follicles of all true glands. It also covers the membrane of Demours, the posterior surface of the iris (uvea), the inner surface of the choroid coat (the pigment-cells described on page 133, there forming a scaly epithelium), and the capsule of the crystalline lens; and lines the internal ear and the Graa- fian vesicle. The simple scaly epithelium lining the seminiferous tubes merges into the simple conoidal at the head of the epididymis, and thence the latter variety lines the vas deferens. Peculiarities.—In some of the large arteries and some of the veins, the epi- thelial cells are quite ir- regularly elongated, fusi- form, and slender, being ii-is to 5gu of an inch long. Being also not per- fectly matched to each other, narrow spaces are here and there left be- tween them. (Fig. 141.) Distinct and well-marked epithelium maj- be traced in vessels only TT'2J to j^ of an inch in diameter. In the walls of the capillaries, however, only scattered nuclei can be seen; which, Scaly epithelium of serous membrane. a. A fold showing thickness of the cells at its dark edges, b. One of the nuclei. c. Line of junction of two cells. (Mag- nified 300 diameters.) Fig. 141. ~. "^ 7^. ■ n i i • duct. (Magnified 155 diameters.) Peculiarities.—The epithelium of the skin EPITHELIUM. 241 varies much, in different parts, in thickness. Its outer portion con- stitutes the cuticle, and its inner part the rete mucosum, or stratum Malpighii, of anatomists. The outer layers of cells in case of the mucous, membrane also become flattened into coherent scales (the epithelial plates). These may be detached in flakes or sheets from the oesophagus, and are often so by disease, from the tongue. (Fig. 147.) The epithelium Fig. 147. Epithelial plates of oral cavity, a. Large. 6. Middle-sized, c. Same, with two nuclei.—Magnified 350 diameters. (Kolliker.) upon this organ is sometimes even -g\ of an inch thick. Still, it is very endosmotic, various fluids penetrating it from without, and the blood-plasma also exuding through it from the vessels which underlie it. (Kolliker.) In the lower animals we find various modifications of this epithe- lium—as in the sheaths of the beaks of birds and of Chelonian reptiles; in the scales of fishes; in the jaws of certain invertebrate animals; in whalebone so-called, tortoise-shell, and the teeth of some fishes; in the spines and plates of the tongues of many animals, and the spines of the oesophagus of the Chelonia; in the teeth-like appendages of the stomachs of some of the mollusca, and the horny plates of the gizzards of most birds, and of the cardiac half of the stomach of the horse. II. Conoidal Epithelium. A. Simple Conoidal Epithelium. This variety of epithelium, consisting of a single layer of conoidal - cells, is represented by Figs. 148, 149, and 150. Distribution.—It commences at the cardiac orifice of the stomach, 16 242 THE TISSUES. and lines the whole alimentary canal thence to the rectum (Kolliker says, to the anus). It lines the excretory ducts of all glands; the Fig. 148. m Fig. 149. CrCXQo Fig. 148. Simple conoidal epithelium of inner surface of stomach and its favuli. a. Free ends of epithelial cells. 6. Nuclei visible at a deeper level, c. The free ends seen obliquely, d. Deeper ends of do. near which are the oval nuclei (300 diameters.) Fig. 149. Simple conoidal epithelium of Lieberkuhn's follicles. A. Transverse section of follicles showing (a) the basement-membrane, the epithelium, and the inter-follicular areolar tissue, (&) cavity or lumen of the follicle (200 diameters.) b. Single tube showing (a) basement membrane, and (c) internal surface of the wall of the tube (200 diameters). sinuous fossae (mucous glands) of the cervix uteri; the male ure- thra and all ducts opening into it, and the vas deferens to the head of the epididymis. Its appearance in the gastric tubes is shown by Fig. 148. It is also ciliated in all the following parts—the finest bronchial tubes, and all the sinuses (frontal and maxillary), and the cells (sphenoidal and ethmoidal), of the face; on the inner surface of the membrana tympani; the up- per two-thirds of the cavity of the uterus, and through the Fal- lopian tubes, and the canals in the Wolffian body in the foetus. Peculiarities.—The fact that this kind of epithelium lines the uterine glands, is an exception to the law before stated, that the ultimate follicles of all glands are lined by simple scaly epithelium. (Kolliker) If several of these cells still cohering, after being detached from Simple conoidal epithelium from intestinal villus of a rabbit, a, a. Membrane connecting the free surfaces of the cells, raised by the action of water. EPITHELIUM. 243 the subjacent membrane, are treated with water, they seem to be surmounted by a delicate membrane. This is, however, merely a continuous sheet formed by the ends of the cells; they having been separated by the endosmosis of the water. (Fig. 150.) B. Compound Conoidal Epithelium. This variety consists of two or more layers of cells, the outer- most being conoidal. It is shown by Figs. 151 and 152. Where- ever found it is always ciliated. Fig. 151. Fig. 152. Fig. 151. Simple conoidal ciliated epithelium, a. Nucleated cells, b. Cilia and their free extre- mities. Fig. 152. Compound conoidal ciliated epithelium of nasal passages, a. Superficial series of ciliated cells. 6. Deeper series becoming elongated vertically, c. Various shapes of deepest ciliated cells. (180 diameters). Distribution.—Commencing about three-quarters of an inch within the nostrils, it extends through the nasal passages, covers the upper part of the pharynx and posterior surface of the soft palate; then enters the larynx to line that, the trachea, and the bronchial tubes to their finer subdivisions. It also lines the Eustachian tube, and the lachrymal duct and sac. Ciliated Epithelium. Epithelium is so called when the outer layer of cells are sur- mounted by cilia. These, seen under the microscope, resemble very fine hairs, and the average number attached to each cell is 10 to 22. (Valentin.) They grow from the free (or outer) extremity of the cells, and are generally so arranged as nearly to cover it, though sometimes but a single one is found. They are fine, soft processes of the cell-membrane, broader at their base and terminating in a point. They are in incessant motion; constantly striking forward from a vertical position to very nearly a horizontal one, and in- stantly returning again. The author counted one hundred and forty such strokes in a minute, in case of cells from the pharynx of 244 THE TISSUES. a frog. It has been asserted that they all strike towards the outlet of the passage on which they are found; an assertion needing confir- mation however. The motion seems to depend much upon the state of the cells in respect to fluidity; since it will continue many hours after death (even 78), in case of man (Gosselin), if the cells are kept moist.1 The cilia are among the most minute objects oc- curring to the histologist; being 7300 to 54V4 01>an incn l°ng? aQd not exceeding 4^,^ to 57^^ 0I"an inc^ in diameter. They were discovered by Purkinje and Yalentin in 1834. Figs. 151 and 152 show them on both kinds of conoidal epithelium. (Also Fig. 91.) Distribution.—It has been seen that the ciliated epithelium (either simple or compound conoidal), lines the whole extent of the air- passages from just within the nostrils to the termination of the finest bronchial tubes, and the communicating cavities also; as the sinuses and cells of the face, Eustachian tube, and membrana tym- pani, and the ductus ad nasum and lachrymal sac. Further than this, the ciliated epithelium lines the upper two- thirds of the cavity of the uterus, and the Fallopian tubes through- out. The canals in the Wolffian bodies of the foetus must also be added. Peculiarities.—It is an interesting fact that the epithelium of the upper part of the uterus and of the Fallopian tubes is not ciliated previously to puberty. Disease respects the distinctions made in regard to the different varieties of epithelium. In croup, the nasal passages are almost invariably first affected, and the disease follows the course of the ciliated epithelium over the posterior surface of the velum, and thence into the larynx and trachea, and not along the oesophagus into the stomach. Again, a disease commencing in the lower half of the pharynx, or the tonsils, does not soon extend to the larynx and trachea, as a general rule. Besides, the uterine glands may be diseased for an indefinite period without the disease extending either to the uterine cavity or to the vagina; its conoidal epithelium being bounded both above and below by the scaly variety. Development of Epithelium. The first cells laid down to form an epithelium are probably de- 1 The motion of the cilia is destroyed by many chemical and mechanical agents ; and Virchow has recently found that a solution of potassa or soda re-excites it. He infers from his experiments that the substance of the cilia nearly approximates musculine. EPITHELIUM. 245 veloped according to the method first described (page 120),/ree cell- development; they being formed in a plasma exuded upon the base- ment-membrane.1 They subsequently multiply by the fissuration of the cells and nuclei in the lower layers. They are constantly growing, and on reaching maturity, they lose their vitality and become detached or desquamate. In the mouth and alimentary. canal they are detached also by mechanical causes. The reparation of epithelium also takes place by fissuration, unless all the layers of cells have been removed; in which case there is doubtless a development de novo, as at first. Sometimes, however, a long time is required for the formation of a perfect epithelium; as is seen especially upon the surface of cicatrices after entire loss of the skin. Functions of Epithelium. The functions of epithelium vary with the different varieties, and also in different parts of the body. I. The scaly epithelium is specially for secretion and protection. The simple scaly epithelium of serous membranes, mucous folli- cles and glands, and, in part, of the eye and the internal ear, and the compound scaly epithelium of synovial membranes—are for secretion of serous or mucous fluids, as the case may be. The simple scaly epithelium of the lymphatics and bloodvessels, of the ocular membranes, not alluded to in the preceding paragraph, and of the Graafian vesicle; the compound scaly epithelium extend- ing from the lips to the cardia, at the commencement of the nostrils, on the lachrymal ducts, conjunctiva, and tympanic cavity; that covering the vulva, vagina, and lower third of the uterine cavity; and that lining the bladder, ureters, pelvis of the kidney and female urethra—are for protection, and doubtless also, to some extent, for secretion. The compound scaly epithelium of the skin—the epidermis—is almost exclusively protective. II. The conoidal epithelium is for secretion, absorption, or pro- tection. The simple conoidal epithelium extending from the cardia, through 1 It has been suggested that the fusiform slender epithelial cells of the larger arteries and some veins, are related in their development to the striped lamellae which underlie them. 246 THE TISSUES. the alimentary canal, nearly to the anus, is both secretive (of mucus) and protective. The cells covering the villi are also believed to be subservient to absorption of alimentary materials into the blood. Indeed, epithelium is everywhere remarkably endosmotic. In the cervix uteri it is more especially for secretion; in the excretory ducts of all glands, secretive and protective; as it is also in the male urethra and all ducts opening into it, and in the vas deferens. Ciliated epithelium (whether simple or compound conoidal) owes its peculiarities to its cilia. Independently of them, it may be, and probably always is, secretive and protective. It lines only the whole of the air-passages (except the air-cells), and the passages opening into them, and a part of the genital passages of the female. Its peculiar function, in the former case, seems to be to secure the con- tact of new portions of air in the air-passages, air-cells, and others, to subserve the function of aeration. The cilia may also aid in preserving a due state of moisture on every part of a membrane, or to prevent occlusion of narrow passages by a normal or abnor- mal secretion—as in the Eustachian tube, the lachrymal duct and sac, the finest bronchial tubes, and the Fallopian tubes. It has been suggested that the cilia on the cells covering the upper two-thirds of the uterine cavity, and lining the Fallopian tube, carry the semen to the ovary to secure impregnation; and that, by a reversed action, they also return the impregnated ovum to the uterine cavity, where it remains to be developed during the period of gestation. Though this idea of reversed action is purely hypo- thetical, it is still probable that the cilia have reference to the func- tion of menstruation or impregnation, or both, since they are not developed till the period of puberty arrives. But it is a gratuitous assumption that the cilia of the cavities in the face (antrum, &c.) are subservient to smell, since we know that the olfactory nerves are not distributed to these cavities at all. Since secretion is in all cases performed by epithelial cells, all the normal secretions contain them, or at least their nuclei or their debris; as has already been seen in the description of them respect- ively in the Second Division of this work. Epithelium is corrugated and rendered opaque by the action of alcohol, and hence the effect of holding brandy, &c, in the mouth. In some diseases it becomes entirely detached; and thus is produced the extreme redness of the tongue which is so often met with. An irritable condition of the mucous membrane of course results from EPITHELIUM. 247 its removal. Nitrate of silver blackens the epidermis and renders opaque the epithelium of mucous membranes, but destroys nothing beneath them. It is therefore not a caustic, in any scientific sense. The epidermis is separated from the corium by a blister, and by exudations underneath it from other causes—as in all vesicular skin diseases. Pathological Conditions of Epithelium. 1. Epidermic and epithelial tumors (epithelioma) are of very fre- quent occurrence. Warts (verrucas) and callosities of the skin, espe- cially corns (clavi), are minor instances of this group. In the case of warts, however, the papillae as well as the epidermis become hypertrophied. The wart-like naevi materni, ichthyosis, and ele phantiasis Arabum, also belong to this class, though this last is not limited to the epidermis alone. 2. Condylomata (more properly termed papillomata), mucous tu- bercles, and similar vegetations, apt to form around the orifices of mucous canals from the irritation of syphilitic or other discharges, belong also to this class. Fig. 153, b, shows one of these vegetations Fig. 153. Epithelial new formations, a. Papilloma highly magnified, b. Epithelial tumor from lip. (Lebert.) as figured by Lebert; it being a papilla formed by a layer of closely imbricated epithelial scales, the deeper portions consisting of less flattened cells, or nuclei in an amorphous blastema, and extending to the corium of the skin. Horns are also epidermic productions, and sometimes appear on the human body. They originate in the sebaceous follicles, whose epithelium, thrown off in abundance and together with fatty secretion, forms a conical mass which protrudes from the skin (usually of the head or of the forehead), sometimes even to the length of six inches. 3. Epithelial cancer should be distinguished from mere epithe- lioma; the former being doubtless malignant, though not so certain to affect the lymphatic glands, and the body generally, as the other forms of cancer. It occurs on the skin and mucous membrane, the 248 THE TISSUES. cheek and lips being its most common seat. On the skin it is gene- rally a hard, well-defined tumor, irregularly nodulated, and covered with minute watery papillae. On a mucous surface it appears as a cauliflower-like growth, more or less red from vascular injection, variously consistent, and easily separated into parts by pressure. In either case the papillae and the epithelium covering them become greatly hypertrophied; the corium and areolar tissue also becoming Fig. 154. Section of epithelial cancer of the cheek, a. Epidermic scales, and fusiform cells and fibres on the external surface, b. Group of epidermic scales, c. Areolar tissue of the corium. d. Cancer- cells in the latter tissue. (Bennett.) converted into a fibroid substance. Fig. 154 shows the microscopic structure of an epithelial cancer of the cheek. _ 4. New formations of epithelium are common in certain patholo- gical cysts. A very delicate ciliated epithelium has been found on Fig. 155. Oidium albicans, a. A mass of epithelial cells covered with the granular matrix of the fungus (b), from which a luxurious growth of mucedinous filaments (c) proceeds.—Magnified 350 diameters (Kolliker.) THE NAILS. 249 the intersaccular partitions in ovarian tumors, and in those of the testis.1 5. Some of the peculiar appearances of the tongue in disease are due to changes in its epithelial cells. They may even become a nidus for the development of parasitic vegetation; of which the pe- culiar white coat produced by the oidium albicans (Fig. 155) in some cases of diphtheritis, is an illustration. SECTION II. THE NAILS. Fig. 156. Nails are merely a modification of the epidermis, being histolo gically a very much condensed compound scaly epithelium. (Fig 156.) They are also, by maceration, detached in continuity with it. And, according to Mulder's investigations, they differ from epidermis in chemi- cal composition, only in containing a larger proportion of sulphur and car- bon. The surface covered by the nail, and upon which it is developed, is called the bed of the nail. A trans- verse section of it, and of the nail also, is seen in Fig. 157. It presents a series of peculiar ridges on its sur- face, beginning under the root of the nail, and at first radiating outwards from the centre for a distiance of 2 J to 3J lines; whence they become pa- rallel and more prominent, and take Transverse section of nail and its matrix. A. Skin. b. Stratum Malpighii of nail. c. Horny layer of same. a. Papillae of nail- matrix. 6. Cells of the Malpighian stra- tum, c. Ridges of horny substance of nail. d. Deepest layer of perpendicular cells of Malpighian layer, c. Upper layer of flat- tened cells of the same. /. Nuclei of the true nail substance. Body and bed of nail, transverse section, a. Bed of nail, with its ridges, b. Corium of lateral portion of wall of the nail. c. Stratum Malpighii, with its ridges (white), d. Papilla, e. Cuticle of wall of the nail. /. Horny layer of nail, with short notches on its under surface.—Magnified S diameters. (Kolliker.) ' London Lancet, Sept. 1856. 250 THE TISSUES. on the form of true laminas, -gfo to T^ of an inch deep. The line of transition of the ridges into the laminas divides the bed of the nail into two sections, differing in color and in extent; the posterior smaller one underlying its root and lunula, and the other portion its body. The ridges and laminae number from fifty to ninety. At their edges they are beset with a series of short papillae. On the little toe, however, the papillae are frequently not seated upon the ridges, but are dispersed. (Kolliker) The wall of the nail is the process of the skin continuous with the bed of the nail, laterally and posteriorly; forming the folds on the sides, by which the nail is limited. The corium of the wall and of the bed of the nail contains but little fat; but in the ridges and the laminae is an abundance of fine elastic fibres. The capillaries, 24!o~o" *° 1-515-5 or> an mcn in diameter, form simple loops in the pa- pillae; and the nerves have the same relation as in the skin. The nail itself is divided into the body, the root, and the free edge. These are shown by Fig. 158. The lunula is the opaque semilunar portion of the nail (not seen in all cases), at its posterior part. When not apparent, it is covered entirely by the fold of the skin underneath which the root of the nail lies, and which is called the matrix of the nail. The lower surface of the nail corre- sponds with the surface of the ridges and laminae of the bed. Furrows and ridges therefore appear on the former as upon the latter. It is by the mutual interlock- ing of these opposite surfaces that the intimate union of the nail with the co- rium of the skin' is effected. (Fig. 157.) In structure, the nails, like the epithelium of the skin, consist of two layers; the deeper being soft (the Malpighian layer, sometimes improperly called the stratum mucosum), and the superficial, consti- tuting most of the thickness of the nail (the horny layer). This stratum consists wholly of cells, like that of the epidermis (except that they are nucleated); and in the negro is black. Hassall states that the younger cells of this layer generally contain pigment in the white races. The horny layer is quite smooth on its under sur- face at the root, but becomes ridged further forwards; the ridges Relations of nail to the cuticle, n, n. Cuticle and nail; m, m. Corium and bed of nail. THE NAILS. 251 appearing in transverse sections as pointed processes, T3^(j to g^ of an inch in length, and even 3^ to 3^ of an inch at the edge of the nail. The upper surface also frequently shows distinct parallel longitudinal streaks, appearing as the almost effaced impressions of the laminae below. The nail increases in thickness from the root to near the free edge, being at least three times as thick anteriorly as posteriorly (4*0" to 3*15 OI> an mcn)- Unprepared sections of nails give very little indication of any structure whatever. But on boiling them in dilute caustic soda, they at once display a beautiful arrangement of cells, like a scaly epi- thelium, but nucleated; these being flatter in the superficial than in the deeper layer, and not more than one half as thick. One or several layers of these cells constitute a lamella; and the lamellae closely united and not sharply defined, form the whole of the horny substance. The greater hardness of nails as compared with epi- dermis, is said by Lauth to be due to a greater proportional amount of phosphate of lime in the former. The nails continue to grow only so long as they are cut. Ee- maining uncut, they attain to the length of one and a half to two inches, and curve over the ends of the fingers and toes. Among the Chinese, of whom the literary class never cut the "nails, the length is, according to Hamilton, two inches. The growth takes place at the expense of the cells in the Malpighian layer, both at the edge of the root and under the body of the nail. Thus, the latter becomes longer and thicker at the same time. The longitudinal growth is, however, by far the most rapid; since the first round cells become more and more flattened and elongated as they move forwards and upwards from their first position. The time necessary for a nail to grow its whole length, varies in different parts from twelve to twenty or more weeks; and hence this length of time is required for the formation of a new nail.1 The nail is thicker on its most convex portion than at its edges. If the changes in the nail cells are investigated as compared with those of the epidermis, a striking similarity is discovered. 1. The original cell-membranes (those of the Malpighian layer) become 1 According to M. Beau, the nails of the fingers grow four times as rapidly as those of the toes ; the thumb growing two-fifths of a line per week, and its whole length in twenty weeks—while the nail of the great toe requires ninety-six weeks, or nearly two years, to grow its length. The portion of a nail growing during a disease is thinner than the rest, as is shown by a transverse groove or depression 252 THE TISSUES. harder, and more phosphate of lime is deposited in them or within the cells. 2. Like the horny cells of the epidermis, they become flattened and increase longitudinally and transversely. 3. They coalesce more completely, so that they cannot be separately recog- nized. But their nuclei do not disappear as do those of the epider- mis; and herein is a characteristic distinction. The nails are constantly suffering loss from friction and other causes. Much of the matter accumulating under them consists of epithelial cells. The development of the nails commences in the third month of intra-uterine life; they not being at first distinguishable from a soft epidermis. The ridges of the bed of the nail are well marked at the end of the fourth month. They cover the whole bed, and have assumed the consistency of a nail at five months, and reach the extremities of the finger at eight months. The free edge of the nail of the new-born infant is cast off once at least (Weber says many times), soon after birth; probably from external violence which it is too delicate to resist. This free edge appears to be a nail of an earlier period, probably of about the sixth month, which has been thrust forward in the course of deve- lopment. Six or seven months after birth the first set of nails is completely replaced by new ones (Kolliker); and at two or three years the horny layer is not distinguishable in appearance from that of the adult. Nails, when destroyed, are almost always imperfectly regenerated, on account of injury done to the laminae and vessels. A rudi- mentary nail sometimes appears on the second phalanx of a finger in case of loss of the first. In some rare cases, a periodical loss and regeneration of the nails occurs. The hoofs and claws of the lower animals are the analogues of the nails, both physiologically and histologically. Uses of the Nails.—The nails support the pulp of the fingers and toes, and thus conduce to the perfection of touch. They also in- crease the power of the fingers as prehensile organs; and in a state of nature at least, (i. e. if remaining uncut), they become not ineffi- cient means of attack and defence. Pathological States of the Nails. Any abnormal condition of the bed of the nail will, of course, affect the growth of the latter. In the lamellated nails of old peo- ple, Kolliker found all the capillaries in the anterior segment of the THE HAIE. 253 bed closely filled with fat-granules of various sizes. It is an inte- resting fact, and not well explained, that the nails become deformed (curved toward the free edge), in phthisis and cyan6sis. In the rabbit, it was found by Steinriick that the division of the ischiatic nerve caused the nails and hair to fall off. SECTION III. THE HAIR. Fig. 159. Each hair consists of its shaft (scapus), and the root; the former including all that projects free from the surface of the skin; the latter, the portion beneath the surface. (Fig. 159.) The bulb is the deepest portion of the root, and is from 1| to 3 times the diameter of the shaft. A. The shaft in straight hairs is rounded and straight; undulated and flattened in the wavy; and spirally twisted and flat, or slightly ribbed, in curly and woolly hairs. It consists of 1, the cortical or fibrous substance, 2, the cuticle, and 3, the medulla, which is, however, often absent. 1. The fibrous substance, which con- stitutes the greater part of the bulk of the hair, is striated longitudinally, streaked or spotted, and more or less colored, except in white hairs, in which it is transparent. The color is some- times pretty regularly distributed through its whole substance; at others, concentrated in a few elongated granu- lar spots. By the action of hot con- centrated sulphuric acid, the fibrous portion of the hair is shown to be made up of flat, elongated fibres of various breadths (g^ to 3JCIJ of an Structure of hair. a. The shaft, b. Root. c. Bulb. d. Epidermis, e. Inner root-sheath, g. Basement-membrane of inch), of marked rigidity and brittle- ^£™\J£™™m^^ ness, and with notched margins and ends. In dark hairs, they have a dark tinge; in pale ones they are clear. These fibres are not, however, the ulti- k. Excretory duct of sebaceous glands, with epithelium. I. Corium at the aper- ture of the sac. m. Stratum Malpighii of the skin. n. Cuticle of do. somewhat re- tracted into the sac. o. Outer root-sheath. —Magnified 500 diameters. (Kolliker.) 254 THE TISSUES. mate elements of the fibrous substance; each of them consisting of an aggregation of flat fusiform fibre-cells or plates—the plates of the fibrous substance—5J^ to -gg-j of an inch long, g^^ to sqQ0 of an inch broad, and t^uo" to faces and irregular edges. 750" 0" Fig. 160. of an inch thick, with uneven sur- They very frequently exhibit a darker streak in the interior, and sometimes contain granular pigment. In other respects, they are homogeneous, and present no minuter elements. (Fig. 160.) The dark spots, dots, and streaks of the fibrous portion are of three.kinds: 1, granu- lar pigment; 2, cavities filled with air or fluid; 3, nuclei. The pigment granules are de- posited in the plates of the hair, are especially abundant in dark hairs, and vary much in their size and form. The cavities filled with air appear in the form of round dots; to t^^tt of an inch in 3TJTJTJTJ 1S61515 diameter; or of longish streaks an inch in length, i nf 3151515 oi and 3W5 t0 TFO-7JT5 ofan iucn in breadth, running parallel with the axis of the hair. They are most frequent in white hairs, and often occur in fair, bright brown, and bright red hairs, in great numbers. They are absent in very dark hairs, and in the root of all hairs. The nuclei are, in dark hairs, commonly connected with the extremi- ties of the pigment spots, and are y^ to 7^ of an inch long, by Plates, or fibre-cells of fibrous substance of the hair, treated with acetic acid. A. Isolated plates. 1. From the surface (3 single, 2 united.) 2. From the side. B. A lamella composed of many such plates.—Magnified 300 diameters. (Kolliker.) THE HAIR. 255 stisutj *o ttj^tjtj 0I> an incn wide. Very similar appearances are, how- ever, sometimes produced by the boundary lines of the hair-plates. This description of the fibrous substance of the shaft applies also to that portion of the root which is solid and brittle. In the deeper and softer portions, the hair-plates are less rigid and have the form of more or less elongated cells with cylindrical, straight, or serpentine nuclei, easily rendered apparent by acetic acid. Fi- nally, in the bulb they are merely round cells 4^5^ to 330 o~ 0I" an inch in diameter; closely packed together, and, like the Malpighian layer of the epidermis, sometimes containing colorless granules, and sometimes so full of colored ones as to constitute true pigment-cells in appearance. The color of the fibrous portion of the hair is due partly to granules of pigment, to some extent to the air-cavities, and partly to a pigment blended with the substance of the hair-plates. The granule-pigment presents all shades, from clear yellow through red and brown to black. The last mentioned, or diffused pigment, is quite absent in white hairs, and is scanty in clear fair hairs. It is most abundant in the more opaque fair hairs, and in red as well as in dark hairs; it alone sometimes producing an intense red or brown color. These two pigments vary in their proportion; but are about equal in very light and in very dark hairs. 2. The cuticle of the hair is a very thin, transparent pellicle in- vesting the hair, and in intimate union with the fibrous substance. It consists of but a single layer, composed of plates arranged like tiles; and is g^1^ to ^'g^ of an inch thick. Each plate is -gfo to 3£-g of an inch in the transverse direction of the hair, and 7A^ to g£o in that of its length (Fig. 161, d, df); and is only about ^o^o" of an inch thick. On the lower part of the root, however, there are two layers of epidermis. (Fig. 162, c, d) The cells of the outer layer are thicker than those of the inner, its whole thickness here being 1^-5 to g^ of an inch; while the inner is ^fa to jJ55 of an inch thick. Kolliker states that the two layers of epidermis pass into the outer nucleated cells of the bulb. 3. The medullary substance varies most of all of the constituents of the hair. It is a cord extending in the axis of the hair from near the bulb almost to the point. It is usually present in the thick, short hairs, and the stronger long ones, and the white hairs of the head; and absent in the down (lanugo) and the colored hairs of the head. It consists of from one to five columns of superimposed cells, 256 THE TISSUES. rectangular or quadrangular, and rarely rounded or fusiform, T7Vu to T2Vo- of an inch in diameter, containing dark, fat-like granules, and a clear nucleus, 7^T to BoV an incn in diameter, and occupy the medullary cells in great amount, exist- ing both in white and in dark hairs. In the latter the air appears of a brown-red or brown tinge, from being seen through the colored fibrous substance; in white hairs it is of a silver white. It appears certain that the air may pass from one air-vesicle to another in the hair. Just above the bulb, and sometimes also in spots in the shaft, there are some of these air-vesicles, and therefore a paleness results. In some hairs, especially the red, there is often no definite line of demarcation between the fibrous portion and the medulla. The medulla usually constitutes from one-fifth to one-third of the THE HAIR. 257 Cells of medulla of Rodentia, &c. a. Hair of musk-deer, formed almost entirely of polygonal cells, b. Hair of sable, showing large rounded cells in the interior, covered by imbricated scales or flattened cells. Fig. 164. whole diameter of the hair; being both relatively and absolutely thickest in short, thick hairs, and thinnest in the lanugo and the hairs of the head. It presents Fie 16S a rounded or flattened figure in a B transverse sections. (Figs. 161, a, and 163.) Very rarely the me- dulla is double throughout; but it is more frequently divided for a distance into two trunks, which soon unite again. In the Bo- dentia (beaver, squirrel, &c.) the medulla is divided by dissepi- ments ; in the musk-deer it con- stitutes the entire hair, except a very thin cuticle, and in the sable its cells are very large. (Fig. 163.) The hair of the bat and the squirrel is shown by Fig. 164. B. The hair-sacs are flask-like follicles, T2 o to 4V of an inch long, extending into the upper layers only of the corium in case of the finest hairs; about one-half through it in case of those of medium size; and even through to the subcutaneous areolar tissue in case of the longest and strong- est (the whiskers, on the head, pubes, and axillae). They are merely involutions of the skin, at the bottom of which the hair-papilla is situated. They have there- fore an internal epithelium or root-sheath, and an external or fibrous layer; the latter being continuous with the corium, and the former with the epidermis. (Fig. 162, i, k, and e,f g) The root-sheath, or the epidermic investment of the hair-sac, is continuous with the epidermis around the aperture of the sac, and consists of two layers, an internal and an external. The external root* sheath (g) is continuous with the Malpighian layer (rete mucosum) of the skin, and rests on a distinct basement membrane; which, how- ever, cannot be demonstrated between this and the internal fibrous 17 Small hair of squirrel, b. Large hair of squir- rel, c. Hair of India bat. 258 THE TISSUES. layer of the hair-sac, except on the lower half of the sac. At the bottom of the latter, the cells of this layer pass gradually into the round cells which cover the papilla. It is generally three to five times as thick as the inner layer; containing from five to twelve layers of cells, and terminating below in a very thin lamella. The inner root-sheath (Fig. 162, e,f) is a transparent membrane, extending from the bottom of the hair-sac over more than two- thirds of it. It is connected externally with the external layer just described (g), and internally with the cuticle of the hair; being, in fact, blended with the latter (c, d). It is very dense and elastic, and consists, except in its lowermost part, of two or three layers of poly- gonal, elongated, transparent, and somewhat yellowish cells, with their longitudinal axes parallel to that of the hair. The cells form- ing the outermost layer of the two (or three), and which alone was formerly known, are elongated and without nuclei. Those of the innermost layer (Huxley's layer) are also polygonal, but shorter and broader, and always (in the lower half, at least, of the root- Fig. 165. Cells, &c, of inner root-sheath, a. From its outer layer: 1, its isolated plates; 2, the same in gonnection after the action of caustic soda ; a, apertures between the cells b. b. Cells from the inner layer, with elongated and slightly notched nuclei, c. Nucleated cells of the lowest part (single layer) of the inner sheath.—Magnified 350 diameters. (Kolliker.) sheath) possessed of distinct elongated nuclei. (Fig. 165.) This layer, however, also blends with the cells of the hair-bulb, like the exterior. (Fig. 162, m) Finally, the papilla of the hair (I) belongs to the sac, and corre- THE HAIR. 259 sponds to a papilla of the skin. It is ovate or fungiform, ,'g to ^ of an inch long, yi^ to ^T of an inch broad, and is connected with the fibrous tissue of the sac by a pedicle. Its surface is perfectly smooth, and it consists, like the cutaneous papillae, of an indistinctly fibr,ous tissue, with scattered nuclei and granules, but no cells. Nei- ther Hassall, Giinther, nor Kolliker has found in it either vessels or nerves. In some animals, however, the vessels may easily be seen; and we must not yet positively infer that they do not exist in the papillae of human hairs also. Chemical Composition of Hair. This subject is still not sufficiently understood; but the hairs are chiefly composed of a nitrogenized substance (keratine), soluble in alkalies, and insoluble in boiling acetic acid. Mulder considers that 10 per cent, of sulphamide is combined with this nitrogenized com- pound. Scherer finds 10 per cent, of the hairs to be sulphur. Hairs also contain a considerable amount of dark or clear fatty matter. Chemical analysis does not discover any special pigment, though the microscope does, as has been seen (p. 255). The ash of hair amounts to 1 to 2 per cent., in which are found oxide of iron (more in dark hair), oxide of manganese, and traces of silica. Jahn found phosphate of magnesia and sulphate of alu- mina in white hairs; and copper occurs in the greenish hairs of those who work in copper and brass. (Langin) Hairs withstand putrefaction better than any other part of the organism. Even those of mummies are found to be quite un- changed. Hence, also, the hair is preserved as a cherished relic of the departed. Metallic oxides color it as they do the epidermis. Hence the salts of silver and manganese blacken the hair, a sul- phuret of these metals being produced. Chlorine bleaches it after prolonged action. Wool and bristles do not differ essentially in composition from hair. Scherer finds, however, that feathers differ much from the other horny tissues, and especially from hair. Gorup-Besanez found a considerable quantity of silica in feathers. Physical Properties of Hair. The hairs are quite elastic. They stretch, without breaking, to nearly one-third more than their original length; and if stretched only one-fifth, they contract again so perfectly that they permanently remain only TV longer than at first. (Weber) Still, their strength 260 THE TISSUES. is great, though so extensible. A hair of the head will support at least six**ounces without breaking. The hairs readily imbibe water, and as readily give it out again; hence they are sometimes dry and brittle, and sometimes moist and soft, according to the amount of moisture the skin or the atmo- sphere contains. They are also longer or shorter, in proportion as they contain more or less moisture; and hence their use in hy- grometry. The hairs become slowly colored during their development; being quite colorless in the embryo, and paler in youth generally than in middle age. In the adult, the palest are the downy hairs which have remained, as it were, in the fcetal condition; while the longer ones are always darker, and the darkest of all are those of the head, beard, and pubes. The durability of the hair results from its indestructibility by external agents, before alluded to. False hair may be continually worn for many years. Distribution and Size of the Hairs. The hairs are distributed over every part of the surface of the human body, except the palm of the hand and the sole of the foot, the dorsum of the last joint of the fingers and toes, the inner sur- face of the prepuce, the glans penis, the upper eyelids, and the lips. They present differences in size and number in different regions; and also according to age, sex, race, and individual peculiarities. In size, three varieties maybe mentioned (Kolliker): 1. Long, soft hairs, 1 to 3 feet and more in length, and g^„ to 3^T of an inch in thickness; 2. Short, stiff, thick hairs, \ to \ of an inch in length, and 4^0 to T4^ of an inch thick; 3. Short and very fine hairs or down (lanugo), T]2 to £ of an inch long, and 3^00^ to y^Vo thick. The first includes the hairs of the head, beard, &c.; the second, those of the nostrils (vibrissas), the eyelashes (cilia), and those in the ex- ternal auditory passage; the last includes the hairs on the face gene- rally, on the trunk and extremities, on the caruncula lachrymalis, and those (often absent) of the labia minora. (Henle) Other things being equal, black hairs are the coarsest, and blonde the finest. On the heads of females, the length of the. hairs has sometimes equalled that of the whole body, and the coarsest hairs are also found on women. ( Wilson) Beards also not seldom reach down to the waist. The hairs are not true cylinders, as usually supposed, but present THE HAIR. 261 an oval section, or some form differing still more from circular. (Fig. 161, a, b) Those of the scalp are the most nearly cylindrical in form.—Nor are they of equal diameter throughout; but fusiform rather, and usually terminating in a very acute point. Indeed, hairs cut off transversely, become pointed again in a short time; apparently by the wearing away of the more external portions of the fibrous substance. The number of hairs upon a given extent of surface varies with their color and the particular part of the body. On the same ex- tent of surface, Withof found 147 black hairs, 162 brown, and 182 blonde. On a surface one-fourth of an inch square, he found in case of a moderately hairy man, 293 hairs upon the scalp, 39 on the chin, 34 on the pubes, 23 on the forearm, 19 on the outer mar- gin of the back of the hand, and 13 on the anterior surface of the leg. In men, closely set hairs not unfrequently occur on the chest, shoulders, and extremities. At the period of puberty, a sudden development occurs in both sexes upon the pubes and axillae; and in males on the chin, cheeks, abdomen, and chest also. In a very hairy man, mentioned by Wilson,1 52 hairs were found on a certain surface on the chin, and 45 on the pubes. Being married soon after, there were found, at the end of four years, 59 on the chin and 50 on the pubes. On all other parts of the body the hairs were diminished. The hairs are implanted either singly or in twos and threes, or even four or five together. The last is the rule in the foetus, and, so far as the lanugo is concerned, in the adult also. The direction of the hairs and hair-sacs, is seldom perpendicular to the skin, but oblique; they being arranged in curved lines which either converge towards certain points or lines, or diverge from them in two or more directions. Hence result a variety of figures, which Eschricht termed " streams, whorls, and crosses;" which are easily made out on the median line of the back, chest, and abdomen, on the line between the thorax and the abdomen, in the axilla, on the scalp, at the internal angle of the eye, and on the elbow. The natural di- rection of the hairs is, in general, downwards, as shown especially on the various parts of the head. It may, however, here be changed by persevering efforts. Very rarely, two hairs are found implanted in the same hair-sac. 1 Treatise on the Skin. 262 THE TISSUES, Development of the Hairs. Hairs are first seen in the foetus, upon the forehead and eyebrows, from the third to the fourth month; the first rudiments of the hair- sacs consisting of flask-shaped solid processes of the Malpighian layer of the epidermis, formed by its growth inwards. (Fig. 166.) The internal cells of these be- come converted into a delicate hair, surrounded by. its internal root-sheath; and the external still remaining soft, constitutes the MjgjgSBr outer root-sheath and the hair- bulb. Thus the hairs, unlike the teeth, arise at once in their to- tality. (Kolliker) The first hairs are formed merely of elongated cells similar to the fibrous sub- stance of the later hairs, the me- dullary cells being entirely ab- sent. The cuticle is, however, clearly visible. The papilla is to be regarded as an outgrowth of the fibrous layer of the hair-sac, analogous to the papillae of the skin.1 (Kolliker) The hairs themselves never appear under from three to five weeks after the rudiments just described, e. g. at the nineteenth week, the hairs themselves are nowhere to be seen except on the forehead and eyebrows; and, in the twenty-fourth week, they are 1 The translators of Kolliker's work (Drs. Busk and Huxley) adopt Reichert's view of the development of the hair, viz., that it results from the cornification of a dermic papilla, and regard a hair as homologous with a tooth, in all its parts. " The substance of the shaft corresponds with the dentine, offering even rudiment- ary tubes in its aeriferous cavities ; the inner layer of the cuticle answers to the enamel, the outer to Nasmyth's membrane, and whoever will compare these struc- tures will be struck by the similarity even in their appearance. The sac answers to the dental capsule ; the outer root-sheath to the layer of epithelium (enamel organ) next the capsule; the fenestrated membrane to the stellate tissue, and what Professor Kolliker calls ' Huxley's layer,' to the columnar epithelial layer of the A. Rudiments of hair-sacs I, I (foetus, 16 weeks). B. Single hair-sac seen laterally, a, b. Cuticle and stratum Malpighii of the skin. i. Basement- membrane of hair-sac prolonged from between the stratum Malpighii and the corium. ra. Round- ed and elongated cells forming the matrix of the hair. THE HAIR. 263 not yet developed on the hand and foot, and on some parts of the forearm and leg. In some parts, the hairs penetrate the epidermis as soon as formed (on the eyebrows and eyelashes); in others, their points engage ob- liquely between the pro- per epidermis and the Mal- pighian layer, and grow for a time under the for- mer—as on the chest, ab- domen, back, and extre- mities. The lanugo is fully developed in the twenty- third to the twenty-fifth week. It gradually ac- quires a darker color; be- coming even almost black on the head, before birth in some cases. A small portion, however, falls off, is swallowed by the foetus with the liquor amnii, and thus appears in the meconium. Fig. 167 shows the pro- gress of the development of the hairs. The hairs are shed after birth, new ones forcing out and taking the place of the old ones. The new are formed in processes shooting off from the original hair-sacs. Kolliker discovered and first propounded this law, though it is not yet certain that all the hairs fall out, nor at what precise period after birth. The hairs of the head in many children are known to fall out within the first two to six months. The stages of development of the new hairs, as well as the relation of the hairs to the sebaceous follicles already alluded to (p. 227), is shown by Figs. 168 and 135. The periodical shedding of the hairs of the lower animals is pro- bably secured in the same way; new ones being formed in the old organon adamantine" (p. 190). Without precisely adopting all the analogies just quoted, we admit that a hair is very analogous to a tooth ; for we regard a tooth as j well as a hair, as being essentially an epidermic (epithelial) production. The manner in which the hairs fall out, and are succeeded by others, shows (as well as their development), that they are the analogues of the teeth on the one hand, and of the epidermis on the other. Fig. 167. Development of hair (eyebrows). A. First separation of inner and outer portions of the matrix, b. First formation of the hair, the point not yet appearing above the skin. c. Hair seen after its emersion, a. Cuticle of skin. b. Stra- tum Malpighii of do. c. Outer root-sheath, d. Inner root- sheath, e. Bulb. /. Shaft, g. Point of the hair. h. Pa- pilla, i. Basement-membrane, n, n. Commencement of the sebaceous glands. 264 THE TISSUES. Fig. 168. Development of second eyelashes (infant, one year old). A. Formation of matrix of second hair. B. Incipient development of the young hair. c. The same more advanced and pushing up the old hair. d. The young hair emerging from the opening, and the old one about to fall out. a. External root-sheath. 6. Internal do. of young hair. c. Cavity for the formation of papilla, d. Bulb of old s% hair. c. Its shaft. /. Bulb of young hair. g. Its shaft, h. Its point, i, i. Sebaceous glands. k, k. Sweat ducts. I. Passage of external root-sheath into the stratum Malpighii of the skin. m. First appearance of young hair. sacs, and thus displacing the first hairs, after cutting off their supply of nourishment. The striking analogy in these particulars of the hairs to the teeth, will become ap- parent when we come to speak of the development of the latter. r Is. 1 , a 811 I 11 Before the old hair falls out, it becomes entirely horny in consist- ence, and its bulb is no longer soft and cellular, but solid and fibrous like the shaft, with a clavate en- largement. (Fig. 169.) This condition marks the end of development and of growth; and all hairs which fall out present it. Old hair falling out. A, shows a diminished activity of growth by the small amount of pigment in the cells of the pulp, and the interrupted line of dark medullary substance. At B, provision is made for the formation of a new hair, a new pulp appearing in connection with the old one. At c, the hair has died and fallen out, deprived of its sheath and of the cells composing the pulp of a living hair. THE HAIR. 265 And since it is certain that in full health, the hairs are constantly falling out, doubtless the formation of new ones, as just described, is also simultaneously taking place. Hence not unfrequently, two hairs are seen coming out of the same aperture, as before stated— the old and the new one. When a hair is pulled out, however, it breaks off just above the bulb, and another is produced from the latter directly, as at first. Heusinger found that on pulling out the whiskers of dogs, they were reproduced in a few days from the old sacs. And when the hairs fall out after sickness, it is probable that they are reproduced from the old sacs, since the latter remain for a long time. (E. H. Weber) Uses and Physiological Relations of the Hair. The uses of the hair are various, depending partly upon its phy- sical and partly on other characteristics. 1. The hair is for protection, whether against cold, or other agents, as on the head, &c; against exposure to light, as in case of the eyebrows. 2. It is for concealment, as on the pubes, &c. 3. It prevents the ingress of foreign bodies into the passages opening externally; as the vibrissas of the nostrils, the cilia of the eyelids, and the hairs sometimes existing in the external meatus auditorius. 4. The hair gives character and expression, as the beard; which is also protective against changes of temperature in circumstances requiring its agency in this respect. A tendency to affections of the bronchial mucous membrane is, therefore, frequently removed by allowing the beard to grow. 5. The hair is for ornament, as that of the head. The hairs, like the nails, grow again if cut or worn away; other- wise they remain at their typical length in the various parts of the body. Berthold found the hairs of the heads of females from 16 to 24 years old, grew about 7 lines a month. If the beard were shaved every 12 hours, it would grow to from 5 J to 12 inches, and if every 24 hours, to from 5 to 7J inches, per annum. Shaving once in 36 hours would reduce the annual growth to from 4 to 6 J inches. The beard grows B faster by day than during the night; and in 18 days, about ^ more in summer than in winter. Kolliker supposes that each sac is supplied by the vessels of the papilla with a sufficiency of nourishment to develop the hair to its typical 266 THE TISSUES. length, and to keep the whole hair in a state of moisture and vi- tality ; and that if the hair be cut, the then superfluous amount of nourishment develops the hair till it again attains to the previous length. This is equivalent to saying that the hair-sacs have, each, the power to develop a hair of a determinate length, it being also the function of each to maintain this length; so that if the hair is cut, it again attains to it. Kolliker states that cut hairs do not pro- duce new points, while others have asserted the contrary. When- ever they become pointed again after being cut, as is quite certain in many cases, it is doubtless from mere mechanical causes already suggested, and not from developmental agencies. The growth takes place in the hair-sac, and at the root; the shaft being thus constantly protruded, till the hair attains its normal length. Though the hairs are not vascular they are not a dead substance. Fluids are, doubtless, effused through them which serve for the maintenance of their vitality, ascending from the bulb through the fibrous portion and the medulla to every part, probably by mere imbibition. After accomplishing their object, they pass off by eva- poration, and another supply is afforded. From without, the hair can absorb fluids only in the form of vapor. The oily matter of the sebaceous follicles is spread upon the cuticle of the hair, but does not, probably, penetrate it at all; nor is there any greasy fluid afforded within by the medullary cells. The existence of air-vesicles in the medullary axis, can arise only from a diminished supply of the fluids from the sac, compared with the amount evaporated. It is thus due to a partial drying up of the hair. The fibrous portion appears to be the most actively nou- rished, and is the most rich in fluids, though comparatively so hard. Gray hairs contain more of the air-vesicles, and to them its silvery appearance is due. That their vitality is not, however, essentially diminished, is proved from the fact that they grow rapidly when cut. Thus the hairs live, and must, of course, be modified in their de- velopment and growth by the vital conditions of the skin. The condition of the hair is, therefore, an index of that of the skin. If they are soft and shining, it may be inferred that the skin is tur- gescent and active; if dry and harsh, that it is in a collapsed and inactive condition. Any essential modification, therefore, in the circulation of the skin, and hence of the blood supplying the hair-sacs, modifies the THE HAIR. 267 condition of the hair. Thus it may fall out after sickness, espe- cially from fevers. In old persons, also, it falls out, probably from an obliteration of the vessels of the hair-sacs. The process of whitening of the hairs (gray hairs) is very ob- scure. Its immediate cause is chiefly a decoloration of the fibrous portion of the hairs, and an increase of the air-vesicles; but how this is produced is not understood. Intellectual activity, grief, nervous influences, and old age, are certainly concerned in it. The rapidity with which this change may be effected, also testifies to the vitality of the hair; cases having occurred in which it has become gray within a few hours, under the influence of violent emotions.1 Dzondi and others have succeeded in transplanting hairs with their sacs. The fact that the hairs of the head may become erect under the influence of powerful emotions, is usually associated with the cutis anserina, so called. We should, however, associate it with the fact established by Eylandt, that the hair-sacs of various parts of the body have smooth muscular fibres inserted into them, and which he has termed the arrectores pili. The presence of sulphur in hair accounts for the peculiar odor evolved by its combustion. The various hair-dyes also act by combining with it, and producing a sulphuret of the metal they respectively contain, as silver, manganese, &c. The nitrate of silver is most frequently used (p. 257). Pathological States and Developments of the Hair. There may be an excessive growth or a falling out of the hairs. They may also be developed in abnormal directions, as is often seen on the head. They may be found abnormally, on even mucous sur- faces. Hairs have been developed in the intestines, the gall-bladder, in ovarian cysts, in steatomatous and encysted tumors, and in the lungs even. (Mohr's case) They are often largely developed on moles and nasvi. In all these cases they possess sacs and root- sheaths, and in all respects a normal structure. Indeed, since they 1 A Captain P., of Vermont, was captured by a party of British soldiers in 1813 on the Canadian frontier, and put under guard in the evening, with the assurance that he would be shot the next morning. When the appointed time had arrived his hair had entirely changed from a jet black to gray. Dr. J. W. Richards, of New York city, mentioned to the author a man whose hair changed from a jet black to gray and back again three times in the course of ten years. No cause could be assigned. He was in perfect health, and not of an excitable temperament, and the change began at the age of thirty-five years. 268 THE TISSUES. are an epithelial production, we should not be unprepared to find them wherever an epithelium exists, though they have not been found on the serous membranes. ISTo hairs are developed upon cicatrices on the skin. The falling out of the hair of the head, constitutes baldness (alopecia). When due to an atrophy of the hair-sacs, remedies are, of course, of no avail. One cause of its far greater frequency in men than in women, is, very probably, the style of hat so generally worn, especially in this country; and which by its stiffness, its form, and its heating powers, at the same time banishes all comfort, and violates the principles of good taste, common sense, and physiolo- gical science. Some diseases of the hair are produced by vegetable parasites (fungi) in the interior of the hair itself. This is the case with herpes (or tinea) tonsurans (Gruby); and Dr. Jenner, of London, has shown that the sulphurous acid destroys the parasite and cures the four varieties of this disease.1 In porrigo decalvans (Willan), the fungus is under and around the cuticle of the hair. (Gruby) In plica Polonica, in which the hair becomes matted together, and appears even sensitive, a fungus is developed, according to Guensberg and Walther, in the bulb and shaft of the hairs, and partly destroys them. Munter, however, found no such fungus. CHAPTER II. YELLOW FIBROUS TISSUE. The yellow fibrous tissue (elastic tissue), presents three varieties of form:— 1. The most common form consists of solid fibres of a yellowish color, bifurcating or even trifurcating, and anastomosing very freely; curled or coiled up at their extremities, and sometimes being coiled around other tissues. These fibres vary from ^^ to ^^^ of an inch in diameter, and are often studded with nuclei. More or less of them are always found in connection with the white fibrous tis- sue. (Fig. 170, A.) 2. Another form found by Queckett in the ligamentum nuchae of the giraffe, consists of similar coiling and bifurcating fibres, each 1 Tinea favosa, tonsurans, decalvans, and sycosa. See Am. Med. Monthly, March, 1854, p. 240. YELLOW FIBROUS TISSUE. 269 being marked with transverse striae, not extending quite across them, but being principally confined to the centre of each. Kolli- ker asserts that this appearance is due to the formation of little cavities within the fibres. (Fig. 170, B.) A. Yellow elastic fibres from the ligamentum nucha: of a sheep, b. Yellow fibres from the W mentum nucha of the giraffe, c. One of the same, magnified 500 diameters, d. Vessels of the liga- mentum nuchas of a young calf. (Queckett.) 3. The third variety consists of flat, rather broad, somewhat brittle, and much ramifying bands (Fig. 171), often so arranged as to form a network (or in the form of the finest, straight threads (Fig. 172), as in the peritoneum of some young animals), as found in the middle coat of arteries.—The elastic fibres studded with nuclei have been called nuclear fibres. But all may have been so at first; at least the largest were originally as small as those. (Fig. 173). Elastic fibres cannot be isolated for examination by mere mecha- nical means, since they never occur independently of other histo- logical elements. They always appear where the white fibrous tissue exists, and are often blended, as in the middle coat of arteries, with the smooth muscular fibres. The last two elements may, how- ever, be removed by boiling with acetic acid, and then adding a dilute solution of potash, when the isolated elastic fibres remain. 270 THE TISSUES. The elastic fibres are arranged in three principal forms in the various organs: 1, wide-meshed or intricately formed nets with hook-like indentations, and forming considerable masses; 2, as Fig. 171. Fig. 172. Fig. 171. Elastic network from the tunica media of the pulmonary artery of a horse, with cavities in the fibres.—Magnified 350 diameters. (Kolliker.) Fig. 172. Yellow fibrous element of the areolar tissue of serous membrane, from the mesentery of the rabbit, treated with acetic acid. (Magnified 300 diameters.) bundles of fibres nearly parallel (as in certain ligaments), or twining around other tissues in a spiral manner; 3, forming a fenestrated membrane with tolerably large intervals, as in the arteries. When the yellow elastic fibres form masses, as in the ligamentum nuchae, &c, no nerves or lymphatics are found among them. The vessels, comparatively few in number, lie between the fibres and parallel to them, much like those of tendon. (Fig. 170, D.) The connecting branches, however, are not transverse, but pass off at angles of about 40°; so that the spaces inclosed by the vessels have a somewhat rhomboidal outline. Chemical Composition of Elastic Tissue. The investigations of chemists have not yet led to any very ac- curate knowledge of the composition of this tissue, and its general chemical relations. Cold acetic acid does not act upon it; and therefore displays it when blended with white fibrous tissue, by dissolving the latter, and thus isolating the former. Mulder and Dundas found the fibres entirely unchanged after boiling forty hours, and obtained no gela- YELLOW FIBROUS TISSUE. 271 tinous substance from them. Scherer states that elastic tissue is proteine plus two equivalents of water (Pro + 2HO). Bobin and Yerdeil have, however, found in it a peculiar immediate principle, which they have called elasticine (p. 100). Elastic tissue is unaffected by all the weaker acids, and is not dis- solved by the gastric fluid. It resists decomposition longer than any other soft and moist tissue. Its ash constitutes 17 per cent, of it. Properties and Uses of Elastic Tissue. The yellow fibrous tissue manifests no vital properties,' except so far as to secure and maintain its own development. As a con- stituent part of the organism, it manifests only physical properties; of which its extensibility and elasticity are the peculiar and essen- tial ones. It is, however, also flexible, and considerably strong. Mr. Queckett found that the ligamentum nuchas of a giraffe, 6 feet and 2 inches in length during life, contracted at once, on being removed, to 4 feet; and that an immense' force was required to stretch it again to 5 feet.1 The elasticity of this tissue is preserved for almost an unlimited period; it being revived by the application of water after the fibres have been long kept in a dried state. Uses.—The yellow fibrous tissue is useful by reason especially of its extensibility and elasticity. Whenever a tissue is required pos- sessing these properties, as in extensible ligaments (the ligamentum nuchae, chordae vocales, &c.) and in the bloodvessels, this is the one found. Its properties, indeed, are very similar to those of gum- elastic, except that it is much stronger. Its use in each particular part or organ will at once be inferred, therefore, from the following account of its distribution in the various organs of the human body. Distribution of the Yellow Fibrous Tissue. The yellow elastic tissue forms the greater portion of the follow- ing structures: the ligamentum nuchas, the ligamenta subflava, the crico-thyroid and the thyro-hyoid membranes, the thyro-arytenoid ligaments (chordae vocales), the stylo-hyoid ligament (Hassall), the longitudinal bands of the trachea and bronchi, the internal lateral ligament of the lower jaw, and the ligamentum suspensorium penis. It is also found at the base of the epiglottis, and the fascia trans- versalis is composed in great part of it. It combines with the white The weight of the entire ligament was more than 8 pounds. 272 THE TISSUES. fibrous tissue to form the areolar tissue, wherever found; and of the third form of it the middle coat of the large arteries is almost ex- clusively, and that of the smallest in part, formed. It also abounds between the air-cells of the lungs. "None of the preceding structures are, however, formed of the elastic tissue alone. E. g. between the yellow fibres of the liga- menta subflava, "which are not collected into either fasciculi or lamellae., but are continuously connected throughout the entire thickness of each yellow ligament, there is interposed some white fibrous tissue; upon the whole in small quantity, but demonstrable in every pre- paration, and occurring in the form of lax, undulating fasciculi, which are arranged parallel with the principal direction of the elastic fibres." (Kolliker, p. 284.) Distribution of the Elastic Tissue in the Lower Animals. In all the vertebrated classes this tissue is found in the same localities as in man, and in some places besides—as in the ligaments of the cat's claw, and in the alary membrane of the mammals. In large animals, as the elephant and rhinoceros, the yellow fibrous tissue is employed in the form of a belt to support the abdominal parietes. (Queckett) In the ligamentum nuchas of the giraffe, before alluded to, the fibres are marked with transverse striae, extending through about the central third of their width. The internal por- tions were, however, made up entirely of the common plain fibres. Similar striated fibres also are found in the rhinoceros, and the sheep; and even in arteries. A variety of this tissue constitutes the ligament supporting the expanded wings of the larger birds, as the eagle, crane, heron, &c. It also exists in the lungs of birds. It is a ligament of elastic tissue which in the bivalve mollusca keeps the valves open whenever the adductor muscle ceases to close them by its contraction. In the oyster this tissue is placed within the hinges, and therefore is compressed whenever the valve is closed. Hence the compressed elastic tissue forces the valves apart when the muscle ceases to keep them closed. In the cockle the elastic tissue is placed externally to the hinge, and being stretched when the valves are closed, pulls them open by its elasticity whenever the adductor muscle ceases to act. The form of this tissue occurring in the middle coat of arteries, was found in that of the aorta of a whale to be 1J inch thick; the diameter of the vessel being 12 inches, and its length over 50 feet. Development of Elastic Tissue. The supposition of Schwann, that this tissue is developed from YELLOW FIBROUS TISSUE. 273 cells, receives increasing support from recent investigations. These are peculiarly fusiform or stellate, sharply-pointed cells, producing long fibres or reticulations by their coalescence. The nuclei some- times remain in the elongated or fibriform cells, and thus the latter have been termed nucleus fibres. (Gerber) In other cases all traces of the nuclei disappear, and perfectly homogeneous fibres or net- works are produced. These may remain fine through life as at first, or become coarse by increase in thickness. When once per- fectly developed, the fibres undergo very little change; though so long as the nuclei or other indications of the original cells still appear, a certain amount of metamorphosis and repair may take place (p. 269). It is the development of the nuclear fibres almost alone that has been accurately examined; and Kolliker has demonstrated that they are formed from fusiform cells, 12*0 o to suo" of an inCQ iQ lengtn> which first appear in the foetus of from two to three months (Fig. 173), the fibres of the white fibrous tissue being already well formed. In the foetus, at birth, the cells have so elongated, and coalesced into a network, that they can no longer be isolated as before. What is asserted of the nuclear fibres also holds good of the larger elastic fibres; for there is reason to believe that all these have at one time been nuclear fibres. In fact, there is not a single true elas- tic fibre in the new-born child; since even those of the ligament- um nuchas, &c, when largest, are not more than j-ghus t0 tsW °? an inch in diameter (Fig. 174), and from these, dovibtless, the coarse fibres are subsequently developed. In some places, even in the adult, the original condition of a system of canals (tubular cells) is still to 18 Fig. 173. Fig. 174. Fig. 173. Formative cells of the elastic fibres from the tendo-Achillis. a. Of a four months' embryo, b. From a seven months' foetus ; a few cells free, with one and two processes, others united by twos and threes. (Mag'd 350 diams.) Fig. 174. Stellate formative cells of the nu- clear fibres out of the tendo-Achillis of a new- born infant.—Magnified350diam'rs. (Kolliker.) 274 THE TISSUES. some extent retained. But it by no means follows, as Virchow asserts, that all the nuclear fibres are hollow tubes for the nutrition of the white fibrous tissue blended with the elastic. On the con- trary, Kolliker maintains that all fine elastic fibres, which no longer present any traces of the original cell, are solid, and are useful only so far as they are elastic—as those of the areolar tissue, of the co- rium of the skin and serous and mucous membranes, of the fascias, the perimysia, the periostea, the dura mater, and the walls of vessels. For the cornea alone, where the elastic tissue remains in quite an embryonic condition, does he adopt Yirchow's hypothesis. In any instance or any part where the elastic tissue is still undeveloped, this may be the case also; but, if so, this result is secondary and incidental, and not the definite object of the tissue under consi- deration, as Virchow maintains. Donders maintains that all cell- membranes consist of a substance identical with, or at all events very similar to, elastic tissue. This opinion rests, on the one hand, on the supposed development of elastic tissue, and especially of nuclear fibres, from the walls of cells; and, on the other, on the circumstance that certain membranes and textural elements, which in their physical and chemical properties closely approximate to elastic tissue (e. g. nerve-sheaths), may be found to be formed from cell-membranes. (Lehmann) We cannot, however, accept this view in its general application; for the walls of very young cells, of cytoid corpuscles and blood-cells, and the cells of the deepest layers of compound epithelia, are readily soluble in acetic acid and in very dilute alkalies. If the elastic tissue is removed or destroyed, it is not regenerated; but an imperfect areolar tissue takes its place. Pathological new formations of it are, however, not rare. The growth of the yellow fibrous tissue is secured by an increase •in size of each fibre, as well as by the formation of new ones, doubt- less. Kolliker found that the fibres in the ligamentum nuchas of the calf are considerably finer than those of the ox; and that in the new-born child not a single true elastic (coarse) fibre exists, but only the nuclear (fine) fibres. Pathological New Formations of Elastic Tissue. Fibres of this tissue often occur in pathological epigeneses, in great numbers and in considerable masses; the contiguous fibres being also interwoven into a close and fine lattice-work, presenting the same morphological conditions as coagulated (fibrillated) fibrine, and WHITE FIBROUS TISSUE. 275 for which the finer fibres may be mistaken. They are, however, at once distinguished by their unchangeableness under the action of acetic acid and dilute solutions of the alkaline carbonates. CHAPTER III. WHITE FIBROUS (COLLAGENOUS) TISSUE. Much confusion has resulted from the blending together by au- thors, in their descriptions, of the white and the yellow fibrous tissues, under the name of connective tissue. Kolliker includes under the latter designation the white fibrous tissue on the one hand, and on the other, as mixed with it, elastic fibres, fat-cells, cartilage-cells, and pigment-cells of different kinds. Lehmann regards connective tissue and areolar tissue as being the same, and both as being iden- tical with the white fibrous tissue; the areolar tissue being its amor- phous (or loose—Kolliker), and the connective tissue the formed or solid variety. True connective tissue, or that which connects together different parts and organs, is almost invariably found to consist of two or more distinct tissues interwoven, of which the white fibrous tissue is usually merely the most abundant. White fibrous tissue alone, therefore, cannot properly be termed connective tissue, any more than the yellow fibrous which is almost always blended with it. We shall therefore adhere to both fact and simplicity if we describe the white Fig. 175. 276 THE TISSUES. parent fibres are united by a clear connecting gelatinous substance (homogeneous substance), and fasciculi are thus formed, averaging 30V0 to 24V0- of an incn in diameter. These bundles somewhat resemble the striated muscular fibres, but have no actual striae, or external investments at all comparable to the myolemma, and are smaller. They are arranged, like long, wavy cords, so as to form large lamellae and bundles (as in ligaments); or they coalesce, like the elastic tissue, into networks and meshes. In rare cases the bundles appear to be homogeneous, and not composed of fibres, as in the perineurium (Remak's fibres). In some cases, indeed, neither bundles nor fibres can be made out; and this has been called homo- geneous (or Reichert's) connective tissue. This may be regarded as either white fibrous or areolar tissue, in an undeveloped state. Todd and Bowman—and, since, Reichert and Dr. Paulsen—main- tain that the fibrillation of this tissue is merely apparent; it being really, in its normal state, a homogeneous mass, marked by longi- tudinal parallel streaks, having at times a tendency to split up "ad infinitum," and splitting into membranes rather than fibrous frag- ments. Though we agree with the writers just quoted, the fibril- lated appearance justifies the name we still prefer for this tissue; and it at once occurs that if no minute fibres exist, like those de- scribed by Kolliker, then the bundles, so called, become fibres of larger dimensions. For every histological purpose, therefore, the term white fibrous tissue is to be preferred. No nerves or lymphatic vessels are supplied to this tissue. The manner in which vessels are distributed to parts composed of it, will be shown further on (Fig. 176). Chemical Composition of White Fibrous Tissue. This tissue is about 63 per cent, water, and, like bone and the teeth, affords gelatine to boiling water. It has hence been termed one of the gelatinous tissues. That the gelatine does not, however, pre-exist in these three tissues, but is formed by decomposition of another substance, has already been shown (p. 98). The substance thus converted into gelatine is called osteine, and is the same in bone, teeth, and white fibrous tissue. The apparent fibres, before mentioned, swell up and assume a viscid, hyaline appearance in alkalies, and cannot be again brought into view by the addition of water. The same result follows if a solution of caustic potash of WHITE FIBROUS TISSUE. 277 10 per cent, be used, and the transparent mass may be torn with equal ease in any direction. If, however, the potash be now re- moved by acetic acid, the original texture returns. (Paulsen.) While acetic acid obscures the parallel lines, and renders the mass transparent, it usually brings into view broken, elongated cor- puscles, the remains of the developmental cells. (Kolliker) The addition of a mineral acid brings the lines into view again. It is the white fibrous tissue which some histologists have termed the collagenous element of the areolar tissue, and the fibrillated col- lagenous1 substance. It will be frequently termed the "collagenous tissue" and the " collagenous element," in the subsequent portions of this work. Properties and Uses of White Fibrous Tissue. White fibrous tissue, like the yellow fibrous, manifests no vital properties (save the power of securing and maintaining its develop- ment), but physical properties merely, viz: great strength, great flexibility, and almost total inextensibility. It may, however, be somewhat extended by a slowly-acting and long-continued force. The strongest cords used in the arts are made of this tissue—as musical strings, &c. Mascagni calculated that the human tendo- Achillis will sustain a weight of 1,000 pounds. Its flexibility is owing to the water it contains. When dried, it becomes quite rigid. In this state, also, it completely resists the putrefactive process. Uses.—In all cases where a tissue, strong, flexible, and totally inextensible, is needed, this is the one found. Ligaments and ten- dons are composed almost exclusively of it. Its uses in particular parts and organs vary, as seen in the following paragraphs. Some- times it is merely protective of the softer parts it incloses; as in case of the sclerotica, the tunica albuginea testis, &c. Distribution of the White Fibrous Tissue. 1. White fibrous tissue constitutes the greater portion of tendons, aponeuroses, and articular ligaments. It also constitutes a large portion of the fibrous membranes, so called—viz., the periosteum, perichondrium, and dura mater—and enters with the yellow fibrous into the formation of the areolar tissue. Hence it forms the greater 1 From Ko\\a, glue, gelatine, and yivp?; gelatine-producing; synonymous with gelatigenous. 278 THE TISSUES. Fig. 176. part of the corium of the skin, and of serous and mucous mem- branes ; and of the vascular membranes, so called, as the pia mater and the plexus choroides. 2. It also forms the white, dense tunics of many soft organs; as the perineurium, the sclerotica and cornea, the fibrous coat of the spleen and kidneys, and the fibrous tunic of the testis, ovaries, penis, and clitoris. In all the preceding structures the yellow fibrous tissue is found in combination with the white. The arrangement of the latter, in all except the true membranes, will be disposed of here. 1. Structure of tendons and ligaments. These consist of parallel bundles of white fibrous tissue, united by loose areolar tissue into large cords. Between these the vessels ramify, and a relatively very small number of elastic fibres, or of networks formed of them. Fip:. 261 shows a transverse section of a tendon. The latter and the ligaments have no nerves or lymphatics. The vessels of a tendon of an ostrich are shown by Fig. 176. The manner of union between tendon and muscle, and further particulars in regard to the tendons, will be explained in the chap- ter on "Striated Muscular Tissue." 2. Aponeuroses are composed of fas- ciculi of white fibrous tissue, so inter- woven as to form a membraniform ex- pansion of varying thickness. If very thin, no vessels are sent among the fasciculi, but only to the areolar sheath in contact with each surface. If thick, the vessels penetrate between the fasciculi in an irregular manner. Aponeuroses are fpund at the origins of muscles, as the tendons constitute their insertion. They also exist distinctly from muscles, as in the case of the deep fascia of the extremities (femoral and brachial aponeurosis, &c). 3. Fibro-cartilages have the same structure as tendons and liga- ments, except that cartilage-cells are scattered among the bundles of white fibrous tissue, and that they contain no finer elastic fibres. Fig. 202 represents a section of fibro-cartilage. They exist as spe- cial organs (interarticular fibro-cartilages and the cotyloid liga- a. Vessels of the tendon of an ostrich. b. c Vessels of muscle and tendon, unit- ing at d. (Queckett.) WHITE FIBROUS TISSUE. 279 Fig. 177. ments), or are found developed in the tendons, tendinous sheaths, and the ligaments. 4. The fibrous membranes, so called, differ from the tendons only by the frequent interweaving of the bundles, to give them their difference in form, and by the greater amount of elastic fibres. Under this head may be mentioned— First. The deepfascioz (femoral, &c), which very nearly resemble the aponeuroses in structure, and some of which are classed with them. Secondly. The periosteum and perichondrium, which sometimes contain a great number of elastic fibres, are more vascular than the preceding, and are sparingly supplied with nerves and lymph- atics. The dura mater also belongs here, it being the internal periosteum (endosteum) of the cranium, while it at the same time protects the encephalon. 5. The white, dense tunics included under the second head, except the cornea—viz: the fibrous tunic of the testes and ovaries, penis and clitoris, and the fibrous envelop of the spleen and kid- neys—consist of solid white fibrous tissue, with elastic fibres interwoven. In the case of these organs, also, the fibrous layer projects into the interior, where, mixed to a greater or less ex- tent with smooth muscular fibres, it constitutes dissepiments or a kind of framework, or forms a stroma or a trabecular network. The object here is to inclose and protect the parenchyma of the organs in question. The sclerotica, how- ever, has no such internal projections; and the perineurium is homogeneous in structure, as has been already stated (p. 276). Fig. 177 shows the fibrous tra- beculae in the testis, radiating from the mediastinum. 6. The so-called vascular membranes—the pia mater, choroid plexus, the choroid coat of the eye, and the iris—all have numerous vessels; for the nutrition, however, especially of other parts. They vary in structure. The iris and the pia mater have parallel, matted, and anastomosing bundles of white fibres, without any elastic tis- sue. The choroid plexus and the choroid membrane of the eye, Section of testis. 1. Ca- vity of tunica vaginalis. 2. Tunica albuginea. 3. Medi- astinum testis, giving off the trabecule ; between which are the lobules (5) of semi- niferous tubes. 4. Pia ma- ter testis. 6. Epididymis, and below it the corpus Highmorianum, above 3. 280 THE TISSUES. have a homogeneous tissue like the perineurium, to which the pecu- liar anastomosing pigment-cells, described on page 133, are added. 7. Structure of the cornea.—The true cornea is to be included his- tologically under white fibrous tissue; though in chemical compo- sition it is allied to cartilage, since it affords chondrine, and not gelatine on boiling. The cornea considered as a whole, consists of five layers: 1, the true lamellaied cornea; 2, 3, the anterior and posterior elastic layers, and 4, 5, the anterior (external), and posterior (internal) epithelium. The anterior epithelium consists of three or four strata of cells, and the posterior of one. The anterior and the posterior elastic layers are merely basement-membranes underlying the epithelia. The posterior is called the " membrane of Demours." The anterior is bound to the lamellated cornea by fine elastic fibres, while the pos- terior is not. The former is probably what remains of the vascular conjunctiva covering the cornea of the foetus. But the true cornea (lamellated cornea, Todd and Bowman), con- stitutes the greater part of the substance of this organ. This con- sists of about sixty superimposed lamellas, composed of transparent fibres interwoven so as to leave tubular spaces1 between them, and is continuous with the white fibrous tissue of the sclerotica. These tubular interspaces are arranged with tolerable regularity and con- stricted at intervals, as shown by Fig. 178. This lamellated tissue is the only portion of the cornea which is continuous with the Fig. 178. Tubes of the cornea proper, as shown in the eye of the ox, by mercurial injection. Slightly magnified. sclerotica, and its fibres appear similar to those of the latter, except that they are transparent (Todd and Bowman). Their continuity is 1 Kolliker, however, believes these tubes are artificial dilatations by injection between the transparent fibres. WHITE FIBROUS TISSUE. 281 shown by Fig. 179. The tubular interspaces are doubtless filled with a transparent fluid. No vessels extend into the substance of Fig. 179. Vertical section of the sclerotic and cornea, showing the continuity of their tissue between the dotted lines, a. Cornea. 6. Sclerotica. In the cornea, the tubular spaces are seen cut through, and in the sclerotic the irregular areola. Cell-nuclei, as at c, are seen scattered throughout, rendered more distinct by acetic acid. (Magnified 320 diameters.) the cornea. Those of the sclerotica form loops extending to its margin, as shown by Fig. 180. Some superficial branches belong- ing to the conjunctiva extend, however, in front of the cornea to the distance of ^ to J of a line from its margin, as seen in the figure. It is suggested by Kolliker that vessels carrying the li- quor sanguinis alone, may communi- cate with these, and extend through- out the cornea. That the fluid in the tubular inter- spaces is the blood-plasma, may be in- ferred from the fact that though there are no vessels in the cornea, incised wounds heal very readily. This is the case usually after the removal of cata- ract by extraction. Since the plasma must, however, be afforded by the pe- rimetral vessels, it is important not to carry the incision further round than is actually necessary. In diseased conditions of the cornea, however, the deep-seated vessels may be prolonged into its entire substance, while the super- Nutrient vessels of the cornea, a. Su- perficial vessels belonging to the con- junctival membrane, and continued over the margin of the cornea. B. Ves- sels of the sclerotic returning at the margin of the cornea. 282 THE TISSUES. ficial form a dark band of considerable breadth around its margin. Opacity very frequently results from the organization of plasma in the tubular interspaces, and between the laminae; the new forma- tion not being transparent like the original tissue. The arcus senilis, occurring mostly in aged persons, results from a fatty degeneration of the cornea. Distribution of White Fibrous Tissue in the Lower Animals. This tissue is found in all vertebrate animals in about the same conditions as in man; while in the invertebrata it is very rare. In mollusca the tendinous fibres are very large; in the terebratula, even ¥^ of an inch in diameter, and collected into strong bundles presenting a beautiful silvery aspect. In birds, the tendons of the legs are very large, and more or less ossified. Every one has noticed this, especially in the case of the turkey, goose, and other species most frequently used as food. The analogy of this tissue to bone, in a chemical point of view, has already been suggested (p. 276), and will account for its tendency to ossification. Development of White Fibrous Tissue. Donders and Virchow coincide in the opinion that the true white fibrous tissue (the gelatinous intercellular tissue of white fibrous tissue, bones, and teeth), does not originate from cells, but is directly separated from a plastic fluid; while the other elements—lacunas and pores, cartilage-cells, and nuclear (elastic) fibres—are primarily formed from cells. Kolliker thinks differently as to the develop- ment of the fibres of white fibrous tissue; asserting that the nuclear fibres are developed not from the nuclei of the cells of the white fibrous tissue of the embryo, but from the cell-walls; while the cell-contents are converted into the collagenous element, or white fibrous tissue. We agree with Reichert and Virchow that the elastic fibres blended with the collagenous element, or true white fibrous tissue, represent the cells of cartilage; while the white fibrous tissue re- presents the matrix or homogeneous substance of cartilage; and, like the latter, is not developed from cells. This view is confirmed by an examination of the insertion of tendons into bones in young animals, and in which the surface of the latter is still in a state of cartilage. The white fibrous tissue alone has been confounded with the areolar, under the name of the connective tissue. Kolliker's " areo- lated connective tissue" is the true areolar tissue, and will be de- WHITE FIBROUS TISSUE. 283 scribed in the following chapter. Cells appear to perform an im- portant part in the development of the latter tissue, as will be seen. But, for the present, we may adopt the view which regards the elastic fibres as developed from cells, while the collagenous element, or white fibrous tissue, is at first formed directly from the plasma. The growth of white fibrous tissue is secured by a gradual in- crease of the bundles before described; and this occurs probably from the plasma directly—each fasciculus assimilating to itself the amount required. The reparation of this tissue, if inflammation occurs, is imperfect; e. g. if a portion of a tendon be removed, or if the ends of a divided tendon be separated (as in operations for club-foot), the new tissue is similar to white fibrous tissue; but is developed from cells, and is a condensed form of areolar tissue, rather. If inflammation does not occur, the exuded plasma is directly (i. e. without the interme- diation of cells), converted into a collagenous tissue precisely iden- tical with the original development. Pathological States and New Formations of the White Fibrous Tissue. 1. It is difficult to distinguish between a new formation and a hypertrophy of the white fibrous tissue, if the change occurs in a part or organ in which this tissue naturally exists. A hypertrophy, so called, of the capsule of Glisson produces the granular liver, or cirrhosis; and hypertrophy of the collagenous tissue between the tubes in the kidney, produces the granular kidney, or one form of Bright's disease. In both these cases, the parenchymal substance is diminished by the pressure consequent on the increase of this interstitial element. 2. This tissue is also, like all others, liable to atrophy, if its usual supply of blood be cut off; as by pressure upon the vessels by tumors, aneurisms, &c. 3. Pathological new formations of this tissue are very common, and constitute many of the pathological epigeneses. Fibroid tumors of the uterus are often formed of it without any admixture of the elastic element. Condylomata, warts, and vegetations on the skin and the mucous and serous membranes, are essentially new forma- tions of collagenous tissue, usually covered by a distinct epithelium (p. 247). The walls of cysts are formed of white fibrous tissue, as well as most of the substance of nasal, laryngeal, and uterine polypi; though in all these cases, the loose arrangement of the fibres may rather entitle it to the name of areolar tissue. The same re- mark may also be extended to nasvi materni. Sarcomatous tumors are formed in great part of this tissue. The kehides is also a development of it in the corium of the skin, giving 284 THE TISSUES. rise to an appearance like a cicatrix. Even the lupus exedens is merely a development of white fibrous tissue in the corium of the skin; but in such a way as to cause atrophy and ulceration of its structure, and thus its progressive destruction. The pathological development of white fibrous tissue alone, is not generally regarded as producing a malignant epigenesis. But this distinction of malignant and non-malignant is evidently of less importance, when we consider that the atrophy of the parenchyma of the liver from a hypertrophy of Glisson's capsule, is as sure to be fatal if it continues to progress, as is any form of cancerous development. CHAPTER IV. THE AREOLAR TISSUE. Several different terms have been used by different histologists to designate this tissue. Long ago termed the cellular tissue, it has more recently been called the connective tissue; the reticulated con- nective tissue (Kolliker); the fibro-cellular tissue; the fibrous cellu- lar (Hassall), and the areolar tissue (Todd and Bowman). Of all these, the last is the only appropriate name. The term " connective," as applied to any tissue has already been objected to (p. 275), though it is really more applicable to this than to any other, as expressing one of its functions. By a cellular tissue can, now-a-days, be meant only a tissue composed of an aggregation of cells, like the epithe- lium, &c.; and by a fibro-cellular, one composed of fibres and cells. The tissue under consideration is composed of fibres so inter- woven, either separately or in fasciculi, as to leave-larger or smaller irregular spaces—areoloz—between them. And this arrangement constitutes the peculiarity of the tissue; for the fibres are those of the white-fibrous tissue and the yellow-fibrous tissue, just described. It has been seen that white-fibrous tissue is almost invariably ac- companied by the yellow, as in the tendons, fibrous membranes, &c. (p. 278). But while in these the elastic element exists only in a very small amount, and both are so intimately blended as to form a very compact structure; in the areolar tissue the elastic element is more abundant, and the areolae give rise to a loose and spongy tissue. A description is, therefore required:— THE AREOLAR TISSUE. 285 1. Of the solid fibrous tissues. 2. The areolae and their contents. 1. The collagenous element (white-fibrous tissue) of the areolar tissue always greatly predominates over the elastic element, though varying in its precise proportional amount in different parts and organs. It occurs in fasciculi, as shown in Fig. 181, of &■ more or less wavy outline, and of various length and size; they frequently being about 3^ of an inch in diameter. Among these the elastic fibres are distributed, sometimes in bundles, but more frequently Fig. 181. The two elements of the areolar tissue, in their natural relations. 1. The white fibrous element with cell-nuclei (9) sparingly visible in it. i 2. The yellow fibrous element, showing the branching or anastomosing character of its fibres. 3. Fibres of the elastic element, much finer than the rest. 8. Nucleolated cell-nuclei, often seen apparently loose. (Magnified 320 diameters.) single, and being ^oV o~ to soV o 0I"an mcn iQ diameter. Frequently also they are coiled around the other fasciculi, as shown in the figure. Messrs. Todd and Bowman first called attention to the fact that this tissue is a compound of the two just mentioned. The elastic fibres are easily isolated from the white fibrous tissue under the microscope, by the action of acetic acid; which renders the latter indefinable, soft, and gelatinous (pp. 270 and 277). 2. The areolce are merely irregular cavities between the solid 286 THE TISSUES. elements, just described. (Fig. 182.) They consequently have no distinct walls, and they freely communicate with each other. Their size varies extremely; sometimes occupying much more space in the aggregate than the solid portions, in which case the tissue is very loose; while in other cases they are very small, from a con- densation of the fibres around them. It is this free communication which accounts for the ready diffusion of blood and other fluids in the areolar tissue under the influence of gravity. The smallest meshes, however, in some parts are so disposed as to constitute secondary cavities of a somewhat de- terminate shape and size, and which are visible to the naked eye. These generally contain fat-cells; and the much-branched, sometimes tubular, sometimes fissure-like spaces connect- ing them, are termed the areolar pas- sages. The contents of the areolae are: (1), a fluid of an alkaline reaction, resem- bling a weak serum; or (2), fat-cells. This fluid is a mere transudation, and not a secretion, from the bloodvessels traversing the tissue, and its general composition has been specified on page 181. In some parts, however, the areolae are partly or entirely filled by fat-cells; in which case the serous fluid is proportionately ex- cluded. This is especially the case with the subcutaneous areolar tissue, or superficial fascia. But in certain parts, fat never accu- mulates ; as underneath the skin of the eyelids, of the scrotum, &c. The amount of fluid in the areolae is liable to sudden increase or diminution, often from slight causes; the former producing oedema or swelling, and the latter a shrivelled appearance of the skin over the part in which it occurs. Sometimes the areolae become filled to a greater or less extent with air, to the exclusion of the fluid. Occurring as a pathological condition it constitutes emphysema. This may, indeed, be produced with the blowpipe experimentally; and Bichat tells of mendicants who excite the commiseration of passers-by, by the singular ap- Fig. 182. Portion of areolar tissue, inflated and dried, showing the general character of its larger meshes. Each lamina and fila- ment here represented, contains numer- ous smaller ones, matted together by the mode of preparation. (Magnified 20 dia- meters.) THE AREOLAR TISSUE. 287 pearance produced by inserting a quill under the skin of the chest, and blowing forcibly through it—a general emphysema being thus promptly produced. The air is, however, removed by absorption within a few hours without any injurious results. This experiment also demonstrates the free communication of the areolae with each other over the whole body even. Chemical Composition of Areolar Tissue. Areolar tissue abounds in water, since its serous fluid consists mostly of it. Besides, both the white and the yellow fibrous tis- sues contain a considerable percentage of it. Of course, glutin is obtained from areolar tissue by boiling; from the osteine contained in its white fibrous tissue. Elasticine exists in the elastic tissue. In addition to these, we have only to refer to the composition of the transudations for the amount of albumen and saline matters they contain (p. 182). Properties of Areolar Tissue. Areolar tissue has no characteristic vital properties, since this is the fact with regard to both of its two component elements. Like them it is distinguished by physical properties merely; the princi- pal being extensibility and elasticity, with a good degree of strength. It owes the last property to the collagenous element, and the other two to the elastic tissue. If it be asked how a tissue formed in great part of an entirely inextensible element (the white fibrous tissue), becomes extensible, we have to remember that in extending the areolar tissue the individual fasciculi of white fibrous tissue are not stretched, but are merely displaced upon each other; while the elastic fibres restore them to their original relations after the tension is re- moved. The only vital property manifested by this tissue is the one common to all the tissues mentioned thus far; viz., the power of maintaining its own nutrition. The nutritive changes are, however, probably but slowly brought about, after it is once fully developed, and the vessels in its substance are mostly on their way to other tissues. Fig. 183. Vessels of areolar tissue from the neck of a young pig. a, a. Nerves. (Queckett.) 288 THE TISSUES. Nor can the nerves detected in it be regarded as belonging to it, since they proceed beyond to terminate. Consequently, it mani- fests but a slight degree of sensibility when divided by the sur- geon's knife. The vessels in areolar tissue are generally arranged so as to include hexagonal spaces, as seen in Fig. 183, from Queckett; and which also shows the appearance of the nerves. Uses of Areolar Tissue. The functions of areolar tissue depend on the physical properties just mentioned. 1. It isolates the various organs by constituting their external envelop. 2. It at the same time lies between and connects the various organs together in the body, and yet so as to allow of a certain amount of motion of one upon another. It is, therefore, the true connective tissue (p. 275). 3. It protects the proper substance or parenchyma of various organs. 4. It gives support to organs, and maintains them in their place. Thus, with few exceptions, it accompanies the bloodvessels and nerves to their minutest subdivisions. It must, therefore, be regarded as a subordinate tissue, wherever found, though quite indispensable on account of the mechanical uses just described. Distribution of the Areolar Tissue. The areolar is more extensively diffused than any other tissue in the body. Indeed, it enters to such an extent into the structure of every part and organ, with very few exceptions, that if all the other tissues were entirely removed from the body, its conformation would still be preserved in every part by the areolar tissue; and, except from the removal of the osseous and the muscular tissues, its weight would be but slightly diminished, as the following particulars will show:— 1. It surrounds and supports the arteries and veins everywhere, and sometimes the capillaries also, and thus enters with the vessels into every organ. 2. It also forms sheaths (perineuria) around all the nerves; accompanying them, however, to their finest ramifications, in an undeveloped form (p. 276). The brain, however, does not contain THE AREOLAR TISSUE. 289 it, except as it surrounds the vessels, two or three removes from the capillaries. 3. Areolar tissue invests the muscles externally, forming their sheaths or perimysia, which give off prolongations (internal peri- mysia) investing the fasciculi of fibres. The heart, however, con- tains this element in very small proportion, its fibres intertwining in such a manner as to render an extraneous bond of connection unnecessary. It also lies between and underneath the muscles, and in greater quantity in proportion to the required mobility. 4. This tissue is abundant around internal organs which undergo changes of form, size, or position in the performance of their func- tions, and which are partially or wholly without a free surface, as the pharynx, oesophagus, bladder, lumbar colon, &c; and its fila- ments are long, tortuous, and largely intertwined. It also envelops all the glands, and sends prolongations into their interior among their lobules; it being more abundant in proportion as the gland is less compact, and allowing motion of one part upon another. E. g. it is far more abundant in the mammary gland than in the liver. "*• 5. Under the skin and the mucous and serous membranes, it forms a distinct layer, though presenting great varieties in respect to quantity and denseness. 6. Finally, the corium of the skin and of mucous and serous membranes is merely condensed areolar tissue, as will be seen. Peculiarities of Areolar Tissue. A peculiar form of areolar tissue is said by Henle to exist in company with the arteries at the base of the brain; the elastic fibres forming rings and spirals around the fasciculi of the white fibrous tissue. The subcutaneous areolar tissue is also of peculiar practical im- portance, and will therefore receive some additional notice here. The Subcutaneous Areolar Tissue. The layer of areolar tissue under the skin was formerly called the cellular membrane. It is properly termed the superficial fascia, or the. subcutaneous areolar tissue. It, singularly enough, is de- scribed by Kolliker as one of the layers of the skin itself; and whenever it contains fat-cells in its areolae, it is by him called the panniculus adiposus. He also restricts the term superficial fascia to 19 290 THE TISSUES. its innermost layer, where, as upon the trunk, thighs, &c, it forms a tolerably firm texture without fat-cells. The inner surface of the subcutaneous areolar tissue is most loosely adherent to the subjacent parts upon the trunk, the forearms, legs, the back of the hands and feet, the eyelids, penis, and scrotum, and on the extensor side of the articulations. A closer connection exists where tendinous fibres or processes are inserted into the skin (leva- tor labii superioris, palmaris brevis, &c); and where this tissue is connected with subjacent muscles by short, strong filaments of white fibrous tissue, as on the head, alas nasi, and lips, the forehead and temples, the ear, mouth, and occiput; also on the glans penis, beneath the nails, &c. Generally the skin is less movable where the fat forms a thick layer, than where, from any reason, it is less abundant, or entirely absent. The external surface of the subcutaneous areolar tissue is con- nected by numerous filamentous processes of white fibrous tissue with the corium of the skin, and is not everywhere distinct from the latter, as under the skin of the penis and scrotum (dartos). Generally, however, the areolar tissue is pretty easily separable from the skin, especially where the former contains an abundance of fat; except where the follicles of the larger and more closely-set hairs penetrate deeply into the fat, as on the head, cheeks, chin, &c. The thickness of the subcutaneous areolar tissue varies much in various situations. That of the eyelids and the upper and outer part of the ear is -£% of an inch thick; of the penis, ^s; and of the scrotum, T'g of an inch. (Krause.) In these situations there is no fat; in those next mentioned there is. On the cranium, brow, nose, lobe of the ear, back of the hand and foot, the knee and elbow, the thickness is 1 line, while in most other situations it is \ to \ of an inch thick. The thickness, however, in the same part, varies with the age, sex, and the individual. Women have more fat in its areolae, generally, than men; and hence a greater thickness of this layer, as well as a greater plumpness of form. It is thicker, pro- portionally, in healthy infants and children than during adolescence. In corpulent persons the subcutaneous areolar tissue may become so laden with fat as to be 4 inches thick even; while in lean per- sons, in the same situation, it may not exceed 1 line. Similar extremes in thickness may also present themselves in the same person on passing from a state of emaciation to one of corpu- lence, or the reverse. And this is a fact of great practical import- THE AREOLAR TISSUE. 291 ance to the surgeon, especially in regard to the making of incisions preliminary to the ligation of arteries. It is, of course, only in situations where the areolas are large, and filled with fat-cells, that these changes occur; as on the abdomen, the neck, and the limbs espe- cially. It less affects the back of the trunk, since there the tissue is much more condensed, and the areolae are therefore very small. Development of Areolar Tissue. In the earliest period at which the areolar tissue can be examined, Schwann has described it as consisting of nucleated particles, send- ing offsets on the opposite sides, and uniting themselves with others in the vicinity. The threads thus formed are at first homogeneous; the longitudinal streaks and the wavy character appear subsequently. Normally and originally, however, we believe that the yellow fibrous element alone is developed from cells (p. 283). The development of areolar tissue consists, in fact, merely of the simultaneous development of the white and the yellow fibrous tis- sues in the same blastema. These elements subsequently become blended, as found in the different situations already described. When new formations of areolar tissue occur, however, as in in- flammatory exudations, subcutaneous wounds, &c, the white fibrous element may be developed either from cells or directly from the plasma, as has been shown by Mr. Paget. 1. In case of repair by granulation, and of inflammatory adhe- sions and indurations, the white fibrous element of the areolar tissue is developed from cells. "The cells first formed in the plastic exu- dation are round, very slightly granular, and from x^o- to 20\-q of an inch in diameter; they have a distinct cell-wall, which is readily brought into view by the action of water, if not apparent at first: and they present a round, dark-edged nucleus, whose sharp defini- tion distinguishes it from that of the colorless corpuscles of the blood, to which these cells otherwise bear a close resemblance. It is in this nucleus that the first developmental change shows itself, for it assumes an oval form, and its substance becomes clearer and brighter. Very soon, however, the cell itself elongates at one or both ends, so as to assume the caudate, fusiform, or lanceolate shape (Fig. 184); and its contents become more minutely and distinctly granular, whilst the cell-wall thins away, or becomes blended with its inclosure. As the. cells elongate more and more, so as to assume the filamentous form, they also arrange themselves in such a manner 292 THE TISSUES. Fig. 184. that the thickest portion of one is engaged between the thinner ends of the two or more adjacent to it; and thus fasciculi are gradually formed, of which every fibre is developed from one elongated cell, except where two or more cells have united end to end, so as to form one long, continuous filament. In the production of areolar tissue in inflammatory exudations, or in granulating wounds, the nuclei of these fibre-cells appear to waste and be absorbed: but in the normal course of development, which may be seen to take place on this plan in the subcutaneous areolar tissue of the foetus, as well as in many other situations, it is probable that they develop themselves into the 'nuclear fibres' of Henle, which constitute, in fact, the yellow or elastic filaments that are intermin- gled with the white in this tissue"1 (p. 273). 2. In case of the filling up of subcutaneous wounds, as of tendons especially, the white fibrous element is formed directly by the fibril- lation of a nucleated blastema. This, when first effused, "seems like a mere fibrinous exudation, usually containing a quantity of finely- molecular or dimly-shaded substance, but having no appearance of distinct nuclei; these, however, gradually present themselves in it, as oval bodies, with dark, hard outlines, which soon become elon- gated, and are so firmly imbedded in the surrounding substance that they can scarcely be dislodged. The blastema gradually acquires a more and more distinct fibrous appearance, and at last exhibits a regular filamentous structure; the nuclei themselves undergoing little change during this time, but appearing to govern the direction of the fibrillation. As the texture goes on to completion, the nuclei are either absorbed—which seems to be the case in the connecting tissue formed for the reparation of injuries, as well as in the normal development of tendons—or they undergo a further development into 'nuclear fibres.' This is effected by their extension at both ends, so that the nuclei thus prolonged meet and unite; their par- ticles taking on that very uniform linear arrangement by which the Development of fibres from cells, a Circular or oval nu- cleated cells, b. The same, Be- coming pointed, c. The same, become fusiform, the nuclei being still apparent, d. The same, elongated into fibres, the nuclei having disappeared. 1 Paget's "Lectures on the Processes of Repair and Reproduction after Injuries," in Medical Gazette, 1849, vol. xliii. p. 1069. THE AREOLAR TISSUE. 293 fibres of this tissue (i. e. the yellow fibrous) seem to be characterized, and sometimes perhaps undergoing a partial or complete develop- ment into cells. The rate at which the production of fibrous tissue takes place in the manner now described is at first very rapid, well- marked filaments being detectable in the blastema within seven or eight days; and the tenacity of the bond thus formed between the two ends of a divided tendon is such that in one of Mr. Paget's experiments, within ten days after the operation, the reunited tendo- Achillis of a rabbit (the new tissue being a cord of not more than two lines in its chief diameter), supported a weight of above fifty pounds. The subsequent changes take place more slowly; but'the reparation of divided tendons has been found to be so complete within five months after the operation, that no trace of the sections could be discovered even by microscopic examination."1 It is, how- ever, to be remembered that non-inflammatory exudations alone can become organized in this way; they passing at once into tissues, while the inflammatory require an intermediate process of cell-life to accomplish the same result (p. 186). Regeneration of Areolar Tissue. Areolar tissue is very perfectly regenerated if removed; but the most completely so in situations where it is most condensed, or ap- proaches more nearly to mere white fibrous tissue. Indeed, it is an imperfectly-developed areolar tissue, rather than the original one, which repairs losses of substance in most parts and organs, as the skin, tendons, and even the parenchyma of organs— as when parte of the liver or brain, &c, are removed by suppura- tion or by injury. Pathological States and New Formations of Areolar Tissue. Here we have to distinguish the pathological conditions— I. Of the fibrous framework of this tissue. II. Of the areolae and their contents. I. The fibrous framework is liable to atrophy, in which the blood- vessels collapse, together with the framework in which they are dis- tributed. It is quite probable that the hypertrophy, so called, of the areolar tissue is a new formation of the same. II. But the most important changes occur in the contents of the areolas. 1 Paget, "Lectures," &c, ut supra, p. 1070-71. 294 THE TISSUES. 1. An increase of the natural serous fluid of the areolae consti- tutes oedema or swelling; and if of considerable extent, and occurring in the subcutaneous areolar tissue, it constitutes anasarca or dropsy, and which usually occurs in the lower limbs first, for the reason specified at the end of the next sentence. In dropsy, moreover, the tissue yields to pressure, or "pits," since the fluid is forced from one areola to another; and it also passes from one part to another under the influence of gravity. 2. In case of inflammation in the areolar tissue (areolitis), the areolae become filled with an exudation instead of the natural trans- udation, and which may become subsequently organized (p. 187). If so, the areolar tissue presents an indurated feeling, since the areolas are filled by a solid substance; and the skin becomes quite immovable over the indurated portion.1 3. If the exudation filling the areolar tissue degenerates into pus, it will be evacuated by ulceration, if it is not so artificially. 4. A sudden diminution of the fluid in the areolae sometimes oc- curs, as in Asiatic cholera and other diseases attended by profuse liquid alvine discharges. Here the fluid is absorbed into the blood directly, to compensate the loss from this fluid by the transudation into the alimentary canal from its vessels. The immediate effect is a rapidly-induced shrivelled appearance of the skin; and which is more apparent in infants, while it is also soonest removed in them after the discharges cease. 5. Extravasated blood may accumulate in the areolas, and gravitate from one to another, as is seen in case of ecchymosis under the skin. The blood is removed by absorption, or, undergoing a change, is discharged by the ulcerative process. 6. The normal fluid in the areolae may be replaced by air, consti- tuting a pneumatosis or emphysema. This may result from decom- position in the tissue, but more frequently from the air being forced into the areolas from without. In the latter case it .may be soon reabsorbed without producing injurious consequences (p. 286). 7. Fat-cells may fill the areolae where they do not usually exist, or may greatly increase where ordinarily found. This state is, how- ever, rather a hypertrophy of the adipose tissue, as will be seen. It, however, interferes with the elasticity of the areolar tissue, and thus with the mobility of parts and organs; and so far produces a patho- logical condition of the tissue under consideration. 8. In case of atrophy of this tissue, the areolas are filled with plates of cholesterine, pigment-cells, and often also the carbonate and phos- phate of lime. 9. The subcutaneous areolar tissue is the seat of numerous patho- logical changes, especially sarcomatous and lipomatous tumors. The surgeon must also bear in mind the changes in thickness it under- 1 An areolitis sometimes occurs in the superficial fascia of r.ew-born children, and is sometimes termed the "skin-bound" condition. ADIPOSE TISSUE. 295 goes—as has been stated (p. 291)—in case of ligation of the large arteries, since they lie under the deep fascia, which does not vary in thickness, and require a division of the superficial fascia to arrive at the latter. 10. Reparative new formations of areolar tissue have already been described (p. 292). Pathological new formations are not infrequent; often constituting, as they do, the stroma of cancerous growths, in the areolae of which the cancer-cells are deposited. It is, however, often very difficult to decide, in particular instances, whether a pa- thological new formation consists mainly of the white fibrous or of the areolar tissue, on account of its imperfectly-developed state; and some of the formations mentioned on page 283 would by some ob- servers be regarded as of the areolar, rather than of mere collagenous tissue. CHAPTER V. ADIPOSE TISSUE. Adipose tissue and fat, are terms often used to denote the same thing. But we have seen that human fat is a fluid—a compound of oleine, margarine and stearine; the first holding the other two in solution (p. 76,1). It is also found constituting in part the gran- ules in almost all kinds of cells (epithelial, &c), and in the form of minute drops (fat globules), in the interstices of many tissues (p. 73). But in adipose tissue, the fat is contained in, and completely fills the adipose cells; and the tissue consists of the two following ele- ments :— I. The adipose, or fat-cells. II. A matrix of areolar tissue diffused among the cells, and holding them together—the intercellular areolar tissue. I. The adipose cells (Fig. 185), are peculiar in several respects. 1st. They contain no granules; but only the clear fluid before men- tioned. 2d. When fully developed, they have no apparent nucleus or nucleolus; though Kolliker always finds a nucleus when they are but partially filled. 3d. The cell-wall is apparently of simple 296 the tissues. membrane, but very thick comparatively—even TJ?XiT> of an inch.1 4th. The fat-cell is also larger than other cells, being from TT1^ to rfa of an inch (Kolliker), and averaging g^o of an inch in diameter. They are smallest in young animals. Those, however, of the same mass differ in size. They present no peculiarity in respect to form; Fig. 185. Fig- 186. Fig. 185. Normal fat-cells from the breast, a. Without reagents, b. After being treated with ether, whereby the fat is exhausted and the folded delicate membrane remains.—Magnified 350 diameters. (Kolliker.) Fig. 186. Fat-cells assuming the polyhedral form from pressure against one another; from the omen- tum. (Magnified about 300 diameters.) being globular originally and in young animals, and polygonal when pressed together in a mass in the adult. (Fig. 186.) In color, adipose cells are usually of a yellowish shade; but lighter in young than adult animals. Hence adipose tissue is usu- ally of this color. The contents of the fat-cells become solid at the temperature of 63° (Fahr.) and lower, since the oleine congeals at this temperature. After death, therefore, human fat is solid. II. The connective tissue between the fat-cells usually presents nothing peculiar, it being mere areolar tissue. It is, however, sometimes merely a connective substance or plasma. (Kolliker) It has already been shown that fat-cells often fill, partially or entirely, the areolas of areolar tissue, as of the superficial fascia; though a small amount of areolar fluid still exists between the cells, except where they are in perfect contact. But in case of adipose tissue, the cells are aggregated in larger masses, and the connective areolar tissue is comparatively slight in amount. These masses take the 1 Todd and Bowman think each fat-cell has its own envelop of areolar tissue, and its distinct vessels. This is, however, certainly not the case with all of them, though it is with some. ADIPOSE TISSUE. 297 Fig. 187. form of lobes or lobules, which are also bound together by still larger fasciculi of areolar tissue. The relations of the fat-cells and the intercellular connective tissue are shown by Fig. 187. Vessels of Adipose Tissue.—Each fat-cell is surrounded by a loop or loops of capillary bloodvessels; all the capillaries of a single terminal artery looping around the cells of a single lobule. (Fig. 188.) Hassall com- pares such a lobule of cells to a bunch of grapes. The vessels of the lobule do not, however, apparently grow from the cells like the stems of grapes, though there is a gene- ral analogy. No nerves or lymphatics be- long to the adipose tissue, though both may Adipose tissue. a>a. Fat^ells. be found traversing it on their way to other 6>6- Fibres of intercellular areo- lar tissue. tissues. Peculiarities.—Sometimes a minute star-shaped body may be seen in a fat-cell in the human subject. (Fig. 189.) This is generally Fig. 188. Bloodvessels of fat. 1. Minute flattened fat-lobule in which the vessels only are represented. 3. The terminal artery. 4. The primitive vein. 5. The fat-cells of one border of the globule separately represented. (.Magnified 100 diameters.) 2. Plan of the arrangement of the capillaries on the exte- rior of the cells, more highly magnified. said to consist of the margarin in a crystalline form. Kolliker, however, regards it as margaric acid. This appearance is more common in the aged. 298 THE TISSUES. Fig. 189. In the emaciated subject scarcely any nor- mal fat-cells are met with; but this topic will be resumed in the last subdivision of this chapter. Peculiarities in the Lower Animals. Fat cells do not exist in the invertebrata, though fat-globules do (p. 73), and often in great abuudance. There is, therefore, in them no true adipose tissue. The larvae of insects contain a large amount of fat-glo- bules. The fat-cells of the pig are generally some- what kidney-shaped. In birds, they are smaller than in man, and often contain a bright colored fluid; e.g. the bright colors about the beak, and of the legs in some spe- cies, are said to depend on layers of cells beneath the skin containing colored fat. The bright colors of cer- tain crustaceans and reptiles, are also due to a similar cause, when not dependent' upon pigment-cells. Wagner believes that the color of the iris in birds is also due to a deposit of fat. The fat of different animals presents four varieties, so far as its density after death is concerned; viz., oil, lard, tallow, and sperma- ceti—the first containing the most oleine, and the last the most stearine. The fat of the bear does not congeal at ordinary tempe- ratures, i.e. it remains an oil; and hence its value to perfumers. Lard is obtained from the hog; tallow from the ox, sheep, &c, and spermaceti from cavities in the cranium of the whale. Human fat is intermediate in density between lard and tallow. The fat upon the omentum of the sheep is called suet. Fat-cells with crystals of tnargaric acid. a. Cell with a star of crystalline needles, as they may be found not un- commonly in normal fat. 6. Cell quite filled with crystals, from the white fat-lobules of an emaciated subject.—Mag- nified 350 diameters. (Kolli- ker.) Chemical Composition of Adipose Tissue. This includes, (1) the composition of the fluid fat itself; (2) that of the walls of the fat-cells; and (3) of the intercellular areolar tissue. 1. If adipose tissue be exposed to a high temperature the fat-cells burst, and the fat escapes; the cell-walls and the areolar tissue form,- ing a solid residue. It has already been shown that the fat consists of oleine, stearine, and margarine; and their composition has been specified on page 76. 2. The composition of the cell-wall is not precisely known; but there is no room to doubt that it is an albuminous compound. ADIPOSE TISSUE. 299 3. The intercellular areolar tissue has the same composition as areolar tissue in other situations (p. 287). It should be added that a small amount of serous fluid bathes the fat-cells—the intercellular fluid; and which does not differ in com- position from that in the areolas of the areolar tissue. Distribution of Adipose Tissue in Man. This tissue is very generally diffused throughout the human organism, and in the adult usually constitutes about 2V part of the weight of the body. In women and children, however, it averages somewhat more than this proportion. It has been seen (p. 290), that fat-cells exist in the areolas of the superficial fascia, in most situations. This is, however, not much developed in the foetus till the sixth month, and hence a foetus born at or before this period, has a peculiar shrivelled look; while at the full term it is plump and well-rounded. Some of the areolar fluid also remains between the fat-cells in the superficial fascia. In the following parts, fat is most abundant in the adult; upon the soles of the feet and the palms of the hands; upon the pubes and the nates; around the mammary gland of the female; upon the great omentum, and beneath the skin of the abdomen.1 It is also accumulated between the inner layer of the pericardium and the substance of the heart; around the origin of the large vessels; in the orbital cavity; in the spinal canal, outside of the theca verte- bralis, and in the medullary cavities of the bones. In cases of the extremest emaciation, the fat does not entirely disappear in the parts mentioned in the preceding sentence. Fat is also deposited around joints, and in many fossas. The fat in bones is called mar- row, and differs from ordinary adipose tissue only inasmuch as its cells contain somewhat more oleine (Lehmann); are more globular, from not being exposed to pressure; and in containing but a slight admixture of areolar tissue. On the other hand, since the contents of the fat-cells are liable to undergo sudden variations in quantity, there are certain parts in which no adipose tissue is ever found. These are the eyelids, the ears (except the lobule), the lungs, the penis and scrotum, the cli- toris, the nymphas, between the rectum and bladder in the male, and between the rectum and vagina in the female; on the brain and 1 In those situations where the areolae of the subcutaneous areolar tissue inclose fat-cells, Kolliker terms it the panniculus adiposus. 300 THE TISSUES. in the axilla; and hence these parts (except the brain) become highly cedematous (p. 294, 1) from inflammation, contusions, &c.; as the parts whose areolas are filled with fat-cells cannot. Besides, it does not exist under the epicranial aponeurosis, under the mucous membranes,1 in the corium of the skin, nor between overlapping muscles. The fat in the brain and nerves, is not in the form of adipose tissue—not in fat-cells; but enters into the chemical composition of the tissues themselves. Fat-cells are never entirely absent in the heart, in the orbit, and between the muscles of the face. Peculiarities of Distribution of Fat. The adipose tissue under the skin of the abdomen sometimes accumulates to a great amount, in one instance forming a layer 14 inches thick! This increase is most likely to occur in men at the age of about forty years. Occurring also in women at this period, or somewhat earlier, and most frequently in those who have never had children, the consequent enlargement has sometimes been mis- taken for a time for pregnancy. It has been observed that Hottentot women manifest a peculiar tendency to the accumulation of fat upon the nates; which does not, however, appear till after the birth of a child. This is by them considered an important element of female beauty. In all male animals, on the other hand, a tendency to accumulate fat is pro- duced by castration. It often also accumulates in women when they cease to conceive, and in those who are barren. Certain individuals are remarkable for the accumulation of fat upon the body generally, while others are as remarkable for a desti- tution of it. A Greek writer tells of a person who was obliged to attach iron to his sandals, lest he be blown away when he went abroad. On the other hand, Daniel Lambert, the Lancastershire giant, weighed 739 pounds; the circumference of his body being 9 feet 4 inches, and of his leg, 3 feet 1 inch. His coffin was 6 feet 4 inches long, 4 feet 4 inches wide, and 2 feet 4 inches deep. The author saw a young woman in Paris, 18 years of age, who weighed over 500 pounds. Paolo Moccia was so fat as to weigh 30 pounds less than his bulk of water, and consequently he could not ' An exception is found in the soft palate, where there is an abundance of yellow fat, often seen through the membrane in the case of anemic subjects. ADIPOSE TISSUE. 301 sink in water. And a Spanish general, who was enormously cor- pulent, is said to have removed the fat so rapidly by drinking large quantities.of vinegar, that he could wrap the. loose skin around him like a cloak. Such extreme degrees of obesity must, however, be regarded rather as a pathological condition, and which is incompatible with a long life. So great a weight of fat encumbers the heart especially, and hence the pulse becomes feeble, and loss of blood is not well tolerated. In view of the ultimate consequences, therefore, this condition (called polysarcia) often requires the adoption of means to diminish the amount of fat. The- author is cognizant of an in- stance in which this object was very promptly secured by the use of nitric acid. But it has been shown by Dr. T. K. Chambers, in his "Lectures on Obesity,"1 that the most reliable remedy in such cases is the liquor potassas. It is possible that the fat is reabsorbed into the blood from the fat cells, to combine with the potassa and form a soap or emulsion; after which it is burned up by combina- tion with oxygen, as a calorific element. For such an absorption into the blood, doubtless occurs from the fat-cells in cases of emacia- tion; and Henle has seen the blood so laden with fat after a profuse hemorrhage, that it formed a distinct pellicle on its surface. A superabundance of adipose tissue, or a privation of it, has alike, in all ages, been regarded as a legitimate subject of derision. Sir John Falstaff is the impersonation of the class included in the first category, except perhaps in respect to his activity; who repre- sents himself as being "a man of continual dissolution and thaw," and who had "a kind of alacrity in sinking."2 The dramatist has, however, committed a physiological mistake in the last expression, as has already been shown. He has, however, in another passage, recognized the effect, in diminishing the deposit of fat, of intense and continued intellectual effort and anxiety, and consequent loss of sleep:— " Let me have men about me that are fat; Sleek-headed men, and such as sleep o' nights. Yond' Cassius has a lean and hungry look : He thinks too much: such men are dangerous." Julius CcBsar, act i. sc. 2. 1 London Lancet, for 1850, vol. ii. p. 443. 2 "You may know by my size that I have a kind of alacrity in sinking." "Think of that; a man of my kidney—think of that; that am as subject to heat as butter; a man of continual dissolution and thaw. It was a miracle to escape suffocation."—Merry Wives of Windsor, act iii. sc. 5. 302 THE TISSUES. It has been sometimes remarked that fat men can endure loss of sleep better than the lean. So far as this is the fact—and it is be- lieved to be generally true—the author is inclined to associate it with more active powers of nutrition, which secure the deposit of fat in spite of the privation of sleep. The dyspeptic, on the other hand, requires more sleep; though with it, even,.he remains lean. There is, however, in some, a constitutional tendency to deposit fat; and who, though they become confirmed dyspeptics, still continue in good condition in this respect. Indeed, there are also national differences in this respect. Englishmen are more prone to corpu- lence than Americans; a result, probably, of the combined influence of a freer use of fermented liquors, and of a damper climate in England: for the former contain elements favorable to the depo- sition of fat, and the latter induces a less active condition of the skin. The Bedouin Arabs are, on the other hand, remarkable for their leanness; for which their simple and spare diet and the dry atmosphere in which they live, together with their active habits, must mainly account.1 Circumstances modifying the Deposit of Fat. A constitutional tendency to deposit fat has been alluded to; but several circumstances also exert a powerful influence in this respect. The most important are:— 1. The kind of diet. 2. The amount of exercise. 3. The state of the function of respiration. 1. The non-nitrogenized elements of our food—starch, sugar, gum, dextrine, and fat—tend specially to the development of fat. So also do distilled and fermented liquors. 1 Not a few epitaphs have been suggested by the present subject, and two may be forgiven here. The first commemorates the burial-place of a remarkably cor- pulent deacon:— "Take heed, gentle traveller, and do not tread hard, For here lies Deacon Stafford in all this churchyard."' The other epitomizes the life and .the death of an honest tallow-chandler, who, becoming very wealthy from success in business, retired to the country, and there became so obese from inaction, that he died in consequence :— " Here lies in earth an honest fellow, Who died by fat, but lived by tallow.'" ADIPOSE TISSUE . 303 2. A sedentary or a sluggish life also favors the deposit of fat. Even carnivorous animals, though always lean in their natural state, become fat when closely caged, and fed on a mixed diet. 3. Breathing an atmosphere imperfectly supplied with oxygen, is a third cause of fatty deposit. To this we may also, doubtless, add privation of solar light, and a damp atmosphere. 4. On the contrary, a diet more exclusively nitrogenized (albu- men, musculine, &c, as in eggs and lean meat), abstinence from distilled and fermented liquors, and habitual active exercise in the open air, tend to prevent an accumulation of fat, or to remove it if already existing. Moreover, emaciation may be induced by a prolonged discharge of any fluid containing a considerable proportion of fat. Hence profuse suppuration or hemorrhage, or excessive sexual indulgence, produces leanness, since pus, blood, and semen are rich in fat (p. 74). While the fat in the fat-cells is the most rapidly formed, it is also the most rapidly resorbed, of all the immediate principles of the human body. It is its sudden diminution around the eyeball which gives the sunken appearance to the eye, even a few hours after the invasion of certain acute diseases. This change is most rapid in children; and they also most rapidly refill the fat-cells when con- valescence is established. Distribution of Adipose Tissue in the Lower Animals. Carnivorous animals are naturally lean, since they are necessarily active, and live principally on the nitrogenized immediate princi- ples contained in the flesh of other animals. Herbivorous animals, on the other hand, manifest a tendency to accumulate fat. They are less active, and consume large propor- tions of starch and gum. By way of exception, however, the rabbit is said to be almost entirely destitute of fat, and in some instances none at all can be discovered. There is a species of sheep in Asia which accumulates a mass of fat which is situated in the place of a tail; which swings to andsfro as the animal walks, and sometimes weighs even 40 pounds. Fat is, however, usually most abundant, in ruminating animals, about the kidneys. In others it abounds in the mesentery and the omentum; and in others still, in the areolar tissue under the skin. The latter, in the seal and the whale, is called "blub- ber ;" and from a single whale 120 tons are sometimes obtained— the deposit being from 4 to 20 inches thick. Spermaceti is, however, found in the sperm-whale, in two cavities of the cranium; while the cells of the adipose tissue also contain crystals of it. (Fig. 190.) The 304 THE TISSUES. Fig. 190. Adipose tissue of sperm-whale. A, A. Cells containing crystals of sperma- ceti, b, b. Crystals of spermaceti on the outside of cells. (Queckett.) cranial cavities sometimes yield 20 tons. Hibernating animals lay up a large store of fat as the winter sea- son approaches, and which is consumed to maintain the animal heat during their dormant winter state. Hence they are found to be again comparatively ema- ciated on emerging in the spring from their winter quarters. In the camel, the "humps" are masses of adipose tissue, and are absorbed to sustain the animal, if suffering from privation of food. In birds, fat is found deposited prin- cipally between the abdominal muscles and the peritoneum. In aquatic birds it is deposited in the bones of the legs, and the last bone of the wings and of the tail. In reptiles, fat is found chiefly in the abdomen. In fishes, fat-cells are distributed throughout the body generally, except in the cod, the haddock, and the whiting. In all these, fat is found only in the liver. (See p. 79.) It has been seen that fat-cells do not exist in the invertebrate ani- mals." Fat, however, abounds, in the form of globules, in the mol- lusca (oyster, &c.); and in the insect, both in the pupa and in the perfect (or imago) state. The trying out the fat of the lower auimals consists in heating the adipose tissue till the fat-cells burst and set free their contents. The scraps are the remaining areolar tissue and vessels. Uses of Fat as a Tissue. Adipose tissue fulfils merely chemico-physical offices in the or- ganism. \. It renders the skin soft and flexible. Eeference is here made to the fat in the superficial fascia, or subcutaneous areolar tissue. 2. It gives roundness and symmetry, and hence grace and beauty, to the body. Hence it is more abundant in the female. 3. It is a protection against pressure; as on the nates, mons ve- neris, lacteal glands, &c. 4. It facilitates motion; as package between muscles, as depo- sited under the skin, around the eyeballs and the heart, and in the omentum. 5. It is a protection against cold, being a bad conductor of heat. Thus it is found under the skin, around the heart and large vessels, the lacteal glands, in the great omentum, &c. ADIPOSE TISSUE. 305 6. Fat, by its low specific gravity, renders the human body lighter than its bulk of water in proportion to its amount. Hence it is an aid in swimming. 7. Lastly, the fat in the adipose tissue may become useful as nu- tritive material in cases of emergency; the fat being reabsorbed into the blood, and then becoming "fuel for respiration" (p. 77, 2). Fluid fat alone is, however, merely calorific, and will not long sustain an animal (p. 76, 3). But adipose tissue, taken as food into the stomach, will nourish for a long period, as demonstrated by Magendie; since it also contains albuminous elements in its cell- walls, and osteine in its areolar tissue. The fact that all cells need fat for their development, since all nucleoli consist of fat (Hune- feld), has already been specified (p. 78,5). Hence its necessity in the blood; whence it is also derived for the formation of bile and other secretions (p. 77,2). The use of fat in the food, as an aid to digestion, has also been specified (p. 78, 5); and Lehmann suggests that the pancreatic fluid owes its power in this respect to the fat it contains. But in all these fluids we find mere fat-globules, and not fat-cells. Development of Adipose Tissue. The adipose or fat-cell manifests no peculiarity in its develop- ment. At first small and nucleated, it subsequently increases in size, and its nucleus disappears. Kolliker never fails to find the nuclei, however, when the cells are only partially filled with fat; and it must there- fore be persistent. (Fig. 191.) The first lobules of fat appear in the fourth month of intra-uterine life, in the palms of the hands and the soles of the feet. The subcuta- neous adipose tissue is rapidly developed from f r JL i „ A ^t-cell to show the the seventh month to birth. Hence the foetus at nucleus; from Schwann. five or six months has a wrinkled condition of c; Cell_walL d- Nu- cleus. the skin generally. Is the fat in the organism formed from fat alone in the food ? There is reason to believe not only that starch, sugar, &c, may be converted into fat in the organism, to a very slight extent, but that even from albumen also fat may be formed in small quantity in the alimentary canal (p. 74). Still, neither of these two points can be regarded as established. (Lehmann.) 1 Physiological Chemistry, vol. i. pp. 230-32. 20 306 THE TISSUES. Growth of Adipose Tissue. Hassall maintains that the fat-cells of each individual persist through life; they being merely larger or smaller, or more or less full, in the varying states of the adipose tissue. In cases of extreme corpulence, however, there can be no reasonable doubt of their in- crease in number. Hassall finds the fat-cells several times smaller in infants than in adults; and they doubtless increase after birth, as do the cartilage-cells (though probably more slowly), in size rather than in number. The growth, however, appears to proceed at different rates in different parts of the body after birth, and also in the same part in different persons of the same age. Harting states that in the adult the fat-cells in the orbit are twice as large, and in the palm three times as large, as at birth. Regeneration.—It is doubtful if fat-cells are reproduced after a mass of the adipose tissue is removed; the loss being repaired by a more condensed areolar tissue, such as usually constitutes the sub- stance of cicatrices. Pathological Staies and New Formations of the Adipose Tissue. I. Atrophy of the adipose tissue is one of its most common patho- logical conditions, occurring in all cases of emaciation, and in ana- sarca. Here either the cells are partially collapsed, or their contents become changed. Kolliker specifies the following conditions of the contents of atrophied fat-cells:— 1. The cells are granular, containing numerous small fat-drops, forming whitish-yellow clustered lobules. 2. Cells containing a dark globule only of fat, the rest of their contents being removed. 3. Cells containing serum alone, the fat having been entirely re- moved. The last two varieties occur in anasarca. Kolliker states that in this disease the cells also assume a stellate form (with from three to five processes), and become diminished in size. Wedl, however, suggests that these are young cells of white fibrous tissue. When the fat leaves the cells, it must first be mixed with the intercellular fluid, and then reabsorbed by the lymphatics. It is the accumulation of the. serous fluid in the areolas of the areolar tissue in dropsy, which causes the fat in the cells to disappear, partly perhaps by exosmosis; when the fat-cells become entirely filled, in turn, with the serous fluid. ADIPOSE TISSUE. 4. Fat-cells containing crystals of margaric acid, with a drop of fat; or which are entirely filled with the former. The varieties just men- tioned % are represented by Fig. 192; and in all of them the nucleus and nucleolus become very distinct. 5. Wedl adds another variety, in which the fat is subdivided into a multi- tude of globules, often group- ed around a lighter-colored Fig. 192. Atrophied fat-cells from the subcutaneous areolar tis - sue of an aged and much-emaciatedperson. a. Fat-cell shrunken, with crumbling, dark brownish-yellow con- tents ; beneath it one of lighter color, with crystals ra- , diating towards the border, b. An atrophied pigmented Space ^SerumJ. in many 01 fat-cell in apposition with one in the normal condition. these Cases the Cell-mem- c- Cells filled with a serous fluid, and presenting in their contents well-marked circles (fat-globules in suspension), and delicate, oval, simple or double granules (nuclei). d. Cells containing serum, and whose walls are lami nated.—Magnified 350 diameters. (Wedl.) Fig. 193. branes are no longer visible, they having doubtless been dissolved; and no vestige of the nucleus can be per- ceived. He also finds that the cell-membrane is thickened in some cases of atrophy of the cell-con- tents, several concentric layers being visible on its inner aspect. These two conditions are shown by Fig. 193, where three normal fat-cells are also added, for the sake of comparison. Remarks.—Emaciation occurs in almost all chronic, and in many acute diseases. It is especially marked before death by tubercu- losis and by dropsy. In some cases of the latter, the fat of the adipose tissue entirely disappears, except around the heart, and serum takes its place in the adipose cells, as has been explained. It is, however, a singular fact that even phthisis generally produces little or no ema- ciation (even though the structure of the lungs is in a great measure destroyed), provided the liver is also at the same time diseased; especially if from stearosis, or the "nutmeg liver," as it is called. In tubercu- Atrophied adipose tissue from the capsule of a gelatinous sarcoma, a, a. Rows of atro- phied fat-globules, for the most part without any cell-membrane, b. Groups of normal fat- cells accompanying the above, c. Enlarge- ments and bifurcate division of the elastic fibres running among the rarefied fat-cells.— Magnified 350 diameters. (Wedl.) 308 THE TISSUES. losis, also, the saponified fats are far more diminished in the blood than in any other fluid.1 (p. 78.) II. In case of hypertrophy of the adipose tissue, the cells are filled to distension with fat; and in extreme cases of its general hyper- trophy—as those mentioned on page 300—new cells are doubtless formed in great numbers, together with an extension of the vessels, and the matrix of areolar tissue; in other words, there is, a new formation of this tissue. In those cases, also, the accumulation in- terferes with the action of the muscles, and the general nutrition is impeded. Occurring in infants at the breast, it produces an impo- verishment of the blood, frequently causing death rapidly and un- expectedly. (Engel) The hypertrophied fat occurring in drunkards is soft, unctuous, of a grayish-white color and mawkish smell; and it not unfre- quently presents similar characters in persons who have been cured of secondary syphilis. In cancerous deposits, especially in the skin and subcutaneous areolar tissue, abundant deposits of firm, granular, deep-yellow fat also obtain. (Engel.) III. The adipose tumor (Lipoma) is to be regarded as a new forma- tion of the adipose tissue. So, also, are various forms of Steatoma. If entirely removed in these cases, it is not reproduced. In the Lipoma, some of the fat-cells may be of enormous size (even T^g of an inch or more in diameter), mixed with others of the normal size. As the new formations of fat-cells never take place without that of the areolar tissue, the density of a fatty tumor depends upon the relative amount of the latter. (Fig. 194.) When the fat- cells are gradually replaced by a fibrous tissue, a lardaceous growth (Steatoma) is produced. Fat-cells are also met with imbedded * in other tumors, as in polypus uteri, throughout which they are sometimes disseminated. The Lipoma arborescens (J. Mutter), rather frequently occurring in the knee-joint, is to be regarded as a new formation of fat-cells in addition to those normally existing in the adipose ligament, so called, of that articulation. Encysted tumors are also found con- staining fat, but in the form of globules and granules, and not in cells. These are, therefore, not modifications of adipose tissue. The 'Cholesteatoma (J. Mutter) is the most common. Here the cyst or sac is lined with a delicate epithelium, and filled with concentric laminas consisting of strata of cells resembling those of sheep's fat Fig. 194. Structure of a fatty tumor (Lipoma) ■removed from the back. a. Isolated cells, showing the crystalline nucleus, imargaric acid. (Bennett.) 1 Becquerel and Rodier. ADIPOSE TISSUE. 309 (though only one-half as large in diameter); and between which laminae, crystals of cholesterine are found in abundance. Fig. 195. Cholesteatoma of the brain, consisting of layers of epidermis-like cells, mostly with a parietal nucleus. Cholesterine plates are disseminated among the layers of the cells.—Magnified 350 diame- ters. (Wedl.) Fatty Degeneration, or Stearosis. The phrase "fatty degeneration" suggests the idea that certain parts or organs have been converted into fat, or into adipose tissue. Neither of these ideas is, however, correct. An organ in a state of fatty degeneration is one, some or all of whose structural elements have been replaced by fat, in the form of globules or granules, and not inclosed in fat-cells. (Fig. 40.) This subject has, therefore, no histo- logical connection with the adipose tissue; but it is introduced here to insure a correct understanding of it, as contrasted with the patho- logical formations of adipose tissue. Fatty degeneration, or stearosis, most frequently occurs in the following organs:— 1. In the bones, stearosis is usually inaptly termed osteomalacia, or mollities ossium.1 In this disease the osseous matter disappears, and the interstices thus formed are filled with fat-globules; and, on ma- ceration, the bone seems to consist of a mere gauze-like tissue. The lacunas also become enlarged, and the pores less distinct. Fig. 196 Fig. 196. a. Lacuna and pores of bone in the normal state, b. Enlarged as in mollities ossium. (Dalrymple.) 1 Mollities ossium may also result from other diseases ; e. g. from cancer of bone. 310 THE TISSUES. shows their appearance as compared with the normal state. In an extreme case of mollities ossium, Lehmann found in the ribs the following elements, in 100 parts:— Fat.......56.92 Other organic matters .... 24.665 Phosphate of lime .... 15.881 Carbonate of lime .... 2.534 2. In fatty degeneration of the heart, only one or two fat-globules at first appear within the myolemma of the fibres; but, finally, in some cases the whole fibre is occupied by them. Then the fibres become fused together into a more or less opaque mass, in which nothing of the original tissue can be traced. Fig. 259 shows the incipient and the most advanced stage of this disease. An accumulation of the fat-cells naturally existing under the pericardium and in contact with the heart, especially if it also in- sinuates itself somewhat between the muscular fasciculi and fibres, is often mistaken for fatty degeneration. But the microscope shows the fat to be in the ordinary fat-cells, and of the average size of -gfa of an inch in diameter; while in true stearosis, the fat-drops vary from a mere microscopic point to gtjW of an incn iQ diameter, and are contained within the myolemmata. 3. In case of stearosis of paralyzed muscles also, the change just mentioned occurs; oil-globules being contained within the myolem- mata (instead of the fibrillae hereafter to be described), and the striae having disappeared. But stearosis also occurs in smooth muscular fibre, at least in that of the uterus during its atrophy after parturition. Here, also, as Kolliker has demonstrated, the fibre-cells become gradually filled with fat-drops; after which some entirely disappear, while others are reduced to their size previously to gestation. 4. In fatty degeneration of the kidney, the fat-drops exist partly in the epithelial cells of this organ, and partly in a free state among them. The disease affects the cortical substance more especially. Sometimes the epithelial cells are found detached, and the urinifer- ous tubes entirely filled with fluid fat. Oppoltzer conjectured that the urine contains fat whenever there is stearosis of the kidney; which, if correct, would prove a great aid in diagnosis. Lehmann, however, never found fat in the urine in this disease, except in a single instance. The fat globules some- times seen in the urine of women, frequently proceed from the ADIPOSE TISSUE. 311 external genitals. They are sometimes, but not invariably found in the urine during slow fevers. It should be borne in mind that the human kidney naturally con- tains a small quantity of fat. (Frerichs) Prof. Beale1 has also shown that in diabetes the kidney is in a state of comparative stearosis— or increase of fat. The normal amount of fat being 3.98 parts out of 100 of the solid matter of the kidney, from three to five times as much was found in the diabetic kidney; and rather more than six times as much (26.97) in a case of actual stearosis. On the other hand, the liver in diabetes contains only from about one-third to one-half of its normal amount of fat. It is thus in a state op- posed to fatty degeneration. 5. The cells of the liver naturally contain a few minute oil-drops imbedded in a mass of granular matter; the fat amounting, accord- ing to Prof. Beale, to from 12.15 to 15.81 out of 100 parts of the solid matter in this organ. In fatty degeneration, the cells are filled to the extent of one-half or two thirds; and are sometimes com- pletely engaged with colorless fluid oil; the whole liver in some cases containing but 24.93 per cent, of water, and 75.07 of solid matter—of which latter 65.19 per cent, is fatty matter. A yellow matter is also sometimes seen mixed with the oil. The nuclei of the cells disappear, and the cell-wall sometimes becomes thickened and striated. In advanced cases, the cells are found even to be broken up and lost, and their place is occupied by granules, among which are multi- tudes of oil-drops of various sizes. (Fig. 197.) The cells being enlarged by the increased amount of oil, the whole liver undergoes an increase of size, and the minute vessels being pressed by the development of the cells, it also becomes paler than usual. It also is found to secrete less sugar, though the amount or quality of the bile seems not to be essentially modified, as a constant result. There is reason for the belief that fatty degeneration of the liver Fatty degeneration of the liver, a. Empty ruptured cell from which the oil has escaped. 6, e, d, e. Hepatic cells con- taining much oil. 1 British and Foreign Medico-Chirurgical Review, vol. xii. p. 226. 312 THE TISSUES. may be produced by an excess of fatty elements in the food; espe- cially if combined with inactive habits. This state of the organ is directly produced in fowls, by keeping them quiet (hence a dark place is better), and cramming them with oily food; as in produc- ing the livers, of which to make the pate de foie gras. No such connection is, however, known to exist between the food and fatty degeneration of the other organs mentioned. 6. Something very analogous to fatty degeneration also occurs in arteries; being termed atheroma. It is a deposit in the middle coat of the artery, and visible through the inner coat, of a pulpy dif- fluent substance, and which has sometimes, therefore, been mis- taken for pus. Some authors maintain, on insufficient grounds, it is believed, that fibrine merely, is first deposited in consequence of arteritis; and that atheroma is merely a fatty degeneration of the • fibrine, and not of the arterial coat itself. It consists principally of fat-drops with crystals of cholesterine. Figs. 198 and 199 show Fig. 198. Fig. 199. Fig. 198. Early stage of atheroma. Fig. 199. Fatty granules with crystals of cholesterine from atheromatous deposits in the aorta [Bennett.) its appearance in the early and in the advanced stage. It conforms to the law of symmetry in a remarkable degree; occurring gene- rally in the two arteries of the same name at the same time° e. g. the two iliacs, and the carotids. It is most common in the aorta, and the divisions of it nearest the heart. 7. Fat abounds in encephaloid cancer; being here also in the form of drops. CARTILAGE. 313 CHAPTEB VI. CARTILAGE. Cartilage is sometimes a simple, but generally a compound tis- sue. It is described here more especially because of the advantage of a knowledge of the structure of cartilage as preliminary to that of the development of bone. Cartilage is a solid, elastic, bluish, milk-white, or yellowish sub- stance, presenting two varieties :— 1. Simple cellular cartilage. 2. Compound cartilage; consisting of cells and a homogene- ous intercellular substance. 1. Very few instances of the simple cellular cartilage, or cartilage without interstitial substance, occur in the adult mammal. To this class, however, belong the chorda dorsalis of the human embryo, and of many adult fishes. Many, indeed, of the foetal cartilages are merely cellular; as are also the gill laminae of fishes in part, and those of the external ear of many mammalia. Fig. 200 shows the cells of the chorda dorsalis of the lamprey, and Fig. 201, the cellular cartilage of the mouse's ear. Fig. 200. Fig. 201. Fig. 200. Four nucleated cells from the chorda dorsalis of the lamprey. 1. Nucleus with nucleo- lus. 2. Another, seen in profile. Fig. 201. Cellular cartilage of mouse's ear. 2. The compound cartilages (those with intercellular substance), are of two kinds: 1. True cartilage (or hyaline cartilage), the inter- cellular substance being homogeneous, and yielding chondrine on 314 THE TISSUES. Section of fibro-cartilage ; showing disposition of car- tilage-cells in areolae of white fibrous tissue. Fig. 203. ' boiling. 2. Those with a fibrous intercellular substance; either white fibrous tissue, or elastic tissue. The latter are termed fibro- cartilage, in case the intercellular substance is white fibrous tissue (Fig. 202); and reticular carti- p- orio lage (or yellow cartilage), if it be the elastic tissue. This last form of fibro-cartilage is found in the external ear, and the cartilaginous portion of the Eustachian tube, and in the epiglottis. The cartilages of San tori ni and Wrisberg (of the larynx), and that on the condyle of the lower jaw, are of this class. The struc- ture of the reticulated carti- lage is shown by Fig. 203. Hoppe found that the reticu- lated cartilages yield chon- drine in small quantity on boiling. He, however, main- tains that this substance is not derived from the cells, nor from the elastic fibres, but from a third (a chondrine yield- ing) substance, surrounding the cells. Indeed, from his conclusions in regard to carti- Reticulated cartilage; human epiglottis.-Magnified lage-Cells, he Was led tO the 350 diameters. (Kolliker.) . axiom that cell-membranes and cell-contents never consist of gelatigenous substance (osteine or cartilageine); and can never be metamorphosed into it. Fibro-cartilage yields only glutin, since the white fibrous tissue constitutes its intercellular substance. All the intra-articular fibro- cartilages are of this kind. Its structure has been shown by Fio\ 202. True Hyaline Cartilage. True cartilage consists of (1), cartilage-cells, and (2) a hyaline (or usually granular) homogeneous substance (p. 108). CARTILAGE. 315 The relative amount of these two elements varies much in differ- ent cartilages; either element alone also sometimes constituting almost the whole mass. 1. Cartilage-ce?/s present no peculiarities in form, being rounded or elongated, flattened, or fusiform, and very rarely stellate, as in enchondroma, and in cuttle-fishes and sharks. From 1 to 4 (or even 20 to 30) cells exist together in a single cavity1 in the inter- cellular substance; and sometimes they are arranged in regular rows, as in cartilages in which bone is about to be developed. (Fig. 225.) The cell-walls are usually thick, and frequently are invested by concentric laminae. They are not dissolved by boiling, and long resist alkalies and acids; thus resembling the elastic but not the collagenous tissue (p. 282). The contents are clear and fluid; in which, generally, but not always, one or many fat-globules are contained. They coagulate in water and dilute acids, and are readily dissolved by alkalies. Some- times the fat-globules are so numerous as to render the nucleus in- visible. But a single nucleus is contained in each cell. 2. The intercellular (or interstitial) homogeneous substance is some- times hyaline, but generally finely granulated. It is permeated by a peculiar fluid which has not yet been investigated. (Lehmann) Fat-globules are also often found in it. Finally, the permanent cartilages are invested by a fibrous mem- brane, the perichondrium (e. g. costal cartilage). This is less vascu- lar than the analogous sheath of the bones—the periosteum, (p. 279, 4.) Chemical Composition of true Cartilage. The chemical characters of cartilage are, in some respects, very little known. It is certain, however, that the cells and the inter- cellular substance are different. The latter is converted, partially at least,2 by boiling into chondrine, in case of the true cartilages, and is itself cartilageine, as has already been seen (p. 99). In reti- culated cartilage chondrine exists in small amount (Hoppe), and pro- bably also elasticine (p. 100). 1 Kolliker and others term these cavities the cartilage-cells, and the true cells just described, the secondary cells or nuclei. We adopt Robin's view as the correct one. 2 Lehmann infers from its behavior towards concentrated sulphuric acid that the intercellular substance contains three different, though allied substances. 316 THE TISSUES. What are the precise chemical characters of the cartilage-cells and their contents, is unknown. The amount of water varies in the different true cartilages be- tween 54 and 70 per cent. (Lehmann)', and exerts an important influence on their physical properties. The fat constitutes from 2 to 5 per cent, of the dry cartilage. Mulder first proved that a small amount of sulphur is combined with the chondrine (cartilageine). It, therefore, probably exists in the intercellular substance alone. In the costal cartilages from 3 to 6 per cent, of mineral substances have been found, viz., phosphates of lime and magnesia, chloride of sodium, carbonate of soda, and a large amount of sulphates. The chloride of sodium varies ex- tremely in the ash of cartilage (from 1 to 8 per cent.); there, how- ever, being more of it in cartilage than in any other tissue. (Leh- mann) These variations suggest the idea that it is combined not with the histological elements of the cartilage, but exists in the peculiar fluid which permeates the intercellular substance. Properties and Uses of Cartilage. True cartilage manifests only physical, and no vital properties, in the organs of which it forms a part; viz., solidity and elasticity. When fully developed, cartilages contain no vessels at all; and hence constitute an extra-vascular tissue, like the cornea and epi- thelium and its modifications (p. 281). Nor do they contain lym- phatics or nerves.1 Uses.—The uses of the true cartilages depend on the two proper- ties just noticed. Hence they are found where a tissue is required to resist pressure, as in the articular cartilages; whose elasticity and insensibility (from possessing no nerves) are at the same time put into requisition. The costal cartilages afford sufficient strength for the walls of the thorax, while their flexibility and elasticity favor the movements of respiration. The cartilages of the nose afford to that organ the requisite firmness and flexibility. Finally, cartilages exist in the embryo instead of bones; and which finally assume the form of the bones to be subsequently de- veloped. These subsequently giving place to the bones, and thus disappearing, are termed temporary cartilages, and in their aggre- gate, constitute the cartilaginous skeleton; while the others in the 1 In the septum narium of the calf, Kolliker found both arteries, and small nerv- ous twigs. The costal cartilages also contain a few vessels. » CARTILAGE. 317 body are, in contradistinction from these, called permanent carti- lages—e. g. articular cartilages, costal cartilages, &c. Development of Cartilage. True cartilage originates in cells not distinguishable at first from those from which the other tissues are developed. Between these cells a hyaline substance is deposited, which, on being boiled, be- comes chondrine; and which usually increases simultaneously with the bulk of the cells. Thus, the original cells are pushed further and further asunder. But new cells are also produced from germs in the hyaline sub- stance; while at the same time the original ones are multiplied by bipartite and tripartite subdi- vision (p. 126). Thus, it is very common to meet with groups of two, three, or. four cells (or more) in a single ca- vity, as shown by Fig. 204. If the intercellular substance consist of collagenous fibres, a fibro-cartilage results. And sometimes the cells entirely disappear, and the whole re- maining maSS is fibrOUS. The Section of the branchial cartilage of tadpole, a. n-i_____ j i t . , •, Group of four cells, separating from each other, b. fibres are developed in the Pair of cells in apposition, c, c. Nuclei of cartilage- external portions first. When cells- d- Cavity containing three ceiis. elastic fibres are developed from the intercellular substance, a reti- culated cartilage results. The growth of cartilage is secured both by the reduplication of the cells, and the increase of the intercellular substance. The plasma doubtless permeates the intercellular substance, and the peculiar fluid, before alluded to, is probably a modified plasma, and contains the elements for the nutrition of the cartilage. The car- tilage-cavities of the new-born infant are three or four times as numerous as in the foetus of four months; but the intercellular substance is now double the bulk of the cavities, while at the latter period it hardly exceeds the latter—at least in the costal cartilages. After birth, the cavities (and contained cells) and the intercellular substance, increase in pretty nearly an equal ratio. According to Harting, the cavities (and contents) are 8 to 12 times larger in the adult than in the infant at birth. 318 THE TISSUES. As cartilage contains no vessels, very slight nutritive changes probably occur, after it once attains to its full development. Cartilage, if removed, is never regenerated. White fibrous tis- sue is developed instead, to fill up the breach; or a cretification of the entire cartilage may take place. (Dr. Redfern) The costal car- tilages, if fractured, are, however, repaired by osseous union. These cartilages are normally ossified in some of the lower animals, and are not seldom ossified in the latter period of life, in the human subject. Articular cartilages are, in the foetus, covered by an epithelium. This appears to be destroyed after birth by pressure and attrition. While it exists, vessels are found between it and the cartilage; and which subsequently return to the circumference of the latter. Their appearance before and after birth is shown by Figs. 205 and 206. Fig. 205. Vessels situated between the attached synovial membrane and the articular cartilage, at the point where the ligamentum teres is inserted in the head of the os femoris. Human foetus between 3 and 4 months, a. The surface of the articular cartilage, b. The vessels between the articular cartilage and the epithelial layer, c. The surface to which the ligamentum teres was attached, d. The vein. e. The artery. Their connection with the bones will be explained in the following chapter. Fis- 206- In the costal cartilages, vas- CARTILAGE. 319 tilage, and they usually do not anastomose with each other. Similar canals are also seen in the temporary cartilages near the points where the process of ossification is going on. The changes undergone by the cartilaginous skeleton, will be spe- cifie'd under the head of the development of bone. Pathological States, and Neiv Formations of Cartilage. 1. As cartilage normally contains no vessels, nor passages for the circulation of plasma (like bone and the cornea), it can hardly be regarded as capable of being attacked by inflammation. It is, how- ever, susceptible of ulceration, or a gradual removal of its substance, and in this condition appears to become vascular on the eroded sur- face. The vessels are, however, not in the substance of the carti- lage, but in a membranous expansion which is formed de novo on its rough surface. 2. The hose cartilages, so called, which are often found in joints (especially the knee-joint), are not actual cartilages, but merely the non-vascular processes of the synovial membrane, which increase in size and solidity and then become detached from the vascular folds. Sometimes, however, they are mere fibrinous exudations, or solidified deposits from the synovia, as Virchow has shown. 3. A new formation of cartilage constitutes enchondroma. It occurs in bone more frequently than in any another normal tissue. The bones of the fingers and toes are most liable to it, though the ribs, sternum, and vertebras are not exempt; and the cranium, the ilium, and the long bones have been attacked by it. Enchondroma may originate on the surface of bone, or in the Fig. 207. Fig. 208. Fig. 209. Fig. 207. Thin section of the circumference of an enchondroma from the pelvis. Fig. 208. Cells from the softened part of the same tumor. Fig. 209. The same, after the addition of acetic acid. (Bennett.) cancellated tissue. It usually grows slowly and seldom exceeds an orange in size. It is not attended by pain or disorganization of the 320 THE TISSUES. surrounding parts. Fig. 210. Enchondroma; microscopic structure. Lebert) (After It, however, sometimes ulcerates and pours out an exhausting discharge.— When externally situated, it is ta- bulated and surrounded by an ex- pansion of the periosteum. W.hen internal, it presents a semi-elastic feel, and, on section, the knife passes through a thin crackling shell of bone, and then shows a white cartilaginous mass; which on microscopic examination, some- times cannot be distinguished from true cartilage, and at others resem- bles fibro-cartilage. Figs. 207, 208, and 209 show the structure of the first variety; and Fig. 210, that which resembles fibro-cartilage. The former yields chondrine on boil- ing, and the latter glutin. The external variety has no investment of bone, and is met with chiefly in the pelvis, cranium, and ribs. Enchondroma generally, but not always, manifests no disposition to ossification. It is chiefly met with in early life, and Miiller has shown that it is generally due to mechanical injury interfering with the development of bone at the period when ossification occurs and bone is formed; and the process usually commences at the point of attachment of the growth to the bone on which it is developed. When completely ossified, the enchondroma becomes an exostosis. 4. Atrophy of cartilage is not uncommon. Here the hyaline in- tercellular substance, especially in case of the articular cartilages, is replaced by a soft ligamentous or fibrous structure, easily scraped by the knife, and of a* dirty brownish-yellow color, the fibres disap- pearing under the action of acetic acid. The cartilage-cells become, at the same time, more or less filled with fat-globules. The inter- vertebral cartilages of aged persons are usually of a dusky color, and dry; the intercellular substance being also fibrous, and contain- ing pigment-cells. Atrophy of the articular cartilages may be pro- duced by cancer or sarcoma, when occurring near them in the ex- tremities of the bones. 5. Necrosis (or death) of cartilage occurs—as in the cartilage of the larynx—from inflammation of the perichondrium (perichondri- tis—Albers). A formation of pus in the cancelli of the articular extremities of bone, often produces necrosis of the articular car- tilages. 6. Cartilage is liable to fatty degeneration, this affecting both the cells and the intercellular substance; both losing their transparency, and ultimately becoming wholly unrecognizable. Suppuration in the contiguous bone sometimes produces this effect. OSSEOUS TISSUE. 321 CHAPTER VII. OSSEOUS TISSUE, AND THE BONES. Osseous tissue is peculiar to the bones and teeth, and will be first described; after which the structure of the bones, consisting as they do of the osseous and several other tissues blended together, will be specified. SECTION I. OSSEOUS TISSUE. To the naked eye the bones present two forms of the osseous tissue—viz., the compact, and the cancellated or spongy. But, how- ever important these distinctions are in a practical point of view, microscopic examination shows them to be essentially identical, as will be seen. The ultimate histological element of the osseous tissue is a pale, oval, oblong, or angular granule, g^1^ of an inch in diameter.1 (Kolliker) These granules (Fig. 211) are blended together so as to form membraniform expansions of Fig- 211. varying thickness (the lamellae), or irregular masses inclosing cavities of a peculiar form (the lacunas and pores); and from the different conformations and ar- rangements of these lamellae and masses, result the compact and the cancellated bone-substance already ultimate granules , _ of bone, isolated, mentioned. and in small mass- The thinnest lamellae or a simple plate of bone is es; from the femur. . . . „ . —Magnified 320 di- formed by the apposition at their margins of a single ameters. (Tomes.) stratum of granules. It must be remembered, how- ever, that the osseous tissue is not always granular. It is sometimes a perfectly clear hyaline substance. This form appears to be a more recent and less perfect development than the granular; and both often appear in the same bone, and even in the same lamella of an i flj.'jjjj to yj&o-jj °^ an mcn- (Todd and Bowman ) One-sixth to one fifth the diameter of the blood-corpuscles. (Tomes.) 21 322 THE TISSUES. Haversian rod. In the latter case the lamina is seen to consist of two distinct layers—an external granular, and an internal, hyaline. As a general rule, no particle of osseous tissue is found more than y^ of an inch from a bloodvessel. If, therefore, a plate of bone be not more than double this thickness (^s of an inch), no vessels will be found to enter it; but they will be distributed upon its two surfaces only. It is, however, indispensable for the nutri- tion of bone that the plasma be brought more nearly than this to each molecule of the osseous tissue; and for this purpose cavities of a peculiar form (lacunas and pores) are hollowed out in the sub- stance of all but the thinnest laminae of bone, whose forms are shown by Fig. 212. In some of the thinnest bones of the smallest Fig. 212. Two lacunse of osseous tissue seen on the surface, showing the disposition of their pores. The ultimate granules of the tissue, both on their walls and around them, are well represented. (Magni- fied 1,200 diameters.) From the cancelli of the femur. (Tomes.) animals, however—as the os unguis of the mouse and certain small birds—even these cavities do not exist; every molecule of the osseous tissue being so near to the blood in the vessels distributed upon the surfaces of the bone, that no arrangement for the trans- mission of the plasma alone, as before mentioned,.is required. Such a bone is therefore everywhere granular and homogeneous in struc- ture, like the portions between the pores in Fig. 212. If, therefore, a layer of bone is not more than g^ to 4^5 of an inch thick, the substance is solid; if another layer be superim- posed upon this, cavities for the plasma (lacunae and pores) are formed between them, or in their substance; and if the whole thickness be more than fc of an inch, vessels also (the Haversian vessels) are found in canals traversing it. These cavities and canals will be next described. OSSEOUS tissue. 323 1. The Lacunce and Pores of Osseous Tissue. The lacunce (or bone-corpuscles) in man vary but little in size and shape. Most of them are shaped like a melon-seed; though some are more fusiform, or even spherical. Their length averages some are, however, as short as 3^0B of an T20"0" to 5g7j of an inch They are 4^ to T1J»D1j, inch, and some as long as 5^0 of an inch or even y^^ of an inch broad; and from g^g to 3-oW of an inch thick or deep. Their three dimensions are usually as 6 : 2 :1. The spherical lacunas are from 2^^ to T5-V?j of an inch in diameter. They are placed so near together that 709 to 1120 (average 910) occur within a surface of ^ of an inch square (Harting) The pores, or canaliculi, average T5Vo to ^ig of an inch in length, the highest extreme being g^ of an inch. They are Tg-^^ to* T2&Tro- of an inch in diameter at their origin from the lacunas, and gx^oTT *o y o^ott at their finest extremities—the average being about s-uh-ois- In horizontal sections of the lacunae they appear as holes- T5^o(T to g^Vu of an inch apart. In transverse sections they pro- duce the radiating striae from being viewed in several planes, and appear to be somewhat closer together—or T5-tjtjtt to T^^ of an inch apart. The canaliculi ra- t p 1 1 -77 j- Fig- 213. diate from the lacunas in all di- rections; and are branched and irregular, and often curved, in their course. A lacuna, there- fore, together with its radiating pores, forms an imperfect sphere, so-tj to 3^tj of an inch in diame ter. The pores of the different lacunae anastomose freely with each other, and two thus con- nected sometimes measure 3^ to s4tt °f an lucn *n length. They terminate in ccecal extre- mities only on limited spots; the most external, opening on the sur- face of the bone (except when this is covered by cartilage or the insertion of ligaments and tendons), as shown by Fig. 213. Thus- the entire structure of the bones is everywhere penetrated by a connected system of cavities and pores, by which the nutritive fluid from the vessels is carried to every part. Portion of the surface of the tibia of the calf, seen on the external aspect. The numerous point" are the openings of the pores; the dark, larger, in- distinct spots indicate the lacunse to which these pores belong, appearing from a greater depth.— Magnified 360 diameters. (Killiker.) 321 THE TISSUES. Tomes and De Morgan (with Virchow, and more recently Hoppe) assert that the lacunas and pores have distinct walls,1 as is the case with the dentinal tubuli. Like the latter, they are also sometimes filled up with a solid matter, so as to leave only a small space in the centre. These observers also found a modification of the lacunae in the circumferential laminae of bones; they there being elongated tubes, and passing, in bundles or singly, more or less obliquely, from the surface towards the interior of the bone. The largest are sometimes bent once or twice at a sharp angle. They have distinct walls, and are connected laterally with the pores. The contents of the lacunas are—first, a nucleus; and, secondly, a clear fluid; thus resembling the contents of cartilage-cavities. (Kol- liker) Their relation to the cartilage-cells will be explained under the head of " Development of Bone." The fluid is doubtless the nutritive fluid of the bone, and is therefore plasma, or a modifica- tion of it. The lacunas and pores do not present precisely the same condi- tions in the compact and the cancellated substance of bone, as will be shown (pp. 328 and 330). 2. The Vascular Canals of Osseous Tissue. The vascular or Haversian canals are minute tubular passages in the bone-substance, averaging ygVo" to 24-tj of an inch (the ex- tremes being jtjtjtj an0^ e's) j and which exist everywhere in the compact bone-substance, except in the thinnest layers of it, forming a network similar to that of the capillaries in the soft tissues. In the long bones, and in the ribs, clavicle, os pubis, and ischium, they chiefly run parallel to the long axis of the bone; and almost always either parallel to the surface, or perpendicular to it, and from 20-tt to gig- of an inch apart. These are, however, connected by transverse or oblique branches. Thus they form a network con- sisting of elongated and generally rectangular meshes, as seen in the longitudinal section of a long bone, Fig. 214. F^ew transverse communicating canals occur, however, in foetal and still undeveloped bones. In the fiat bones, almost all the Haversian canals run parallel to their surface, and sometimes, indeed, in lines radiating from one point (as the parietal protuberance, upper and anterior angle of the 1 Lehmann infers, also, from Hoppe's experiments, that the lacuna; and pores are lined by an albuminous membrane, insoluble in boiling water. OSSEOUS TISSUE. 325 Haversian canals, seen on a longitudinal section of the com- pact tissue of the shaft of one of the long bones. 1. Arterial ca- nal. 2. Venous canal. 3. Dila- tation of another venous canal. scapula, articular portion of the ilium, &c). Less frequently, however, they are parallel to each other—as in the sternum. In the short bones there is usually one predominant direction for the Haversian canals; they being vertical in the vertebras, and parallel to the long axis of the extre- mity, in the carpal and tarsal bones. In the spinous processes, however, as in the cora- coid and styloid processes, the canals are arranged as in the shorter cylindrical bones. Finally, a few Haversian canals exist in the walls of the cancelli of bone, but only when they are of considerable thickness. Since the Haversian canals contain ves- sels, they open—first, externally on the outer surface of the bone; and, secondly, internally on the walls of the medullary canals and spaces. In both these positions, indeed, very many of them can be seen by the unassisted eye; they being more numerous in proportion as the compact sub- stance of the bone is thicker. The larger passages are, however, merely for the vascular branches communicating with the proper capillary plexus in the interior of the bone-substance. Kolliker has never noticed ccecal terminations of these vascular canals. The internal network must, however, in some parts have little or no communication with vessels from the surface of the bone—as at the points of insertion of many tendons and ligaments, &c. It should be added here that Tomes and De Morgan have de- scribed still another kind of cavities in bone, which they have named Haversian spaces. These are apparently formed by the ab- sorption of previously-formed bone, between and parallel to the Haversian canals; present rough parietes, and are sometimes formed at the expense of portions of two or three of the Haversian sys- tems or rods at the same time. After attaining their full diameter, ossification commences within them, and each of them becomes a new Haversian canal, surrounded by its concentric laminae, and its lacunas and pores. These cavities are very large and numerous in newly-formed bone situated near ossifying cartilage; they are, how- ever, never absent in the oldest subject, and may be accepted as a 326 THE TISSUES. demonstration of the fact that bone is constantly undergoing an active disassimilation and repair. Indeed, one side of an Haversian space may be becoming the seat of a new Haversian rod of bone, while the opposite is undergoing further enlargement from ab- sorption. The contents of the Haversian canals are—first, the vessels; se- condly, the nerves of bone; and, thirdly, in case of the larger canals, a small quantity of marrow surrounding the former. Differences in the Compact and the Cancellated Forms of Bone-structure. All bones contain both the cancellated and the compact forms of structure; the former constituting an external layer of varying thickness, and the latter the internal portions. In the shafts of the long bones, however, the entire thickness is formed of compact bone-substance; and the same is true of the thinnest portions of some of the flat bones. The extremities of the long bones, however, like all the short bones, consist of a thin layer of compact substance externally, and cancellated substance within. In both forms, however, the bone-tissue is arranged in the form of laminae or' plates, formed of granules or hyaline substance (or both), as already described (p. 321); and the manner in which these laminae are arranged, determines the two forms of bone-substance now to be described. 1. Cancellated Bone-structure.—The cancellated bone-structure consists of an aggregation of cavities, eaofo of which is called a can- Fig. 215. Spherical cancellus (diagrammatic). Its walls consist of three lamella, with their lacuna; and pores. OSSEOUS TISSUE. 327 cellus, whose walls are formed of laminae of osseous tissue. These cavities are quite irregular in form, and communicate freely with each other, as may be seen in a section of the short bones, or of the extremities (epiphyses) of the long ones. Indeed, their appearance is so similar to the areolas of the sponge, that the terms spongy, areolar, or reticulated bone-structure are also applied to them. The walls of the cancelli are formed of several concentric laminae of osseous tissue, between and in the substance of which lacunas and pores exist* and through an opening the vessels are sent into the cavity of the cancellus, to ramify upon its inner surface. If the cancellus be supposed, for the sake of simplicity, to assume a sphe- rical form, its appearance on section will be represented by Fig. 215. Fig. 216. The cancelli, however, in fact, communicate so freely with each other, that their walls lose the structural regularity there represented; 328 THE TISSUES. and hence this form of bone-substance seems rather to present an interlacement of lamellae, rods, and fibres, very irregularly arranged. (Fig. 216.) If the connecting rods are of considerable size, they contain vascular canals; otherwise, merely laminae, lacunas, and pores. The lacunas are disposed in every possible direction; but mostly with their long axes parallel to that of the fibres and rods, and with their flat surfaces directed towards the cancelli, into which the most superficial lacunas freely open. The vessels of different cancelli freely anastomose with each other. The cancelli contain—first, the vessels already mentioned; se- condly, a prolongation of the periosteum or endosteum supporting these vessels; and, thirdly, more or less fat-cells with red contents (marrow). Nerves also, fourthly, are distributed to the marrow, especially in case of the bodies of the vertebras. 2. Compact Bone-structure.—The thinnest layers of compact tissue consist merely of parallel superimposed lamellae, between and in the substance of which lacunae and pores (but no vessels) exist; e. g. some portions of the lachrymal and palate-bones. Indeed, the wall of a cancellus, as before described, is essentially a very thin layer of compact bone-structure. When the compact structure, however, attains to a thickness of g'g- of an inch, and more, a different arrangement of the lamellae is found. And in the long bones the compact substance consists of two systems of lamellae (the general and the special), and the inter- stitial osseous tissue, or that between the Haversian rods. 1. The general (fundamental) lamellae are parallel to the external and the internal surface of the bone. These alone exist where the compact substance is very thin. They, however, rarely entirely surround the long bones, and are absent in the fast-growing bones of young animals.1 (Tomes and De Morgan) They are in immediate connection at many points with those next to be described, and are seen in Fig. 217. The lacunas are placed with their surfaces parallel with those of the lamellas; their pores opening in part on the ex- ternal and internal surfaces of the bone, and in part communicating with each other, though they probably terminate in blind extremi- ties at points covered by the articular cartilages. The thickness of 1 In these the circumferential laminae are replaced by a series of undulating laminae, which, subsequently extending outwards, arch over and inclose the nearest vessels of the periosteum ; and in the spaces thus formed, Haversian rods are de- veloped (p. 357). OSSEOUS TISSUE. 329 Fig. 217. A. Transverse section of ulna, deprived of its earth by an acid. The openings of the Haversian canals seen, natural size. A small portion is shaded, to indicate the part magnified in B. B. Part of the section A, magnified 20 diameters. The fundamental or general lamellae are seen at a, and between the concentric lamellae the lacunae appear as little dark specks, b. Portion of a cancellus. each lamella averages yi^ to ^g- of an inch in the cranial bones, and their number varies from 10 to 100. The layer formedJ^y them varies between g^ and 3^ of an inch in thickness. It gives off pro- cesses, g^7j to T7j7j of an inch thick, between the Haversian rods. 2. The special lamellae—those concentrically surrounding the Ha- versian canals—constitute, as it were, the walls of the latter, and are intimately united to each other. The number surrounding the canal, and the consequent thickness of the system—the Haversian rod—formed by them, bear no constant relation to the size of the canal; smaller canals being sometimes surrounded by numerous lamellae, and larger ones by but few. Generally the largest canals, and the most minute, have but few surrounding lamellae, and there- fore have thin walls; while those of a middle size have thick ones. The thinnest walls measure T5-V0- to g^ of an inch, and the thickest t£o- to t£tj of an inch. (Kolliker) Each lamella is from g^Tj to j^tjtj of an inch thick, averaging from ^tj'o-tj to -jtjVtj of an inch. 330 THE TISSUES. Fig. 218. They frequently present two distinct layers; the outer being dis- tinctly granular, the inner clear and transparent. The innermost lamella of an Haversian rod is, however, sometimes transparent throughout. The number of lamellae in each Haversian rod is usually from 8 to 15; but sometimes there are only 4 or 5, and occasionally as many as 18 to 22. The whole Haversian rod ave- rages about T^7j of an inch in diameter. Between and in the substance of the lamellae, the lacunae and pores exist. The lacunas have their long diameter curved*so as to lie concentrically with the lamellae in a transverse section of the Haversian rods, their flat surface presenting towards the Haversian canal. Their very numerous pores produce a very close striation ra- diating from the Haversian canals, as shown by Fig. 218. The lacunae are sometimes very numerous, at others very scanty. In the former case, they are ge- nerally arranged in tolerably regular al- ternation, or one behind another in the direction of the radius of the Haversian rod. Frequently, however, they are very irregularly crowded together, or are se- parated by wider interspaces. All the pores arising from the inner aspect of the innermost lacunae penetrate into the Haversian canals. From the edges and external aspect of the same lacuna other pores are given off which communicate with the proximate pores of the more distant lacunas, and thus the Haversian rod is completely pe- netrated by the pores and lacunas, and permeated by the nutritive fluid contained in them. The various forms of lacunas and pores are shown by Fig. 219. The outermost lamella is often of somewhat irregular outline from its being the first formed in the pre-formed irregular Haver- sian space. 3. The interstitial osseous tissue between the Haversian rods, when it exists in small quantity, frequently presents only one to three lacunas in a transverse section (Figs. 220 and 217), both of a rounded form and quite irregularly disposed. When more abund- ant, it is distinctly lamellar, and the lacunas are more regularly dis- Transverse section of a part of the bone surrounding an Haversian ca- nal ; showing the pores commencing at the inner surface, a, anastomo- sing and passing from lacuna to lacuna.—Magnified about 300 dia- meters. (Tomes.) snt- OSSEOUS TISSUE. Fig. 219. b 331 ^0^50^* i-_5w Various forms of lacunae and their pores, a. Simple regular cavities without pores, from an ossi- fication of the pleura, b. From healthy human bone. 6'. One of the outer lacunae of an Haversian system, with pores all bending down towards the Haversian canal, e. Other forms from human bone, showing the lateral connecting pores, d. From the Boa, external lacunae of an Haversian sys- tem with unusually large pores dipping towards the vascular surface, d'. Cavity intermediate be- tween a lacuna and a pore. e. Another variety from the same reptile. (Mr. Tomes.) posed, and with their sides parallel to those of the lamellae. The pores of these lacunae communicate with each other, and with those of the surrounding Haversian rods, and thus their nutrition is pro Fig. 220. Transverse section of human clavicle, showing the orifices of the Haversian canals, and the con- centric arrangement of the laminae of bony matter and of the lacunae around them ; and the inter- stitial osseous substance. (Magnified 85 diameters.) 332 THE TISSUES. vided for. In man, however, the rods are so crowded that no la- mellae exist between them; but only the interstitial tissue with a few lacunas (and their pores), as described in the preceding sen- tence. (Kolliker) Chemical Composition of Osseous Tissue. It is almost impossible to isolate the osseous tissue completely from the vessels and nerves distributed to it; and hence there is some uncertainty in regard to its precise chemical composition. On removing the vessels and nerves from the compact bone- structure, as far as possible, the following results are obtained by the best chemical analysis of dried compact osseous tissue:— Organic substance (osteine) Mineral constituents Phosphate of Lime Carbonate of Lime Phosphate of Magnesia Fluoride of Calcium 33 67 57 8 1 1 Osseous tissue also contains the chloride of sodium, and some alkaline sulphates and fat. The last, amounting to from one to three per cent, in some bones, must belong, in all probability, to the blood in the vessels, or to the marrow in the cavities of bone; while Lehmann believes the chloride of sodium (.25 to .38 per cent.), also, is derived probably from the vessels or the fluid in the lacunas and pores; and the alkaline sulphates are a product of the incineration of the bone. The amount of water in bone is about 13 per cent. (Robin and Verdeil)1 The flat bones contain more water than the cylindrical; probably because they are more vascular. Human bones contain more water than those of any other mammal (Stark); the bones of birds still more; and the bones of fishes most of all animals. Nasse maintains that the hardness of bones is not affected by their pro- portion of water; a proposition which seems untenable in respect to diseased bones at least. The bone-cartilage, as Lehmann terms it, may be separated from the mineral matters by the prolonged action of dilute (1 to 7 of 1 Dr. Stark found only three to seven per cent. OSSEOUS TISSUE. 333 Fig. 221. Thin layer peeled off a softened bone, as it appears under a magnifying power of 400. The figure, which is intended to represent the reticular structure of the osteine of a lamella, gives a better idea of the object when held rather further off than usual from the eye. water) and frequently changed hydrochloric or nitric acid; and thus obtained, it perfectly retains the form of the bone of which it constituted a part. In its moist state, it is a tolerably elastic, yellowish, translucent substance; and in its che- mical analogies it is found to coincide perfectly with glutin, except that the former has always a little sulphur which is absent in the latter. Under the microscope it shows a network of obliquely decussating fibres, as seen in Fig. 221. The bone-cartilage is, therefore, actually osteine, as shown on page 99. It is converted by boil- ing water into three or four times its volume of glutin. On the other hand, the osteine may be removed from the mineral constituents by calcination, or by careful boiling in dilute alkalies. In this case, also, the mineral constituents alone remaining, preserve the original form of the bone. It is probable that the phosphate and carbonate of lime are united together, before combining chemically with the osteine (Robin and Verdeil); and possibly the fluoride of calcium and the phosphate of magnesia are also previously combined with the two first men- tioned salts. Still, the organic and mineral matters are by no means always in the same proportion in the different bones of the same person. The bones of the extremities contain more earthy matter than those of the trunk; and the humerus and femur more than the other cylindrical bones. The ribs and the clavicles con- tain on an average more osteine than the vertebrae; and the bones of the pelvis approximate the latter. Of the different mineral mat- ters, the phosphate of magnesia always rises and falls with the phos- phate of lime; while the ratio of the carbonate of lime to the phos- phate varies,1 though within certain not very wide limits at the same age. Lehmann found the proportion of the carbonate to the phos- phate of lime in the bones of a new-born infant to be 1:3.8; in a male adult, 1:5.9; and in a man 63 years old, 1: 8.1. In disease, however, the carbonate of lime often increases while the phosphate diminishes; and hence it has been asserted, incorrectly, that the 1 Von Bibra asserts that these two salts are always In nearly the same ratio. 334 THE TISSUES. total amount of the earthy matters in bone remains constantly the same. The herbivora have more carbonate of lime in their bones than the carnivora, and the pachydermata and cetacea most of all. The bones of fishes contain the least earthy matter of all (21 to 57 per cent.). The varying amount of phosphate of lime in the different bones has already been stated (p. 54). The bones of birds contain more of it than those of mammals, it sometimes rising to 84.3 per cent. Carnivorous birds, however, have but little more than mammals. In pregnancy, the consumption of phosphate of lime is so great in the development of the skeleton of the foetus, that sometimes scarcely any traces of it can be found in the urine of the mother; and fractures now occurring, unite with extreme difficulty, and sometimes, indeed, not at all. The softened condition of the bones constituting rickets also most frequently occurs during dentition, while the phosphate of lime is required for the development of the teeth, the latter not being affected by this disease. It is a singular fact that the cranial bones exhumed at Pompeii contained more fluoride of calcium than the bones of the present generation. Doubtless the food must exert some influence on the composition of the bones. Softening of the bones occurred in chickens de- prived, by Chossat, of the phosphate of lime. There is no appreciable difference in composition of the bones of the male and the female. Alumina, oxide of iron, and silica, are frequently found in fossil bones; their presence being probably due to infiltration. In diseased bones, a great diversity of chemical composition is found. The mineral substances are, however, almost always ab- stracted from the osseous tissue earlier and in larger quantity ( Von Bibra); so that a relative increase of the osteine is observed. Of the earthy matters, the phosphate of lime is the first to be re- moved, and the last to be re-deposited after the cessation of dis- ease. The osteine is very rarely affected in diseased bones. From some cases of rachitis, however, both Marchand and Lehmann failed to obtain any true glutin. The carbonate of lime frequently exceeds its normal amount, only in osteophyte and new formations of bone. It appears usually to diminish and afterwards to increase, with the phosphate. In primary sclerosis (eburnation), there is no excess of earthy mat- ters in proportion to the osteine; but a considerable augmentation of the carbonate of lime in proportion to the phosphate. OSSEOUS TISSUE. 335 In most osteophytes (puerperal or otherwise), there is an excess of osteine and carbonate of lime above the normal standard. Very likely, however, they approximate more nearly to true bone in pro- portion to the time since their first formation. The analyses of exostoses tend to the same conclusion. In osteoporosis (dilatation of the cancelli and of the Haversian canals), the resorption of the mineral matters proceeds more rapidly than that of the osteine, and the cavities formed are filled with fluid fat. In rachitis there is a relative deficiency of earthy matters, with an absolute excess of the osteine; the latter remaining unchanged in its nature. The assumption that the carbonate of lime is in- creased in rachitis is incorrect. Nor can rachitis be conditional on the occurrence of free acid in the bones, though the phosphate of lime is often much diminished. In softening of bone in the adult (osteo-malacia), the earthy con- stituents are more diminished than in any bone disease yet men- tioned. A large portion also of the osteine is destroyed. The brittle network of bony tissue remaining, floats in thin, fluid fat, sometimes amounting to twenty or thirty per cent. C. Schmidt proved the existence of free lactic acid in the fluid of the long boues. This may, however, be the result and not the cause of the breaking down of the bone into fragments—a chemical process having occurred in the latter. In caries, the earthy matters most rapidly disappear, and the ca- j / vity formed is filled with fat. Properties and Uses of the Osseous Tissue. The characteristic properties of osseous tissue are its hardness, density, and rigidity—due to the earthy constituents; and its elasti- city and flexibility, dependent upon the osteine. It manifests no vital properties, except so far as to secure its own nutrition and reparation. The uses of the bones will be specified after their structure is described, in the second section of this chapter. Distribution of the Osseous Tissue. The osseous tissue is found:— 1. In the bones, of which the skeleton is composed; to which the ossicula auditus, and the os hyoides also belong. 2. In the bones developed in the tendons; as the sesamoid bones, patella, &c. 3. In the cementum of the teeth. Many of the cartilages also ossify pretty regularly as age ad- vances ; as the costal cartilages, and those of the larynx. 336 THE TISSUES. Distribution in the Lower Animals. In the invertebrata true osseous tissue is never found; the exter- nal calcareous skeleton taking its place. In the other vertebrata, osseous tissue is more extensively distri- buted than in man. It exists, 1, in the skin (of the armadillo, tor- toise, lizard, and fishes); 2, in muscles and tendons (the diaphragma- tic bone of the camel, lama, and porcupine, and the ossified tendons of birds); 3, in the eye (the sclerotic ring of birds, chelonians and saurians, and the bony scales of the sclerotic of many fishes); 4, in the external portion of the nose (the proboscis of the pig and mole and the os pronasale of the sloth); 5, in the tongue (os entoglossum of fishes and birds); 6, in the air-passages (the laryngeal, tracheal, and bronchial bones of many birds); 7, in the sexual organs (penis- bone of some mammalia); 8, and as additions to the skeleton (ossa sterno-costalia of birds and some mammals). SECTION II. STRUCTURE OF THE BONES. The bones are usually divided into the long,1 the short, and the flat; and the largest bones, especially the long ones, have the follow- ing elements entering into their structure:— 1. Osseous tissue. 2. Bloodvessels. 3. Nerves. 4. Marrow (adipose tissue). Besides, the external surface of the bones is covered at every point by some one of the following structures:— 1. Periosteum. 2. Articular cartilages, and interarticular fibro-cartilages. 3. Synovial membranes. 4. Insertions (or origins), of tendons or ligaments. The periosteum2 has already been described in general (page 279); it being the fibrous membrane which invests the bone, and in which the vessels ramify before entering the substance of the latter. A more definite description of it will be given in the order above. 1 The long bones consist of the shaft (diaphysis) and the two extremities (epi- physes) ; the structure of the latter being like that of the short bones. ' From irlei, around, and tur-rim, a bone. STRUCTURE OF THE BONES. 337 1. The True Osseous Tissue. This peculiar element of the bones has been described at length (pages 321—335). 2. The Bloodvessels of the Bones. The bloodvessels of the bones are first sent to the periosteum, which, besides the branches it transmits directly into the substance of the bone, presents a pretty close network of capillaries, 2yV^ of an inch in diameter in its outer layer. The vessels entering the substance of the bone are very numerous. On the long bones are distinct vessels for the nutrition of (1) the cancellated structure of the extremities, (2) of the compact sub- stance of the shaft, and (3) of the marrow. The latter, called the vasa nutritia, enter the medullary cavity of the bones, one or two to the shaft, and several to the epiphyses, through large openings and canals; and, except a few twigs given off to the innermost Ha- versian canals of the compact substance, ramify in the marrow, where they form a capillary plexus whose vessels are from ^Vo to 3-55-$ 0I> an incn iR diameter. (2.) The vessels of the compact substance rise principally from those of the periosteum. They very soon lose their muscular coat, and form in the Haversian canals (which they fill either alone or in connection with some medullary substance), a network of wide vessels. The latter can hardly be regarded as capillaries, how- ever, since they show a layer of areolar tissue and an epithelium; and fine capillaries co-exist with the main vessel only in the larger canals. (3.) The cancellated structure of the extremities of the long bones is supplied by the vessels transmitted by the numerous canals seen by the unaided eye upon their external surface. The venous blood is returned from all the long bones in three ways: (1), by a large vein accompanying the nutrient artery, and whose ramifications it follows; (2), by numerous large and small veins at the articular extremities; and, (3), by many small veins in- dependent of each other in the compact tissue of the shaft, in which their roots occupy the wider spaces and sinuses, or pouch-like ex- cavations, which are very evident in sections of bone. (Fig. 214, 3.) All the vessels of bone just mentioned freely communicate, so 99 338 THE TISSUES. that it is possible for the blood of any one part to reach any other part. In the short bones, the bloodvessels present very nearly the same conditions as those of the epiphyses of the long bones; the arteries and veins of larger and smaller size entering and quitting the bone at numerous points on the surface. In the flat bones, as the scapula and coxal bone, there are distinct apertures for the larger arteries and veins; the compact substance receiving finer vessels from the periosteum, and the cancellated structure being supplied by numerous and large vessels. In the flat cranial bones the arteries mostly enter the compact and the spongy portions (diploe) from both surfaces; while the veins have only their extremities free in the cavities of the diploe as in other bones, and their trunks contained in large, arborescent canals, emerge at definite points through large apertures (emissaria Santo- rini), and communicate freely with the veins of the dura mater. The veins of the cranial bones, however, become obliterated as age advances, coincidently with the diminution of the diploe. In the new-born infant, arteries as well as veins, occupy the emissaria. The articular cartilages have no vessels at all. Those of the syno- vial membranes will be described further on. Lymphatic vessels in bone have been described by some anatomists. Kolliker, however, does not admit their existence in either bone, periosteum, or synovial membranes; though they pretty certainly exist in the loose areolar tissue around the last, especially at the knee. 3. Nerves of the Bones. It is necessary to distinguish the nerves of the bones from those of the periosteum, in which the former lie, before entering the sub- stance of the bone. The nerves of the bone are larger than those of the periosteum, and sometimes give off the latter as branches. They exist in all bones—except, perhaps, the small bones of the ear, and the sesamoid bones—though not in all bones fulfilling the same conditions. In the large cylindrical bones, they, first, penetrate into the medullary cavity with the nutrient vessels of the marrow (whe- ther there be one or two); the trunks being visible to the naked eye, and as much as ?'5 of an inch in diameter. They are distri- buted to the marrow, following the course of the vessels, though not always in apposition with them, towards the epiphyses; forming /■ . '' '■' l-r ''' STRUCTURE/OF THE BOXES. ' many ramifications, and but few anastomoses. Secondly, numerous finer nerves penetrate with the numerous bloodvessels into the can- cellated tissue, and ramify in the medulla. And, thirdly, extremely delicate nervous filaments are sent into the compact structure of the epiphyses, in company with the minute arteries by which they are penetrated. The smaller cylindrical bones of'the hand and foot present the same conditions as the larger ones just described, except that the nerves are not so regularly divided into epiphysal and dia- physal, on account of the undeveloped condition of the medullary cavities. Of the short bones, the vertebras are most abundantly supplied with nerves; and especially their bodies. (Kolliker) They enter anteriorly, posteriorly, and on the sides, in company with the ves- sels, and are distributed to the marrow of the spongy substance. In the fiat bones—as the scapulae and coxal bones—the nerves are very numerous, and enter the bone with the larger vessels before described. In the occipital, parietal, and frontal bones, microscopic nervous filaments enter as far as to the diploe, upon the finer arteries. The nerve-fibres thus richly distributed to bone are both cerebro- spinal and sympathetic; the former constituting about two-thirds of all the fibres, and being g^o to.-g^^ of an inch in diameter. (Kolliker) The periosteal nerves are also, apparently, mainly spinal; though some participation of the sympathetic cannot, perhaps, be denied in their case, also. How the nerves of bone terminate, is not yet decided. They sometimes have Pacinian bodies upon them just before entering the bone-substance. The principal function of the nerves of bone seems to be to regu- late the flow of blood and plasma through the part. (Kolliker) The synovial membranes also contain nerves. The ligaments (in man) do not; and the same is true of the articular cartilages. 4. The Marrow of the Bones (Medulla). Almost all the larger cavities in the bones are filled by a soft, transparent, yellowish or reddish, highly vascular substance, the marrow. It is found chiefly in the medullary canals of cylindrical bones, and in the cancelli of all bones; though it also enters into the larger Haversian canals of the compact substance. In the shafts of the long bones it appears as a yellow semi-fluid substance, differ- ing essentially in chemical composition from the red kind of marrow 339 340 THE TISSUES. which occurs in their epiphyses, and in the short and flat bones, the sternum, and the bodies of the vertebras. These two forms are also quite different in chemical composition. While the former is made up (in the bones of the ox, according to Berzelius) of 96 per cent. of fat, 1 of areolar tissue, and 3 of fluid with extractive matter, the latter (in the diploe) contains 75 per cent, of water, the rest (25 per cent.) being made up of solid matters, albumen, fibrine, and ex- tractive matter, similar to those of muscle, with merely traces of fat. In its structure, marrow presents, besides vessels and nerves, areo- lar tissue, fat-cells, free fat, and a yellowish fluid ; and, lastly, pecu- liar minute cells—marrow-cells. 1. The areolar tissue inclosing the marrow of the shaft of long bones is of a firm consistency, but is improperly described as an endosteum (internal periosteum), since it cannot be separated as a distinct structure. It also penetrates the marrow of the long bones, and supports the vessels and nerves; while it does not enter at all into the marrow of the cancelli, except in case of the larger masses of it. 2. Fat-cells, 7^ to ^s of an inch in diameter, and often with a distinct nucleus, occur in both forms of marrow; more abundantly, however, in the yellow, dense form, and generally not aggregated into lobules. In the red variety they are far less numerous, and often isolated even; and hence the small quantity of fat in the diploe. (Berzelius.) In dropsical marrow, these cells are frequently only half filled with fat, or with but one or more globules; con- taining, besides, a large quantity of serum (p. 307). In hyperasmia of the bones, they are sometimes diminished in size, and are also elongated and fusiform. 3. Free fat-globules, and a clear or yellowish fluid, are often met with in the softer kinds of marrow. The former may possibly have been derived from cells which no longer exist. Lastly, the marrow-cells*ocexiT in the red or the reddish marrow, but never in the yellow. They exist normally in the vertebrae, the cranial bones, the sternum, and the ribs; and in the upper maxil- lary bone, also, where they have been mistaken for cancer-cells. They also occur in the hyrjerasmiated red marrow of the articular extremities of the cylindrical bones; but are normally absent in all the bones of the extremities, and in the scapulas and the coxal bones. They precisely resemble the cells of the young medulla (p. 355). Use of the Marrow.—The cavities of the bones in man must be THE PERIOSTEUM. 341 filled either with a fluid or a solid substance, since they do not com- municate with the air. The marrow being a form of adipose tissue, answers the purpose,therefore—first, of mere package; but, secondly, it also, from the fat it contains being lighter than other animal fluids, renders the bones lighter than they would be, were the latter sub- stituted; and, thirdly, in the emergency of starvation, it is reab- sorbed into the blood, and thus prolongs life—its cells becoming at the same time filled with a serous fluid (p. 307). In most birds, the cavities of the long bones communicate indi- rectly with the atmosphere, and therefore contain no marrow. The Periosteum. The periosteum is a more or less transparent, slightly glistening, or whitish-yellow extensible membrane. It is also vascular, and invests the surface of the bones, except where certain muscles and ligaments are inserted, and where the surface is covered by the articular cartilages. It is, however, not everywhere constituted alike. When only covered by the skin, or connected with fibrous structures (as liga- ments, tendons, fasciae, and the dura mater), it is opaque, thick, and generally glistening like tendinous structures. On the other hand, it is thin and transparent when muscular fibres rise directly from it, and when the muscles nearly rest upon the bone (as on the ex- ternal surface of the cranium); also in the vertebral canal and in the orbit. When mucous membrane rests on bone, the periosteum is generally very intimately united to it by the submucous areolar tissue; so that the two cannot be separated, and constitute a single membrane of varying thickness (in the ethmoid cells, maxillary sinus, &c). The connection of the periosteum with the bone is sometimes very loose, it being merely in apposition, or attached by delicate vessels penetrating the bone; and sometimes very firm and intimate by means of larger vessels and nerves, and numerous tendinous filaments. The former occurs more generally where the periosteum is thin, and the osseous tissue more compact, as in the shafts of long bones and in the sinuses of the cranium; the latter, where the peri- osteum is thicker, and the compact substance thinner, as in the epi- physes, in the short bones, the palate, and at the base of the cranium. In its intimate structure, the periosteum presents almost always, except where muscles rise from it directly, two layers, differing 342 THE TISSUES. more or less in structure, though closely connected. The external layer is composed chiefly of white fibrous tissue, with occasional fat-cells, and in this are the true vessels and nerves of the peri- osteum. The inner layer contains elastic fibres, usually of the finer sort, constituting very thick networks—true elastic membranes— superimposed one upon another. The white fibrous tissue consti- tutes the least important element. Nerves and vessels occur in this layer, also; but they merely pass through it, preparatory to entering the bone itself. The following surfaces of the bones are not covered by peri- osteum :— 1. All surfaces where the bone is covered by the articular (or other) cartilage, or fibro-cartilage. 2. Where ligaments and tendons are attached to bones at a cer- tain angle; e. g. the ligamenta subflava, ligamentum teres, liga- mentum patellae, and the intervertebral, ilio-sacral, and interosseous ligaments; and the tendons of the deltoid, the coraco-brachialis, popliteus, triceps, psoas-iliac, gastrocnemii, quadriceps femoris, glu- tasi, &c. On all these surfaces the structures just mentioned are attached directly to the bone, and not a trace of periosteum is found. Articular Cartilages. The articular cartilages cover the bones at their articular extre- mities. They are closely applied to the bone with a rough, hol- lowed, or raised surface, but are not united to it by any intermediate substance. On its free surface, it is in most joints quite bare in the adult; but covered in the foetus by a delicate epithelium like that lining the vessels, as has been already asserted (p. 318). The fibro- cartilages of circumference, so called (glenoid and cotyloid ligaments, &c), are firm, yellowish-white rings of white fibrous tissue, con- taining a few isolated cartilage-cells, attached at the border of the articular cartilage, by a wider base, immediately to the bone, or partly also to the cartilage. They are generally free, and not co- vered by the synovial membrane or any epithelium. Reichert found fine desquamated flakes of cartilage in the synovia, which fell readily into folds, and thus resembled a fibro-cartilaginous tissue. In»its intimate structure, articular cartilage is peculiar only in the fact that the cartilage-cavities near the free surface are small, nu- merous, flattened, and parallel to it; while those in the deeper por- tions next to the bone are elongated, and arranged perpendicularly ARTICULAR CARTILAGES. 343 to the surface of the latter. (Fig. 222.) Neither the articular carti- lages nor the fibro-cartilages of circumference contain either nerves or vessels, though the vessels of the synovial membranes sometimes intrude upon them at their borders. Dr. Leidy, of Philadelphia, has also Fig- 222. observed numerous minute lacunas in articular cartilages. These are lenticu- lar in outline, j^^ to 3 1 215 of an inch in length, and most abundant in the deepest layer of the cartilage, and de- crease in number towards its free sur- face. Another peculiarity, also de- scribed by Dr. Leidy, is the penetra- tion of the structure of the articular cartilage by fibres or columns of bone. These fibres are compressed and c}din- drical in shape, and present an ellip- tical outline on a transverse section. They are not numerous, are concen- trically laminated, and present a radi- ated appearance, not very unlike an Haversian rod; but neither the Haver- sian canal, nor the lacunas and pores, are to be seen. The condition of the bone beneath the articular cartilages is peculiar, con- sisting, in almost all joints, of a layer of incompletely formed osseous tissue. This layer is ,fo- to -fa (average T^) of an inch thick, and is a yellowish, mostly fibrous, hard, and truly ossified matrix; containing, however, not a trace of Haversian canals or medul- lary cavities, nor any perfectly formed lacunae. Instead, however, of these, are found roundish or elongated cor- puscles, aggregated into little masses or rows 5tnro- *° shv of an ^nc^ long, and y^V^ to ?TTO of an inch broad. These give thin sections of the bone a perfectly opaque aspect; and are really thick-walled cartilage-cells, retaining their contents (fat and nuclei), occasionally Articular cartilage of a human meta- carpal bone, cut perpendicularly, a. Most superficial, flattened cartilage-cells, b. Middle round cells, c. Innermost cells, disposed perpendicularly in small rows. d. Outermost layer of the bone, with os- sified fibrous matrix, and thick-walled cartilage-cells, in this instance appearing dark from their containing air. e. True bone-substance. /. End of the cancelli of the epiphyses, g. One of the cancelli. —Magnified 90 diameters. (Kolliker.) 344 THE TISSUES. presenting indications of pores, and being perhaps also partly calci- fied. In other cases they are, in fact, undeveloped lacunas. This layer is bounded towards the cartilage by a straight line, and towards the bone by a sinuous contour. It occurs in every articulation, except that of the lower jaw, and those on the os hyoides. (Kolliker) (Fig. 222.) In pathological states, the articular cartilages sometimes assume a fibrous structure, a change often attended by an increase of thick- ness. These fibres are sometimes half an inch in length. (Cruveilhier) Sometimes they wear away rapidly, or even entirely disappear, leav- ing the bones bare. They may also be attacked by ulceration; this penetrating to the bone, or commencing next to it and extending towards the free surface. The Synovial Membranes. The synovial membranes are not closed cavities, as generally de- scribed; but merely of the form of rings, or short tubes, whose two open ends or borders are attached to the circumference of the articu- lar surfaces of the bones, and thus connect them together. They are delicate transparent membranes, but are often invested exter- nally by the capsular or other ligaments of joints, from which they are with difficulty separated. The precise relations of the synovial mem- branes are as follows: They are attached simply to the border of the articular surface, and either thrown across directly to the other bone, or they may in the first place invest a small surface of the first bone also, as well as the cartilage, and then pass to the other bone. (Fig. 223.) In either case, the syno- vial membrane does not adhere directly to the hard tissues underneath it; but is more or less closely connected with the periosteum or the perichondrium. It finally terminates, without any distinct margin, near the border of the articular cartilage, being inseparably united with its perichondrium. In their intimate structure, the synovial membranes consist—first, of a layer of con- densed areolar tissue, with vessels and nerves; and, secondly, an epithelium. Fig. 223. Diagram of a longitudinal sec- tion of a phalangeal articula- tion ; partly after Arnold, a. Bones, b. Articular cartilage. e. Periosteum continuous with the perichondrium of the latter. d. Synovial membrane at the edge of the cartilage, connected at first with the perichondrium. e. Its epithelium. (K'ttiker.) SYNOVIAL MEMBRANES. 345 1. The corium (or layer of areolar tissue) sometimes, though rarely, contains fat-cells in its meshes, and a few scattered cartilage- cells with thick, opaque, walls. 2. The epithelium is composed of from one to four layers of large tessellated cells, j^o- to y^os of an inch in diameter, with roundish nuclei of go'oo" ^° Woo" OI" an inch. The synovial membranes present large adipose masses and vascu- lar processes. The former, once erroneously termed Haversian glands, are found principally in the hip- and knee-joints, and consist of collections of fat-cells in vascular portions of the synovial mem- brane. The vascular processes constitute red, flattened projections of the synovial membrane, with an indented and polished margin, furnished with minute processes. The folds are usually placed close to the junction of the synovial membrane with the articular cartilage, and lie flat upon the latter, forming a sort of coronal around it. They differ from the rest of the membrane in structure, principally in their great vascularity, since they consist of little else than minute arteries and veins, and delicate capillaries forming wavy loops at the edge of the processes; and hence resemble the choroid plexus in the ventricles of the brain. Besides the vessels, these processes consist of areolar tissue and the epithelium found elsewhere on these membranes. At the edge of these processes, projections of the membrane, of extraordinary forms (sometimes resembling the stems of a cactus), are found. It is these non- vascular processes which, being enlarged and then detached, con- stitute one of the forms of the erroneously so-called loose cartilages in joints, as has already been shown (p. 319, 2). The nerves of the synovial membrane are but few in number. The synovia is evidently secreted by the epithelial cells upon the vascular processes; and to a very slight extent also, doubtless, by those on the rest of the membrane. The properties of this fluid have already been stated (pp. 180 and 198). Its function is to diminish friction in the varied movements of the joints. Inter-Articular Fibro- Cartilages. The inter-articular fibro-cartilages may be mentioned here, though they do not actually come into contact with the bones. They are interposed between the two articular-cartilages of some joints (arti- culations of lower jaw, sternum and clavicle, &c); or form mere projections between them (semilunar cartilages, so called, of the 346 THE TISSUES. knee-joint). In intimate structure they do not differ from other fibro-cartilages; except that the cartilage-cells are smaller and more abundant in the deep, and less so in the. superficial portions (p. 314). In old persons, they lose their distinct fibrous structure, and assume a yellow or brownish color. The inter-articular ligaments, so called, must also be classified with the preceding fibro-cartilages. They are not covered by sy- novial membrane; nor even by an epithelium, except for a small extent at their attached borders (e. g. ligamentum teres, &c). Connection of Tendons and Ligaments with the Bones. Tendons and ligaments are generally inserted into the periosteum. Both are, however, in some instances inserted into the bone itself; there being no trace of periosteum intervening. This is the case with the tendons of the quadriceps femoris, pectoralis major, del- toid, latissimus dorsi, psoas-iliac, glutasi, the tendo-Achillis, &c, and the ligaments, mentioned on page 342, 2. In these cases the fasciculi of the tendon rest at an acute or a right angle on the surface of the bone, and become attached to all the elevations and depressions of its surface. Close to the bones, the tendons frequently also con- tain delicate cartilage-cells. They also, in exceptional cases, be- come entirely incrusted with calcareous salts in the form of granules, next the bone. Fig. 224 shows the peculiarities just mentioned. The general structure of the proper joints or movable articula- tions (diarthroses) may be gathered from what has preceded. Each diarthrodial articulation contains the following elements:— 1. The articular cartilages, covering the extremities of the bones, described on page 343. 2. The synovial membrane, secreting the synovial fluid (p. 344). 3. In some instances, inter-articular fibro-cartilages (p. 345). 4. Ligaments of various forms; inter-articular and circumferen- tial (pp. 346 and 342). The amphiarthroses, or symphyses, have a simpler structure. Here the connection of the bones is by cartilage alone, or associated with fibro-cartilage and white fibrous tissue. In the symphysis pubis, sacro-iliac synchondrosis, and the articulations of the bodies of the vertebras, the surfaces of the bones are directly covered by a layer of true cartilage; and which in the first two situations, is directly connected with the opposite layer, and in the last, by means of fibro- cartilage and white fibrous tissue in consecutive layers. In the PROPERTIES OF THE BONES. 347 first two cases also, there is frequently a cavity in the interior of the connecting substance; so that the sacro-iliac symphysis in par- Fig. 224. Insertion of the tendo-Achillis into the calcaneum of a man sixty years old. A. Bone with lacunse, a ; cancelli and fat-cells, b. B. Tendon ; with tendinous fibres and cartilage-cells, c.—Magnified 300 diameters. (Kolliker.) ticular may be regarded as a sort of movable articulation. (Zaglas) Some of the articulations of this class are also surrounded by liga- ments, described in all anatomical works. In the synarthroses, the bones are united merely by an extremely thin membranous whitish streak, incorrectly termed the sutural cartilage. It is really white fibrous tissue, and it gradually disap- pears in old age, and is at last in many parts entirely removed, especially on the inner part of the sutures; and even before the complete obliteration of the latter. It is properly termed the sutural ligament, therefore. Properties of the Bones. The properties of the bones are those of the osseous tissue, already specified (p. 335), the most important being their rigidity 348 THE TISSUES. and density, and others incidental to these. Upon these proper- ties their uses depend. The cohesive force of bone is truly astonishing; it being twice as great as that of oak, though its specific gravity is to that of oak as 92:65.1 The vertical strength of bone, or its power as a column of sup- port, and to resist pressure, is still more wonderful. Prof. Robin- son found that a disk of bone one inch square, supported a weight of 50002 lbs. He does not, however, specify the thickness of the disk. The power of the bones to resist flexion and fracture, or as mere levers, must also be mentioned here. Prof. Robinson found bone re- lated, in this respect, to freestone, lead, and several of the strongest kinds of wood, as follows:— Fine freestone . . 1. Lead .... . 6.5 Elm and ash . 8.5 Box, yew, and oak . 11. Bone . 22. In other terms, bone is 22 times as strong in this respect as fine freestone; about 3\ times as strong as lead; nearly 2f times as strong as elm and ash, and twice as strong as box, yew, and oak. Uses of the Bones. The bones in their aggregate constitute the osseous skeleton of the vertebrate animals.3 1. The skeleton gives firmness to the body and preserves its sym- metry. The spinal column and the cranium at the same time also protect the spinal cord and the encephalon; and the bony walls of the thorax and pelvis, the contents of these cavities respectively. All the bones, moreover, afford fixed points for the attachment of the muscles. 2. The long bones are acted upon by the muscles as levers, and hence are the passive organs of the motions; those of the lower extremities being subservient to locomotion, and those of the upper, 1 London Lancet, April, 1846, p. 346. * Ibid., p. 240. 3 At the age of 21 years, the weight of the skeleton is to that of the whole body (the latter being 125 to 130 lbs.)—as 10.5 : 100 in man, and as 8.5 : 100 in woman. USES OF THE BONES. 349 to the infinity of movements of which the latter are capable. The ribs are thus subservient to the movements of respiration. 3. The long bones especially manifest the power to resist fracture before illustrated, and to this effect the hollow cylindrical form of their diaphyses greatly contributes. Indeed, if the weight of the shaft, and the length, be the same, its strength as a lever varies (within certain limits) directly as its diameter, i. e. if the shaft of the os femoris, weighing sixteen ounces, and being seventeen inches long, is hollow and one inch in diameter, it is twice as strong as if of the same length and weight, and condensed into a solid rod half an inch in diameter. Thus we perceive the advantage result- ing from the function of the medullary canal in the long bones; viz., to increase the strength of the bone, the amount of material in it being given. Every blade of grass, indeed, is constructed on the same principle. This arrangement is also apparently more conso- nant with the power of rapid repair after fracture in the long bones; in which fractures must necessarily be most frequent. Finally, the existence of the cavity necessitates the presence of a substance to fill it, which is accomplished by the marrow, as above explained (p. 341). 4. But the long bones are also for support, especially in the lower extremities; and in this relation some interesting facts are ascer- tained. The strength of bone as a mere column of support, its weight and general conformation being the same, varies inversely with the square of its length; i. e. an os femoris 8J inches long, and weighing 17 ounces, would be four times as strong as one twice as long, but of the same weight. Hence the short bones are vastly stronger in proportion, in this respect. Indeed, we may imagine the lower extremities of an animal to become incapable of sustain- ing its weight, from a slight increase of their length, while the bones become no heavier. Hence only animals having light bodies have long extremities; while the very heavy have proportionally short columns of support. Hence, also, the tarsus and carpus of the lower animals, as well as man, consist of short bones. Moreover, the speed of animals cannot be increased in proportion to size; the skeleton becoming at length so heavy that much muscular force is exhausted in merely sustaining it. 5. Man has comparatively a long column of support, especially so far as the os femoris is concerned; and thus the power of rapid locomotion is secured. The diminution of strength consequent on 350 THE TISSUES. its length is, however, in part compensated by the fact that the peculiar attachment of the cervix femoris converts this bone (as a column of support) into an arch; and thus brings its elasticity also to bear on its strength. Development of the Bones. Most of the bones are developed in cartilages, which, in the aggre- gate, constitute the cartilaginous skeleton (p. 316); the rest being formed in a soft blastema. The former are sometimes termed pri- mary, and the latter secondary, bones. The cartilages constituting the cartilaginous skeleton are deve- loped like other true cartilages (p. 317), and grow in a similar man- ner, till ossification commences within them; and which extends from within outwards till the whole is converted into—or, more accurately speaking, is replaced by—bone. The cartilaginous skeleton, and its conversion into the various bones, will first be described; and then the development of the secondary bones (the flat bones of the cranium, &c.) will be ex- plained. It follows that the primary cartilaginous skeleton is not so complete as the osseous skeleton; but it also presents some portions which either remain in a cartilaginous state, or are subsequently entirely removed. It consists—-first, of a complete vertebral column, with as many cartilages as there are afterwards osseous vertebrae, and with intervertebral ligaments; secondly, cartilaginous ribs and sternum; thirdly, cartilaginous extremities with as many pieces as there are subsequently bones, except that the pelvic cartilages are in a single mass; and, fourthly, an incomplete cartilaginous cranium. The last forms a continuous cartilaginous mass at first, and corresponds to the occipital bone (except its upper half), the sphenoid (except the external lamina of the pterygoid process), the mastoid and petrous portions of the temporal bone, the ethmoid, the inferior turbinated bone, the hyoid bone, and the ossicula auditus. The cartilaginous cranium also presents the parts before alluded to, as either remain- ing in a cartilaginous state, or entirely disappearing—as Meckel's process, two cartilaginous lamellae below the nasal bones, a narrow band connecting the styloid process with the hyoid bone; another extending from the outer part of the ala parva to the lamina crib- rosa;. and a third reaching upwards and forwards from the carti- laginous mastoid and petrous portions of the temporal bone. DEVELOPMENT OF THE BONES. 351 Thus in the cartilaginous cranium the vault is entirely wanting, and almost all the lateral portions, as well as nearly all of what afterwards becomes the facial bones. The parts not formed of car- tilage are, however, closed by a fibrous membrane, so that the cra- nium is nevertheless at this time complete. It is also in this mem- brane that the secondary bones are subsequently developed. The changes which occur in the primordial cartilaginous skeleton are, therefore, of three kinds: 1. Some portions subsequently dis- appear altogether, as already stated. 2: Other portions undergo subsequent development with the rest of the skeleton, constituting the permanent cartilages of the nose, joints, symphyses, and syn- chondroses. 3. The third and greater part finally becomes ossified, forming all the bones of the trunk and extremities, and a great part of those of the cranium. It is this portion—the ossifying cartilages— whose changes are to be described here. The general description of the ossification of the cartilages is as follows: At one or more points in their interior, calcareous matter begins to be deposited, simultaneously with a change in the elements of the cartilage. The latter, in most cases, ceases to grow in one direction while this change is going on, and is therefore soon en- tirely converted into bone; while in other directions its growth continues, so that a new cartilaginous material is offered for the progressive increase of the bone. When the bone has attained to its ultimate length, the cartilage becomes completely ossified, and ceases to be developed, its perichondrium now being a periosteum. The diameter of the bone is, however, still increased by the forma- tion of concentric laminae (the fundamental laminae, p. 328) under- neath the periosteum, from the blood-plasma in the periosteal vessels. The minute changes in the ossifying cartilage are next to be de- scribed, and Kolliker's view of this difficult subject will be adopted as the most satisfactory. It should, however, be premised that the cancellated tissue alone is developed from the primordial cartilages, the compact tissue being derived from another source. When, therefore, the cartilages have become ossified, the bones thus formed all consist entirely of cancel- lated tissue. The following description, therefore, of the ossification of the cartilages is the history of the development of the cancellated bone-substance, wherever found:— I. Before ossification actually commences, vessels begin to pene- trate the ossifying cartilages. They appear from and after the 352 THE TISSUES. middle of foetal life, preceding by a longer or shorter time the ap- pearance of the centres of ossification, and accompanying the latter as they increase. They may still be seen in the epiphyses of the long bones in a person even eighteen years old. They always lie in wide canals (g^ to 3^ of an inch even in a foetus of five months) excavated in the cartilage, and bounded by narrow, elongated car- tilage-cells. They enter the cartilage from the perichondrium at first, and, after an osseous centre exists, from the border of the latter also; proceeding in straight lines in various directions, and giving off a few branches, which seem not to anastomose at all, but to terminate in blind, club-shaped dilatations. These canals are produced by an absorption of the elements of the original cartilage- substance, and they originally contain a plastic material (cartilage- marrow) composed of minute rounded cells, from which true blood- vessels are developed. Of the vessels themselves, sometimes but one large one; frequently two, distinctly arterial, with muscular walls; again, only capillaries in various numbers—are found in a single canal. It is not precisely understood how the circulation is carried on by them. Their object is, doubtless, to afford a greater amount of nutritive material, both for the changes in the cartilage preparatory to ossification, and for the development of the bone itself. That they are merely an accidental production, as H. Meyer maintains, is highly improbable. II. Together with the formation of vessels in the cartilages, the elements of the latter undergo important changes. The cartilage- cavities, before of small size, and containing but few cells, begin to grow, and successive generations of cells to be produced in them in the following manner: Each cell is first divided into two by seg- mentation transverse to the line of ossific advance; these are again subdivided, and the process repeated till long lines of cartilage-cells extend in the elongated cartilage-cavities from the border where ossification has taken place.1 The size of the cavities, however, does not increase after birth. When the ossification of the cartilage proceeds in one direction only, they are grouped in rows at the border of the cartilage, in which the long cavities are being de- veloped. This is best seen in the extremities of the shafts of the larger long bones; the rows of cavities being arranged in parallel lines, close together, and of considerable length, as shown by Fig. 225. 1 Tomes and De Morgan. DEVELOPMENT OF THE BONES. 353 Where, however, the ossification ex- tends in all directions from a centre, the cartilage-cavities are confusedly grouped in roundish or oval, irregular little masses, as in the short bones, and the epiphyses of the long bones. In both these cases, however, the cavities containing the cells (the latter being in a single or double linear series, or in a more globular mass), are the elon- gated original cartilage-cavities. The thickness of the layer around and be- yond the bone, which presents the ar- rangement of cells j ust described, varies in the different cartilages; being Jg to ^4 of an inch in the shafts of the lono- bones, and very thin around the os- seous centres, in the epiphyses, and in the short bones. It is always yellowish, streaky, transparent, and apparently fibrous; while the surrounding cartilage is, as usual, bluish-white, with a hya- line or granular intercellular substance. III. The preparations for ossification being completed by the development of the vessels and the arrangement of the cartilage-cells just described, the osseous tissue now begins to appear. And as true cancellated bone-substance consists originally of only the lacunas and pores and the surrounding true osseous tissue, and the cancelli (with their marrow and its vessels), we have to inquire how these are developed respectively. 1. The true osseous tissue is usually developed before the lacunas and pores are formed; and its formation occurs mainly in the inter- cellular substance of the cartilage, its cells still remaining unchanged. The first apparent change in this is the deposit of very fine granules of the earthy constituents of bones, varying in size from an im- measurable minuteness up to tsW to pVo of an inch in diameter. When the cells are disposed in rows at the ossifying border, this disposition of earthy matter always forms columns between the 23 Fig. 225. Vertical section of cartilage at seat of ossification. The clusters of cells are arranged in columns, the intercellular spaces between them being l-3250th of an inch in breadth. At the lower end of the figure osseous fibres are seen oc- cupying the intercellular spaces, at first bounding the clusters laterally, then splitting them longitudinally, and en- circling each separate cell. The greater opacity of this portion is due to a three- fold cause: the increase of osseous fibres, the opacity of the contents of the cells, and the multiplication of oil-globules. 354 THE TISSUES. Fig. 226. p^Mittltll li4|!i|ii?"J Bllgf' - rows of cartilage-cells, forming pointed tooth-like processes between the individual cells, and surrounding the lower portion of the rows like short tubes. (Fig. 226.) . If, however, this granular deposit be traced back from the ossifying margin into the substance of the new bone, it gradually becomes clearer, more homogeneous and transparent, and ultimately acquires the aspect of perfect bone; the earthy granules apparently be- coming gradually fused together, and thus disappearing as isolated distinguishable particles. And thus the true osseous tissue is developed (though not entirely, as will appear), in the matrix or intercellular sub- stance of the ossifying cartilage. (Fig. 225.) 2. But while the intercellular substance thus gives place to true bony tissue, the cartilage-cells also are being converted into the future lacunae and pores of the bones. And it may now be'regarded as established by Kolliker's investigations, that each car- tilage-cell becomes converted into a single lacuna and its pores as follows, except where several are fused together into a com- pound lacuna: 1. The cartilage-cells be- come filled with concentric layers of osse- formed by the absorption of parts ous tissue, the external one being formed of this. e. Its cancelli filled with „ i . 1 l • , ^ ^ i medulla first, and the last or internal layers show- ing imperfections or indentations. This proceeds till the cartilage-cell is more or less completely filled with the osseous matter, though a cavity always remains (the future la- cuna), containing generally the nucleus of the original cartilage- cell, and a fluid plasma. 2. Minute canals (the pores) are next formed by actual absorption1 of the bone-substance; and thus are completely perforated by them, both the osseous tissue deposited within the cartilage-cells, and that previously found in the intercel- lular substance of the cartilage. 3. Finally, the osseous tissue within the cells becomes fused with that preformed between them, so that Vertical section through the car- tilage and incipient bone of the diaphysis of the femur ; in an in- fant a fortnight old. a. Cartilage- cells arranged in longitudinal piles near the ossified surface. 6. Plane of ossification, the osseous matter inclosing the basis of the piles. e. Close osseous network first formed, d. Cancellated structure 1 The cause of this absorption is not understood. DEVELOPMENT OF THE CANCELLI. 355 no distinct walls of the lacunas can be recognized (p. 324); and thus the formation of the whole of the true osseous tissue is accounted for, together with the lacunas and pores. 3. The cancelli are developed by absorption of more or less per- fectly formed bone-substance. During the ossification of the shafts of the long bones, the osseous tissue, to the thickness of gV to ^g of an inch, is compact, and without a trace of larger cavities; being composed partly of the ossified intercellular substance of the carti- lage, and partly of the cells of the latter, more or less advanced in their transformation into lacunae and pores. But beyond this depth, cavities at first small, and, more internally, larger, are seen, which appear to be eaten out of the bone, and involve both the osseous tissue, the lacunas, and pores, and the still unossified portion of the cartilage. How this absorption takes place is also unknown. Thus it appears that while the formation of bone progresses in one direction, an active resorption of a part of the bone thus formed follows. The cancelli thus formed are of different form, size, and direction, in different bones. As the medullary cavities or cancelli become developed, they are also filled with a soft reddish substance—the foetal medulla—con- sisting at first of merely a small quantity of fluid and many rounded cells containing one or two nuclei, and faintly granular contents. Subsequently, however, these cells become identical with those already described as occurring in certain bones in the adult (p. 340); and are developed in the usual way into areolar tissue, bloodvessels,. fat-cells, and nerves—or the true marrow of the bones (p. 340). The vessels are formed very rapidly, and the fat, and then the nerves, afterwards; so that vessels appear in the cancelli very soon after the formation of the latter. The fat-cells are few even at birth, and the nerve filaments much fewer than subsequently; the medulla being now colored entirely red by the blood, and the light-reddish medulla-cells. These vessels extend into the cancelli from the car- tilage vessels already described (p. 352). Thus the bone-substance formed from cartilage alone, is merely cancellated. Hence the shafts as well as the epiphyses of the long bones, at first contain only cancellated or spongy tissue; the com- pact bone-substance being subsequently superadded from another source, as next to be described. 356 THE TISSUES. Development of the Compact Bone-Substance. This is developed from a layer of plasma, underneath and afforded by the vessels of the periosteum. In the foetus of five months, this layer is so firm as to be detached with the fully formed periosteum, forming upon the latter a moderately thick, soft, whitish-yellow lamella very much resembling immature collagenous (white fibrous) tissue, and containing granular, oval, or round nucleated cells, 50V0- t0 tsVo of an incn m diameter. This lamella is very exten- sively connected with the superficial layer of the bone, and on being detached, a, few little fragments of bone and scattered masses of reddish soft medulla from the most superficial cancelli, will be seen on the inner surface. The cells just mentioned appear exactly like the foetal medulla- cells, but not at all like those of cartilage. And it appears that the collagenous matrix is next ossified by the simple uniform deposit of the calcareous salts, though without the previous appearance of calcareous granules as before described (p. 354); while from the cells the lacunas and pores are developed. Bone formed in this way, however, does not constitute connected and parallel layers, but interrupted reticular lamellas, and the spaces left between the latter 1\JS to 5^ of an inch in diameter, are the rudiments of the Haversian canals of the compact bone-substance. These spaces at first contain only the unossified portion of the plasma just described. But vessels communicating with those of the interior of the bone (of the cancelli), and with those of the perios- teum, soon appear in them; as well as the usual light-reddish me- dulla-cells, and certain peculiar cellular corpuscles, with from three to twelve or more vesicular nuclei and nucleoli, which are probablv referable to the multiplication of the latter. The vessels just men- tioned are the future Haversian vessels; and finally the Haversian rods consisting of the concentric (or spiral) lamellas, with their lacunas and pores, are developed around the vessels—the outer la- mellas first; and thus the development of the compact bone-sub- stance is completed. The manner in which the interrupted laminae are formed, and which are now seen to constitute the interstitial (or inter-Haversian) bone-substance (p. 330), is shown by Fig. 227. A vertical section of the sub-periosteal layer of developing osseous tissue is shown by Fig. 228. The compact tissue continues to be formed, as just described COMPACT BONE-SUBSTANCE—DEVELOPMENT. 357 until the bone attarns to nearly its full development, when the general (fundamental) laminae (p. 328) are formed externally to the Haversian rods from a plasma afforded by the vessels of the peri- Fig. 228. Fig. 227. Vertical section from the surface of the shaft of the metatarsus of the calf; magnified 45 diameters, a. Periosteum, b. Ossifying blastema, c. Young layer of bone with wide cavities (a) in which are lodged remains of the ossifying blastema, and reticular spiculae (6), which towards the blastema present a tolerably abrupt border, d. More developed layer of bone, with Haversian canals (c) surrounded by their lamellae. (KiMiker.) Fig. 228. Sub-periosteal layer from the extremity of the shaft of the ossifying tibia. The cartilage and more open bony tissue have been scraped off from the inside of the crust, except at (a), where a dark shade indicates a few vertical osseous areolae, out of focus and indistinctly seen. The part (a, 6) of the crust is ossified; between (b and c) are the clear reticular fibres, into which the earthy deposit is advancing. (Magnified 150 diameters.) osteum, to constitute the structure represented by Fig. 217. And by these the thickness of the bone is increased. But, while this change is going on in the outer portions of the shaft of the long bones, another is occurring in its interior; viz., the whole original shaft of cancellated bone-substance, formed from the cartilage, becomes by degrees absorbed, and thus the medullary canal is formed. The extremities, however, of the long bones being formed entirely from the original cartilages—the latter constantly growing and becoming ossified, while the bone is increasing in size—are not absorbed in- ternally ; but, like the short bones (which also are not formed from a collagenous matrix derived from the periosteal vessels), continue to retain the cancellated structure through life. It is, however, suf- ficiently obvious that the medullary canal is formed, not at the ex- pense merely of the cancellated substance in the shaft of the foetal Fig. 227. 358 THE TISSUES. bones; but that it also implies an absorption of a considerable por- tion of the compact tissue at first formed. In fact, while, during the growth of the bones new osseous tissue is constantly deposited externally, that also which is already formed is as constantly ab- sorbed in its interior. So that during its growth each bone is seve- ral times regenerated ; and the humerus, for instance, of the adult, does not contain an atom of the osseous tissue existing in it at birth. The fact, however, that a thin layer of compact bone-substance is formed by the periosteum on the exterior of the short bones also, has been stated. Absorption and regeneration of the cancellated structure occurs also in the short as well as in the long bones; but far more slowly. Hence in them (e. g. the vertebras) we find more or less still remaining, of the earlier bone-structure. It should also be added that some of the Haversian vessels being enlarged, con- stitute the vasa nutritia of the interior of the long bones. And finally, when the long bones attain to their full length, the osseous tissue of the diaphysis and of the epiphyses becomes completely fused together, the disk of cartilage which hitherto intervened, now disappearing entirely; and the vessels originally distributed sepa rately to the shaft and the extremities, at last forming anastomoses, though not very numerous, through the last formed portion of the bones. If the question occurs how bone is developed externally at points covered directly by tendons and ligaments, without the inter- vention of periosteum (p. 346), it may be suggested that these also must and do increase in size, and are also constituted of the colla- genous tissue, like the blastema afforded by the periosteum. At any rate, interstitial changes must be occurring in the ligaments and tendons till they attain to their full development; simulta- neously with which, similar changes must occur in the surface and the size of the bones to which they are attached. It is only by admitting interstitial changes in bone, moreover, that we can account for the increase in size of their foramina, and in the length of the laminae of the vertebras, &c. Development of the Secondary Bones. Bones not previously cartilaginous occur in man, only in the roof of the cranium and the face. They are called secondary, be- cause their development does not commence till after that of the primordial or cartilaginous cranium (p. 350). This class includes DEVELOPMENT OF THE SECONDAEY BONES. 359 the upper half of the expanded portion of the occipital bone, the parietal and frontal bones, the squamous portion and tympanic ring of the temporal, all the bones of the face, except the inferior tur- binated bones; and apparently the internal lamella of the pterygoid process of the sphenoid bone. It will, however, appear that these bones are developed in precisely the same manner as the periosteal layers, or compact tissue of the other bones. The secondary bones of the cranium all commence in a mem- braniform blastema lying between the dura mater and the integu- ments, whose growth advances with the development of the osseous tissue within it. The latter commencing in a single point, radiates in all directions and thus forms a delicate lamina of reticulated osseous spiculas, giving off slender rays into the still unossified blastema. Minute examination shows that the spiculas are formed by the ossification of the elements of the blastema, though to a certain extent the latter is absorbed to give place to them, while it still fills the interstices between them; and that the formation of the bone-tissue proceeds exactly in the same way as in the periosteal layer of the primary bones. (Kolliker) At first, the growth pro- ceeds in a superficial plane only, the rays forming a network as they come into contact with each other, as shown in Fig. 229. Addi- tional layers are, however, soon added to both surfaces of the ori- ginal one, and thus the structure becomes thicker, and at the same time also more compact. The thickening layers are, however, re- ferable to the periosteum which is found on the secondary bones soon after their development has begun; so that in fact only the primary layer presents any apparent peculiarity in development. The bone increases in extent by the formation of new blastema in contact with that just about to be ossified, until it has attained to its full size; and it is constantly increasing in thickness by the ad- dition of the periosteal layers as just explained. Interstitial changes are also at the same time going on, and the final result is, the for- mation of the bones with their compact layers and Haversian canals; and their cancelli internally, constituting, in case of the cranial bones, the diploe. The cells in the blastema never resemble carti- lage-cells, except those at the edges of the newly formed bone. But Kolliker doubts if even these be true cartilage-cells. It has already been seen that it is not true cartilage which connects the cranial bones together in the adult, but collagenous tissue instead (p. 347). There is usually but one centre of ossification for each of the se- 360 THE TISSUES. condary cranial bones; or for each half, when one is symmetrical. The spaces left between them at birth, from the fact that their angles Fig. 229. Process of ossification in parietal bone of an embryo-sheep of two and a half inches in length. The small upper figure represents the bone of the natural size. The larger figure is magnified about 12 diameters. The curved line (a, b) marks the height to which the subjacent cartilaginous lamella extended. A few insulated particles of bone are seen near the circumference, an appearance which is quite common at this stage. are still undeveloped, are termed the fontanelles; and this condition allows an overlapping of the bones of the vault of the cranium, by which parturition is very much facilitated. The secondary bones are more vascular while growing than after- wards; more so even than the periosteal layer of the other bones; many of the vascular canals afterwards becoming much contracted, or even obliterated. For the facts in regard to the precise period when each bone is developed in the foetus, the works on anatomy are referred to; the law being that the bones, and even the parts of bones, first needed in the skeleton are first developed. Remarks.—1. In regard to the amount of osseous tissue developed in a given time in a young animal, the following facts may be REMAKKS ON BONE-DEVELOPMENT. 361 noted. Boussingault determined from his experiments that the skeleton of a pig increases daily during the first eight months after birth, about 2.9 drachms in weight (average); amounting to a for- mation of about 1.55 drachm daily of osteine, and 1.35 drachm of earthy matter, including .6 drachm of phosphoric acid. Subse- quently to the eleventh month, the daily increase in weight averages but 1.5 drachm daily ; there being only about .65 drachm of earthy matter, including .35 drachm of phosphoric acid. 2. Much discussion has arisen on the question whether bone is always developed from cartilage—those who maintain the affirma- tive asserting that the blastema in which the periosteal layers of the primary bones, and the whole of the secondary bones are deve- loped, is also cartilage, but in its rudimentary stage of development. It has already been seen that the cartilage-cells cannot at first be distinguished from the primordial cells of other tissues. So far as this fact is considered, therefore, it is as valid a proof of the assump- tion that the blastema is a rudimentary collagenous, as that it is a rudimentary cartilaginous tissue. The fact, however, that the iuter- sutural substance contains no chondrine and never becomes cartilage, though remaining till late in life, and finally ossifies, especially in- ternally, without going through that change; it being, on the other hand, white-fibrous tissue (the sutural ligament, p. 347)—militates against the idea that the secondary bones are developed from carti- lage. Moreover, Kolliker appears to be correct in the assertion that the periosteal layers of the primary bones are developed in precisely the same manner. We, therefore, believe with him— against Meyer and many other histologists—that while the cancel- lated substance of the primary bones is developed in cartilage, the secondary bones, as well as the periosteal layers of the primary, are developed in a matrix homologous with white fibrous tissue. Indeed, if we trace the development of the skeleton through the animal series, we find, 1, that in all vertebrated animals those parts of it requiring some degree of firmness during the early periods of development, consist of cartilage; while the rest is developed from a softer substance. The cartilaginous portion will constitute more or less of the whole future skeleton, according to the habits, &c, of the animal; e. g. the cranium of the pig is more exclusively carti- laginous than the human cranium. 2. In some of the lowest ver- tebrata (cartilaginous fishes), the skeleton remains in the cartilagin- ous state through life. 3. In all the land vertebrata, however, a 362 THE TISSUES. firmer skeleton is required, and the greater part of the cartilaginous skeleton therefore becomes replaced by bone; while equally firm bones are at the same time developed from the softer blastema be- fore described. Thus there appears to be no necessity for cartilage as a matrix for the development of bone, unless required on account of its greater firmness; and Meyer's assumption that everything in which bone is formed is cartilage, is both a begging of the ques- tion, and, at the same time, incorrect. 3. The manner of development of bone is, however, essentially the same, whether cartilage or a soft blastema be the matrix. In both cases it is developed as an entirely new tissue, and the pre-existing tissue disappears and gives place to it. It has been seen that the true osseous tissue is first developed in the intercellular substance of the cartilages, and finally the whole of it appears to be converted into bone. There are, however, no facts indicating that chondrine can be converted into glutin, or cartilageine into osteine (p. 100). This element of the cartilage is therefore merely replaced by the osseous tissue. On the other hand, it has been seen that the carti- l&ge-cavities remain for a time, increasing in size and changing their forms; but the cartilage-ceZfe within them, after increasing in num- ber, disappear (except probably their nuclei), the lacunae (and pores) taking their place in part (p. 354, 2). Again, while the secondary bones are forming in the membranous expansion of collagenous tissue, the latter disappears, being replaced by them (p. 359). It is apparently only the soft and still unorgan- ized blastema in contact with the collagenous tissue that can be converted directly into osseous tissue. And the probable reason why the latter is transparent when first formed in the case of the periosteal layers, is, that perfect osseous tissue is at once formed; while, when formed in cartilage, the earthy matter only is first de- posited, and the osteine is subsequently formed and combined with it. In both cases, therefore, the cartilage and the collagenous tissue respectively are merely the matrix in which the bone is formed, and which disappears progressively with the formation of the latter. Nor can the idea that the same modified plasma may be developed into the collagenous tissue on the one hand, and the osseous on the other, be deemed singular. Both contain the same organic imme- diate principle (osteine); and the latter differs from the former more especially in containing a greater amount of mineral constituents. GROWTH AND REPARATION OF BONE. 363 Growth of Bone. The long bones increase in length principally at the expense of the cartilage intervening between the shaft and the epiphyses; this constantly growing in the longitudinal direction, and giving place to bone. But the growth of the short bones, and of the long ones in thickness, has been regarded as a difficult subject to com- prehend. The difficulty has, however, arisen from the erroneous assumption that the osseous tissue, once developed, undergoes very slight, if any, interstitial changes. Tomes and De Morgan have shown (p. 325) that very active processes of disassimilation and re- generation occur in the bone-substance. But, once admitting this fact, there is no more difficulty in understanding how a bone than how a muscle or any other organ increases in size, whether in all or only in particular directions. Much stress has been put upon experiments with madder upon young animals, in connection with this question.1 This coloring matter has a strong affinity for the phosphate of lime in the bones, and hence, when given in the food, imparts to them a pink color; and it was assumed that it combines with only the osseous tissue which is formed while the madder is being taken by the animal. It has, however, been proved by Brulle- and Hugueny that it colors all the osseous tissue, even in adult animals, within a certain dis- tance of the bloodvessels; and that the color remains in adult bones, though it is again removed in growing animals. Very little im- portance, therefore, can be attached to these experiments, except so far as that, when rightly interpreted, they also show (contrary to what had been meanwhile assumed), that a very active metamor- phosis is constantly going on in the osseous tissue, at least till the osseous system has attained to its full development. Reparation of Bone. Osseous tissue is more perfectly regenerated than any other tissue whatever. This fact may be associated with another—viz., that no other tissue can, in case of the long bones especially, at all supply the place of the true osseous tissue; so that nothing less than a complete regeneration of the original tissue is compatible with the continued function of the injured bone. 1 In very young animals a single day serves to color the entire substance of the bones. 364 THE TISSUES. This proposition is illustrated in caries, where there is merely a loss of bone-substance, and in solutions of continuity, or fractures; the repair in both cases taking place by the formation of true osseous tissue. In the former case, the new bone is formed from a blastema poured out by the periosteum of the bone; but repair after fracture demands a more particular description. In most cases of fracture of the long bones of the lower animals, and in those occurring in man which are, for any reason, with diffi- culty kept in apposition during treatment, the formation of the new osseous tissue is preceded by that of cartilage; and in which the osseous tissue is subsequently developed, as are the primary bones at first (pp. 351—8). This cartilage has been incorrectly termed the provisional callus, and has been said by many writers to be always necessary for repair after fracture. Mr. Paget has, however, shown that this is not the fact; and that where the fractured extremities of the bones are kept in accurate apposition, and at rest, it is not formed at all in man; but the new bone is developed directly from a blastema, in the exudation of which the periosteum doubtless performs the most important part. Indeed, all unbiased observers must have been unable to perceive any trace of provisional callus during recovery from the most favorable cases of fracture of the radius and of the tibia, where it may be felt whenever it actually exists. In fracture of the shaft of the long bones, the newly-formed bone at first entirely closes up the medullary canal; thus forming a plug entering and connecting the fractured extremities.1 But when this becomes more consolidated and sufficiently strong, the central por- tions are reabsorbed, and the medullary canal again extends through the shaft of the bone as before. It usually requires two years or more to accomplish this object; after which the new bone-tissue at the point of fracture is as perfect as that of any other part of the bone, though some sign of the injury probably always remains. In some cases, however, fractures do not unite by the reproduc- tion of bone; but the fractured extremities are united merely by cartilaginous tissue (or ligament), and then a sort of articulation is found at the point of fracture. This is the case almost invariably in fractures of the neck of the thigh-bone within the capsular liga- 1 It is this which Dupuytren, who first used the term, designated as the provi- sional callus. PATHOLOGICAL STATES OF BONE. 365 ment, fracture of the olecranon process, and that of the patella. It is also common in fracture of the spongy bones, and may occur in fracture of any bone under unfavorable circumstances; of which a want of rest at the point of fracture is the most common, though by no means the only one. In some cases a want of plasma or of plasticity in it, is the cause of non-union by bone. The question whether the plasma from which the new osseous tissue is developed is exuded by the periosteum alone, or by the other soft parts also,- is not so important as some authors seem to have held. Obviously it can make no difference whether it be poured out by the vessels of the periosteum alone (as it certainly is in part), or not. Whencesoever derived, however, it can be organ- ized into bone only while in contact with either bone or periosteum; and hence the importance of leaving all the spiculas of bone in place, in cases of comminuted fracture, as centres of ossification for repairing the injury—provided they are not so detached as to cause irritation as foreign bodies. Finally, cases occur in which entire bones have been reproduced after removal, provided the periosteum had been preserved. This has occurred with the lower jaw-bone, the ribs, the scapulae, and the clavicle in a case known to the author. A rudiment of bone has sometimes been reproduced in the lower animals, when the whole periosteum, as well as the bone, nad been excised. (Heine) Pathological Conditions and New Formations of Bone. The changes in the chemical composition of bone in its various pathological states have already been noticed on pages 334—5. I. Hypertrophy of bone assumes various forms, which may, how- ever, be reduced to two classes: (1), external deposits (hyperostoses), formed chiefly from the periosteum; and (2), internal deposits, or sclerosis. 1. In regard to the hyperostoses (exostoses and osteophytes), Virchow shows that those of the cranium are formed directly from white fibrous tissue, without the intervention of cartilage. Some- times the new bone-structure is perfectly normal; sometimes not so. They appear from periostitis, and in arthritis, syphilis, &c. 2. In sclerosis (osteosclerosis), the substance of the bone is more dense and harder than usual, and the term eburnation has been here applied. Here the Haversian rods are increased at the expense of the cancelli and the medullary canal. The lacunae also appear to contain calcareous salts, and are more opaque than usual. II. Atrophy of bone manifests itself in old age (senile atrophy of the bones), and a similar condition may occur in tuberculosis, sy- 366 THE TISSUES. philis, gout, rickets, &c; or from the presence of aneurism, abscesses, sometimes from tumors, osteophytes, &c. The latter produce their effect by cutting off the supply of blood to the bone, from compres- sion of its nutrient vessels. If the circulation through the vessels of the medulla be inter- rupted, a brownish-yellow pigment is formed in the medullary canal, in the areolar tissue of the marrow. This is most common in old persons. If the circulation through the periosteum be interrupted, it first becomes atrophied itself, as is indicated by its shrinking, or by the softening of its substance, together with the loss of its silvery lus- tre, and its diminished adhesion to the bone. Simultaneously, also, the bone becomes atrophied. In some cases of dropsy, the bone- substance becomes lighter, it having undergone a partial resorp- tion (as in senile atrophy, syphilis, cancerous cachexia, paralysis, &c); in others, it may disappear entirely (as in chronic diseases, paralysis, and anchylosis). III. Fatty Degeneration of the Bones (Osteostearosis) may be re- garded as one form of atrophy. It is most common in old persons affected with apoplexy or cancer, and is indicated by the presence of one or two, or even of entire groups of fat globules in the lacu- nas, and sometimes even in the pores. (Fig. 196.) In the latter case they are, however, isolated, wide apart, and far smaller. The bone has a yellowish color, and a greasy feel, and a diminished transparency when examined in thin plates. It has a greasy, lique- fied medulla, and oil continues to exude in spite of repeated boiling. This also constitutes one form of mollities ossium, while rachitis is another. IV. Death of bone (necrosis), occurs sometimes from ostitis, and always where the periosteum has been destroyed. There the lacu- nas are but little changed; while the true osseous tissue is granular and of a dark color. V. Peculiar conditions exist in osteoporosis, osteomalacia, and rachitis, and the chemical changes in the last disease have al- ready been specified (p. 335). Osteoporosis consists in a dilata- tion of the cancelli, and of the Haversian canals. In osteopsathyrosis, the bone becomes extremely brittle from atrophy, with resorption of the lamellae surrounding the Haversian canals. VI. Cancer and tubercle occur in bone, the former, however (espe- cially the medullary form), far the most frequently. The latter is believed by some to constitute the true pathological condition of the bone in morbus coxarius. Here we find invading the bone substance, the cancer-cells, and the tubercle-nuclei (pp. 139 and 117). VII. Pathological new-formations of bone (true ossification), occur in a variety of parts and organs, especially in the periosteum and dura mater, and in tendons and ligaments. Indeed, the possibility must be admitted that true bone, distinguished by lacunae and pores, may be developed in any part or organ consisting previously of « THE TEETH — DENTINE. 367 cartilage, or of the white fibrous tissue. The ossification, so called, of arteries, and the valves of the heart is not actually so, since no true osseous tissue is formed. It is mere calcification, and consists merely in a deposit of calcareous salts (mainly the carbonate and phosphate of lime) among the histological elements of the part affected. True ossification occurs in the permanent cartilages (of the ribs and larynx, and, rarely, the epiglottis), in tendons, in the dura mater and arachnoid (the latter is very doubtful); in the eye (Valentin); in the ovary; in fibrous membranes (the obturator mem- brane); in enchondroma; in fibrous and carcinomatous growths, and in the lungs. (Mohr.) On the other hand, no tissue is exempt from a liability to calcification, except hair, nails, and epidermis. CHAPTER VIII. THE DENTAL TISSUES, AND THE TEETH. SECTION I. THE DENTAL TISSUES. The solid portion of the teeth within which the soft portion, or the pulp, is inclosed, consists of three distinct parts so far as the structure is concerned. 1. The Dentine, which constitutes by far the greatest part of the whole solid portion. 2. The Enamel, a peculiar structure which covers the body of the tooth, or the part which is free and exposed to view. 3. The Cementum, which is a layer of true bone, covering the fang and the neck of the tooth, i. e. the part also covered by the gum. Fig. 230 shows the relations of these three. The dentine is sometimes not covered at the neck of the tooth by the cementum. I. The Dentine. Dentine is replaced by true bone in the teeth of some of the lower animals; and its histological relationship to bone even in human teeth, is shown by the fact that an Haversian rod is some- times seen in sections of teeth. In other respects, however, the analogy is not striking in man. A section of dentine presents under the microscope but two elements. (Fig. 231.) 368 THE TISSUES. 1. The solid, homogeneous intertubular substance. 2. The dentinal tubuli. A. The intertubular substance is perfectly structureless, and con- sists in great part of the phosphate of lime in combination with an Fig. 230. Fig. 231. Fig. 230. Vertical section of human incisor, showing the general arrangement of its constituent parts. The dentine, the pulp-cavity, the enamel on the body, and the bone or cementum on the fang, are seen. a. Neck of the tooth. (Magnified 3 diameters.) Fig. 231. Transverse sections of tubules of dentine, showing their cavities, their walls, and the intertubular tissue, a. Ordinary distance apart, b. More crowded, c. Another view. Human molar. (Magnified 400 diameters.) organic substance, doubtless osteine.1 According to Mr. Tomes, it is made up of minute granules closely united; and these pass into his " granular layer" between the dentine and the enamel. (Fig. 232, d) Chemical analysis of the solid substance of dentine gives the fol- lowing results. There is more mineral matter in the molar than in the incisor teeth. Phosphate of Lime ...... 64J Carbonate of Lime ...... b\ Phosphate of Magnesia and Soda, and Common Salt 2J Organic Substance (Osteine).....28 100. 1 For it affords glutin on boiling. THE DENTINE. 369 When dentine is fractured, it presents a fibrous appearance; the fibres radiating from the centre to the circumference of the latter. The tubuli, of course, determine their direction; they being merely columns of the solid intertubular substance. B. The tubuli of the dentine commence on the internal surface of the dentine, in contact with the pulp. Their general direction is upwards and outwards in the lower teeth, downwards and outwards in the upper. They average TW-J-ff^ of an inch in diameter at their com- mencement, but divide into many smaller subdivisions, separating at acute angles from the main trunk, and at last terminate in the outer surface of the dentine in contact with the enamel or the cementum, as the case may be. (Fig. 232.) The tubuli have a distinct and ap- parently very thick wall, occupy- ing two thirds of the diameter of the whole tube. This appearance is, however, due to the numerous short curves in the tubes, about to be described. They are naturally filled with a clear fluid, for the nourishment of the teeth, and which does not contain salts of lime, as is sometimes stated.— Hoppe finds that the walls of the tubuli do not contain gelatine. Each tubule presents two or three large curvatures and very many small ones—sometimes even 2000 within 1 line. (Retzius.) Se- 24 Fig. 232. Dentinal tubuli from the fang. a. Inter- nal surface of the dentine, witb scattered ca- nals. 6. Their divisions, c. Terminations with loops, d. Granular layer, consisting of small dentinal globules at the boundary of the dentine, e. Bone lacunse, one anastomosing with dentinal canals.—Magnified 350 diame- ters. (Kolliker.) 370 THE TISSUES. veral of these occurring in a thin section of dentine seen under the microscope, causes the wall to appear shaded within, and thicker than it actually is. (Fig. 231, a, b, c) The branches of the tubuli are, 1st. Principal divisions, leaving the main trunk at acute angles; and, being repeated two to five times in the thickness of the den- tine, amount to Four, eight, or even sixteen in all. These terminate in a granular layer between the dentine and enamel, or between the fibres of the latter, or unite in pairs to form loops in the dentine. 2d. The anastomosing branches are very minute and numerous, and most so in the root of the tooth. These and the primary divisions just described, are seen in Fig. 232. Their finest subdivisions are not more than g^o"Tnr of an inch in diameter. Seen in dried sections, the tubuli appear black; being filled with air merely, as is the case with the pores and lacunas of dried bone. Certain projections are found in the dentine, called dentinal globules ,A which are bounded by irregular spaces called interglobular spaces. The former are found mostly in the outer portion of the dentine, though they also occur in the deeper parts. They are globular or capitate, as represented by Fig. 233. Section of dentine, with dentinal globules, and interglobular spaces filled with air.—Magnified 350 diameters. (K< lliker.) The interglobular spaces are naturally filled by a soft substance, like tooth-cartilage (osteine), and possessing a canaliculated structure, like the dentine itself. II. The Enamel. The enamel forms a layer completely investing the dentine of the body of the tooth. It is thickest on the crown and the outside 1 Hoppe finds the globules to be distinct cells with nuclei. ENAMEL. 371 and inside of the bodies of the teeth, and thinnest on the surfaces where adjoining teeth come into contact. It forms ridges on the surface and free borders of the incisor teeth—of the permanent set only. Enamel consists of solid fibres of a prismatic form, and marked by transverse lines, whose length determines the thickness of the enamel. (Fig. 234, a.) Their inner extremity abuts upon the dentine; their general direction being nearly at right angles to the surface of the latter. In form they are hexagonal prisms, slightly undulating, and from Fig. 234. a. Vertical section of enamel, showing the striae of the fibres, b. Enamel fibres seen endwise.— Magnified 350 diameters. (Retziue.) 5 5go to Ei'ga OI< an incn in dia- meter. Hence the external sur- face of the enamel presenting the hexagonal extremities of the fibres, resembles the simple sca- ly epithelium. (Fig. 234, b.) A delicate membrane covers the external surface of the enamel, named "Nasmyth's membrane," from its discoverer. This is so closely united with the latter that its existence can be demon- strated only by the action of hydrochloric acid on the subjacent enamel. It is a calcified1 simple membrane, only about yetst oi* an inch thick. It is distinguished, however, by the great resistance it offers to chemical reagents, and its consequent appropriateness as a protection to the bodies of the teeth. Boiling water, concentrated acetic acid, hydrochloric and sulphuric acids, have no effect upon it; and nitric acid only renders it yellow. Nor is it changed by the caustic alkalies. The assertion by Retzius that a similar membrane exists between the inner surface of the enamel and the dentine, is probably incor- rect. Though the enamel-fibres are so firmly united, no intermediate substance can be discovered. Nor does Kolliker find the canals mentioned by Todd and Bowman between the enamel-fibres. Clefts are, however, often seen between, them, especially in the middle of 1 Dr. Huxley maintains that this is the calcified membrana prseformativa of the whole pulp.— Quarterly Journal of Microscopic Science, vol. i. p. 149. 372 THE tissues. the thickness of the enamel; and the dentinal tubes often extend to some distance between them. Chemical Composition.—Enamel contains but two parts of water in 1,000,1 and is the hardest substance in the human body. It can hardly be touched by the knife, and yields sparks with steel. Ena- mel does not, like dentine, contain cartilage (osteine); but its organic matter—only 2 to 6.6 per cent, of the dried mass—appears like a membranous tissue, after being treated with acids. According to Lehmann, dry enamel contains 81 to 88 per cent, phosphate of lime, with 7 or 8 per cent, of carbonate of lime; and Berzelius found 3.2 per cent, of fluoride of calcium in the enamel of a human tooth. The following is Von Bibra's analysis:— Organic matter . . . 3.59 Inorganic matter . . . 96.41 Cartilage (?)........3.39 Fat.........0.20 Phosphate of Lime with some Fluoride of Calcium 89.82 Carbonate of Lime......4.37 Phosphate of Magnesia......1.34 Salts.........0.88 In young or developing teeth, the enamel is soft, and may be cut with a knife; and here the fibres may be easily isolated. They also show transverse striae, somewhat like striated muscular fibre, (Fig. 235,) especially after the addition of hydrochloric acid; but a further addition converts the fibres into transparent tubes, and finally entirely dissolves the latter. It follows that neither this acid, nor any other agent that acts upon the enamel, should form a part of a dentifrice, or a wash for the teeth. III. The Cementum. The cementum is a layer of true osseous tissue covering the fangs and the necks of the teeth. It commences where the enamel ter- minates, as a very thin layer, and increases in thickness to the end of the fang. Internally it is very intimately united with the den- tine, but without any intermediate substance. Externally it is very closely surrounded by the periosteum of the alveoli; but it is less firmly united with the gum. It is the softest of the three dental 1 Robin and Verdeil, vol. ii. p. 115. THE CEMENTUM. Fig. 235. 373 Isolated human enamel prisms, after the slight action of hydrochloric acid.—Magnified 300 diameters. (Kolliker.) tissues, and is chemically almost identical with bone. It consists of:— Organic matter (osteine) . . . .32.24 Earthy matter .....67.76 Phosphate of Lime and Fluoride of Calcium 58.73 ~] Carbonate of Lime Phosphate of Magnesia Salts Cartilage (Osteine) Fat . 7.22 .99 J-67.76 .82 J 31.31 .93 32.24 100.00 Like bone, the cementum consists of lacunae and pores, and the intervening true osseous tissue. It rarely contains Haversian canals and vessels; though it has peculiar canals analogous to the tubes of the dentine, and other abnormal cavities. The osseous tissue may be granular, amorphous, sometimes trans- versely striated, or laminated like bone. The lacunae essentially resemble those of bone; but present great varieties of number, form, and size (2?Vtt to even two- of an inch). The pores are unu- sually numerous and long (jfo of an inch); and often resemble feathers and brushes. (Fig. 232, e) 374 THE TISSUES. Fig. 236. The thinnest part of the cemen- tum contains no lacunae, they ge- nerally commencing about the mid- dle of the fang, where they are scattered and solitary; and becom- ing more numerous, and having their lacunae freely communicating towards its extremity. (Fig. 230.) The thick cement occurring upon old teeth, presents immense numbers of lacunae, and very com- monly, Haversian canals also, as seen in Fig. 236. In hyperostoses of the teeth, one, three, or more canals are sometimes seen enter- ing the cementum from without, branching two or three times, and then terminating in blind extremi- ties. Cavities resembling the dentinal tubes are also sometimes found in the cementum; and which frequently communicate with the end of the tubuli on the one hand, and the pores of the osseous lacunae on the other. Other cavities still have been described, but they are evidently pathological. Remarks.—Thus it appears that the dentinal tubuli, and especially the finest subdivisions, are homologous with the pores of bone. In the latter the lacunae are added as if expansions of the pores, to insure a freer circulation of the plasma from which the bone is nourished; while in teeth such a development would not consist with the degree of solidity and strength required in them as organs of mastication. Cement and dentine of the root of an old human tooth, a. Pulp cavity. 6. Dentine. c. Cement, with lacunse. e. Haversian canals. (Kolliker.) SECTION II. THE STRUCTURE OP THE TEETH. The teeth consist of—first, the external solid (cortical) portion; and, secondly, the internal soft portion, the pulp. The teeth are also in contact with—first, the gum; and, secondly, the periosteum of the alveoli (the cavities in which, the teeth are inserted). 1. The cortical portion of the teeth consists of dentine, enamel, and cementum, as already shown in Fig. 230. STRUCTURE OF THE TEETH. 375 2. The dental pulp rises from the periosteum at the bottom of the alveolus, enters the fang, and fills the cavity of the tooth, and the dentinal canals; being everywhere in close adherence to the inner surface of the dentine. It is a reddish, soft, very vascular and nerv- ous substance; and consists of mere rudimentary collagenous tissue, inclosing many dispersed, round, and elongated nuclei, and a fluid substance, with the vessels and nerves. It is invested externally by a basement-membrane, underneath which is a layer g^ to 3^ of an inch thick, composed of many series of cells, T^ffg of an inch long, and ?0'00- of an inch broad, arranged perpendicularly to the surface of the pulp like a conoidal epithelium—the formative cells of the dentine, to be described further on. The vessels of the pulp are very numerous. Three to ten small arteries enter the pulp of a simple tooth, and form both internally and upon its surface a loose plexus of capillaries, g^^ to 2553 of an inch in diameter. There are no lymphatic vessels. (Kolliker) The nerves of the pulp are extremely abundant. Into every fang enters a large trunk (^i^ to 3^ of an inch), and six or more fine branches (of y^1^ to B^ of an inch), containing fibres of T3^i5 *° ts'uo" of an lnch. Kolliker inclines to the opinion that they ter- minate in loops; but this is not yet demonstrated. 3. The gum (gingiva) is the portion of the mucous membrane of the mouth uniting the necks of the teeth and the alveolar margins of the jaw-bones. It is pale red, and rather soft, though feeling firm because resting on the bone and teeth. Upon the teeth it is £ to 1^ line thick, and has papillae of ^ to J5 of an inch long—in old people even T'7 of an inch. Like the papillae filiformes of the ton^he, they are covered with secondary papillae, and a conoidal epithelium, which between the papillae is ?£0 to 3^ of an inch thick. Some- times on its upper portions there are rounded depressions in it, T'5 to | of an inch in diameter, with cells more cornified, and which may be mistaken for glands. 4. The periosteum of the alveolus is very intimately connected with the fangs of the teeth, having the same structure as any other periosteum, except that it is softer, contains no elastic tissue, and possesses an abundant nervous network containing many of the large nerve-fibres. Properties and Uses of the Teeth. The principal function of the teeth, viz. as masticatory organs, is well understood. They are also subservient to speech. 376 THE TISSUES. The teeth are affected by contact, by heat, cold, and chemical agents; their sensibility arising from the nerves in their pulp. It is quite delicate on the masticatory surfaces, where the smallest foreign bodies—as small grains of sand, &c—are at once perceived when those surfaces are opposed to each other. It may also in dis- ease become excessively acute. Slight mechanical influences can only act by the vibration which 0 they produce. Yet the teeth have a certain sense of locality, since we can distinguish whether they are touched internally or exter- nally, above or below, on the right or the left side. Acids cannot penetrate the enamel, though it is not impermeable; since the nerves of the pulp are not affected by them while the enamel is entire, but are so at once when, as in the incisors, the dentine is exposed. Nasmyth's membrane is doubtless still more impenetrable than the enamel itself. Development of the Teeth. The first set (deciduous or milk-teeth) contains twenty, and the second (permanent teeth) thirty-two teeth. Each tooth, during its development, presents a papillary, a follicular, a saccular, and finally its eruptive state. The development of the milk-teeth commences in the sixth week of foetal life; twenty dental papillae making their appearance from this period up to the tenth week, in a groove called the dental groove. Next, partitions are formed between the papilhe, and each then lies in a special follicle or cavity; and thus the papillary has merged into the following stage. During the fourth month these ca'Wties contract, and finallyclose up completely, the papillae within them at the same time assuming the forms of the future teeth; and thus the saccular stage is arrived at. A little cavity is, however, at the same time prolonged from each closed tooth-sac; these being the "reserve-sacs" in which, during the fifth month, are developed the pulps- of the twenty anterior teeth of the second set. These reserve-sacs, however, gradually retract backwards, and fall into hollows in the jaw-bones; and lie at considerable depth in the latter by the time the first set make their appearance—by having attained to the final or eruptive stage. The four stages just mentioned, and the relations of the "reserve- sacs," are shown by Fig. 237. The last are produced at their apices into a solid cord, which has erroneously been called the gubernacu- lum dentis, or guiding cord for the permanent teeth in their eruption. DEVELOPMENT OF THE TEETH. 377 mucous mem- Fig. 238. Formation of a temporary and its corresponding permanent tooth, in a sac of the _ brane. a to d. Papillary stage; e to g. Follicular do.; htom. Saccular, do.; n, o. Eruptive stage ; p to t. Falling out of first set. From the manner in which the primary tooth-sacs are formed— i. e> by elevations of the mucous membrane around the papilla?, as shown in Fig. 237, d, e—it follows that the papilla, even after attain- ing to the form of the body of the future tooth, does not cause the layer covering it, of the ori- ginal mucous membrane of the mouth, to come into contact with the layer which has closed over it; and therefore a space is left between these two layers—the cavity in which the ena- mel is formed (Fig. 238, B) from cells (the ena- mel pulp) contained in it. The general account of the development of the teeth is as follows: 1. A thin layer of den- tine is formed from the vessels in the pulp, and which incloses the latter like a cap. This is fol- lowed by other layers within each other, the pulp itself meanwhile contracting. 2. The enamel is formed from the cells in the enamel- cavity ; a thin layer being at first adherent to the outer layer of dentine, and which is followed by others till the requisite thickness is acquired, the enamel-pulp meantime gradually disappearing. 3. The body of the tooth thus being developed, the formation of the fang next takes place; the pulp of the dentine now extending into the alveolus, and dividing into two or three processes if the fang is A. The cavity containing the pulp, and the dentine when formed. B. Closed sac in which the enamel is formed. 378 THE TISSUES. to be double or triple. The development of the fang from the den- tinal pulp is precisely like that of the dentine in the body just de- scribed ; and this process elevates the latter through the gum, and thus the eruption of the tooth takes place. The enamel, of course, covers the body only, since the enamel-sac extended only over the latter. 4. Finally, as the alveoli close around the necks of the teeth during their eruption, and afterwards more completely around the fangs, the vessels of the periosteum of the alveoli deposit a plasma from which the cementum (tooth-bone) is formed; and which be- comes adherent to the dentine, and forms a layer becoming thicker as it approaches the apex of the fang, as before described (p. 374). The explanation of the minutiae of this process requires a know- ledge of the minute structure of the dentinal pulp, and the enamel- sac and its contents. And the following statement is deemed the most accurate, in its details, of the various accounts given by dif- ferent authors:— 1. The dentinal pulp precisely resembles, in size and form, the body of the tooth to be developed from it, consisting of an internal portion rich in vessels, and an external portion which is entirely Fig. 239. A. Tooth-sac of the second incisor of an eight months foetus, seen on the broad surface, a. Dental sac. b. Enamel-pulp. c. Enamel-membrane, d. Enamel, e. Dentine. /. Dentinal cells, h. Dental pnlp. i. Free edge of the enamel-organ.—B First incisor of the same embryo, seen on the narrow surface; letters as before, a. Dentinal cap in toto. k. Nerves and vessels of the pulp.—Magnified 7 diameters. (Kolliker.) DEVELOPMENT OF THE TEETH. 379 Fig. 240. destitute of them; and is bounded by a simple membrane—the mem- brana proeformativa. (Raschkow) (Fig. 239.) Beneath this is a layer of elongated cells (7£5 to F^ of an inch long, by g^ to ^\ji of an inch wide), with vesicular nuclei and distinct single or double nucleoli, arranged like an epithelium, though not so sharply defined internally; and next is the paren- chyma of the pulp, consisting of a sort of rudimentary collagenous tissue, with many rounded or elon- gated nuclei, and the vessels. (Fig. 240.) The latter become very nu- merous at the period when the den- tine begins to be formed, the most numerous perpendicular loops of capillaries, 3^^ of an inch in di- ameter, being in contiguity with the surface of the dentine. The nerves are developed later. Their distribution, as well as that of the vessels, in the pulp of the perfect tooth, has already been described (p. 375). It is from the epithelium-like layer of cells that the dentine is formed; and the former seems to maintain a constant thickness by the elongation of the original cells internally (while the dentine is formed externally), accompanied by a continual multiplication of their nuclei. The parenchyma of the pulp, therefore, progressively diminishes as the dentine increases; the latter being formed in concentric layers from without inwards, like the lamellae of the Haversian rods of bone (p. 356). It appears that the cells just described become the solid dentine by the gradual reception of calcareous salts. The largest tubuli are probably the remaining unossified portions of the cavity of the cells, and are hence analogous to the lacunas of bone. The divi- sions of the tubuli may result from a longitudinal division of the cells, or from a single cell coalescing with two of its predecessors. The finest lateral branches appear to be of secondary origin, and probably result from resorption of already formed dentine, like the pores of bone (p. 354). During the ossification of the dentine, and while recently formed Surface of the dentinal pulp of a new-born infant, a. Dentinal cells. 6. Their appendages. c. Vascular part of the pulp.—Magnified 300 diameters. (Kolliker.) 380 THE TISSUES. 241. and slightly hardened, the whole appears to consist of isolated glo- bules. Some of them are also visible at later periods, the spaces between them being the interglobular spaces already described (p. 370). Usually, however, these spaces are filled by a deposition of dentine also, so that the latter becomes quite homogeneous and clear. 2. The enamel-cavity is a closed sac, and contains the enamel-pulp, which is applied to the dentinal pulp like a cap, and presents a pe- culiar structure. 1. Its mass consists at first of anastomosing stellate cells (Fig. 239), containing a great quantity of fluid, rich in albumen (and mucus, Kolliker), in its meshes. It forms a layer ^ to y'g of an inch thick in the foetus of five or six months, and but n\ to g1^ of an inch at birth; when it contains vessels in its outer third, and its network is metamorphosed into white fibrous tissue. 2. On the inside, however, of this spongy tissue lies a true cylindrical (conoidal) epithelium in contact with the dentinal pulp. This is incorrectly termed the enamel-wem- brane (membrana adamantinae, Rasch- kow). Its cells are y^ of an inch in length, and g^^ of an inch in breadth, are finely granular, and their nuclei are frequently situated at their extre-1 mities. The en&mel-fibres are formed by the complete and direct ossification of the cells just mentioned, without a pre- vious deposit of calcareous matter in a granular form. (Kolliker.) (Fig. 241.) The first layer of enamel is deposited upon the outermost layer of dentine, already described, and the successive ones are formed externally to this, till the required thickness is obtained. Meantime the epithelial layer con- stantly remains of the same thickness Formation of enamel, h. Primary eells suspended in fluid blastema, g, i. The same more fully developed, and be- come angular, j. The same becoming prismatic, k. The nucleus disappear- ing. I. The modified prismatic cells filled with calcareous salts, forming the fibres of enamel. ERUPTION OF THE TEETH. 381 by a progressive development, while the spongy tissue proportion- ately diminishes, and at last entirely disappears, together with the epithelial cells; when the development of enamel is completed. Thus the membrana praeformativa (p. 379) has an epithelial layer upon both of its surfaces; the dentine being developed from the inner one, while the enamel is formed from the outer one; the ves- sels affording the plasma being on the distal side of the epithelial layer, from the membrana praeformativa, in both cases. 3. The cementum is believed by Kolliker to be formed by the "portions of the dental sac lying between the pulp and the enamel- organ." We consider that the sac merely embraces the enamel- organ, and isolates it from the dental pulp; while the latter affords the epithelial layer whence the dentine is developed. Another source of the cementum must therefore be sought, and none is more pro- bable than the periosteum of the alveoli. After the body of the tooth is completed, the pulp elongates towards the bottom of the alveolus, and thus the fang is developed from it, the body at the same time penetrating through the gum in the opposite direction. Kolliker states that the sac elongates at the same time with the pulp, and thinks that its inner surface affords a blastema whence the cementum is formed and deposited on the outer surface of the den- tine of the fang. It is difficult to account for the development of Nasmyth's mem- brane. On the supposition, however, that the membrana praeforma- tiva originally lines the whole of the enamel-cavity, it may be produced by calcification of the membrane, gluing together and protecting the outer ends of the prisms of the enamel. The permanent teeth are also developed in the manner just de- scribed, from the secondary pulps mentioned on page 376, 1. The two sets of teeth appear at the following ages:— I. MILK-TEETH. Four central incisors (the lower first), 7th month. Lateral incisors (lower first), 7th to 10th " Anterior molars, 12th to 13th " Canine teeth, 14th to 20th " Posterior molars, 18th to 36th " 382 THE TISSUES. II. PERMANENT TEETH. Central incisors . 8 years. Lateral " . 9 " First bicuspid . 10 " Second " . 11 " Canines . 12 to 12 Second molars . . 12| to 14 Third . 17 to 19 | years. Growth of the Teeth. The enamel does not increase in amount after the eruption of the teeth. It is, however, susceptible of some molecular changes, as its diseases indicate—especially caries. The latter is true of the den- tine also, and the cementum; both of which, moreover, become thicker after the eruption of the teeth. Indeed, in old persons the pulp has sometimes entirely disappeared, and its cavity been filled with an imperfect dentine; and the cementum amounts to an exos- tosis (p. 374). The fissures between the enamel-prisms, the dentinal tubuli, and the lacunae and pores of the cementum—all during life contain a nutritive fluid, and permit of nutritive changes. Since, however, perfect dentine is not colored by madder when an animal is fed with it, it is probable that these changes are far less active than in the bones. In case of caries threatening an exposure of the pulp of the teeth, the dentine very often becomes thicker within, and opposite the carious portion; the new dentine being formed to protect the pulp. Any portion of a tooth being once removed, is never reproduced; nor is the loss at all repaired. A third dentition sometimes occurs late in life, though the teeth are imperfectly developed and few in number. A tooth extracted and at once replaced, may become firm again at the end of some months (fifteen in one case). Pathological Slates of the Teeth. 1. Hypertrophy of the cement (exostosis), deposits of dentine projecting into the pulp cavity, and ossification of the pulp itself, are very common results of chronic inflammation of the perios: teum and the pulp. In the first, the pores become dilated, so as to form Haversian canals. (Wedl.) 2. A partial disappearance of the fang is quite common. The whole fang sometimes becomes transparent like horn. MUSCULAR OR CONTRACTILE TISSUE. 383 3. Necrosis occurs where the periosteum has been removed, or the pulp has died. Here the tooth becomes rough, dark, and even black, and at length falls out. 4. Caries of the teeth, as in bone, is a gradual loss of substance. Its cause is not well understood. Since it always commences on the exterior, the fluids of the mouth are supposed to have an influ- ence in producing it. There must, however, be a coincident putre- factive decomposition of the organic elements of the tooth, which becomes covered with infusoria and fungi. (Kolliker) Indeed, Ficinus thinks the latter are the principal cause of caries, since it usually commences in the cracks and pits of the enamel, where un- disturbed opportunity is given for these organisms to develop. The discolored spots on the enamel first lose their salts, and then break up into angular pieces. Next the dentine becomes soft, yielding not more than ten per cent, of ash (Ficinus), and then de- composed, and the dentinal tubuli become filled with the fluids pro- ceeding from its decomposition; and which, reaching the pulp, may produce pain. Carious teeth contain an excess of carbonate of lime. (Marchand) 5. In jaundice the teeth often become yellow, and in asphyxia, red: the dentinal tubuli being penetrated by the coloring matter of the bile, and the blood, respectively. In rickets, the teeth are not affected (p. 334). The mucus upon the teeth always contains fungi; and, on accumulating, it hardens and constitutes the tartar of the teeth. This consists of earthy phosphates, 79; mucus, 12.5; ptya- line, 1, and organic matters soluble in hydrochloric acid, 7.5. (Berze- lius) 6. Finally, teeth are sometimes developed in abnormal situations, as in ovarian cysts. CHAPTER IX. MUSCULAR (CONTRACTILE) TISSUE, AND THE MUSCLES. SECTION I. MUSCULAR OR CONTRACTILE TISSUE. Muscular tissue has recently been regarded as presenting three varieties: the elongated or fusiform contractile cell; the smooth or non-striated muscular fibre, and the striated muscular fibre. Kolliker has, however, shown that the elongated contractile cell and the smooth muscular fibre are histologically identical. He, therefore, includes both these under the name of " contractile (or 384 THE TISSUES. muscular) fibre-cells;" since in case of both, cells are found, more or less elongated into the form of fibres. Only two varieties, there- fore, of muscular tissue need be recognized; viz., the fibre-cells just mentioned, and the striated muscular fibre. I. The Contractile, or Muscular, Fibre-cells. The larger fibre-cells have generally been named smooth, or non- striated, muscular fibres, and have been described as jointed fibres, presenting nodosities, as represented in Fig. 242. This is, however, their appearance, very nearly, when acted upon by water. An ac- curate description of them was first given by Kolliker. The muscular fibre-cells are from g^0 to 3^ of an inch long, by gTJoo" to 4TH5 0- OI< an incn broad; and are composed of a soft, nearly homogeneous light-yellow substance. The nuclei are visible only when acted upon by acetic acid, and are usually long and staff-like, as seen in Fig. 243, which also shows the usual long and slender form of the cells. Very sel- dom a nucleolus exists in the nucleus, and the latter is al- ways in the middle of the fibre. The substance of the cell sometimes exhibits pale, dark granules, partially ar- ranged in rows parallel to the axis of the cell; but, in other respects, the cell, like the nucleus, is homogeneous and hyaline. It is, however, doubtful if any cell-membrane exists.— Kolliker thinks he has seen it in some individual fibres; but Lehmann cannot demon- strate its existence chemi- cally, and concludes that these fibres are never in- Fig. 242. a. A non-striated muscular fibre from the urinary bladder. Two of the nuclei are seen. b. A non-striated muscular fibre from the stomach. The diameter of this and the preceding fibre, midway be- tween the nuclei, was 1-1750 of an inch. (Magnified 600 closed by a true myolemma. Should his opinion be de- opinion diameters.) Fig. 243. Fusiform cells of smooth muscular fibre from the renal vein of man. a. Two cells in their natural monstrated to be Correct the state, one of them showing the staff-shaped nucleus. 6. . ~-, ,, ' A cell treated with acetic acid, with a nucleus, o, c, term fibre-Cell mUSt be again brought strongly into view. replaced by fibre merely. We MUSCULAR FIBRE-CELLS. Fig. 244. Fig. 245. Fig. 246. Human muscular fibre-cells from the innermost layer of the axillary artery: a, without, b, with acetic acid. a. Nucleus of the fibre.—Magnified 350 diameters. (Kolliker.) shall, therefore, quite as frequently term them smooth muscular fibres. The more common forms of the fibre-cells have been mentioned. But in the walls of the bloodvessels (Fig. 244), they are so much less elongated as sometimes to have been mistaken in the smallest, for epithe- lial cells; while in the alimentary canal, uterus, &c, they become what have long been called the non-stri- ated muscular fibres of these organs. The lar- gest of all appear in the impregnated uterus; and Fig. 245 shows one of the long cells as compared with those of Fig. 244. Rarely, also, the cells are in the form of elongated, quadrangular, or club- shaped plates, with fring- ed margins. (Fig. 244, a, and 245, b, c) Muscular fibre-cell from the fibrous investment of the spleen of the dog.—Magnified 350 diameters. (Kolliker.) 25 386 THE TISSUES. When the muscular fibre-cells exist in abundance in an organ (e. g. the alimentary canal, bladder, &c), they are (1). Collected into little bundles or fasciculi, which are invested by a very delicate layer of areolar tissue—a kind of perimysium; and which also in- closes a peculiar fluid lying among, and bathing the cells. (2). The fasciculi thus invested, are interwoven to form the required mass or thickness in the part or organ. (3). Bloodvessels are also sent in among the fasciculi to a considerable amount (Fig. 247); Bloodvessels of the smooth muscles of the intestines.—Magnified 45 diameters. (KillikeT.) while but a relatively small number of nerves is distributed to this tissue. Chemical Composition of Muscular Fibre-Cells. 1. The fluid which bathes the fibre-cells in the fasciculi is identi- cal with that contained within the myolemma of the striated mus- cular fibre; and will be spoken of further on in this section under the name of the muscular juice (p. 395). 2. The demi-solid and most important element of the fibre-cells is musculine (p. 98), also called muscular fibrine, and named syn- ionin by Lehmann. But since this also forms the solid substance of the fibrillae of the striated muscular fibre, it will be described on a subsequent page (396). MUSCULAR FIBRE-CELLS. 387 Distribution of Muscular Fibre-Cells. The smallest forms of these cells are found in the walls of the smallest arteries and veins, and the larger lymphatics. The follow- ing general account of the distribution of all their forms is from Kolliker. It should, however, be premised that this kind of mus- cular tissue never forms isolated muscles in the human body. The fibres are either scattered in the areolar tissue, or form membranous expansions—as the muscular layer of the bladder and alimentary canal; and in either case the fasciculi are either parallel, or woven into a network. 1. In the alimentary canal, these fibre-cells form the muscular coat (tunica musculosa), from the lower half of the oesophagus, where striated fibres are mixed with them, to the internal sphincter ani. They also form the muscular layer of the mucous membrane from the pylorus to the anus in man, and constitute the scattered fasciculi in the villi. 2. In the air-passages, a layer of contractile fibre-cells (smooth muscular fibres), exists in the posterior wall of the trachea, and extends through the bronchial tubes to their finest subdivisions, as a complete muscular membrane. 3. In the urinary organs, the smooth fibres were first found to extend throughout the male urethra by Mr. Hancock, of London. They also form two distinct layers in the bladder, and a layer ex- tending through the ureters into the pelvis of the kidney. 4. In the male sexual organs, they are found in the dartos, exter- nally to the tunica vaginalis, in the vas deferens, the vesiculae semi- nales, the prostate, around Cowper's glands, and in the corpora cavernosa penis, and the subcutaneous areolar tissue of this organ. 5. The female sexual organs contain the smooth muscular fibres in the corpora cavernosa of the clitoris, the vagina, the uterus (where they become even ^ of an inch long during pregnancy), in the Fallopian tubes, in different places in the broad ligaments of the uterus, in the round ligaments, and those of the ovaries. They also exist in the areolae of the lacteal glands, and the nipples. 6. In the vascular system, these fibre-cells exist in the middle coat of all, and most in the smaller, arteries; and in that of most veins, and of the lymphatics, except the finest; also in the lymphatic glands of some lower animals (Heyfelder); and the external tunic 388 THE TISSUES. of many veins. In the smallest arteries they are elongated, or even round cells; which is to be regarded as a less developed form. 7. In the skin, this tissue appears in the form of minute fasciculi upon the hair-sacs, and which are hence called arrectores pili (p. 267); and in many of the sudoriparous and sebaceous follicles. Similar arrectores have also been found by Mr. Lister in the scalp; these little muscles being about 2^ of an inch in diameter. Their existence in the dartos, the areola and the mammilla, has already been mentioned; and Kolliker asserts that they exist in all situa- tions where hairs occur. 8. In the eye, smooth fibre-cells form both the sphincter and the dilator (the circular and the radiating fibres) of the pupil, and the tensor choroideoz (ciliary muscle). [9. The spleen in many animals has this tissue in its outer coat, and in its trabeculae, mixed with areolar tissue; but it is not found in the human spleen.] 10. Finally, this tissue forms an incomplete coat in Wharton's duct, and in the ductus communis choledochus; while the gall- bladder is completely lined by a layer of it. Peculiarities.—The fibre-cells of the uterus demand a special notice. Muscular Fibre-Cells of the Uterus. The fibre-cells of the uterus, while in its normal state, are quite short; being only g^^ to ^^ of an inch in length, and g^1^ of an inch wide. As it enlarges after impregnation, and finally aug- ments to twenty-four times its original size (Meckel), all its histolo- gical elements undergo an increased development. But only the changes in its fibre-cells will be considered here. Kolliker has ascertained .that the walls of the uterus increase in thickness up to the fifth month of gestation, and then gradually become thinner, while its cavity increases up to the full term; and that so far as the muscular structure is concerned, there is both an enlargement of the original fibres and a production of new ones. At the end of 5 J to 6 months after impregnation, the fibres have become 2iT to T£o of an inch long, ^Vs to 5^ of an inch wide, and ssou t0 4255 °f an incn thick; instead of the dimensions men- tioned above. Consequently, their length is increased from seven to eleven times ; and their width from two to five times. Acetic acid brings out a distinct cell-wall inclosing these large fibres. MUSCULAR FIBRE-CELLS. 389 On the other hand, the new-formation of fibres is going on during the first half of preg- nancy; when fibre-cells in all stages of deve- lopment occur in great numbers. Fig. 244, a, re- presents the appearance of these during the sixth month. It appears that no new develop- ment of fibres occurs after the sixth month is completed; subsequently to that period, Kolliker could find only the colossal fibres, already de- scribed. (Fig. 244.) After parturition, the uterus is diminished in respect to all its histological elements. But of its muscular fibres some are doubtless com- pletely resorbed; while others become atro- phied. Indeed, in three weeks after parturi- tion, the fibres are found to be as short as in the virgin uterus. Fat-drops also appear in them; and this change can only be regarded as essen- tially a fatty degeneration, to a certain extent, of the fibre-cells. Their appearance at this pe- riod is seen in Fig. 248. Fig. 248. Smooth muscular fi- bres from the uterus three weeks after partu- rition, showing fat-drops in their interior. The four cells at the left have been treated with acetic acid. (Kolliker.) Distribution of Muscular Fibre-Cells in the Lower Animals. It is a singular fact that the smooth muscular fibre is not found at all in the Invertebrata^ the fibres thought to be such, actually being allied genetically to the striated muscular fibres of the higher animals. (Kolliker) The following peculiarities occur in the Yer- tebrata:— 1. In the mammalia, except man, these fibres form the genito- rectal muscle. In the orang-outang they are found upon the hair- sacs, as in man. They also occur in the spleen of many mamma- lia (p. 388, 9). 2. In birds, smooth muscular fibres exist in the skin, forming the muscles of the quill-feather; the latter having tendons of elastic tissue. In the gizzard of birds they are of a bright red color, and are united with a tendinous membrane. 3. In the amphibia, they exist in the iris. Also in the frog, they are found in the lungs. 4. In fishes, they are found in the swimming bladder. In the plagiostomata they occur in the mesentery, and in the osseous fishes in the campanula Halleri. 390 THE TISSUES. Functions of the Muscular Fibre-Cells. The tissues thus far described, have manifested physical proper- ties only. But muscular fibre-cells are, like the striated muscular fibres, endowed with a vital property, contractility, and the power of contraction; or of spontaneously shortening themselves, when excited by an appropriate stimulus. This latter is often brought to them by a nerve; but not always, nor so generally as is the case with the striated fibres. Hence they are not so abundantly supplied with the large (motor) nerve-fibres. In the alimentary canal, the muscular coat is excited to contraction more especially by the con- tents of the canal itself; and this is probably also true of the bron- chial tubes, the blood- and lymph-vessels, the bladder and the uterus. Hence, the motion is transmitted along a membraniform expan- sion of smooth muscular fibre somewhat slowly. The fibres not being bound up into parallel fasciculi to form muscles, but being interwoven, and each contracting independently of the rest—the movement of the first excites the rest in contact with it, and thus the action is propagated to a distance. This peculiarity has given to the motions of the alimentary canal the name of vermicular or peristaltic motion. The more or less rhythmical character of the contractions of this kind of muscular fibre, is also probably due to the anatomical peculiarity just mentioned. This is best seen in the case of uterine contractions; and also in cases of colic, and of cal- culus in the bladder or in the ureters. The contractions ofthe smooth muscular fibres are not in the least degree under the control of volition. Those who maintain that parturition is in some instances voluntarily deferred (after it actually commences at the end of the full term), and then again voluntarily recommenced, are deceived by appearances which a knowledge of the reflex function of the spinal cord at once explains away. Where a required motion is to be of slight extent, internal, not rapid, and not at all influenced by the will—it is delegated to the smooth muscular fibre. When either or all of these require- ments are to be reversed, the striated muscular fibre is employed instead. It is therefore physiologically inferior to the latter. Histo- logically, also, it may be regarded as a lower development, as will appear. MUSCULAR FIBRE-CELLS—DEVELOPMENT. 391 The smooth muscular fibre manifests the rigor mortis, like the striated (p. 405). Development of Muscular Fibre-Cells. There is nothing peculiar in the development of muscular fibre- cells. They are formed merely by the elongation of cells originally rounded; the cell-wall disappearing (in most cases, at least) after forming the homogeneous soft substance already described—the musculine. The nutrition of smooth muscle is probably very active, though less so than that of striated muscular fibre. Lehmann's investi- gations in regard to the fluid which bathes the fibres show that it has an acid reaction, and contains creatine and inosite, besides lactic, acetic, and butyric acid. Regeneration of Smooth Muscular Fibre. It is not certainly known whether this kind of muscular fibre is reproduced in cases of loss of substance. It is, however, probably not reproduced, but is replaced by areolar tissue. Pathological Conditions and New Formations of Muscular Fibre-Cells. Smooth muscular fibre is liable to hypertrophy and to atrophy, like the striated form. It also becomes paralyzed like the latter, and is very liable to fatty de- i.- Fig. 249. generation. a e 6 Pathological new formations of this tissue occur in some cases of uterine tumors. 1. Hypertrophy of the smooth muscular fibre is usually of limit- ed extent, and recognizable even by the naked eye, by the pale-red fibrillation. Occurring in the py- loric portion of the stomach, this part sometimes becomes an inch or more thick, the circular fibres being mainly increased. An are- olated appearance is produced in the hypertrophied mass by the development at the same time of the areolar tissue surrounding the fasciculi, and which increases in thickness towards the submu- cous tissue. In certain layers of the muscular coat, flattened cells are met with, resembling epithelial cells, but having an oblong nu- Transverse section of the hypertrophied mus- cular layer of the stomach, boiled in acetic acid4 and dried, a, a. Smooth muscular fibres, divided transversely, b, b. Areolar tissue bundles. (Weld.) 392 THE TISSUES. cleus. These are probably the embryonic forms of the fibre-cells. (Wedl.) Fig. 249 shows the fibres and the connective tissue inclosing them, as seen in a transverse section. The submucous tissue is at the same time either thickened, or infiltrated with a gelatinous sub- stance. Hypertrophy of the smooth muscular tissue is usually attributed to a previous inflammation in the part; and Engel has shown that such a connection exists. 2. Atrophy of the smooth muscular tissue occurs as a consequence of old age, and of diseases attended by emaciation. 3. Fatty degeneration of the contents of the muscular fibre-cells is their most common form of involution;1 much fat occurring at the same time in the interstitial connective tissue. This last form is seen most strikingly in the intestinal canal and the urinary bladder. The involution of the smooth fibres of the uterus after parturition has already been explained (p. 389). 4. Pathological new formations of smooth muscular fibre very rarely occur. Their new formation in the uterus during pregnancy (p. 389) must be regarded as a physiological change. II. Striated Muscular Tissue. It is of this tissue mainly that the muscles proper are formed; and its histological and its physiological relations are of the highest importance. This form of contractile tissue consists of fibres marked with transverse striae. (Fig. 250.) The length of the fibres varies ex- ceedingly, they sometimes extending through the whole length of the fleshy part of a muscle. Their diameter varies from -g^ to 4-J-^ of an inch; the average being about g^ of an inch. They are larger on the trunk and the extremities than on the head; but their size is the same in the two sexes, though the contrary has sometimes been asserted. They are about one-third as large in the foetus as in the adult. When packed together in fasciculi, they assume the form of round polygonal prisms, as seen in a transverse section, in Fig. 263; when isolated, they approach to the cylindrical form. The striae are, on an average, about TV&?nr of an inch apart. Various hypotheses have been resorted to, to account for them; but it is believed, with Kolliker, that "it is still doubtful to what the striation is due," though it is clearly a physical and not a vital phe- 1 This term is used to denote a pathological change or descending metamorphosis, in the histological elements of a tissue or organ. It is, however, also applied to the atrophy undergone by the uterus immediately after parturition. striated muscular fibre. Fig. 250. 393 Fragments of striated muscular fibres, showing a cleavage in opposite directions. (Magnified 300 diameters.) 1. Longitudinal cleavage. The longitudinal and transverse lines are both seen. Some longitudinal lines are darker and wider than the rest, and are not continuous from end to end ; this results from partial separation of the fibrillae. 6. Fibrillse separated from one another by violence at the broken end of the fibre, and marked by transverse lines equal in width to those on the fibre. 7, 8, represent two appearances commonly presented by the separated single fibrillae (more highly magnified). At 7, the borders and transverse lines are all perfectly rectilinear, and the included spaces perfectly rectangular. At 8, the borders are scalloped, the spaces bead-like. When most distinct and definite, the fibrilla presents the former of these appearances.—2. Transverse cleavage. The longitudinal lines are scarcely visible. 3. Incomplete fracture following the opposite surfaces of a disk, which stretches across the interval and retains the fragments in connection. The edge and surface of the disk are minutely granular, the granules corresponding in size to the thickness of the disk, and to the distance between the faint longitudinal lines. 4. Another disk nearly detached. 5. Detached disk more highly magnified, showing the "sarcous elements." nomenon. The largest and the smallest fibres are sometimes found side by side. Each striated fibre consists of two distinct por- tions : first, the myolemma; and, secondly, the my- oline. 1. The myolemma1 is the envelop containing the myoline. It is merely a tube, closed at both ends, of simple membrane (Fig. 251); in or un- derneath which (for this point is not yet settled) nuclei are brought into view by acetic acid. (Fig. 254.) Kolliker maintains that it is not an albu- minous compound, but is at least similar to elastic tissue. Certainly it may be proved to be elastic, and to fit closely upon its contents, in the normal state.2 Myolemma of a torn muscular fibre of the skate. 1 From juD?, muscle, and leppa, coat or sheath. It is also, less accurately, named sarcolemma, by Kolliker and others. 2 It should be here remarked that Drs. Busk and Huxley deny the existence of the myolemma as a distinct structure; affirming that it is merely the outer portion of the matrix containing the fibrillse. 394 THE TISSUES. 2. The myoline is the demi-solid substance filling the myolemma, and on the surface of this are the transverse markings before men- tioned. It consists, first, of very minute threads, called fibrillce, placed side by side, from 5^3 to -g^ of an inch in diameter, and averaging about TTT^^ of an inch; between which is, secondly, the muscular juice, to be described under the chemical composition of this tissue. Each one of these fibrillae has its own transverse mark- ings. Fig. 250,1, shows a fibre splitting into its compound fibrillae in consequence of maceration. The same cause sometimes produces a transverse cleavage of the fibres; in which case the fibre has been described as being made up of superimposed disks, instead of fibrillae. Fig. 250, 2, represents this form of cleavage. Often, also, a longi- tudinal striation is apparent. The fibrillae are not tubular in man (as in some of the lower animals), but are homogeneous throughout. The fibrillae are connected together by an albuminous tenacious intermediate substance of a double nature: viz., the "muscular juice" hereafter to be described; and a granular molecular substance— probably fat in part—which certain distinguished microscopists have seen lying between the extremities of the fibrillae of a fibre which had been transversely divided. Each fibrilla is also by Todd and Bowman regarded as being composed of cells, called "the sar- cous elements,"as represented in Fig.250,5 and 6. Fig. 252. These cells average about ^^^ of an inch in di- ameter ; and as the alternate ones are often larger than those between them, the striated appearance of the fibrillae has sometimes been accounted for in this way. Peculiarity.—In the heart (of man, and proba- bly of all mammals), anastomosing and dividing fibres are found. Branched fibres are also found in the human tongue. (Fig. 252.) The striated muscular tissue is abundantly sup- plied with bloodvessels and nerves (both the fine Anastomosing fibres , . , from the human heart. and the coarse nerve-fibres), and scantily with (Kcuiker.) lymphatics. (See Section II. of this chapter.) Chemical Composition and Physical Properties of Striated Muscular Tissue. There is reason to believe that the chemical composition of the two forms of muscular tissue is identical. 0. Schmidt supposed he STRIATED MUSCULAR FIBRE. 395 had proved this to be the fact some years ago. We have to con- sider the composition of— I. The muscular fluid. II. The musculine. III. The myolemma, containing both of the preceding. I. The "muscular juice," as it is termed by Liebig, surrounds the fibre-cells of the smooth muscle; and is also contained within the myolemma of striated muscular fibre, where it permeates between the fibrillae. It is easily expressed from fresh muscle, and is a de- cidedly acid, albuminous fluid. Its albumen may, however, be in part obtained from the blood of the muscular mass; while its large amount of caseine is peculiar to it.1. It is from 72.56 to 74.45 per cent, water (Von Bibra); there being, on an average, 10 per cent. less water in muscle than in blood-serum. It also contains creatine, creatinine, inosic acid, kactic acid, and a very little fat. Scherer has also found in it acetic and formic acid; and in that obtained from the heart of the ox, he found a peculiar substance which he terms inosite or muscle-sugar. The muscular juice, like most acid fluids, also contains an abundance of potash salts, and of phosphates, while it is poor in salts of soda and in chlorides. It appears that in the horse there are twenty-nine times, and in the ox forty six times, as much potash in the muscular juice as in the blood. There is about ten times as much chloride of sodium, on the other hand, in the blood-serum as in the muscular juice of the horse. (R. Weber.) While the phosphate of lime is far more abundant in the blood than the phosphate of magnesia, the reverse is true of the muscular fluid. It has been seen that the chloride of potassium is more abun- dant than that of sodium, and that the former is often mistaken for the latter (p. 49). About twenty-three times as much phosphoric acid exists in the ash of horse's muscle as in that of the blood- serum; more than is sufficient to form all the neutral phosphates of the alkalies. What the precise relation is between the function of the muscular fibre on the one hand, and the chemical constitution of the muscu- lar fluid on the other, is unknown. Liebig calculates that the stri- ated muscles alone contain more than enough free acid to destroy the alkalinity of all the blood; and that the opposite state, in this 1 The fluid of the smooth, however, contains more caseine and less albumen than that of striated muscle. In the latter, albumen alone is often found. 396 THE TISSUES. respect, of the muscular fluid and the alkaline blood circulating through the muscle, either occasions, or is occasioned by, an elec- trical current; which, it is implied, may be the exciting cause of muscular contraction—a proposition we hesitate to adopt. Experi- ments, however, point- to the conclusion that muscle loses its power of contraction in proportion as its fluid is diluted. II. After the muscular fluid is removed by pressure from the myolemma, the solid substance of the fibrils still remains. This is an albuminous substance, soluble in extremely dilute hydrochloric acid,1 and is the most essential element of muscular tissue. It has already been described as musculine (p. 97). It exists equally in striated fibre and in the muscular fibre-cells, and the vital property of contractility doubtless inheres in it, wherever found. There is less of it within the myolemma of young than of adult animals. III. The chemical relation which the myolemma bears to the in- closed cylinder of musculine has not been determined; but the substance of the nuclei inclosed in it does not differ much from musculine. (Lehmann) From what precedes, there will be less musculine, in proportion, in young animals. In the contractile fibre-cells, on the other hand, the myolemma is absent, or at least is generally not demonstrable (p. 384). Of the three distinct substances included in the analysis of muscu- lar tissue—the myolemma, the muscular fluid, and the musculine— the last alone is an immediate principle. It is impossible to isolate the muscular tissue entirely from the bloodvessels and their con- tents, from the areolar tissue in the muscular sheaths, and from fat between the myolemmata. After instituting all practicable pre- cautions, Lehmann found the following as the average result of his analyses of the muscular substance, more especially of oxen:— Per cent. Water......74.0 to 80.0 Solid constituents . . . 26.0 to 20.0 100.0 100.0 Per cent. Muscular fibre (musculine) . . . 15.4 to 17.7 Gelatigenous substance (myolemmata and perimysia)......0.6 to 1.9 One part to one thousand of water. STRIATED MUSCULAR FIBRE. 397 1.5 to 2.3 0.6 to 0.68 0.66 to 0.70 0.50 to 0.54 0.07 to 0.09 0.04 to 0.09 0.02 to 0.03 0.04 to 0.05 Per cent. Albumen (and caseine) . . . . 2.2 to 3.0 Creatine.......0.07 to 0.14 Creatinine (undetermined). Inosic acid (do.). Fat, within the myolemmata and in the blood between the perimysia Lactic acid (C6H5Os.HO) Phosphoric acid Potassa ..... Soda..... Chloride of* sodium (potassium) Lime.....' Magnesia .... The color of muscular fibre is due not to the blood in the ves- , sels, but to a peculiar pigment, very similar to the haematine of the / blood, but probably not identical with it. At least, it adheres in a free state to the fibrillae, since it may be extracted from them by water, and coagulates with the albumen of the muscular fluid. It is not essential to contractility; since the muscles of many animals are white, though perhaps as vascular as the red muscles of other species. Another physical property of striated muscular tissue—elasticity —will be described in the next section. Distribution of Striated Muscular Fibre. The striated muscular fibre is the peculiar tissue of the muscles properly so called; while none of the latter are ever formed of the smooth fibre, as already stated. It is, therefore, distributed:— 1. In all the muscles proper in the body, including the internal (diaphragm, levator ani, those of the eyeball, &c), as well as those of the head, neck, trunk, and extremities. 2. In the heart and the great veins opening into it—the inferior cava to the diaphragm, and the superior cava, and the innominatae, to the clavicles. 3. Scattered striated fibres are found in the oesophagus, and also in the round ligaments of the uterus—mixed with the smooth fibres. 398 THE TISSUES. Distribution and Peculiar Forms of Striated Fibre in the Lower Animals. I. In the vertebrata, generally, the distribution of striated fibres is as in man. The following peculiarities are noted:— 1. In the oesophagus (with smooth fibres), of some mammalia and of the plagiostome fishes; around the contractile organ of the pharynx of the carp; and in the stomach of cobites fossilis, and the intestine of tinea chrysitis, and around the anal glands and Cowper's gland in mammals. 2. In the skin of some mammalia, birds, serpents, and tailless batrachians (frog, &c), and the tactile hairs of mammals. 3. In the lymph-hearts of many birds and amphibia; and in the right auriculo-ventricular valve, in birds, and the ornithorhynchus. Also in the inferior vena cava of the seal, close above the dia- phragm. 4. In the interior of the eye in birds, and around the poison- gland in serpents. The anastomosing fibres already mentioned, probably occur in the hearts, and the lymph-hearts of all animals. Branched fibres also occur in the tongue of all the vertebrata probably; and are found in the upper lip of the rat. II. In the invertebrata, all the muscular fibres belong genetically to the striated form, whether they are clearly striated or not. (Kolliker) The muscles of insects, and of the medusae, and indeed the heart, intestine, and muscles of the genital organs, of the inver- tebrata generally, are distinctly striated. It is only necessary, therefore, to notice the peculiar forms of striated fibre in this class, which are enumerated by Kolliker. 1. Muscular tubes, with homogeneous semi-solid non-striated contents; i. e. the fibre is like the non-striated or smooth fibre, with a distinct myolemma; as in most of the mollusca, annelidae, and radiata. 2. Tubes (myolemmata), containing a semifluid, homogeneous layer in contact with them, and a fluid or granular central sub- stance frequently transversely striated or nucleated; as in Lumbri- cidas, Hirudinidae, Carinaria, and Petromyzon and Paludina in part. 3. Similar tubes, having the cortical layer of their contents trans- versely striated, but not divisible into distinct fibrillae; as in many muscles of the Hirudinidae. This form is found in the tongue, pharynx, sphincter ani, &c, of fishes even. These tubes contain a fluid in their centre. 4. Tubes precisely like the preceding, except that they have no central cavity (i. e. are demi-solid throughout), and break often into disks, though not into fibrillae; as in many Articulata (Salpce), and some Radiata. STRIATED MUSCULAR FIBRE. 399 5. Tubes readily breaking into fibrillae; or precisely like the striated fibre in the Mammalia, as in certain muscles of insects. 6. Lastly, simple isolated cells, containing a transversely striated substance which fills the whole cell or only forms a thin layer upon its internal surface. These exist also, according to Kolliker, in the endocardium of the Ruminantia; constituting the peculiar cartila- ginous striae first observed by Purkinje. Development of Striated Muscular Fibre. The myolemma is formed originally of nucleated cells, first co- alescing and then becoming absorbed where they come into con- tact, so as to form tubes closed at both extremities. Subsequently the original homogeneous contents of the formative cells are re- placed by the fibrillae, and thus the development of the fibre is com- pleted. In many cases the layer of the contents next the myolem- ma alone gives place to the myoline; while the central part still appears like a canal within the fibrils. It has been seen that this is the permanent form of the striated fibre in some insects. After the fibrillae are developed, and before birth, the nuclei disappear, and, with the exception of being smaller, the fibres present the same appearance as in the adult. More particularly—in the embryo—at the end of the second month, the fibres have the form of elongated bands T5^o °f an inch broad, with nodular enlargements at different points where elon- gated nuclei are situated. Q$ig- 253.) These bands have either a Fig. 253. Fig. 254. ■ M m m mm *m fen i-.i V---I of an inch in diameter. The larger ones, though still flattened, are now of uniform width, thicker than before, transversely striated, and with fibrils capable of being isolated. (Fig. 253, 3). The musculine does not, however, yet entirely fill the myolemma, but forms a tube in contact with its inner surface, con- taining some of the original contents of the myolemma in its cen- tre. Thus the musculine is the part of the fibre which is last de- veloped. The myolemma may occasionally be raised like a very delicate membrane, by the imbibition of water. The nuclei still lie close upon the myolemma, as at first, and are rapidly multiplying; being much more numerous than at first, and often found in groups of three or four, or even six, which are sometimes arranged serially. They are all vesicular, with very distinct, simple, or double nucleoli, and frequently with two secondary cells in their interior, showing the endogenous development of the nuclei from the original ones. At birth, the fibres are %r\5 to T^4 0I> an incn iQ diameter; are solid, rounded, polygonal, and longitudinally and transversely stri- ated, as in the adult; and the nuclei have disappeared. (Fig. 253,5.) Thus the myolemma represents the sum of the membranes of the original coalesced cells, and the fibrillae are the altered contents of the original tubes (myolemmata). A fibre, therefore (and not a fibrilla, as Leidy and Reichert maintain), is histologically analogous to a contractile fibre-cell (p. 390); and the latter may be regarded as a lower development of the former. The growth of the striated muscular fibre, must be referred prin- cipally at least, to increase in the number of the fibrillae, and of course of the size of the myolemma containing them. In other words, each fibre grows larger, while there is no proof that new fibres are formed even after the middle period of intra-uterine life. Thus the fibres are about five times as thick in an embryo at four or five months as at two months; and three or four times as thick in the new-born infant as at the period first mentioned. In the adult, they are perhaps five times as thick as at birth. Donders thinks the number of the fibrillce is the same in the young and the adult animal, and that they only increase in size; they being \ to f smaller in the calf than in the ox. Kolliker, however, relying on Harting's assertion that they are but little thicker in the adult than in the foetus, believes their number increases in each fibre. STRIATED MUSCULAR FIBRE. 401 Striated muscular fibre is not regenerated; and wounds in mus- cles heal simply with a tendinous callus. The development of the accessory parts of muscles (tendons, &c.) is included under that of the muscles as distinct organs (Section II.). The Function of Striated Muscular Fibre. Striated, like smooth muscular fibre, is distinguished by the vital property of contractility; but, unlike the latter, the former may be made to contract voluntarily. The direct result of the contraction of the striated fibres in a muscle, is a shortening of it; which approximates its two extremities, and at the same time produces motion of one of the parts (usually a bone) to which it is attached. But we have here to speak of the con- traction of single fibres only. If a striated fibre be observed while contracting, it is seen to become shorter and thicker; the striae approach each other (Fig. 255); and sometimes the muscular fluid, forced out from between the fibrillae, causes the myolemma to project at points, forming bullae, as seen in Fig. 256. It is scarcely profitable to inquire what causes the shortening of the fibre, by the approximation of its disks, since it is a vital act; and the merely chemical explanation suggested by Liebig is altogether unsatisfactory. But that the musculine alone is endowed with the property of con tractility, is sufficiently certain. Fig. 256. Stages of contraction seen in muscu- lar fibre of the skate. The uppermost figure shows its state previous to the commencement of active contraction. a, a, a. Successive "waves" of con- traction seen moving along one margin of the fibre ; marked by a bulging of the margin, an approximation of the transverse stripes, and a consequent darkening of the spots. b, b, b. Simi- lar "waves" still moving along the fibre, but engaging its whole thickness. Muscular fibre of Dytiscus, showing the contracted state in the centre, the strije approximated, the breadth of the fibre increased, and the myolemma raised in bullae on its surface. It is, however, the fact that ordinarily (and perhaps always) the immediate stimulant to contraction of the striated fibres is an influ- 26 402 THE TISSUES. ence imparted by a nerve distributed among them in the muscle. Electricity, galvanism, and a variety of other agents, will, however, excite it in muscles in the living body, or in portions removed from the same. In fact, the only way in which a muscular fibre can react vitally when acted upon by any external agent, is by con- tracting, since this is its peculiar vital endowment. The shortening also occurs instantaneously. The chemical changes which attend the contraction of a fibre are not all understood. There is, however, reason to believe that the substance of the fibrillae—the musculine—alone is concerned actively in the contraction, and alone undergoes chemical changes during it. It is also certain that the contact of oxygen is necessary to the contraction of a fibre, and that during it carbonic acid gas is formed within the fibres, and not in the bloodvessels distributed among them; while the temperature of the muscle also rises two or three degrees. (Becquerel and Breschet) Hence the contractility of a set of muscles is lost if their supply of blood is cut off. The extent to which a fibre may become shortened during con- traction seldom if ever exceeds two-thirds of its length; or reduces the fibre to one-third of its original length. Some give one-third as the usual amount of shortening, the fibre then being two-thirds its original length. Kolliker states that the average shortening is three-fourths (i. e. down to one-fourth), and in powerful muscles even five-sixths (or down to one-sixth), of the original length. Hassall estimates the shortening at one-third to one-half only, of the original length. In ordinary circumstances, not all the fibres in a muscle contract simultaneously; but each contracts for an instant and relaxes, while of the rest some are contracting at the same time, and others follow these in their turn. It is probably only when the most powerful muscular efforts are made that all the fibres of a muscle contract at once. The absolute extent of motion (or shortening) produced by a striated fibre will, therefore, depend on its length; while its con- tractile force or strength will depend on its size, it being stronger in proportion to the area of the transverse section of the musculine (and of the fibrillae) within its myolemma. So long as a muscular fibre is in a state of perfect nutrition, it also manifests a slight but constantly exerted tension, called tone or toni- city, and in regard to the nature of which very diverse opinions STRIATED MUSCULAR FIBRE. 403 have been held. This property, however, diminishes in proportion to the duration of the contractions of the fibre, and is not again re- covered till the fibre has had time to rest. It does not appear to depend upon the constant influence of the spinal cord, or on any other merely nervous agency. But that it depends merely on a healthy nutrition, and is the expression of the fitness of the muscle for action, is rendered quite probable from the effect of rest in restoring it, and from the loss of tone and the flabby state which are consequent upon long-continued exertion. This tensive force being constantly exerted in ordinary circumstances, produces the some- what flexed position of the limbs in a sound sleep; since the flexors are so inserted as to act to greater advantage than the antagonizing extensors, though actually less strong than the latter. It also ac- counts for the habitual closure of most of the sphincter muscles, and the deviation, to one side, of the tongue or of the mouth when the muscles of the opposite side are paralyzed. In all similar cases, the sound muscles are not in a state of incessant contraction, as often asserted; but merely in a state of tension, and at rest, while the antagonizing muscles have lost both their contractility and their tonicity. The use of the muscles is inferred from the preceding remarks, and will be particularly specified in the second section of this chapter. Modifications of the Contractility of the Striated Muscular. Fibre. 1. An increased or an irregularly acting contractile force of the striated fibfes constitutes spasm. If the contraction is constant, it is termed tonic spasm (as tetanus, trismus, &c.); if irregular and in- termitting, it is clonic spasm, or convulsions (epilepsy, chorea, &c). 2. A loss of contractility constitutes paralysis, and in which, if complete, all motion is of course impossible. 3. The rigor mortis is that tonic spasm of all the muscles which usually comes on several hours after death. It is in some rare cases entirely absent—as after death by light- ning or by asphyxia. It may also be so slight, and last so short a time, as to escape observation. It affects the muscles in the follow' ing order: those of the neck and lower jaw; those of the trunk; and those of the lower and the upper extremities. It departs also in the same order. It affects all the muscles with nearly the same intensity; the 404 THE TISSUES. flexors, however, being usually more contracted than the exten- sors, flexing the fingers on the palm, and the forearm on the arm, and closing the mouth if the lower jaw had previously fallen. It is equally intense even in muscles paralyzed by hemiplegia, pro- vided they have not become much atrophied. The period elapsing after death before its supervention, and its duration, are variable. It usually occurs within seven hours, and continues from twenty-four to thirty-six hours. But twenty or even thirty hours may elapse before it supervenes, and it may be pro- longed through several days. Its departure is immediately followed by decomposition. When early developed, it lasts but a short time, and vice versa. Any cause which has exhausted the muscular energy before death, causes the rigor mortis to come on and to pass off sooner—as a protracted disease, or violent efforts. Indeed, power- ful stimulation of the muscles by electrical currents, immediately after death, also produces the same effect. The following results were obtained by M. Brown-Se'quard, who experimented on four rabbits, reserving a fifth for comparison:— 1. Not electrized; rigidity occurred in 10 hours, and remained 192 hours. 2. Feebly electrized; rigidity occurred in 7 hours, and remained 144 hours. 3. Somewhat more electrized; rigidity occurred in 2 hours, and re- mained 72 hours. 4. Still more strongly electrized; rigidity occurred in 1 hour, and remained 20 hours. 5. Submitted to a powerful current; rigidity occurred in 7 minutes, and remained 25 minutes. In animals hunted to death, the rigidity comes on very early, and lasts but for a short time. On the other hand, M. Brown-Se'quard found that the rigor mortis is deferred by injecting the muscles with fresh blood, after death. Stannius also found it to occur even in living animals, if the supply of blood to a group of muscles is entirely cut off. After death from typhus, the limbs sometimes stiffen within fifteen to twenty minutes. It also occurs rapidly in infants, and in old people. It should, however, be remembered that in certain states of the muscular and nervous systems, a tetanic rigidity immediately en- STRIATED MUSCULAR FIBRE. 405 sues after death, and which may be mistaken for the rigor mortis. This, however, is in a few hours succeeded by a state of relaxation of the muscles, and then the ordinary rigor mortis supervenes. A knowledge of all the facts connected with this subject is essen- tial in certain judicial investigations; in regard to which the works on medical jurisprudence may be consulted. Its cause is not under- stood. It does not, Ijowever, depend upon the diminished tempera- ture of the dead body, since it often occurs while the latter is still warm; nor is it produced by the coagulation of the blood, though in those cases of death in which the blood dQes not coagulate (p. 94, vi.), the rigidity usually manifests itself least. We can hardly say more than that the rigor mortis is the last vital act of the muscles, as the coagulation of the blood is of the fibrine (p. 93, III.). It should be here added, however, that the rigor mortis is equally, if not more remarkable in the smooth muscular fibre. The arte- ries contract so as to force their blood into the venous system; which almost invariably occurs a few hours after death. They then en- large as the rigidity passes off, and become quite flaccid. Hence the old physiologists believed that the arteries naturally contained not blood, but air, and named them accordingly.1 The alimentary canal, the bladder, and the bronchial tubes are also, for a time after death, contracted in a similar manner; and the post-mortem con- traction of the parturient uterus in patients who had died unde- livered, has been known in several instances to expel the foetus. The " concentric hypertrophy" of the heart, as it was formerly called (this organ being thicker than usual and smaller), has been shown by Mr. Paget to be merely the state of cadaveric rigidity which usually occurs in that organ. The ventricles become rigid and contracted within an hour or two after death; and usually re- main in that state for ten or twelve hours (sometimes twenty-four or thirty-six even), when they again relax and become flaccid. Of the lower animals the rigor mortis occurs most rapidly in those possessing the greatest muscular irritability (e. g. in birds), and vice versa—slowest, therefore, in reptiles and fishes. Pathological Conditions and New Formations of Striated Muscular Fibre. 1. Hypertrophy scarcely occurs except in case of the tongue, heart, and certain respiratory muscles; though the increased development 1 From aiip, air, and rh^t», to keep or hold—an air-holder. 406 THE TISSUES. Fig. 257. induced by exercise is constantly seen. Mere increased size of the original fibres may account for the effects of exercise, but there is probably a growth of new fibres in the former case. Wedl asserts that the number of fibrillae in the fibres is increased in pathological hypertrophies; and in hypertrophied heart the fibres are of a tawny or rusty-brown color, soft, and sometimes anastomosing, as seen in Fig. 257. It is also certain that in hypertrophied muscles the con- nective tissue between the fibres sometimes becomes hypertrophied. 2. Atrophy of muscles is very common, and occurs in old age, from lead-poisoning, from paraly- sis (especially of the tongue), and from the development of cancer, fibrous tumors, fat, &c, in the sub- stance of the muscles. All causes of general emaciation also pro- duce it. In extreme old age, Kolliker found the fibres small, sometimes Muscular fibres in a hypertrophied heart. a. A subdividing striated fibre, with dirty yel- low pigment molecules in the myolemma. 6. A slender dichotbmous fibre, e. Anastomosing fibre.—d. Laminated, and e, smooth, colloid- cell.—Magnified 350 diameters. (Wedl.) not more than ^Vou t0 tsco" oi> an inch in diameter; mostly without striae, and with the fibrillae indis- tinct; and often containing yellow- ish or brown granules T5^7 of an inch in diameter, in large quan- tity, and very many vesicular nuclei with nucleoli, together with a clear fluid. In paralyzed muscles, Valentin found the transverse striae were indistinct, or had actually disappeared, and could not be made to appear by water, alcohol, &c.; while the longitudinal striae remained, but resembled those of macerated muscle. Subsequently the altered fibres disappeared in part, and were partly replaced by fat. In a pectoralis major atrophied by cancer, Kolliker noticed conditions similar to those in old age. He also found cells in many of the fibres exactly resembling the so-called cancer-cells. Wedl states that in atrophy some of the fibrillaa undergo absorption. The fibre also manifests a diminished co- hesion, and is easily lacerated; the myo- lemma being easily torn as well as the my- oline within. (Fig. 258.) 3. In fatty degeneration of muscles, minute fat-globules are developed within the myo- lemma, in place of the fibrillae, which gra- The fat-drops also accumulate between the fibres; Atrophy of striated muscular fibre, a. A fibre torn across. 6. Fibrillse hanging out.—Magnified 350 diameters. (Wedl.) dually disappear. STRIATED MUSCULAR FIBRE. 407 and, finally, the latter to a greater or less extent disappear, and give place to areolar tissue and fat-cells. (Fig. 259.) Fatty degeneration of the heart. A. Fibres taken from the columnse carnese of the mitral valves of a woman set. 30 ; the fatty degeneration was scarcely observable in the ventricle, where the fibres still retained their strise. b. An extreme case of fatty degeneration, showing an entire replacement of the myoline by oil globules, still retaining a linear arrangement. From the right ventricle of an old gentleman who had Bright's disease of the kidney and pulmonary phthisis, and was aflfected with fits during the last two years of his life. 4. The condition of the fibres in emaciated muscles is unknown. Donders found them more slender in a frog which had fasted eight months; which he attributed mainly to the removal of the muscular fluid from between the fibrillae. 5. Paleness of the muscles is common in dropsy, chlorosis, para- lysis, lead-poisoning, old age, &c; the coloring matter being, per- haps, converted into the numerous brown and yellow granules before mentioned as appearing within the myolemma. 6. Softening often accompanies paleness. In the former, the fibres exhibit no transverse striae nor fibrils; and readily break up into numerous particles, or even into a pultaceous mass. 7. Muscular fibres ruptured in tetanus, present numerous nodular enlargements, in which the transverse striae are very closely approx- imated; and between them either rupture of the fibrillae, or at least a considerable stretching and disorganization of them. (Bowman) 8. Concretions sometimes exist in muscles. The state of the fibres has not been investigated. 9. True bone is also sometimes formed in muscles subjected to prolonged exercise, as the deltoid and some others. The precise changes in the fibres in this case also are unknown. 10. Of parasites in muscles, the Cysticercus cellulosa, and the Tri- china spiralis are to be mentioned. These are contained in distinct cysts; and which are situated between the fibres. 11. Kokitanski found a new formation of the striated muscular fibres in a tumor of the testis of a person eighteen years old; and Virchow also once detecfed it in an ovarian tumor. 408 THE TISSUES. SECTION II. Fig. 260. STRUCTURE OF THE MUSCLES. The muscles consist of striated muscular tissue, areolar tissue, vessels, and nerves; and all the longer fusiform muscles (as of the extremities) contain a considerable amount of the white fibrous tissue also. The last-mentioned muscles may each' be divided into—first, the aponeurosis of origin; secondly, the tendon by which they are inserted Fig. 261. The aponeurosis, belly, and tendon of the fusiform mus- cles (flexors) on the anterior aspect of the forearm. 5. The flexor carpi radialis; its aponeurosis of origin is seen at its upper extremi- ty, next its belly above the figure 5; and the tendon below the latter. Transverse section of the tendon of a calf. (Magnified 20 diame- ters.) a. Primary fasciculus, b. Secondary fasciculus, c. Nuclear fibres not quite in transverse section, but appearing as little streaks in the former, d. Interstitial connective tissue. (Kolliker.) into the bone or other organ to be moved by them; thirdly, the belly, or intermediate por- tion. (Fig. 260.) Each of these will be sepa- rately described. 1. The aponeuroses are composed of white fibrous tissue, and are generally flattened into the form of a membrane. Their structure has already been specified (p. 278, 2). 2. The tendons are also cords of white fibrous tissue, like the STRUCTURE OF THE MUSCLES. 409 ligaments, and containing very few elastic fibres. The fasciculi of the collagenous tissue are inclosed in sheaths of areolar tissue, which thus forms delicate dissepiments penetrating the substance of the tendons, as shown in Fig. 261; then several of the primary fasciculi (five to ten) are collected into large bundles—the secondary fasci- culi. Finally, the vessels are distributed in the spaces between the fasciculi (Fig. 176); elastic fibres are also sent into them, and the whole is invested by a sheath of areolar tissue (p. 278, 1). £The elastic fibres require a particular description, however. In a transverse section of a tendon, their extremities are seen as dark points in the substance of the fasci- culi, at constant distances of j^^ to Flg* 262, Yjisj of an inch apart, over the whole section; and being ^^ to T5J^ of an inch in diameter. (Fig. 262.) These are also connected together in various directions by other finer fibres, g^o5 to ,w$nTj of an inch in diameter, so that there is in tendons an elastic network penetrating and entwining the collagenous tissue. These are sometimes seen in trans- verse sections, as lines radiating from the coarser points before mentioned. Besides, the tendons in certain situations contain cartilage-cells, as well as even fat-cells—as in the intercostal muscles, the masseter, &c. The glistening appearance of the tendons depends upon their transversely banded aspect, as seen under the microscope; and the latter is produced by the numerous curves in the fibres, which cor- respond with each other throughout the fasciculus. The curves are doubtless produced by the elastic tissue in the fasciculus, and there- fore at once disappear when the tendon is stretched. The tendons consist of 62.03 per cent, of water (Chevreuil); they containing considerably less, therefore, than the muscular tissue (p. 396). 3. The belly of the fusiform muscles, and the red portion of all others, is the only portion that presents a peculiar structure, as alone containing the muscular tissue; and this, therefore, will be particularly described. It consists of— Tendon of the tibialis posticus (man). a. Primary fasciculi. 6. Thicker nucleated fibres, e. Interstitial connective tissue.— Magnified 60 diameters. (Kolliker.) 410 THE TISSUES. 1. The striated muscular fibres. 2. Areolar tissue. 3. Bloodvessels, lymphatics, and nerves. The last three will be described after the two preceding topics, and the connection of the tendons with the bones and the muscular fibres, have been disposed of. 1. The striated muscular fibres, already described, are collected together into bundles (fasciculi), each inclosed in a sheath of areo- lar tissue (internal perimysium1); these are collected together into larger, and the latter into still larger, bundles—secondary and ter- tiary fasciculi; and finally the whole is inclosed in a sheath of areolar tissue—the external perimysium. These parts are seen in a transverse section of a muscle, Fig. 263. The primary fasciculi are Fig. 263. Transverse section from the rectus capitis anticus major of man. a. External perimysium, b. Peri- mysium internum, c. Single fibre, and muscular fasciculi.—Magnified 350 diameters. (Kolliker.) 72 to 2V 0I" an inch thick. The secondary and the tertiary vary extremely in their dimensions. They are very evident to the un- aided eye in the coarser muscles, especially the glutaeus maximus and the deltoid. The direction of the fibres sometimes corresponds with that of the tendon, and sometimes meets the latter at an acute angle (semi- tendinosus, &c). In the former case they are longer than in the latter; sometimes, indeed, extending through the whole length of the belly of the muscle—as in the sartorius. 2. The areolar tissue constituting the muscular sheaths (perimysia) 1 From irepi, around, and fxvi;, a muscle. All the interfascicular areolar tissue taken together is sometimes called the internal perimysium. STRUCTURE OF THE MUSCLES. 411 both supports and transmits the vessels and nerves, and also incloses and supports the muscular fibres while in action. The external perimysium contains more elastic tissue than the internal; and, in estimating its function, it may be regarded as a semi-elastic mem- brane. Liebig found about 5.6 per cent, of the muscle to be con- nective tissue; Yon Bibra but 2.2 per cent. There is proportionally more in the calf than in the ox. In all muscles, but especially the laxer in structure, a certain number of adipose cells also are found in the areolas of the peri- mysia ; and these frequently contain beautiful crystals of margaric acid (p. 298). In fat persons these cells are quite abundant among the primi- tive fasciculi even. Fig. 264. Connections of the Tendons at their Extremities. The tendons are connected at one extremity with the belly of the muscle (or the part contain- ing the muscular fibres), and at the other with the bones or other parts moved by the muscles. I. The tendons are connected with the muscu- lar fibres in two ways: 1. When the latter lie in the direction of the axis of the muscle, and thus extend through the whole length of the belly of the latter, they pass directly into the fibres of the white fibrous tissue in the tendon, in such a way that there is no sharply defined limit be- tween the two tissues; the tendinous fibre being nearly equal in size to the muscular, and appear- ing to be actually continuous.1 (Fig. 264.) 2. But when the muscular fibres join the tendons at an acute angle—as in the penniform muscles—the microscopic conditions are entirely different; there being an abrupt limit between the two tis- sues. Here the muscular fibres end neatly in an obliquely truncated extremity, with.a projecting surface, slightly conoidal, or sometimes per- ceptibly attenuated, and always rounded; and meters. (Kcutker.) A muscular fibre, (a), from one of the inter- nal intercostal muscles of man, continuous into a tendinous fasciculus (b), into which it passes without any defined li- mit.—Magnified 350 dia- 1 Dr. Leidy has described a double spiral arrangement of the tendinous fibres arjound the myolemma. 412 THE TISSUES. attached at a more or less acute angle to the surfaces of the tendons and aponeuroses, and on the borders of the former. (Fig. 265.) Fig. 265. Disposition of the muscular fibres at their oblique insertion into the tendon of the gastrocnemius of man. a. A portion of the tendon cut longitudinally, b. Muscular fibres, with slightly conical or truncated extremities, affixed in small depressions on the inner aspect of the tendon; with the sheath of which the perimysium internum (c) is connected.—Magnified 350 diameters. (Kolliker.) Still, the connection is of the most intimate kind; the extremities of the fibres being inserted into minute pits in the surface of the tendon, while the perimysia interna are continuous with the areolar sheaths of the fasciculi of the tendon. In muscles which have been boiled, the sacciform blind extremity of the myolemma may be seen. In no case does Kolliker find the tendinous fibres connected with the myolemma merely, as stated by Beichert. The preceding arrangement obtains whenever muscular fibres and tendons meet obliquely (all penniform and semi-penniform muscles), and whenever tendons of insertion commence as membranous ex- pansions (soleus, gastrocnemius, &c). And even where tendons and aponeuroses join the muscle in a straight line, there is a greater or less number of fibres which are connected in this way, though most undergo a transition, as described at the commencement of the preceding paragraph. II. The tendons are connected, at their distal extremity or inser- tion, with bones, cartilages, fibrous membranes (sclerotica, tendinous fasciae), ligaments, and synovial membranes (subcruralis, &c). The aponeuroses of origin are also connected with the same parts; and their manner of connection is therefore the same as that of the ten- dons, to be described. The tendons are connected with the bones and cartilages, either first, directly; or, secondly, indirectly—i.e. through the intervention of the periosteum and the perichondrium. 1. In the former case, the periosteum is entirely wanting where the muscle is inserted, and the tendinous fibres and fasciculi rest at VESSELS OF THE MUSCLES. 413 Fig. 266. an acute or a right angle directly on the surface of the bones, being blended with all its elevations and depressions. Close to the bones, the tendons frequently contain delicate isolated cartilage-cells. (Fig. 224.) Sometimes the tendinous fibres are, next the bone, entirely incrusted with calcareous salts, in the form of granules (ossified). This kind of direct connection obtains in the tendo-Achillis, the tendons of the quadriceps femoris, pectoralis major, latissimus dorsi, deltoid, psoas, iliac, glutaei, &c. (p. 346). 2. In case of indirect connection of the tendons, their fasciculi and fibres are continuous with those of the periosteum, fasciae, fibrous membranes, &c, respectively. The insertion of muscles into the areolar tissue of the skin and mucous membranes, without the interven- tion of tendons, should be alluded to here. This is best seen in the tongue and the facial muscles of mammals. Here the mus- cular fasciculi lie in the subcutaneous areo- lar tissue, maintaining the same diameter till they nearly reach their insertions.— Then they divide into several branches, each tapering to a conical extremity, or di- viding into a number of delicate pointed processes. In either case, the fibres gra- dually or suddenly lose their striation, and pass into the nucleated bands of the white fibrous tissue. No myolemma can be seen in the branched ends of the muscles, but the white fibrous tissue is directly continuous with the matrix of the muscular fibres. The Vessels of the Muscles. The arterial trunks reach the muscles in an oblique or transverse direction, and then subdividing, run in the perimysia interna in an arborescent manner, and at an acute or obtuse angle, so that every part of the mus- cle is supplied by them. The minutest arte- ries and veins usually run parallel to the muscular fibres, between which they form a plexus, so characteristic as never to be mis- taken after being once seen. (Fig. 266.) to v Capillaries of a small fascicu- lus of muscular fibres from the neck of the dog. a. Terminal twig of the artery, v. Terminal twig of the vein. p. Plexus of capillaries, e. Single muscular fibre, to show the relative size and direction of those to which the capillaries, here represented, are distributed. 414 THE TISSUES. The longitudinal vessels of the network lie between the fibres, and the transverse ones unite in various ways with the former. Thus each separate fibre is surrounded on all sides by minute vessels, and hence abundantly supplied with blood. The longitudinal vessels are seen in a transverse section of a fasci- culus (Fig. 267) lying in passages in the internal perimysium. The capillaries of muscle are among the smallest in the human body, their diameter being often less than that of the blood-corpuscles themselves. In the pectoralis major, when filled with blood, they measure g^ to ^Vtf of an inch; and, when empty, ^^^ to eoW of an inch. (Kolliker) The tendons present no bloodvessels in the innermost portions, and the smallest are entirely non-vascular internally. The latter, however, present vessels in the sheath inclosing them; and the largest have vessels both in the sheath and in the deeper layers. (Fig. 176.) Yery few lymphatic vessels are found in the muscles. Indeed, the smaller (omo hyoid, subcrural, &c), have none at all, either in their substance or upon their surface; and among the largest mus- cles, it is only in some that solitary lymphatics, fo to Jg of an inch n diameter, are seen accompanying the bloodvessels. It is proba- ble that these do not run among the fasciculi, but in the more vas- cular perimysia between the larger and laxer subdivisions; and especially when the latter contains adipose tissue, and is therefore soft, as in the glutaeus, and in the superficial layers of the muscles. No lymphatics have jet been found in the tendons, aponeuroses, or the synovial capsules of the muscular system. They may, how- ever, exist in the areolar tissue under the latter; as in the subse- rous areolar tissue of the joints. Nerves of the Muscles. The nerves of the muscles come into contact with the fibres only at a few points comparatively, and not throughout their length. The trunks divide pretty suddenly on entering the muscles, into several anastomosing subdivisions, which give off still smaller loops Fig. 267. Transverse section of three fibres of the dried pectoral muscle of the teal (querquedula crecca), treated with weak citric acid; showing the round refract- ing particles separated from one another. The cut edge of the tubular sheath (in- ternal perimysium) of each fibre is also seen, as well as the capillary vessels (a) in the intervals. NERVES OF THE MUSCLES. 415 inclosing the fasciculi, and passing among the individual fibres. ("Fig. 268.) Whether there are also free terminations of the nerve- fibres in man, besides these loops, such as exist in the lower animals, is not certainly determined. Fig. 268. fc=Z Form of the terminating loops of the nerves of the muscles. The trunks entering the muscles are composed mostly of the thick (medullated) nerve fibres; there being only twelve of the finer, on an average to one hundred of the larger. (Volkmann) In the in- Flg' terior of the muscle they, how- ever, become smaller; so that the fibres of the terminal plexus are only tsW t0 4hV Th fr rela. of a new-born child, mag- -J""" l&uu nified250diameters; and tive size, therefore, in the foetus at four months, treated with acetic acid, ,i i i -i j j .1 j i. i -i n r> to show the formation the new-born child, and the adult, are as 1 :1.8 : 6; of the fine elastic fibres. so that the growth of the tendons, after birth at least, seems due to the increased thickness and elongation of their fasciculi; while their number also is constantly increased during foetal life. Pathological States of the Muscles and their Accessories. The pathological states of the striated muscular tissue have already been specified (p. 406); of which hypertrophy, atrophy, paralysis, fatty degeneration, and softening are the most important. The most common pathological state of the tendons and aponeu- roses is atrophy, consequent on the same condition of the mus- cular fibres, and disease of the muscle. The tendons also become shortened in case of talipes (club-foot) and other deformities; since changes in the relations of the bones have brought the points of in- NERVOUS TISSUE. 423 sertion of the tendons abnormally near to the belly of the muscle. Hence the propriety of dividing the tendons, and bringing the bones into their normal relations, in such cases; after which, the former assume the normal length by a new formation of collagenous tissue between the divided extremities. The vaginal sheaths of the tendons, especially of the extensors of the fingers, are liable to dilatations and-accumulations of the syno- vial fluid, forming protrusions called ganglia. The most common seat of the ganglion is on the dorsum of the wrist. The synovial sacs of the muscular system (bursas mucosae) are also liable to inflammation, and consequent distension, from the fluid they contain. The affection usually termed "housemaid's knee" is an inflammation of a synovial sac, not connected with the muscular system, but existing between the patella and the skin covering it. CHAPTER X. NERVOUS TISSUE, AND THE STRUCTURE OF THE NERVOUS SYSTEM. SECTION I. THE NERVOUS TISSUE. Two forms of the nervous tissue are to be described:— I. The fibrous or tubular nerve-tissue. II. The vesicular or cellular (nerve-cells). I. Fibrous or Tubular Nerve-Tissue. This form of nerve-tissue is termed tubular, because, when de- veloped in the highest degree, it presents the form of tubes inclosing a fibre. In other cases, however, the tube is wanting, and then the term "fibrous" is more appropriate. The latter are far more minute than the former; and hence these two forms have been called by Kolliker the coarse and the fine nerve-fibres. (Fig. 272.) There is also a medium size, averaging about the j^Vtt °f an incn m dia- meter. The coarsest nerve-fibres are even T50^ of an inch in diameter; while the finest have only ^ this diameter, or 24^^ of an inch. 424 THE TISSUES. The length of the nerve-fibres also varies extremely; since they have one extremity in the part where they are distributed, while the other enters the ence- Fig. 272. Nerve-fibres. 1. From the dog and rabbit, in their na- tural condition: a, fine ; 6, of medium thickness ; c. coarse fibre from the peripheral nerves. 2. From the frog, with the addition of serum : a, drop of the contents expressed; 6, axis-fibre within the drop continued into the tube. 3. From the spinal cord of man; recent, with serum add- ed : a, neurilemma ; b, medulla with double contour ; c, axis-fibre. 4. Double contoured fibre from the fourth ventricle in man; the axis-fibre (a) projecting, and visible within the fibre. 5. Two isolated axis-fibres from the cord, one undulated, the other of unequal thick- ness, with some medullary substance attached to it.— Magnified 350 diameters. (KbUiker.) phalon or spinal cord (to constitute their white or fibrous portions), or termi- nates in ganglia. 1. The Coarse (large) Nerve- Fibres. It is, of course, impossible to draw any precise line between the coarse" and the medium nerve-fibres, since all grades of size are found between their extremes of iVuu °f an *ncn as tne dia- meter of the coarsest, and 2 4CTFU as tnat °f ^e finest fibres. Nor is it of any importance that the inter- mediate should be distin- guished as such; since they appear to present no pecu- liarity in structure or func- tion. Kolliker, however, mentions as coarse fibres those above 3TT70 ofan inch; as medium those from g^1^ to -gtyVir of an inch; and as fine those less than g^Vu °f an inch. All the nerve-fibres, when examined in their recent state, and by transmitted light, appear perfectly transparent, and with simple dark contours. By reflected light they appear opaline, like fat, and, in large quantities together, white; but generally they do not ap- pear to be composed of different constituent parts. All the coarse fibres may, however, be shown to consist of (Eig. 273, and Fig. 272, 3,4)— LARGE NERVE-FIBRES. 425 A. The envelop, or neurilemma. B. Its contents, the neurine; consisting of the medulla and the axis-fibre. (Fig. 274.) A. The neurilemma1 is formed of simple membrane, and resem- bles elastic tissue, but is less soluble in alkalies. Histologically, it very much resembles the myolemma of striated musdular fibre, and has nuclei upon its inner surface (p. 393, 1). It has not yet been demonstrated in the finest fibres. Moreover, in case of the largest tubes it disappears both at its distal extremity, where it is distributed, and also in the brain or spinal cord, on tracing it to its origin. Sometimes, also, it is wanting even in the coarser fibres through a con- siderable extent of their terminal portions. B. The contents of the neurilemma are a homogeneous substance during life, accord- ing to certain observers;- and the appear- ances described by Rosenthal and Remak are regarded by such as due to post-mortem changes. The conclusions of Kolliker on this question are adopted here. Two entirely distinct substances are con- tained in the nerve-tube; a difference in color, however, and density, being apparent only after death. These are:— 1. The axis-fibre. 2. The nerve-medulla, or pulp. 1. The axis-fibre (Kolliker), primitive band (Remak), or axis-cylin- der (Rosenthal), is a pale, soft, cylindrical or slightly flattened, but An axis-fibre (c) is seen prolonged some way beyond the broken edge of its neurilemma and the white substance, or medulla (d). 1 From vi~pov, nerve, and Xs^a, a coat or sheath. This term is used to correspond with the myolemma of muscular tissue; while the perineurium and the perimysium also correspond. Nerve-tubes of the common eel. a. In water. The delicate line on its exterior indicates the neu- rilemma ; the dark double-edged inner one is the white substance of Schwann (medulla), slightly wrinkled, b. The same in ether. Several oil-globules have coa- lesced in the interior, and others have accumulated around the ex- terior of the tube. The white sub- stance has in part disappeared. (Magnified 300 diameters.) 426 THE TISSUES. elastic fibre (Fig. 274), in the centre of the tube, and usually occu- pying about one-third of its diameter. It is generally homogeneous, though rarely faintly striated or finely granular; is usually through- out of uniform size, solid, and resembles coagulated albumen. It generally pursues a straight course, but may be curved or slightly undulating (never varicose), with an irregular border. Chemical reagents also show that it contains not a trace of fat, but is an albu- minous compound; though it is not identical with the fibrine of the blood, nor the peculiar element of muscular tissue (musculine). Analogically with the latter immediate principle, it may be termed nervine. The axis-fibre is found in all, even the very finest, nerve-tubes; and in the latter, it only can always be satisfactorily demonstrated. Its size varies with that of the nerve-fibre itself. During life, how- ever, it cannot be distinguished from the medulla which surrounds it. In the acoustic nerve of the sturgeon, Czermak has demonstrated the existence of bifurcating axis-fibres in dividing nerve-fibres. 2. The nerve-medulla, or pulp, is a thick, viscid fluid, like thick oil of turpentine, mostly composed of fatty matter, and filling all the space between the axis-fibre and the inner surface of the neuri- lemma. Consequently it occupies the two remaining, or external, thirds of the diameter of the tube. In other words, it is itself a viscid, fluid, hollow cylinder, completely inclosing and isolating the solid axis-fibre, which is placed within it. Hence its designation, also, as the medullary sheath. It has also been called the "white substance of Schwann." The entirely different chemical reactions of the medulla and the axis-fibre, would seem to demonstrate their distinct existence and function; though the microscope does not distinguish them during life. It is the medulla that gives the dark border to nerve-tubes under the microscope; and such are therefore termed medullated or dark-bordered tubes. Although the axis-fibre exists in every nerve-fibre, many are met with which have no medulla—non-medullated fibres. These consist of the neurilemma, the axis-fibre, and an intervening fluid, some- times identical in appearance with the latter, and sometimes similar but more clear. These rwm-medullated fibres are also found to occur in continuation of the medullated, both when they communicate with the nerve-cells in the encephalon and spinal cord, and also at the peripheral extremities of the fibres. FINE NERVE-FIBRES. 427 The medulla is rapidly and invariably altered by the application of cold water, of most acids, &c. This change consists principally in a coagulation of it, sometimes occurring from without inwards, and involving the entire thickness, or only its outermost layer. In the latter case, the nerve-fibres of dou- ble contour lines are produced; in the former, the contents become ap- parently wholly grumous or opaque. The neurilemma gives the single con- tour line. Sometimes, also, the me- dulla accumulates into larger masses in places, and thus the frequently de- scribed varicose appearance of the nerve-fibres is produced. (Figs. 275 and 273.) In this change the neuri- lemma participates; but in all those mentioned, the axis-fibre takes no part. By pressure, the medulla may be made to assume all possible forms. 2. The Fine Nerve-Fibres. The finest nerve-fibres (Fig. 298,3) are only zihss °f an bach in diame- ter; and in these neither neurilemma nor medulla can be demonstrated, only the axis-fibre being apparently present. Most of them are, however, TS&Titf ^o 5(fVo °f an inch; but these also have no proper medulla—/, e. are /■ The medlllla and axis-cyiinder inter- . rupted by pressure, while the neurilemma ?ion-medullated. But ihey contain between fhe axis-fibre and the neuri- lemma a substance sometimes resem- bling the axis-fibre of other nerves, and sometimes more clear. These are often called pale nerve-fibres, as they have only a single contour line. In the nervous centres, also, they frequently present a varicose ap- pearance. (Fig. 275, g') It has already been seen, however, that a nerve-fibre may be me- dullated, coarse, and have a neurilemma, in one part of its course, A. Diagram of a tubular fibre of a spinal nerve, a. AKis-fibre. 6. Inner border of medulla, c, c. Its outer border, d, d. Neurilemma.—B. Tubular fibres, e. In a natural state, showing the parts as in a. remains, g. The same, with varicosities. h. Various appearance of the medulla and axis-fibre, forced out of the neurilemma by pressure, i. Broken end of an axis-fibre with the medulla closed over it. k. Lateral bulging of medulla and axis-fibre from pressure. I. The same, more complete, g'. Varicose fibres, of various sizes, from the cerebellum. (Magnified 320 diameters.) 428 THE TISSUES. while it is non-medullated, pale, or even consists of the axis-fibre alone, in another part. The division into coarse and fine fibres is therefore more important, doubtless, in a histological than in a phy- siological point of view. The axis-fibre alone is a constant structure. Pale or non-medullated fibres naturally occur in the following situations: 1. Those of the Pacchionian bodies; 2. The nucleated pale fibres in the terminations of the olfactory nerves;. 3. The per- fectly transparent non-nucleated fibres in the cornea; 4. The pale processes of the nerve-cells in the central organs and ganglia. It will appear that all the nerve-fibres of the embryo are in the con- dition of the pale fibres now under consideration. We, however. find them in different stages of development in the adult. In the olfactory nerve they remain altogether in the embryonic stage, the contents being much less consistent than an axis-fibre. In the Pac- chionian bodies their contents in all respects represent an axis-fibre; and the processes of the nerve-cells often exactly resemble an axis- fibre, though they are frequently of a softer consistence, correspond- ing with the contents of the nerve-cell.—In the invertebrata, only the pale nerve-fibres are found. The preceding are the only forms of fibres found in the cerebro- spinal nervous system. But is there not still another variety of nerve-fibres (gray fibres) peculiar to the sj'mpathetic or ganglionic nerves? So far as any peculiar appearance under the microscope is con- cerned, the reply may be decidedly in the negative; though Bidder and Volkmann maintained that these fibres are smaller than those in the cerebro-spinal nerves, and also in other respects different. The fact is, the cerebro spinal nerves contain dark-bordered tubes of all sizes, from the finest to the largest; those derived from the sensitive roots of the spinal nerves being generally finer than those from the motor roots. But the branches of the sympathetic also contain the same varieties of nerve-fibres, the only perceptible dif- ference being that the proportion of the finer tubes, T^^xnr to sbou °f an inch in diameter, is greater in the sympathetic nerves. Some of these fine fibres are also known to originate in the ganglia of the sympathetic, but in a manner similar to the origin of the fine fibres of the cerebro-spinal»nerves in the cord and the encephalon. We also find fine fibres, precisely like the so-called sympathetic fibres, constituting the distal termination of the coarsest nerve-fibres; and that all the coarsest double-bordered nerve-fibres are, at a particular GELATINOUS NERVE-FIBRES. 429 period of their development, precisely in the condition of these fibres of the sympathetic. Finally, it is even true that the same fibre in the adult is often seen to assume all possible varieties of size in different portions of its course. There are, therefore, no nerve-fibres peculiar to the sympathetic nerves; there being only the fine and the large fibres already de- scribed as existing in the cerebro-spinal system. How, then, may we dispose of still other fibres found more espe- cially in the peripheral branches of the ganglionic (sympathetic) nerves—the "gelatinous fibres," or "fibres of Remak?" These, when isolated, present the aspect of flat, pale fibres, 57frT to ^v of an inch wide, and 2T£TT of an inch thick, of an indistinctly striated, granular, or more homogeneous substance. In these, acetic acid shows elongated or fusiform nuclei, averaging about 5J0C of an inch in length, and 7HV to 3^ of an inch in diameter, with very fine filaments extending from both sides, of 5^5^ to -^-q^-q of an inch. 5. The external layer of the retina is the bacillar layer, or Jacob- son's membrane (m). Its structure is very remarkable, presenting two elements—the rods (bacilli) and the cones (coni)—blended together in a single layer, 3^3 of an inch thick at the bottom of the eye, 5£g more anteriorly, and quite in front not more than g^ of an inch. The rods are cylindrical, slender, elongated corpuscles, consisting of two portions, the larger external end, or proper rod, and the internal, or filament. The former is a cylinder TBV^ to g^ of an inch long, and T5&00 °f an inch broad, and truncated at the outer end; while the inner is produced into a short point, goVtr to ^Vu of an inch long from the inner extremity of the rod; is of uniform width, and extends through the inner half of the bacillar layer. The substance of the rods is clear and homogeneous, with a faint, glistening, fatty aspect, and is very soft, flexible, and fragile. They Fig. 298. Retinal elements of man. 1. "Rods" and radiating fibres: k, proper "rod;" r prolongation of its pointed inner extremity ; h, "granule" (cell) of the outer granular layer ; I, enlarged extremity of the radiating fibres, proceeding from them to the surface of the optic layer; V " rod" seated on a "cone" (i); r1, fibre proceeding from the latter, connected with the "granule" (/) of the inner granular layer, and the terminal enlargement (I) on the inner surface of the retina ; n, one of the fibrous bundles in which the radiating fibres frequently terminate at their innermost extremity. 2. Rods torn from their fibres. 3. Fibres of optic nerve ; c, fine—a and b, varicose. 4. Two cones torn from their processes, d; with attached rod, a, at outer end; c, nucleus.—Magnified 350 diameters. (Kolliker.) ENCEPHALIC NERVES. 453 Fig. 299. are much altered by all reagents; and a very common change con- sists in their end presenting a hook-like curve or a slight enlarge- ment. (Figs. 298 and 295, m') The cones may be regarded as rods terminating internally in a conical or pyriform body (instead of a filament), whose length equals one-half the thickness of the bacillar layer, and its breadth being -grfw to je'sg °f an inch. Each of these cones has an exter- nal thicker and larger, finely granular extremity, often ventricose, gradually diminishing in size, and passing into a common rod with- out a point; and a shorter inner portion, inclosing an elongated or pyriform, more opaque, and brilliant body, genu to 4sW of an inch long. Kolliker, how- ever, sees in these cones, as just described, only a cell with a nucleus. (Fig. 298, 4.) The rods and cones are arranged vertically upon the retina, like palisades in close appo- sition, one of their ends being directed to- wards the choroid membrane, and the other towards the granular layer. The appearance of the cones and rods when the bacillar layer is seen from without (the cones alone existing over the macula lutea), is shown by Fig. 299. 3. The eighth pair is the nerve of hearing. The acoustic nerve is composed of fibres g^o^ to 24W °f an inch in diameter, which are very easily destroyed^ and are invested by a very delicate perineurium. Hence it has been called the portio mollis. Among these fibres in the trunk, and in both the vestibular and cochlear branches, there occur numerous apolar, unipolar, and bipolar cells, gJc to T4T of an inch in diame- ter. Kolliker suggests that the first two kinds are truncated bipplar cells. Similar but smaller cells are also found in the cochlea, as well as in the nervous twigs in the vestibule. The vestibular nerves finally break up into a rich bundle of smaller and frequently anastomosing branches, which appear to terminate ultimately in fine twigs composed of from two to ten primitive fibres, T2o-TrTT to 5oW °f an inch thick. In the sacculus we find the otoliths in immediate relation with the nervous expansion. These are composed of innumerable hexahedral prisms of carbonate of lime. Bacillar layer from without. 1. At the "yellow spot" (only cones). 2. At the border of the same. 3. From the mid- dle of the retina, a. "Cones," or vacuities corresponding with them. b. "Hods" of the " cones," whose terminal sur- face is often placed rather more deeply than that of the proper "rods," e.—Magnified 350 diameters. (Kolliker.) 454 THE TISSUES. Fig. 300. A highly magnified view of a small piece of the lamina spiralis, showing the manner in which the nerves leave their perineurium as they anastomose ; the natural size of the piece is seen on the side of the figure. 1. Portion of the auditory nerve. 2,2. Osseous canals in the zona ossea of the lamina spiralis. 3, 3. Anastomoses in the zona mollis. 4, 4. The neurilemma leaving the nervous loops, and expanding into the zona memhranacea. Fig. 301. The cochlear nerve, having entered the cavity of the osseous zone from the canal of the modiolus, forms a plexus (Fig. 300) of dark-bordered fibres, g^^ °f an inch in diameter, containing an aggre- gation, at a definite spot, of, at first, 1\^ of an inch wide, of bipolar, oval, minute (yoW to 7f-$ of an inch), and pale ganglion-cells; and which probably intercept all the fibres of the cochlear nerves in their course. (Fig. 301.) The dark-bordered fibres proceeding from the external side of these cells are again disposed in anastomosing, and afterwards in parallel flat- tened bundles. The fibres actually terminate by being pale, T2^^ °f an inch in diameter, and finer; and then ceasing, there being no loops. (Corti) Thus both the auditory and the optic nerves Bipolar ganguon-ceii kave a ganglion at their periphery, which proba- from the zonula ossea of . the lamina spiralis of bly receives the impressions, while the nerve- Leml7.Xfiec^g fibres merel? serye t0 conduct them t0 the brain- STRUCTURE OF THE NERVOUS CENTRES. 455 II. Structure of the Nervous Centres. The nervous centres are— 1. The spinal cord. 2. The encephalon: consisting, 1st, of the medulla oblongata and the pons Varolii; 2dly, the cerebellum; Bdly, the cerebral ganglia; and, 4zthly, the cerebral hemispheres. The centres consist of the white and the gray nerve-substance combined; the former being made up of nerve-fibres alone (and vessels), the latter of nerve-cells and nerve-fibres combined, toge- ther with (in the cerebellum and cerebral hemisphere) a granular substance and free nuclei. The gray substance is also abundantly supplied with vessels. The whole cerebro-spinal axis (i. e. the cen- tres just mentioned) is also enveloped by three distinct membranes; which will be considered after the structure of the former has been described (p. 468). Fig. 302. Transverse section of human spinal cord through the middle of the lumbar enlargement, showing on the right side the course of the nerve-roots, and on the left the position of the principal tracts of vesicular matter. A, A. Anterior columns. P, P. Posterior columns. L, L. Portion of lateral columns, a. Anterior median fissure, p. Posterior median fissure. b, b, b, b. Anterior roots of spinal nerves, c, c. Posterior roots, d, d. Tracts of vesicular matter in anterior column, e. Tracts of vesicular matter in posterior column. /. Spinal canal, not normal, g. Substantia gelatinosa. 456 THE TISSUES. I. Structure of the Spinal Cord. While the white substance of the cord is composed almost exclu- sively of nerve-fibres, the gray portion is formed, in almost equal proportions, of nerve-fibres and cells. A section of the cord shows the gray matter forming a column in the central part of each half of the cord (Fig. 302), whose transverse section is of a crescentic form, its two extremities being termed the anterior and the posterior horns. The white substance surrounds and incloses the gray on every side, except towards the median line, where the gray matter projects through the white, and thus comes into contact from the opposite sides, constituting the gray commissure. This does not normally, in man, contain any canal in its centre, but is constituted principally of nerve-cells of a yellowish color, and is called the substantia grisea centralis. The white matter in the two halves of the cord merely comes nearly into contact behind the gray commissure; but in front of the latter it is continuous from one side to the other, constituting the anterior or white commissure. The portion of each half of the cord between the anterior median fissure and the anterior roots of the spinal nerves, is termed the anterior column; that between the posterior median fissure and the posterior roots, the posterior co- lumn; and the remaining portion between the anterior and posterior roots, the lateral column. At the extremity of the posterior horns of the gray matter is a more transparent layer, containing a prepon- derance of smaller nerve-cells—the substantia gelatinosa of Roland. The gray columns vary considerably in their size and form in dif- ferent parts of the cord, as shown by transverse sections; it being most abundant in the lumbar, and next in the cervical region. 1. On examining the intimate structure of the cord, we find in the white matter two sets of fibres, the longitudinal and the hori- zontal, or transverse. The longitudinal fibres are found in all situations except the ante- rior commissure, are unmixed with horizontal fibres in every part, as a rule, and everywhere run parallel to each other, without either interlacement or being collected into smaller fasciculi. They in- crease from below upwards, since they successively pass inwards towards the gray matter in their descent. They average g^1^ to sthjtj of an inch, and the size of each fibre remains very nearly the same in the white substance; no divisions or other alterations in diameter being found. These fibres are probably continuous with STRUCTURE OF THE SPINAL CORD. 457 the horizontal fibres next to be mentioned, being intermediate be- tween the latter and the fibres of the cerebrum. The transverse or horizontal fibres occur, 1st, in the lateral and posterior columns adjoining the horns of the gray substance; Idly, in the white commissure; and, Sdly, at the point of entrance of the roots of the nerves. The first will be described with the gray sub- stance.—The fibres in the white commissure come from the anterior columns, and, bending obliquely inwards, cross in front of the gray commissure to the opposite side. The white commissure is thus a decussation of the anterior column, and not a commissure, as gene- rally understood. The decussing fibres measure TTj^7j^ to y^^ of an inch, and decrease as they diverge in the anterior horns of the gray matter.—The fibres in the roots of the spinal nerves are con- tained in larger fasciculi, either horizontal, or slightly ascending between the longitudinal fibres to enter the anterior and posterior horns of the gray matter, where we shall again meet them. The fibres do not all communicate with the longitudinal; and in their posterior roots about two-thirds of them measure 3 oW to T-g\^ of an inch, and one-third of them yuVxr to y oVtt °f an inch. In the anterior roots about three-fourths of the fibres measure from 5^Vu to y^gr of an inch, and one-fourth of them -g^^ to yoVo °f an inch. They, however, constantly decrease in size as they proceed through the white matter, and when they enter the gray matter the motor fibres are only 30V0 to sttVo °f an inch, while the sensory are but Tohiso to 4355 of an inch. 2. The nerve-fibres of the gray substance of the cord are very numerous, constituting, in any case, one-half of its bulk, or more. They present the same characters as the fibres of the white sub- stance, except that they are not, on the average, more than one-half as thick (f^hw °f an inch). As they pass among the nerve-cells of the gray matter, some of the motor fibres have no connection with the processes of the cells; but continue to run in the anterior horns to the lateral parts of the anterior commissure, and become continuous with the fibres of the latter. Thus some of the motor fibres are connected with the lon- gitudinal fibres of the anterior columns, with a total decussation. Many of the motor fibres, however, take no part in this decussation, especially those which enter the anterior horns most externally. These penetrate transversely to various depths (one-half or more), then curve upwards, and finally appear as longitudinal fibres. Thus 458 THE TISSUES. another portion of the motor fibres is continuous with the longi- tudinal fibres of the same side, without any decussation. It should be added that though the motor fibres diminish in size after entering the cord, till they enter the gray matter, where they are about goVo °f an inch in diameter, they again enlarge as they emerge from the latter, but never so as to attain their original dia- meter. The sensitive roots also penetrate the white matter of the cord to the posterior horns of the gray matter, and proceed, without any direct connection with the nerve-cells, quite through the sub- stantia gelatinosa into the sub- Fig. 303. stantia grisea. From this point some of the fibres bend up- wards nearly at a right angle, and proceed to become longi- tudinal fibres in the posterior columns. Another portion of them penetrates, in a fascicular form, between the above-men- tioned longitudinal bundles, fur- ther forwards, losing themselves in the posterior and the lateral columns, and also extending into the gray commissure pro- . bably on the opposite side. (Fig. 303.) The sensory fibres also de- crease in size as they traverse the cord, till they reach the gray commissures; being y^^ of an inch in the roots them- selves, never more than ^Vo of an inch in the substantia gelati- nosa, ys^ to y^ of an inch in the substantia grisea, and onlJ Tshms to TTj&TjTj of an inch in the gray commissure. They, however, also increase on leaving the latter, to from T7SUv to ^v of an inch, and afterwards become longitudinal fibres. Besides the motor and sensory fibres, there are still others in the Vertical and antero-posterior section through the cord, midway between the gray cornua and the point of entrance of the roots of the nerves, a. Posterior column, with the sensitive roots (h), traversing it. b. Substantia gelatinosa. c. Prolongations of the posterior roots, which bend round in front of the substantia gelatinosa, and run longitudinally in order there to join more particularly the posterior column, d. Basis of the posterior cornua, with the ends of the horizontal portion of the sensitive roots apparent (from their being cut across), e. Anterior cornua, with the large nerve-cells (the spots), and also the horizontal and divided continuations of the motor roots. /. Anterior column traversed by the motor roots (i).—Magnified 25 diameters. (Kolliker.) STRUCTURE OF THE SPINAL CORD. 459 gray substance, not referable to the roots, and which for the present may be termed special fibres of the spinal cord. The gray substance of the cord, in addition to the fibres just de- scribed, contains cells presenting various forms, but all being inva- riably furnished with processes, which, after repeatedly branching, ultimately Fi§- 304' terminate in extremely fine pale fibrils, like the finest axis-fibres. Kolliker distinguishes three classes of nerve- cells. 1. The cells of the central gray substance (Fig. 304) measure ^tt to ts1ott °f an inch; are always pale and granular, with multiple nuclei and branching pale processes. These con- stitute the principal bulk of the cen- tral gray substance. 2. The cells of the substantia gelatinosa resemble the preceding, except that they are of a faint yellowish color, and have one to three processes, and simple nuclei. 3. Well-marked cells are seated espe- cially at the apex of the anterior horn (Figs. 279, 280), though also occurring Cells from the grav central SUT,stance0f in other portions of the anterior, and the cord in man.—Magnified 350 diame- . ... , ters. (Kolliker.) in less number in the posterior, horn; while they are never met with in the substantia gelatinosa and the gray commissure. All these cells are y^7 to 2£¥ of an inch in diameter, with nuclei of 3tuu to t^otj- °f an inch; frequently con- tain brown pigmentary matter, and have from two to nine or even more branched processes, 3 oVtt to 24-VxT °f an inch in diameter at their origin. These processes may be traced to a length of y^ to /o of an inch, and terminate in fine fibrils, scarcely more than 3 ului) °f an inch thick, all of which are contained within the gray substance. Do the nerve-fibres of the roots of the spinal nerves terminate in the white and gray matter of the cord? or do they all ascend to the brain? Volkmann maintains that they terminate in the cord, and has carried most physiologists with him. We, however, regard Kolliker's reasons for the belief that they proceed to the brain, as far more satisfactory. That the nerve-fibres become attenuated on entering the cord, has already been shown. And the further fact 460 THE TISSUES. that the white substance of the cord constantly increases from be- low upwards, and that the enlargements of the cord depend mainly upon the gray substance, has an important bearing on this question. Moreover, no connection has been discovered between the nerve- fibres in the cord, and the processes of the cells of its gray matter. Still, it by no means follows that these cells may not act on the fibres sent among them; and experimental physiology at present demands the admission that they do impart motor impulses to them, at least in the production of reflex or diastaltic motions. II. Structure of the Encephalon. 1. The Medulla Oblongata and Pons Varolii. The medulla oblongata and pons Varolii constitute a very import- ant part of the encephalon, since ten of the twelve pairs of encepha- Fig. 305. Transverse section of the medulla oblongata through the lower third of the olivary bodies. (From Stilling.) a. Anterior fissure. 6. Fissure of the calamus scriptorius. c. Raphe\ d. Anterior co- lumns, e. Lateral columns. /. Posterior columns, g. Nucleus of the hypoglossal nerve, contain- ing large nerve-cells, h. Nucleus of the vagus nerve, i, i. Gelatinous substance, k, k. Roots of the vagus nerve. I. Roots of the hypoglossal or ninth nerve, m. A white bundle of longitudinal fibres connected with the root of the vagus, n. Soft column. (Zartstrang, Stilling.) o. Wedge-like column. (Keelstrang, Stilling.) p. Transverse and arciform fibres, q. Nucleus of the olivary bodies. r. The large nucleus of the pyramid. *, s, s. The small nuclei of the pyramid, u. A mass of gray substance near the nucleus of the olives (Oliven-Ncbenkern), u, q,r, are traversed by numerous fibres passing in a transverse semicircular direction, v, w. Arciform fibres, x. Gray fibres. (4 diam.) THE MEDULLA OBLONGATA AND PONS VAROLII. 461 lie nerves (all but the first and second pairs) rise from these and the crura cerebelli. It is not consistent, however, with the object of this work to describe their complicated structure at length. A section of the former is shown by Fig. 305. 1. The white substance of the medulla oblongata is in part continu- ous with that of the cord, and partly distinct from it; and everywhere consists of nerve-fibres of the same dimensions as those of the cord. The anterior columns of the cord (Fig. 306) are partly continued into the outer part of the corpora pyramidalia; and partly ascend both internally and externally to the olivary body, and proceed through the pons Varolii into the posterior corpora quadrigemina on the one hand and the tegmentum of the crura cerebri on the other. The lateral columns divide, on reaching the medulla, into three branches; (1,) ascending mostly into the crura- cerebelli, and, in small part, into the tegmentum; (2,) decussating in two or three Fig. 306. Fig. 307. Fig. 306. Anterior view of the medulla oblongata, p, p. Corpora pyramidalia decussating at d. o, o. Olivary bodies, r, r. Restiform bodies, a, a. Arciform fibres, v. Lower fibres of the pons Varolii. Fig. 307. Posterior view of the medulla oblongata, p, p. Posterior pyramids, separated by the posterior fissure, r, r. Restiform bodies composed of (c, c) posterior columns, and (d, d,) lateral. a, a. Olivary columns as seen on the floor of the fourth ventricle, separated by (*) the median fis- sure, and crossed by some fibres of origin of (n, n) the seventh pair of nerves. fasciculi with that of the other side (decussatio pyramidum), and forming the principal bulk of the anterior pyramids; and (3,) ap- pearing between the posterior columns at the bottom of the fourth 462 THE TISSUES. ventricle as the posterior pyramids, and being thence continued on the floor of the ventricle, side by side, into the tegmentum of the crura cerebri. The posterior columns (Fig. 307) in part constitute the corpora restiformia, and finally enter the crura cerebelli; while the remainder, situated externally to the posterior pyramids, also enters the tegmentum of the crura cerebri. There is also a system of horizontal nerve-fibres which are independent of the cord, and which are probably commissural. 2. The gray matter of the medulla oblongata is collected into larger masses principally in three situations; viz., in the olivary and the restiform bodies, and in the floor of the fourth ventricle. 1. The gray matter of the olivary body constitutes a capsule, closed on all sides except the inner; and is entirely isolated from all other gray substance. It is traversed by very numerous nerve-fibres of the horizontal system. 2. The gray matter of the restiform bodies may be regarded as a continuation of the posterior horns of the spinal cord, and even presents some resemblance to their substantia gelatinosa. (Stilling) 3. The gray substance of the floor of the fourth ventricle is a continuation of the central gray matter of the cord, and forms a tolerably thick layer from the calamus scriptorius to the ague- ductus Sylvii. The portion in the anterior half of this ventricle belongs properly to the pons Varolii.—Besides these three masses of gray matter, there are other very small ones in the medulla oblon- gata, not requiring a description here. In no case are the nerve- fibres (the horizontal, or those from the cord) known to be conti- nuous with the processes of the nerve-cells. Do the ten pairs of encephalic nerves, mentioned on page 461, rise from the gray matter of the medulla oblongata to which they have been mostly traced by Stilling and others? We deem it most probable that they rise in the corpora striata and optic thalami, for reasons assigned by Kolliker.1 That the gray matter, however, influences the nerve-fibres which traverse it, is at the same time most probable. 2. The Cerebellum. The gray matter of the cerebellum occurs only on the surface of the convolutions, in the nucleus dentatus, and the roof of the fourth ventricle; all the rest being white substance. The latter consists of parallel nerve-fibres, presenting all the characters of central 1 Pp. 377-8. STRUCTURE OF THE CEREBELLUM. 463 fibres (softness, proneness to become varicose, easy isolation of the axis-fibre, &c); and do not require a special description. They average EV^-S of an inch; the extreme being jo&tttt and -joW of an inch. The gray substance of the convolutions of the cerebellum alone requires a special description. It everywhere consists of a layer externally gray, and internally of a rusty color (ferruginous layer). The latter contains nerve-fibres and large masses, of free nuclei- The fibres are continuations of those of the white substance; and extending through the ferruginous layer to the gray layer, they break up into numerous fine fasciculi, so interlaced that the whole ferruginous layer is penetrated by a close but delicate network of fine fibres somewhat resembling the terminal plexus of the acoustic nerve. The free nuclei lie in the meshes formed by the nerve- •fibres; being from B7r»BIJ to ^Vu of an inch in diameter, and fre- quently exhibiting a dis- tinct nucleolus and some- times other granules.— The nerve-fibres, however, do not terminate in the ferruginous layer. Be- coming attenuated mostly to a diameter of y^ur; °f an inch, they enter the ex- ternal gray layer to termi- nate in its inner stratum, which contains nerve-fi- bres and well-marked large nerve-cells; while the outer portion contains no nerve-cells, but merely a finely granular, pale, light-yellowish substance, agreeing in all respects with the already described contents of the nerve-cells. The cells generally in the gray matter resemble those of the cord, already described. Entirely dif- Ganglion-cells, with their processes, nuclei, and nucleoli. a, a. From the deeper part of the gray matter of the con- volutions of the cerebellum. The larger processes are di- rected towards the surface. 6. Another form from the cere- bellum, c, d. Others from the posterior horn of gray matter of the dorsal region of the cord. These contain pigment which surrounds the nucleus in (c). In all these specimens the processes are more or less broken. (Magnified 200 dia- meters.) 464 THE TISSUES. ferent, however, from these smaller elements are the large cells dis- covered by Purkinje, and which are found only in the innermost portions of the gray, next to the ferruginous layer. (Fig. 308, a.) These measure 1\v to y£^ of an inch, are round, pyriform, or oval, with finely granular colorless contents, and 1 to 4 (generally 2 or 3) long and much branched processes; the largest of these being given off from the sides of the cells which look from the ferrugin- ous layer, and jextending nearly to the outer surface (f or f of its thickness), and producing a striation seen in horizontal sections. At their origin these processes are sometimes gx/ou of an inch thick, and very finely granular or delicately striated. As they proceed they become more homogeneous, and divide into numerous ex- tremely slender branches, the ultimate ones being scarcely go^u of an inch thick. Kolliker has traced these processes even $*$ of an inch without coming to the finest subdivisions. While their principal prolongations are thus continued through the gray layer, they give off their branches at acute or right angles, producing a second striation, crossing the one before-mentioned at a greater or less angle. The crura cerebelli contain nerve-fibres only; being a continua- tion of the white matter of the cerebellum itself. 3. The Ganglia of the Cerebrum. Of these there are three pairs; the corpora quadrigemina, the optic thalami, and the corpora striata. (Fig. 309.) All these are bulky collections of gray substance and nerve-fibres. The latter connect these ganglia on the one hand with the cerebellum and medulla oblongata, and on the other with the hemispheres of the cerebrum. They present no histological peculiarities. Nor is it necessary particularly to describe the gray matter in these three ganglia. Kolliker considers it as made out that the fine nerve-fibres traceable to the outermost part of the ventricular nu- cleus (the posterior and inferior portions) of the corpus striatum, terminate there, and do not proceed to the cerebral hemispheres. He also regards it as probable that the fibres becoming attenuated in the optic thalamus and the tubercula quadrigemina, terminate in like manner. At the same time, it appears to be the fact that nerve- fibres rising in the cerebral hemispheres also become attenuated and terminate in these same ganglia. Other parts connected with these ganglia, and containing gray GANGLIA OF THE CEREBRUM. 465 matter, are—the substantia nigra of the crus cerebri, the commissura mollis, the floor of the third ventricle immediately behind and beneath Fig. 309. Diagram of the mutual relations of the principal encephalic centres, as shown in a vertical sec- tion, a. Cerebrum, b. Cerebellum, c. Sensori-motor tract, including the olfactory ganglion (olf), the tubercula quadrigemina, or optic ganglia (opt), and the auditory (and), with the thalami optici (thai) and the corpora striata (c«). d. Medulla oblongata, e. Spinal cord; a, olfactory nerve; b, optic; c, auditory; d, pneumogastric; e, hypoglossal; /, spinal accessory. Fibres of the medullary substance of the cerebrum are shown connecting its ganglionic surface with the sensori-motor tract. the anterior commissure, and the tuber cinereum. The pineal body contains pale rounded apolar cells and scattered nerve-fibres, and generally also a considerable quantity of sabulous matter (princi- pally carbonate of lime, with phosphate of lime and magnesia). The pituitary body contains in its anterior reddish lobe no nervous elements at all, but the "elementary tissues of blood-vascular glands." (Ecker) The posterior smaller lobe consists of a fine granular substance with nuclei and bloodvessels; and also fine varicose nerve-fibres, which, like the vessels, descend from the in- fundibulum. 4. The Cerebfal Hemispheres. The white substance of the hemispheres of the brain consists en- tirely of nerve-fibres, y^^ to y^ of an inch (average g^ of an inch) in diameter. These never form plexiform interlacements 30 v 466 THE TISSUES. or fasciculi, but all run in parallel and generally straight lines, and certainly proceed from the ganglia of the cerebrum and the corpus callosum to the gray substance of the central convolutions. There are also other fibres crossing the former at right angles (commis- sural fibres), of whose origin nothing satisfactory is yet known. The gray matter of the cerebrum is principally situated externally, covering the convolutions, and being | to ^ of an inch thick. It contains in its whole thickness both nerve cells and nerve-fibres; besides a large amount of granular homogeneous substance pre- cisely like that of the cerebellum. It is, however, conveniently divided into three layers; 1, an internal yellowish-red; 2, a middle, pure gray; and 3, an external, white. The first mentioned, however, Fig. 310. Nerve-cells from the internal portions of the gray layer of the convolutions of the human cere- brum, a. Larger. 6. Smaller, c. Nerve-fibre with axis-cylinder.—Magnified 350 diameters. (Kol- liker.) constituting almost one-half the entire thickness of the gray mat- ter, may itself be divided into four layers; 1, a yellowish-red layer (inner part); 2, the inner white streak; 3, yellowish-red layer (outer part); 4, outer white streak. Then come the two remaining layers above; 5, the pure gray, and 6, the white. The nerve-cells through- out the gray matter have from 1 to 6 processes giving off numerous branches, ultimately becoming very fine pale fibrils of 3-50-^3 of an THE CEREBRAL HEMISPHERES. 467 inch. In the external white layer the cells are few and small, with one or two processes, and scattered in an abundant finely granular matrix. The pure gray layer most abounds in cells, and which are also closely aggregated in a granular matrix. Some of them are very small (4^75 to 241u7J °f an inch), appearing frequently as scarcely more than nuclei; while there are others larger, even to 5^ of an inch. (Fig. 310.) Most of them have from 1 to 6 pro- cesses (usually 3, 4, or 5). Finally, in the innermost yellowish-red layer, the cells are less, though still very abundant, and present the same characters as those of the gray substance. The nerve-fibres of the gray substance of the convolutions, come from the white substance of the hemispheres, and penetrate the yellowish-red layer in all directions, but more especially parallel to Fig. 311. Finest nerve-tubes of the superficial white substance of the human cerebrum.—Magnified 350 dia- meters. (Ki'Uiker.) the surface; and consequently they cross the main fasciculi. It is these horizontal fibres which produce the white streaks before men- tioned; and it is in the external white streak that the fasciculi enter- ing the gray substance are lost. The fibres, however, which do not take a horizontal direction, proceed onwards even through the pure gray layer, and into the external white layer. Here they take a horizontal direction, and form several superimposed layers 468 THE TISSUES. of the finest fibres crossing each other in various directions. (Fig. 311.) Many of these fibres also form loops, and return into the gray-red substance, again, as first shown by Valentin (p. 448). Kolliker has not been able to discover any connection between these fibres and the cells of the gray matter of the convolutions; though the existence of such a connection is nowhere else so pro- bable as here. Doubtless the nerve-fibres originate here, if any- where in the central organs. Professor Domrich has, however, traced the many-rayed cells of the cerebellum into nerve-fibres, as he asserts; and Kolliker has found divisions of the nerve-fibres in the cord, but never in the encephalon. It is probable that the fibres of the corpus callosum and the commissural fibres in general, commence in cells in one hemisphere and terminate in the other. Gray matter is also found in the cerebrum at other points; viz., in the anterior portions of the body of the corpus callosum, above the septum lucidum, the fornix, and the corpus striatum; occasion- ally on the surface of the corpus callosum between the raphe and the striae, and which is continued into the fascia dentata of the pes hippocampi, and in the hippocampus itself. The Membranes and Vessels of the Nervous Centres. The whole cerebro-spinal axis, just described, is inclosed in three membranes; 1, the internal, or pia mater; 2, the middle, or arach- noid; and 3, the external, the dura mater. 1. The pia mater is the vascular membrane of the nervous cen- tres. It is composed of collagenous tissue (p. 279, 6), and conducts the vessels into the nervous substance. Hence it is in intimate contact everywhere with the cord, and covers all the elevations and depressions on the surface of the encephalon; excepting alone the floor of the fourth ventricle, above which it stretches across. On the cerebrum it is more vascular and more delicate than upon the cord. It penetrates into the brain only at one point, viz., the trans- verse fissure of the cerebrum—where, under the name of the velum interpositum it invests the vena magna Galeni and the pineal body ; then forms the tela choroidea superior, the choroid plexus of the third ventricle, and the vascular plexuses of the lateral ventricles, which are continuous with the pia mater at the base of the brain. It con- tains fusiform, brdght-yellow, or brown pigment-cells, both in its spinal and its encephalic portions. They are so abundant in the cervical region as not unfrequently Xo give the membrane a brown MEMBRANES OF THE NERVOUS CENTRES. 469 Fig. 312. Jt§ or even blackish color. They are also found in the medulla ob- longata and the pons Varolii, and still more anteriorly. The vascular plexuses, just named, in the ventricles are composed mostly of vessels, and are covered by an epithelium where they are not adherent to the walls of the ventricles. This consists of a single layer of roundish polygonal cells, y^1^ to T2Vtj °f an mcn in diameter, and y^V^ to s^W of an inch thick; containing, besides the rounded nucleus, many yellowish granules, and one or two dark round oil-drops measuring y2o-T5Tj to gTJ^c of an inch. It is not probable that they are ciliated, as asserted by Valentin. Under- neath the epithelium is a simple membrane; and next, the vessels connected by a hyaline homogeneous substance (p. 108). All the portions of the ventricles not covered by the continuations of the pia mater, have a special lining membrane, the ependyma ventriculo- rum. This is a simple conoidal epi- thelium (Fig. 312); and it is separated from the brain-substance bv a fila- mentous layer y^4^ to ^y^ of an inch thick, of embryonic areolar tissue. Virchow and Kolliker did not find it to exhibit ciliary motion, as asserted by Purkinje and Valentin. 2. The arachnoid membrane does not consist of two lamellae, as usually described; but of a single one, the internal one of authors. This is an extremely delicate transparent membrane, corresponding in extent to the dura mater. It is made up of lamellae of fasciculi of white fibrous tissue, surrounded by fine elastic fibres. In the spinal canal it is loosely adherent to the pia mater, by fasciculi of areolar tissue, so that a space, called the subarachnoid space, exists between it and the latter membrane, and which is filled with the cerebro-spinal fluid. In the cranium it is much more adherent to the pia mater. Thus, there is no continuous subarachnoid space upon the brain, but numerous larger and smaller spaces only par- tially communicating. The larger of these spaces (between the cerebellum and medulla oblongata, under the pons Varolii, the crura cerebri, and the fossa Sylvii), open directly into the subarach- noid space of the spinal cord; while the remaining ones do not. The ependyma in man. A. From the corpus striatum ; 1, from the surface ; 2, from the side; a, epithelial cells; b, nerve-fibres lying beneath, b. Epithe- lium-cells from the commissura mollis.— Magnified 350 diameters. (Kolliker.) 470 THE TISSUES. The arachnoid has no connection with the lining membrane of the ventricles. Finally, the free surface of the arachnoid is covered by a simple scaly epithelium. The external lamina, so called, of the arachnoid, is merely a precisely similar epithelium upon the dura mater. 3. The dura mater of the cord (theca vertebralis), is a whitish- yellow, sometimes glistening, firm, and somewhat elastic membrane, formed of parallel fasciculi of white fibrous tissue, and of a fine elastic fibrous network in almost equal proportions. It is twice as thick posteriorly as anteriorly; and in the latter position is pretty firmly united to the anterior common vertebral ligament, while it is free on the sides and behind. Internally, the dura mater is co- vered by a simple scaly epithelium alone, there being no external lamella of the arachnoid. The ligamentum denticulatum has no epithelium, and presents a structure precisely like that of the dura mater. In the cranium, the dura mater is thicker and whiter than in the spinal canal, and consists of two layers: 1, the external or perios- teal, and 2, the internal. The former, more laxly united to the latter at an early period, is whitish-yellow and rough, and attached more or less firmly to the bones, and supports the larger meningeal vessels. The internal layer, or proper dura mater, is less vascular, whiter, has generally a glistening tendinous aspect, and its surface is quite smooth. Between the two layers, with few exceptions, the sinuses are situated. The processes of the dura mater (the falx cerebri and cerebelli, and the tentorium) are prolongations of the internal layer. The simple scaly epithelium covering the dura mater consists of cells of ^yVir to jxnrtr °f an inch, with rounded or elongated nuclei g^nnr to yxnxxT °f an inch in diameter. Vessels and Nerves of the preceding Membranes.—The dura mater of the cord has in its substance but few vessels, though numerous arteries and veins of the cord perforate it. The dura mater of the encephalon is far more vascular, as already described, especially in its external or periosteal layer. The sinuses in it are simple exca- vations lined with an epithelium. The arachnoid membrane, whether of the brain or the spinal cord, contains no proper vessels. The pia mater both of the brain and the cord, has a tolerably rich capillary plexus of its own, besides supporting the very co- pious ramifications of the vessels of the nervous substance. VESSELS AND NERVES OF CEREBRAL MEMBRANES. 471 Lymphatics are said to have been demonstrated by Fohmann and Arnold in the pia mater, on the surface both of the cerebrum and cerebellum, and in the choroid plexus—an observation needing confirmation. Nerves also are found in the membranes of the nervous centres. The dura mater of the cerebrum has nerves (twigs of the eighth pair), pretty nearly following the course of the meningeal arteries, and especially upon the middle meningeal. A twig from the third branch of the fifth pair is distributed principally to the bones. Another from the fifth pair is called the nerve of the tentorium cerebelli, and goes to the larger sinuses of the dura mater. (Pappen- heim) Neither Kolliker nor Purkinje has detected any nerves in the theca vertebralis; though they occur in the periosteum of the vertebral canal, and on the arteries going to the vertebras and the cord. The arachnoid contains no proper nerves, but the vessels pene- trating it do, especially at the base of the brain. The pia mater of Fig. 313. Fig. 314. Fig. 313. Vessels of the cerebral substance of the sheep, from »ne of Gerlach's injections; a, of the gray; b, of the white substance. (Kolliker.) Fig. 314. Two terminal arteries from a branch on the surface of a convolution of the cerebrum, and dipping vertically inwards; and exhibiting the mode of origin and distribution of capillaries in the gray cortical layer. From an injected specimen. (Magnified 30 diameters.) 472 THE TISSUES. the cord is richly supplied with plexuses of fine nerve-fibres which accompany the vessels. At the base of the brain, many similar plexuses occur on the arteries of the circle of Willis, which are distributed in twigs 7i^ of an inch in diameter through the entire cerebral pia mater, following its vessels, but not those of the cere- bellum. The vessels of the cord and encephalon themselves on leaving the pia mater, are supplied to the gray matter much more abundantly than to the white substance; the capillary plexus being closer (and the capillaries themselves of less calibre), to which the dark color is in part due. The interstices of the capillaries in the white sub- stance are g^ by ^\^ of an inch. (E. Weber) In the sheep's brain the breadth of the interstices of the gray substance is three or four times less than in the white. (Gerlach) (Fig. 313.) The finest capillaries in the cord measure ^y^y of an inch, and in the brain, btjVo °f an inch. The manner in which the terminal arteries merge into the capillaries on entering the gray matter of the convolutions from the pia mater is shown by Fig. 314. Chemical Composition of the Nervous Centres. The composition of the elements of the nerve-fibres has already been given, so far as it is understood (p. 430). The composition of the white and gray matter of the encephalon will now be specified. Vauquelin states that the spinal cord and medulla oblongata have the same composition as the cerebrum, except that they contain much more fat, with less albumen, ozmazome, and water. The ana- lyses of the encephalon alone will be here given; and those of Von Bibra will be adopted as the most recent and reliable.1 The following is Von Bibra's analysis of the gray and the white matter, separately, of the brain of a man aged 30 years, who died of phthisis:— Gray substance of cerebral he-mispheres. White substance of corpus callo-sum. White substance of medulla ob-longata. Water ...... Solids, exclusive of fat 83.57 6.43 10.00 69.19 20.43 10.38 71.55 14.67 13.78 1 Comparative Investigations of the Brain of Man and the Mammalia. Mann- heim, 1854. CHEMICAL COMPOSITION OF NERVOUS CENTRES. 473 The following is his analysis of the entire encephalon of the foetus at different stages, and that of a child at 6 months:— At 10 i At 12 weeks, weeks. At 14 weeks. At 18 weeks. At 20 weeks. At 21 At 37 weeks, weeks. Child 6 months. Water Fat . Solids, exclusive of fat 85.10 | 86.71 ! 86.24 1.26 j 0.99 I 1.53 13.64 12.30 12.23 86.90 | 86.03 1.06 ! 1.07 12.04 12.60 85.93 87.90 1.23 3.06 12.84 9.04 82.96 6.99 10.04 Thus the gray substance contains more water than the white, the water being replaced in the latter by fat. The water in the brain of the foetus is also far more abundant than in the adult, the differ- ence being made up by an increase of fat in the latter. The sudden increase of fat for a short time before and after birth, is a fact of much physiological interest. The quantity of fat in the brain is found to be constant, within certain limits. It is not diminished in diseases occasioning ema- ciation in other parts, nor is it increased in the lower animals by fattening. It seems to be established that the fat has important relations to the functions of the brain. Its amount is a little less in old men than in adults in the prime of life. L'Heritier's analyses also show that it increases from infancy up to adult age. In man, other mammalia, and birds, the medulla oblongata con- tains more fat than the cerebellum and the cerebrum. There is the most fat, relatively and absolutely, in the'hemispheres of the human brain; next in other mammals, and then in birds, amphibians, and fishes. An analysis of the brain-fat shows it to consist of cerebric acid 20 to 21 per cent., cholesterine 30 to 33 per cent., and a series of fatty acids constantly varying in composition, and which contain no nitrogen or sulphur. The white substance contains more cere- bric acid and cholesterine than the gray, and consequently less of the other fats. The quantity of cerebric acid seems to diminish as we descend the animal scale, and is less in the foetus and the infant than in the adult. Phosphorus is also contained in the brain-fat; except the fatty acids, which solidify at a temperature below 38J° (Fahr.). In a man who died at 59 years of age, of Bright's disease, the phospho- rus in the whole brain amounted to 1.68 per cent, of the fat. There was the most in the hemispheres, the cerebellum, and pons Varolii (1.83 per cent.); and the least (1.54 per cent.) in the optic thalami 474 THE TISSUES. and corpus callosum. Von Bibra concludes that the amount of phosphorus in brain-fat is very nearly the same in man, other mam- mals, and birds; that its amount is not essentially modified in in- sanity, in old age, in very young persons, and even in the embryo; and that there is no reason to believe that the intelligence is espe- cially connected with its amount. The fat of the gray matter of the brain, however, contains rather more phosphorus than that of the white matter. The other solids, besides fat, alluded to, are albumen, another albu- minoid substance not coagulable by boiling, and the mineral sub- stances usually met with in other organs and in the formative fluids. Sulphates are, however, almost entirely absent, and the chlorine varies much in amount. Of the earthy phosphates, the medulla oblongata contains b, larger proportion than other parts of the en- cephalon. They are also more abundant in the brain of amphibians and fishes than in the higher animals. In fact, all the inorganic constituents are least abundant in the brain of man and other mam- mals, greater in birds, and greatest in amphibians and fishes. The ratio of the potash to the soda in the human brain is nearly inter- mediate between the ratios occurring in the ashes of flesh and blood respectively (p. 395). Functions of the Nervous System. For definite informatics on this subject, reference must be had to the treatises on physiology. It may here only be remarked that, so far as motion is concerned, the gray matter of the spinal cord is probably the centre of reflex (or diastaltic) motion; the ganglia of the cerebrum are the centre of the emotional (and sensational) actions; and the cerebral hemispheres are the source of voluntary motion. On the other hand, some part of the cerebrum (and, most probably, the optic thalami) is the centre of sensation; while the sympathetic influences ascribed to the ganglionic nervous system are not peculiar to it, but inhere also in the ganglionic nerve-fibres in the spinal nerves; these fibres also being the probable channel through which emotions affect the organic functions, and especially that of secretion—as of the milk, the lachrymal fluid, &c. The cerebral hemispheres are also the centre of the intellectual and moral faculties; while the cerebellum presides over the co- ordination of the voluntary motions, but takes no part in the mental phenomena. Certain facts point to the conclusion that it is also the THE MEMBRANES. 475 seat of the sexual impulse; but this function cannot yet be regarded as established. Pathological States of the Nervous Centres. Certain pathological conditions of the nerve-fibres and the nerve- cells have already been specified (pp. 433 and 437). The encephalon and cord are also affected by softening and various other abnormal states—as from the development of tumors, &c. But the consequent lesions of motion, sensation, and the intellectual faculties, are too numerous and complicated to be described here. CHAPTEE XI. THE MEMBRANES. The synovial membranes (p. 344), the vaginal sheaths, and the bursas mucosae (p. 418, 3), have already been described. Those to be described in this chapter are:— 1. The cutaneous membrane, or skin. 2. The mucous membranes. 3. The serous membranes. Each of these consists of the same histological elements from within outwards; viz., 1, the corium; 2, the basement-membrane; and 3, the epithelium. Thus no tissues, not already described, occur in them. Both the skin and the mucous membranes present elevations and Fig. 315. Typical forms of papillae of the skin and mucous membrane, and intestinal villi, a. Basement- membrane, b. Epithelial layer of secreting cells, mostly detached, c. Layer of capillary vessels in the corium of the skin or mucous membrane, d. Simple papilla or villus, e, f. Compound (branched) papillae. depressions on their surface; the former being termed papillae and villi, and the latter, glands. Fig. 315 represents the forms of the papillae, and Fig. 316 of the glands. 476 THE TISSUES. I. The Skin. 1. The corium of the skin, or innermost layer, constitutes the greater part of its entire thickness in most parts of the body; and this alone is converted FlS*316- into leather when the skins of the lower ani- mals are tanned. Its re- lation to the basement- membrane and the epi- thelium is shown in a vertical section of the skin (Fig. 317); which also shows a sweat gland in the subcutaneous areo- lar tissue, or superficial fascia, described on page 290. It is a tough, slight- ly elastic membrane, com- posed of white and yellow fibrous (areolar) tissue; to which must also be added smooth muscular fibres, bloodvessels, nerves, and lymphatics, in great abun- dance. In the inner por- tions of the corium, the fibres are interwoven in a manner to give indica- tions of lamination. The elastic fibres abound in the corium; but much more in the subcutane- ous areolar tissue. The smooth muscular fibres also abound in some portions of the latter, constituting the dartos, so called, under the skin of the scrotum; and a similar layer under the skin of the prepuce, of the perineum, and the ante- Typical forms of glands, a. Simple glands; a, b, c, as in the last figure ; g, follicle or follicular gland ; h, sacculus, or saccular gland ; i, tubular gland, the tube coiled up. b. Simple racemose glands ; k, of tubular, and I of saccular form. c. Compound racemose glands; m, entire gland; showing branched duct and lobular structure ; n', a lobule detached, with o, branch of duct proceeding from it. d. Compound tubulaT gland. THE SKIN. 477 Fig. 317. rior part of the body of the penis. They also exist under the skin of the areola around the nipple of the female, forming circular bundles of a yellowish-red color, even ^8 of an inch thick, and extending both circularly and perpendicu- larly into the nipple itself. But smooth muscular fibres are also found in the su- perficial portions of the corium, and, in fact, in every part where hairs occur (ar- rectores pili, Eylandt,) forming flat bundles tsVtf to 7F(7 of an inch broad, which are placed singly or in pairs near the upper part of the hair-follicles and sebaceous fol- licles. Eylandt finds the bundles to be only gtfVtf °f an incb thick, and has never seen more than one pass to a hair-follicle. Henle makes them 3^7 °f an inch thick. Kising from the superficial part of the co- rium, they extend obliquely outwards, and are inserted into the hair-follicles close behind, and near the base of the sebaceous glands (p. 267 and Fig. 135). The inner surface of the corium is rough and areolated, to correspond with the outer surface of the superficial fascia into which it merges. Its external surface is also very far from being level, from the development here of the tactile papillae. The reddish-gray, external, superficial por- tion of the corium, containing the upper portion of the hair-follicles and cutaneous glands, and the terminal expansions of the vessels and nerves of the skin, is some- times called the papillary portion of the corium. The tactile papillaz, its most im- portant element (Fig. 318), are small, se- mi-transparent, flexible, but tolerably solid elevations of the external surface of the corium, usually of a conical or clavate form, but sometimes presenting numerous Vertical section of the skin of sole. a. Cuticle; the deep layers (stratum Malpighianum) more co- lored than the upper, and their particles rounded ; the superficial layers more and more scaly, b. Papillary portion, c. Principal portion of corium. d. Sweat-gland lying in a cavity on the deep sur- face of the skin, and imbedded in globules of fat. Its duct is seen passing to the surface. (Magnified 10 diameters.) 478 THE TISSUES. points (compound papillae, Fig. 319). They are very numerous on the palm of the hand and the sole of the foot, and are situated upon Fig. 318. Papillse of the palm, the cuticle being detached. (Magnified 35 diameters.) Fig. 319. Compound papillse of the surface of the hand with two, three, and four subdivisions. a. Base of a papilla, b, b. Their separate processes, c, c. Processes of papillse whose base is not visible.—Magnified 60 diameters. (Kolliker.) ridges visible to the naked eye. E. H. "Weber found upon the vola manus, on a surface 1 line square, 81 compound, or 150 to 200 smaller papillae, disposed with tolerable regularity in two principal series, each having two to five papilla? in the transverse direction; placed on linear elevations T,jo to ^ of an inch broad by ^\v to ^ of an inch high—the ridges of the corium. Elsewhere, the papillae are more irregularly scattered, either very closely together, as in the labia minora, the clitoris, the penis, and the nipple, or somewhat more widely apart, as on the extremities (except the places above named), on the scrotum, the neck, chest, abdomen, and back. The size of the papillae varies much. The shortest (7£2 to ^v of an inch), occur on the face ; and next (^^ to 7|7 of an inch), on the female breast, the scrotum, and at the root of the penis. In most other situations, they are 2|¥ to ^g of an inch long. The longest (3|T to 2^-u of an inch), are found on the palm of the hand, the sole of the foot, the nipple (where they are generally of the compound kind), the anterior and posterior extremities of the bed of the nail (Tg5 to Tl?j of an inch), and the labia minora (5^ to jI^ of an inch). The diameter of the papillae at the base gene- rally equals, or is somewhat less than the length. In the shortest, above-mentioned, it exceeds the length by ^ or more; and hence they resemble warts or even short ridges. In the largest papillae the breadth is J to J the length. The distribution of the bloodvessels and nerves in the papillae will be described on page 483. THE SKIN. 479 Fig. 320. Finally, the thickness of the corium varies from ^ to \ of an inch, being Jg to y'g of an inch in most places. It is thinnest (JB to ^v of an inch) in the meatus auditorius externus, the eyelids, the red border of the lip, and the glans penis and clitoridis; and thickest (2? to A of an inch) on the back, chin, upper and lower lip, the alai nasi, the ball of the sole, the extremity of the great toe, over the scapula and the nates, and on the heel (even ^ to ^ of an inch). 2. The basement-membrane of the skin has been demonstrated only in certain parts; and by Kolliker. it is not recognized as one of its histological elements in the adult; though he admits it exists in the embryo. It is merely a layer of simple membrane accurately covering every part of the external surface of the corium, and supporting the epithelium. 3. The epithelium of the skin has al- ready been in a general way described; it being a compound scaly epithelium (p. 240). Its outer layer, including the harder portion removable by a blister, is usually termed the epidermis, or cu- ticle, or horny layer; and the remaining internal portion, the stratum Malpighii, or rete mucosum. The latter consists of several layers of cells, the innermost being g7Vtf to sihju oi> an mcn ^°ng, an^ ftj'od t0 40W °f an mca broad, and placed perpendicularly to the surface of the corium. Sometimes several layers of perpendicularly arranged cells occur, giving the deepest portion of the stratum Malpighii a striated appearance. Upon these, several layers of elongated or round cells follow. (Figs. 146 and 320.) The cells in the outermost layer become flattened, and thus merge into those of the cuticle or horny layer. The contents of these cells are never quite fluid, but are finely granulated, the granules invariably diminishing in the more external cells. In the negro these granules are colored, as has been shown by Fig. 68; Vertical section of the skin of the thumb, showing the epidermis and outer layer of the corium ; treated with acetic acid. a. Horny layer of the epi- dermis, b. The Malpighian layer, c. Corium. d. Single papilla, e. Com- pound papilla. /. Epithelium of the perspiratory duct, continuous with the Malpighian layer of the epidermis, g. Canal of the same through the corium. h. Its passage through the horny por- tion of the epidermis, i. Perspiratory pore. 480 THE TISSUES. especially those clustered round the nuclei of the cells. In the white races, the granules are also darker in certain parts of the body, and the cells become pigment-cells, therefore, as already de- scribed; as in the areola and the nipple (especially during preg- nancy and after bearing children), in the linea alba, and the face during pregnancy, &c. (p. 136). In the negro, even the horny layer (cuticle) is also inclined to yellow or brownish; while in the white races it is entirely colorless, except in the parts and circumstances just mentioned. It consists usually of many layers of horny plates, the lowermost of which suddenly merge into the subjacent upper- most cells of the rete Malpighii. That these plates are still flat- tened cells, and contain a very minute quantity of viscid fluid, is proved by the addition of acetic acid and potassa, which cause them to swell up and assume the form of vesicles, sometimes, though seldom, containing a rudimentary nucleus. In the lower and mid- dle parts of the cuticle, these plates are pretty regularly polygonal (4, 5, or 6 sided); in the upper layers they present more irregular outlines, and often appear wrinkled and folded. They vary from titjo" t0 tstt of an 1Ilcn m diameter. Upon the glans penis and the outer side of the labia minora, the largest are 7^ to g^ of an inch, and on the labia majora y^g^ to ^\-§ of an inch in diameter. All these larger cells are distinctly nucleated. These plates being applied to each other horizontally, give the cuticle a distinct lamination. The most superficial laminae are parallel to the general surface of the corium, while the deepest take a direction parallel to the surface of .the papillae. Thus depressions corresponding to the papillae in form appear on the inner surface of the cuticle (Figs. 321 and 328), and into which the papillae-, covered by the stratum Malpighii, projected. The thickness of the entire epithelium of the skin varies in differ- ent parts; viz., it is 9^ to gfoj of an inch on the chin, cheeks, and brow, on the eyelids, and in the external auditory passage; gj-^ to 3^o of an inch on the bridge of the nose, the breast and nipple of a female, the back of the toes and the fingers, on the neck and back, on the inner and outer side of the thigh, the scrotum, and the labia minora. It is sfoj to T£2 of an inch on the edge of the eyelids, the male chest and nipple, the hairy scalp, the chin, penis, prepuce, and glans penis; T£5 to T£T of an inch on the red external portion of the lips, THE SKIN. 481 Fig. 321. Under surface of the cuticle, detachell by maceration from the palm ; showing the double row of depressions in which the papillse have been lodged, with the hard epithelium lining the sweat- ducts in their course through the corium. Some of these are contorted at the end, where they entered the sweat-gland. (Magnified 30 diameters.) and the back of the hand; y^ to g1^ of an inch on the flexor side of the fingers and toes. It is 3Xg to 24 of an inch on the palm, and y^ to £ of an inch in the sole of the foot; though here the varieties are greatest. As compared with the horny layer (cuticle) alone, the stratum Malpighii is in some localities always 1\ to 4J times the thicker; viz., in all parts of the face, in the hairy scalp, the penis, the scro- tum, the nipple, and the skin of the thorax in man; in the labia majora and minora, and on the back of the hand and neck. In the glans penis the stratum Malpighii and the cuticle are of equal thick- ness. In other parts of the body the two layers are either equal in thickness, or the horny layer is 2 to 5 (or sometimes 10 to 12) times as thick as the Malpighian. The thickness of the stratum, Malpighii (a't the base of the pa- pillas) varies between y^1^ and 7X5 of an inch. When thicker than the horny layer, it averages 3^ of an inch; when thinner, T5V^ to g^ of an inch. 31 482 THE TISSUES. Chemical Composition and Physical Properties of the Skin. The general composition of the cuticle, as one of the horny tis- sues, has already been indicated (p. 235). Its cell-walls are insoluble in water, but concentrated alkalies and concentrated sulphuric acid easily dissolve them; and hence the skin, if wetted with these agents, feels slippery and greasy. The cuticle contains less sulphur than the hair and nails; and hence, perhaps, salts of lead, mercury, and bismuth color the hair, but not the epidermis. Nitrate of silver colors it violet or brownish black; the oxide, ehloride, and black sulphuret of silver being formed from the chloride of sodium and the sulphur it contains. The tissue of the cuticle is, however, quite unchanged, the microscope merely detecting minute dark granules between its elements. But strong solutions of the iodide and of the cyanuret of potassium remove the color, by dissolving away the horny plates themselves. The horny structure of the epidermis permits no fluids, except those which act chemically upon it, to pass through it; while it readily takes up gaseous-matters, or easily vaporizable substances, as ether, alcohol, acetic acid, ammonia, ethereal solutions of chloride of iron, and alcoholic solutions of acetate of lead. It also gives all these off by cutaneous evaporation. (Krause) Water, ointments, and even solid matter (sulphur, cinnabar), pass through the unin- jured cuticle; but here there is a mechanical intrusion, in and through the sweat-ducts and hair sacs, to the stratum Malpighii, which, on the contrary, is easily penetrated by fluids. Hence, also, the very ready occurrence of absorption after the separation of the horny layer and the superficial portion of the Malpighian, by a blister. The corium affords gelatine on boiling, from the osteine contained in its white fibrous tissue. It putrefies with difficulty, and not at all when tanned. Its toughness and slight elasticity have already been mentioned. Vessels of the Skin. The arteries in the subcutaneous areolar tissue give off many branches to the hair-papillae (p. 259), to the fat-lobules (Fig. 188), and the smooth muscular fibres. More externally, they supply the sweat- and the sebaceous glands (Figs. 138,135), and the inner por- tion of the corium; and finally penetrate into its outer part, and VESSELS AND NERVES OF THE SKIN. 483 • into the papillae themselves, where they terminate in a close capil- lary network. This consists—1st, of a horizontal portion lying immediately under the surface covered by the Malpighian layer, composed of vessels Fig. 322. ts'tjtj t° siuTj of an inch, and of capillaries 4T5W to 375^ of an inch in diameter, with narrow meshes; and, 2dly, of many loops of the finest vessels (4-0V0 to a^Vir 0I" an inch) given off to the papillae. (Fig. 322.) Generally, each papilla has its own capillary loop, which runs either in its axis or near vewei. of thfpapm. from the the Surface, almost tO its apeX. The COm- heel- «• Terminal arterial twig. , .., . , v. Commencing vein. (Magnified pound papillae have several loops. 80 diameters.) Lymphatic vessels also exist in the sub- cutaneous areolar tissue, and form a very close network of fine vessels in its outermost part, 24^ to Tg^ of an inch in diameter. The Nerves of the Skin. But few nerves exist in the subcutaneous areolar tissue; but these, entering the corium, anastomose frequently, and form rich terminal plexuses. Of these, the deeper portions consist of fine branches, still containing many.nerve-fibres, with wide meshes; while the superficial portions consist of fibres, either single or united in pairs, with narrow meshes. In this last there also occur (perhaps not in all the fibres) actual divisions of the nerve-fibres, generally at an acute angle, into two subdivisions; and from the plexus itself the fibres finally enter the base of the papillae in pairs, running to their extremities, and then uniting in a loop. (Fig. 323.) The nerve-fibres in the papillae vary from j-ghuu to g oW of an inch. The axile or tactile corpuscles (corpuscula tactus), described by E. Wagner (Fig. 323), are regarded by Kolliker as consisting of col- lagenous tissue, with much undeveloped elastic tissue. These exist only in a small proportion of the papillae—about 1 in 4 of those on the first joint of the index finger. (Meissner) They resemble a fir-cone in form, and occupy one-third to two-thirds of the width of the summit of the papilla, and one-fourth to three-fourths of its length. The conclusion of Wagner, that the papillae without these corpuscles contain vessels only, but not nerves, needs further con firmation. At any rate, dark-bordered nerve-fibres are found in vascular papillae without axile corpuscles,.in the sole of the foot 484 THE TISSUES. and on the lips. His assertion, also, that the papillae containing axile corpuscles have no vessels, is not confirmed by Kolliker's Fig. 323. Two papillse from the extremities of the fingers, without epithelium, and with axile corpuscles (a) and nerves (6). A. Simple papilla with four nerve-fibres and two terminal loops (c). B. Compound papilla with two vascular points with capillary loops (d), and one nervous point with a terminal oo p (e). (Kolliker.) observations, though it may apply to particular cases. It is very probable that the nerve-fibres do not in all cases enter into the pa- pilla at all, but terminate in the superficial plexus at their base.1 Development of the Skin. The corium consists, at first, entirely of cells; among, and from which, subsequently, the white fibres and the elastic tissue, the vessels and nerves are formed. It evidently grows from within outwards, so that the papillae are developed last of all. It also con- tinues to grow a long time after birth, it being only half as thick in children under seven years of age as in the adult. (Krause) In embryo of two months, it is 2TfV<7 to ^^ of an inch thick, and presents tolerably distinct collagenous tissue. In the fourth month the first lobules of fat appear, and the ridges of the hand and the sole ofv the foot. The epithelium of the skin has its first layers developed by the metamorphosis of the most superficial of the primordial cells of the embryo. The outermost layers of these become the cuticle, and 1 While Kolliker maintains that the nerve-fibres terminate in loops on the sur- face of the axile corpuscle, Meissner regards the cross strise on the latter as the termination of the dark-bordered nerve-fibres. DEVELOPMENT OF THE SKIN. 485 those underneath, the stratum Malpighii. Then, as the former be- comes detached, it is recruited from the latter. The extension in surface of the cuticle implies a series of desquamations in the em- bryo and the foetus, and which must also occur after birth. The multiplication of the cells in the stratum Malpighii is certainly not by free cell-development (p. 120); since at no age are free nuclei present in it. (Kolliker) In the embryo of five weeks, there are but two layers of cells instead of the epithelium; at fifteen weeks, three layers of cells, the two internal for the stratum Malpighii; in the fifth month, the latter consists of many layers of the smaller cells, and the cuticle of at least two, of polygonal flattened cells; and at the seventh month, these two layers are as sharply distin- guished from each other as in adults. In the new-born infant the epithelium resembles that of the adult, except that it is more easily separated from the corium by maceration, and that the stratum Malpighii is disproportionally thick, and the cuticle very delicate. The desquamations of cuticle during embryonic life, already alluded to, aid in the formation of the vernix caseosa, already de scribed (p. 226); this consisting of the external epidermic cells mixed up with the sebaceous secretion of the skin, and containing hairs; and which, especially from the sixth month onwards, covers the whole surface of the foetus. It varies greatly in quantity in the new-born child ; sometimes amounting to even 3| drachms. The pigment in the stratum Malpighii of the negro, appears after birth. The edges of the nails, and the surface around the nipple, become rapidly tinged black; the genital organs become colored on the third day, and the wh&le body on the fifth and sixth. (Camper.) In Europeans also, the pigment in the areola is gradually developed during the first year. The growth of the corium presents no peculiarities. The cuticle is constantly being detached and repaired, and is thus constantly growing. The cells of the stratum Malpighii are developed from plasma exuded from the bloodvessels of the corium; and of which a determinate quantity always exists among these cells, and even those of the cuticle also. In the deep fold of the skin surrounding the glans penis and clitoridis, this continuous desquamation and re- production of the cells of the cuticle produce the substance (not a secretion, as generally supposed) called the smegma prozputii. In the male, however, the secretion of Tyson's glands may be mixed with it; but in the female, neither sebaceous nor any other glands 486 THE TISSUES. Fig. 324. exist on either the prepuce or the glans clitoridis. (Kolliker) Leh- man's analysis of the smegma has already been given (p. 227). The corium is regenerated if entirely removed; but the new de- velopment has neither papillae nor ridges. The epithelium, therefore, though regenerated in all cases when removed, has none of the usual elevations and depressions on both its surfaces, if the corium also has been removed. If the latter has remained uninjured, the new epithelium is rapidly produced and perfect, though it grows up as a whole from the corium below. This is well shown by the application of a blister. Appendages and Accessory Or- gans of the Skin. The appendages of the skin are the nails and the hair, already described (pp. 249—68). The accessory organs are: 1, the sebaceous glands; 2, the sweat-glands; and 3, the subcutaneous bursce mucosae. 1. The Subcutaneous Bursas Mucosal are merely simple or partially subdi- vided reticular spaces in the subcuta- neous areolar tissue; as over the up- per extremity of the olecranon, over the patella, &c. Their internal walls are smooth but uneven, and are form- ed of areolar tissue. They contain a viscid clear fluid, but have no epi- thelium. 2. The Sebaceous Glands.— These glands vary in form from the simple Malpighii of the epidermis; c, contents of follicle (Fig. 324, A) tO the racemose the glands, sebaceous cells, and free fat; •, ■, ,.■,. on a \ mi d, the separate racemes of the compound gland. (V Ig. d24, B). 1 hey OCCUr priU- giand; e, hair-sac (root-sheath), with the cipally upon the hairv parts of the hair, /.—Magnified 50 diameters. (Kolli- , , . J r ker.) body, opening in common with the Sebaceous glands from the nose. A. Simple follicular gland without any hair. b. Racemose gland, having a common opening with a hair-sac; a, glandular epi- thelium, connected with 6, the stratum ACCESSORY ORGANS OF THE SKIN. 487 The hairs hair-sacs; and hence are sometimes termed the glands of the hair- sacs. They in fact occur, of the hairless parts, only on the labia minora, and the glans penis and clitoridis, and the prepuce of both the male and the female. The opening of the gland is sometimes common with that of the hair-sacs, sometimes it terminates in the latter, and sometimes the hair-sac is smallest, and the hairs come out through the glandular opening itself. (Fig. 324, B.) Generally, the small hair-sacs have the larger glands, and vice versa, of the scalp have the smallest, Th^ to 7V of an inch in diameter, and these are simple follicles lodged in the superficial portion of the corium. The largest of all exist on the mons veneris, the labia majora, and the scrotum, where they are compound, and found in the deepest portions of the corium. Frequently two or more (even five) glands are connected with a single hair (Fig. 135); there being generally two in the scalp. The glands upon the nose (also the ante- rior half of the penis, and the areola), often attain to a colossal size and peculiar forms. (Fig. 325.) The sebaceous glands on the glans penis and the inner lamella of the prepuce, called Tyson's glands, some- times occur in very small number, and sometimes in hundreds. Gene- rally, ten to fifty are found on the prepuce, and mostly racemose; while on the glans they may be totally ab- sent, or may exist in its anterior sur- face in great numbers (even to one hundred)—being here more simple. The Meibomian glands in the eyelids must also be regarded as a larger kind of sebaceous gland. (Fig. 136.) In their minute structure the sebaceous glands consist of—1, an external delicate layer of collagenous tissue (or basement-mem- brane—Kolliker), continued from the hair-sac, or the corium where A large racemose sebaceous gland from the nose with a little hair-sac opening into it. The letters (a—f) as in Fig. 324.—Mag- nified 50 diameters. (Kolliker.) 488 THE TISSUES. no hairs are present; within which are (2) masses of cells. The latter are arranged, first in a single, and rarely in a double layer, in contact with the basement-membrane; internally to which are other cells containing more fat, and which pass into the innermost of the cells which are larger (T£T to ,£5 of an inch), and so filled with colorless fat that they might be termed sebaceous cells. (Fig. 326.) Fig. 326. A. One of the caeca of a common sebaceous gland ; a, epithelium sharply defined, but without any basement-membrane, and passing continuously into the fat-cells, 6 (their contours drawn too indis- tinctly), in the interior of the glandular tube. b. Sebaceous cells from A, and the cutaneous seba- ceous matter; a, smaller nucleated cells, still more of an epithelial character, and containing but little fat; 6, cells abounding in fat without visible nucleus ; c, cell in which the fat is beginning to flow into one mass ; d, cell with one fat drop ; e, /, cell from which the fat has partially escaped.— Magnified 350 diameters. (Kolliker.) The fat in them sometimes appears in the form of a single drop quite filling the cells; at others it still retains the form of distinct small drops. In the former case, they resemble the adipose cells. By endogenous development new cells are constantly produced in the bottom of the glands, and thus the pre-existing cells are thrust forward, and finally excreted through the neck of the gland upon the cuticle. It appears that no nerves are distributed to the sebaceous glands. Nor are vessels distributed upon and between their lobules; while numerous vessels and capillaries exist around the glands. These glands are developed from about the end of the fourth month of embryonic life, together with the hairs, since they appear as outgrowths or processes of the hair-sacs. Subsequently the pro- cesses become filled with the cells above described; and, finally, they open on the surface, and the structure of the gland is now complete. All the glands are at first simple, and most are so in the foetus of seven months; and the compound are formed by processes proceeding from these. Sometimes a simple gland growing rapidly THE SWEAT-GLANDS. 489 completely surrounds a hair-sac on all sides, constituting a glandu- lar rosette. The sebaceous glands grow after birth. In fact, those of the labia minora do not exist at all at birth. The composition and uses of the sebaceous secretion are specified on page 227. 3. The Sudoriferous or Sweat-Glands.—These consist of a single delicate convoluted tube, which secretes the sweat. They occur on the whole surface of the skin, except the concave side of the con- cha of the ear, and the external auditory meatus, the glans penis, the inner lamella of the prepuce, and a few other localities—and open upon it by numerous fine apertures. Each sweat-gland may be divided into the gland proper and the excretory duct. (Figs. 138, 317, 321.) The proper gland is rounded or elongated, yellowish, or yellowish-red, and g1^ to gV or> an incn in diameter. On the eyelids, however, and some other parts, they are only T\^ of an inch ; while on the areola they are ^ of an inch, and in the hairy parts of the axilla even 2^ to | of an inch thick, and Tj to J of an inch broad. They are mostly lodged in the deeper layer of the corium, sometimes more superficially, and often in the subcutaneous areolar tissue among the hair-sacs. Number of the Sweat- Glands.—Krause states that in a square inch of the skin there are between 400 and 600 glands on the back of the trunk, the cheeks, the upper arm, and the thigh; 924 to 1,090 on the anterior part of the trunk, on the neck, brow, forearm, back of the hand, and foot; 2,685 on the sole of the foot; and 2,736 on the palm of the hand. Their total number, including those of the axilla, is estimated at 2,381,248; and their volume, including the latter, 39,653 cubic inches. The aggregate length of all the excretory ducts of the sweat-glands in the body has been estimated by Wilson1 at 28 miles. 1. In their minute structure, the sweat-glands usually consist of a single canal, pretty uniform in diameter throughout its length (which Krause once found to be Txg of an inch), twined into a coil, and terminating on the surface on the interior of the latter in a slightly enlarged blind extremity. (Fig. 138.) Most of these, having thin walls, possess an external investment of embryonic collagenous Treatise on Diseases of the Skin. 490 THE TISSUES. tissue, with scattered elongated nuclei, and lined apparently by a basement-membrane, supporting a single, double, or multiple layer of polygonal cells, corresponding to the deep cells of compound conoidal epithelium, except that they generally contain a few fatty, and still more frequently yellowish or brownish, pigment-granules. (Fig. 327, A) The rest, called the thick-coaled canals, contain be- Fig. 327. B Sweat-ducts. A. One with thin walls and a central cavity, without a muscular coat, from the hand: a, connective investment; 5, epithelium ; c, cavity. B. A portion of a canal without a cavity, and with a delicate muscular layer, from the scrotum : a, connective tissue; b, muscular layer; c, cells which fill the glandular canal, with yellow granules among their contents.—Magnified 350 diameters. (Kolliker.) tween the two layers just described a middle layer of smooth mus- cular fibre-cells runniug longitudinally. (Fig. 327, B) This is the case with the large glands of the axilla, of the root of the penis, and the nipple; and the ccecal extremity of the canal is supplied with muscular fibre-cells in the scrotum, labia majora, mons veneris, and some other parts. The size of the canal varies from s JT to 3^, and averages about ?^ of an inch. The walls are BT\yT to 1V\V of an inch thick; the epithelium, SoVo 5 a^d the cavity, or lumen, ^Vo to T2Vo of an inch. The largest glands have canals ^ to 2£T of an inch in diameter, with walls 3-0V0 of an inch thick. The coils of the proper glands are penetrated by collagenous tissue interspersed with fat-cells; which supports the vessels, and unites the separate convolutions. The arrangement of the vessels is seen in Fig. 138. No nerves have yet been found in the glands. 2. The svjeat-ducts are continuous with the upper end of the THE SWEAT-GLANDS. 491 glandular coil, and ascend vertically through the corium, penetrating j between the papillae into the epithelium. Here they twist like a I corkscrew, and, according to the thickness of the cuticle, make two to sixteen spiral turns, and ter- minate by small round or funnel- Fi8- 328- shaped apertures (350 to 2|o OI" an inch), called the sweat pores, on the free surface of the .cuticle. (Fig. 328.) They retain their epi- thelium, consisting of at least two layers of cells, till they reach the surface of the corium. But while traversing the stratum Mal- pighii and the cuticle, they are merely bounded by layers of cells. Sometimes the excretory ducts of two glands unite into one. (Krause) These glands are developed ori- ginally as solid flask-shaped pro- cesses of the stratum Malpighii projecting into the corium, and are very similar to the hair-sacs. They first appear in the fifth month of embryonic life. At the seventh month the sweat- duct is seen perforating the cu- ticle, and the gland has pene- trated downwards to the inner portion of the corium, and be- come bent like a hook, indicative a. Vertical section of the cuticle, frcm the heel p., n , •! o ft. _ detached by maceration. The epithelium of the of the future coils. ^ Soon after sweat.duct continuous with the cuticle has been this, the gland acquires the ap- drawn out of the tube of basement-membrane, as ,1 31. far as to the gland, where it begins to be contorted. pearance it presents in the adult, The cavitv of the duct is seen dilating as it enters and probablv rio new ones are the cuticle,and tnen stretching up to the surface , , j _ 1 • .1 through the epidermic laminae. The deep surface developed alter Oirtn. of the duct ls continuous with the surface of the The Secretion afforded bv the cavities in which the papillse are lodged. 6. Duct at its entrance into the cuticle, more highly mag- SudoriferOUS glands has already nified. (Magnified 35 diameters.) been described (p. 229). The ceruminous glands of the ear may be regarded, histologi- 492 THE TISSUES. cally, as a variety of sweat-glands. Fig. 329 represents their va- rious forms and relations to the hair-sacs. They exist only in the Fig. 329. Cutaneous glandulae of external meatus auditorius. A. Section of the corium : 2, 2, hairs; 3, 3, superficial sebaceous glands; 1,1, larger and deeper-seated glands, by which the cerumen is secreted. B. A hair perforating the epidermis at 3: 1,1, sebaceous glands, with their excretory ducts (2, 2) ; 4, base of the hair in its double follicle (5, 5). C. Cerumen-gland formed by the contorted tube (1,1) of the excretory duct (2); 4, vascular trunk and ramifications. The last two figures highly magni- fied ; the first, 3 diameters. cartilaginous portion of the external auditory meatus; being situ- ated between the lining membrane of the passage and the cartilage, or the fibrous substance supplying its place, in a tough subcuta- neous tissue containing but little fat. The properties and uses of the cerumen have already been spe- cified (p. 228); it being associated physiologically with the seba- ceous secretion. Functions of the Skin. The skin fulfils a variety of functions. 1. Of protection, as the common tegument of the body. 2. As an absorbing organ. Gases are rapidly absorbed, and cer- tain solid and fluid substances (p. 230). Even nutritious fluids are absorbed by the skin, as proved by the effects of nutritious baths. Here the fluid probably enters to the stratum Malpighii mainly through the sweat-ducts (p. 482). PATHOLOGICAL STATES OF THE SKIN. 493 3. Hence the skin is an aerating organ, as accessory to the lungs; oxygen being absorbed directly into its bloodvessels. 4. The skin is a secreting organ, affording the sweat and the sebaceous fluid. 5. The contraction of the skin is shown in the cutis anserina (so called), the erection of the nipple, and the wrinkling of the skin of the scrotum and the penis (p. 477). 6. But the skin manifests its most important function as the organ of the sense of touch. And it is a singular fact that all poiuts of the skin are sensitive, though nerves cannot be demon- strated in all, or even in the majority, of the papillae. Kolliker, however, finds that the same point is sometimes sensitive, and some- times not so. Probably the nervous plexus at the base of the papillae, and not those in the latter alone, are the media of the sensibility of the skin. The various modifications of tactile im- pressions, as those of pressure, warmth and cold, of orgasm, of tick- ling, pricking, burning, and pain, are not well accounted for. The thickness of the cuticle of a part, the paucity or abundance of nerves, the superficial or deep position of the nerve-fibres, the thickness or delicacy of their neurilemma, &c, must doubtless be taken into consideration; and, on the other hand, also, the agents producing the sensations named. Pathological States of the Skin. I. Pathological colorations of the epithelium of the skin have already been mentioned (p. 137). A local thickening of it from continued pressure constitutes the clavus or corn, and its other morbid states are mentioned on page 247. In the vesicular diseases of the skin (pemphigus, &c), an exuda- tion of plasma, occurring from the vessels of the corium into the stratum Malpighii, causes a limited elevation of the cuticle. In eczema, herpes, and miliaria, the vesicles are very small. In ich- thyosis the cuticle is much thickened. II. The corium may (1) become generally atrophied in wasting chronic diseases (tuberculosis, syphilis, &c); it becoming thinner and smoother on its surface, and the sebaceous and perspiratory glands, and the hairs, even, becoming atrophied or disappearing. Local atrophy may be produced by pressure and other causes. 2. New formations of areolar tissue in the corium (papilloma, &c.) have already been described (p. 247). 3. The corium is also the seat of disease in all the exanthemata (scarlatina, rubeola, &c.); most of them affecting the papillary por- tion more especially. 4. In variola, papuloz (so called) are first formed by exudation 494 THE TISSUES. from the capillaries mainly of the papillae, which subsequently ex- tends to the stratum Malpighii, producing a vesicle; and which finally becomes a pustule, since pus is formed in it. The centre of the pustule is depressed, from the fact that the opening of a seba- ceous gland and a hair-sac penetrates there; and which does not allow the cuticle there to become detached and elevated, since it is connected with them. 5. In measles, lichen, and prurigo, papulae alone are produced. There, also, the vascular injection is confined to the most super- ficial layers of the corium. In inveterate cases, however (of pru- rigo), the exudation extends to the deeper layers, and the hairs and sebaceous glands disappear. 6. In verrucas, or warts, the papillae become hypertrophied. III. The sebaceous glands become, 1, hypertrophied in the akrothy- mion, or moist wart, and in ncevuspilosus. 2. They become atrophied, or entirely disappear, when the hairs fall out, i. e. on bald places. 3. The comedones are mere distensions of the sebaceous glands and the hair-sacs with sebaceous matter, and are most frequent where the glands are largest, as on the nose, lips, chin, ear, areola, and scro- tum. Milium is due to a similar distension of the sebaceous folli- cles alone; consisting of white spots on the eyelids, the root of the nose, the ear, the scrotum, &c. In both these cases, the apertures are obliterated or entirely closed. 4. Finally, steatoma, especially as it occurs on the scalp, is to be regarded merely as a colossal se- baceous gland distended with its secretion; and atheroma and me- liceris, if occurring in the corium, must be referred to the same category. 5. The acarus folliculorum residing in healthy and distended hair-sacs and sebaceous glands, has been shown. (Fig. 134.) 6. New formations of sebaceous glands have been found in an ovarian cyst in connection with hair. Indeed, they may probably occur in any part containing new formations of hair-sacs. A new development of sebaceous glands occurs in cicatrices in the skin, of some years' standing. ( Von Bdrensprung). IV. Of the pathological conditions of the sweat-glands but little is known. In elephantiasis Graecorum they become hypertrophied; while they are atrophied in case of corns, and the sweat-duct dis- appears in the outer layer of the cuticle. New formations of sweat-ducts occur in connection with those of hair and sebaceous glands, as in ovarian cysts; and in Mohr's case of a large cavity in the lung lined by a membrane in all its ele- ments like the skin (with a subcutaneous areolar tissue under it), and on which hairs, sebaceous follicles, and papillae were deve- loped. II. The Mucous Membranes. Mucous membranes line the cavities opening externally, and, like the skin, consist of a corium, a basement-membrane, and an epithe THE MUCOUS MEMBRANES. 495 Hum. The basement-membrane is like that of the skin. The corium is also composed of collagenous and elastic tissue, contains vessels, nerves, smooth muscular fibres, glands, papillae, and other peculiar processes (villi). Beneath the corium there is, in most parts, a layer of submucous areolar tissue. The development and regeneration of mucous membranes also resemble those of the skin so nearly as not to demand a separate consideration. The mucous membranes present marked differences in structure in different situations. They will, therefore, be described separately, in connection with the other structural elements of the organs, re- spectively, of which they form a part, viz:— 1. In the Alimentary Canal. 2. " Urinary Apparatus. 3. " Genital Apparatus. 4. " Air-passages. Functions of the Mucous Membranes. All the mucous membranes are, 1, protective of the passages lined by them; 2, they secrete mucus, of different kinds in different parts (p. 195); 3, they absorb also in certain parts; e. g. the villi of the small intestine, &c.; 4, they constitute an aerating surface to some extent (e. g. in air-passage's); 5. some portions of these membranes manifest the sense of touch also (lips, genital organs, &c). Pathological States of the Mucous Membranes. 1. Atrophy of mucous membrane is rare (Engel); but is seen in the alimentary canal of the aged. Here the gastric mucous mem- brane becomes less plicated and smoother; while the peptic glands are diminished in number. In the duodenum, Brunner's glands become atrophied, and the villi of the small intestine become clouded from the apex towards the base, pigmented, lessened in size (espe- cially transversely), and even in number also. The valvulae conni- ventes are also less prominent, and the Peyerian and solitary glands collapse; their situation being indicated merely by a pigmented border. 2. Inflammatory exudations on the mucous membranes (except the mouth, oesophagus, vagina, and palpebrae), generally at once detach the epithelium; and, therefore, no vesicles form upon them, except in the parts mentioned. Thus, the exudation may be at once examined. It is also not so generally circumscribed, as in the case of the skin; and the submucous tissue and the glands it con- tains are very frequently involved. Hence the membrane becomes thickened and swollen. Extravasation of blood is also more liable 496 THE TISSUES. to occur from the weaker vessels; and hence ecchymoses are very common. The polypi, so called, of the stomach, are merely groups of peptic glands, rendered prominent by an exudation deposited around them. 3. The thinness of the corium of the mucous membrane accounts for its tendency to losses of substance by ulceration; the bottoms of which are covered by various products (exudation). The latter sometimes rise like a plug above the level of the membrane (as in typhoid fever). Vegetable parasites are also frequently developed in exudations on mucous membranes. III. The Serous Membranes. The true serous membranes are the peritoneum, the pleura, the tunica vaginalis testis, and the pericardium. All these have a sim- ple scaly epithelium (p. 238, and Fig. 140), generally a thinner corium than the mucous membrane, and which presents neither papillae nor glands; and constitute closed cavities, moistened by the secretion of their epithelial cells, and an accompanying transudation (pp. 180—1). They will be described in connection with the parts and organs into the structure of which they respectively enter. The tunica vaginalis'is originally an offset from the peritoneum. The synovial membranes are often called serous membranes; as are also the bursae mucosae and the vaginal sheaths of tendons. It has, however, been shown that histologically they are not such, since they do not form closed cavities (p. 344, and Fig. 233). The arachnoid also has but a single layer (p. 469) and the ependyma of the ventricles has not everywhere a corium (p. 469). The arach- noid, however, normally presents villi; which, becoming enlarged, constitute the Pacchionian bodies. Function of Serous Membranes. The serous membranes proper, merely subserve the mechanical purpose of facilitating motion of one part on another, and diminish- ing friction; both by the smoothness of their surface and the secre- tion they produce (p. lsl). An abnormal accumulation of the natural secretion of the serous membranes in their cavities, constitutes the various forms of dropsy; e.g. in the pleural cavity, hydrothorax; in the peritoneal, ascites; in the tunica vaginalis, hydrocele; and in the pericardium, hydrops pe- ricardii. An exudation upon the pleura becoming degenerated into pus, constitutes empyema. The conversion of exudations into new formations is explained under the next head. FALSE membranes. 497 IV. False Membranes. This expression is a yery objectionable one; since it may either ■mean merely a coagulated exudation, spread upon a surface, like a membrane, or the same exudation after it has become organized. E. g. the merely fibrillated and never vascular exudation of croup, is termed a false membrane, as well as the highly vascular membrani- . form formation, so common on the surface of the pleura in conse- quence of inflammation of this membrane. The former should be called merely a coagulated exudation; while the latter may be termed a, false membrane, if we intend by this expression to indicate the fact shown by the microscope, that these formations are not (histologi- cally) membranes, though they sometimes, from their form, appear to the unaided eye to be such. False membranes are, therefore (if the term is to be retained), more or less organized exudations of plasma, and are developed espe- cially upon serous membranes (p. 188, 2). They, however, present all grades of development and vascularity, according to the time elapsing since the occurrence of exudation. When fully formed, they consist of a layer of imperfectly developed areolar tissue, con- taining a vascular network, and sometimes even nerves also, and lymphatics. Consequently, they are really mere new formations of areolar tissue. False membranes being a new formation are prone to involution, and ultimately may entirely disappear. Fatty degeneration in them is very common. They are also frequently the seat of pathological epigeneses, especially of tubercle. The bands and adhesions so frequently resulting from pleuritis and peritonitis, are histologically identical with false membranes; being also new formations of areolar tissue. New membranes are sometimes formed to cover the surface of per- manent adventitious cavities; e. g. the membrane lining cavities in the lung, formed by the removal of a mass of tuberculous depo- sit, &c. A new formation of epithelium occurs in many pathological cysts; of the internal surface of which the new formation constitutes the lining. 32 498 the tissues. CHAPTER XII. the vascular system. The vascular system consists of the heart, the bloodvessels, and the lymphatic vessels. I. The Heart. The heart is a thick muscular organ, divided into four cavities, covered externally by a serous membrane—the pericardium—and lined internally by the endocardium, a continuation of the inner tunic of the large vessels. The pericardium presents two layers; the outer (sero-fibrous layer) being much the thicker, and fibrous in its external portion. The inner layer, much thinner, is very intimately attached to the muscu- lar fibres of the heart, except over the sulci containing the vessels and nerves, where it is separated by common adipose tissue. Some- times, however, the fatty sub-serous layer extends almost over the whole heart. The scaly epithelium of the pericardium contains one or two layers of cells, and presents no peculiarities. But few lymphatics exist on the outer layer, while they are more abundant in the muscular substance of the heart. Subdivisions of the dia- phragmatic and recurrent laryngeal nerves have been demonstrated by Luschka in the outer layer. The muscular fibres of the heart are of the transversely striated kind, but they are about one-third smaller than those of the volun- tary muscles (3^o to T2V^ of an inch), and are often more distinctly striated in the longitudinal than the transverse direction. They also almost always contain minute fatty granules, arranged in a series in their axes. Their myolemma is very delicate, and often not to be seen at all. The most striking peculiarity is, however, the intimate union of the fibres; they being everywhere separated by a very scanty connective tissue, and never forming manifestly distinct fasciculi. Besides, anastomoses of the fibres exist (Fig. 330), and also true divisions. For the complex course of the fibres of the heart, we refer to the THE HEART. 499 Anastomosing muscu- lar fibres from the hu- man heart. (Kl'ttiker.) works on anatomy. The muscular structures of Fig. 330. the auricles and" ventricles are completely distinct; both, however, originating chiefly from the ostea venosa of the ventricles, where the so-called fibro- cartilaginous rings are situated. The endocardium is a whitish membrane cover- ing all the internal surface of the heart, as well as the columnar carneae, the chordae tendineae, and the valves. It is thickest (^\ of an inch) in the left auricle, and thinnest in the ventricles. It consists of two layers: 1st, a scaly epithelium of one or two layers of clear, flattened, nucleated cells, rest- ing, without any apparent basement-membrane, upon the surface of, Idly, the elastic layer. The latter, determining the varying thickness of the endocardium, has its superficial layer made up of very fine, longitudinal, elastic fibres, and the remainder of areolar tissue, with scattered nuclei. In the auricles, this membrane becomes almost entirely an elastic membrane, and is therefore quite yellow. It is very delicate over the chordae tendineae. Under the endocardium lies a very deli- cate stratum of areolar tissue, attaching it to the muscular fibres. The chordai tendineoz are composed of collagenous tissue, like the tendons. The auriculo-ventricular valves present three layers—a middle one of areolar tissue with numerous elastic networks, and two lamellae of the endocardium. Towards their free borders, these three are condensed, as it were, into a single layer of areolar tis- Fig. 331. sue and elastic networks, over which the epithelium is contin- ued. The semilunar valves pre- sent the same condition as the free borders of the preceding. (Fig. 331.) The vessels of the heart present only the following peculiarities. The capillaries often encompass several of the fibres in common, on account of the small size of the latter. The endocardium has very few vessels, while they are plentifully distributed to the subjacent layer of areolar tissue. A few vessels are seen in the auriculo- ventricular valves, but never exist in the semilunar. Lymphatics Elastic layer of a semilunar valve, beneath the endocardium. 500 THE TISSUES. exist on the muscular substance of the heart beneath the pericar- dium; but whether they are present in its substance and in the pericardium, is not determined. The nerves (from the pneumo- gastric and sympathetic) contain, except the largest, only pale and fine fibres. Ganglia also exist in the substance of the heart. Dr. Lee, of London, however, mistook for ganglia mere thickenings of the perineuria. (Kolliker) How the nerve-fibres terminate, is unknown. II. The Bloodvessels. The bloodvessels are divided into the arteries, the capillaries, and the veins. A. The Arteries. The arteries1 have three tunics, the external (advenlitia), the middle (media), and the internal (intima). (Fig. 332.) Each of these may, Transverse section of the aorta below the superior mesenteric artery. 1. Inner tunic. 2. Middle tunic. 3. External tunic (adventitia). a. Epithelium, b. Striped lamellje. c. Elastic membrane of the inner coat. d. Elastic lamellae of the middle tunic, e Its muscular fibres and connective tissue. /. Elastic networks of the external tunic. From man, treated with acetic acid.—Magnified 30 diameters. (Kblliker.) however, be subdivided, as will be seen. In general, the external coat consists of-areolar tissue; the middle of elastic tissue, with more or less smooth muscular fibres admixed; and the internal of an elastic network (fenestrated layer), supporting an epithelium. 1. The external coat of the (1st) larger arteries (above 2 or 3 lines in diameter) is both relatively and absolutely thinner than in the smaller—being B^F to -5^ of a line—and presents the same struc- ture as in the smaller arteries on the whole; it being composed of 1 Meaning "air-holders" (p. 405, note); since the ancient anatomists observed that they usually contained air after death. THE BLOODVESSELS. 501 areolar tissue, with an elastic inner layer. In the (2c%) medium- sized arteries (| of a line to 2 or 3 lines) this coat is thicker than the middle coat, being ji^ to 7'5 of an inch thick. It has an inner portion, in the form of a laminated elastic membrane, in the largest arteries of this class (brachial, femoral, &c). The external portions of the external coat also abound in elastic fibres, sometimes pre- senting a laminated aspect. Bdly. In the small arteries (less than f of a line in diameter), the external tunic is merely a layer of areolar tissue, as thick or thicker than the tunica media. In arteries t1q of a line or less in diameter, however, the outer coat contains no elas- tic fibres, but only collagenous tissue and elongated nuclei; and which, though still nucleated, at length, towards the capillaries, become homogeneous, then a thin simple membrane, and finally, in vessels under j^-g-^ of an inch, disappear altogether. Pig. 333. Section of the aorta of the ox, showing the arrangement of the two layers of the longitudinal fibrous tunic, and of the circular fibrous tunic, a and b, the inner coat: a, the epithelial layer ; 6, the internal portion of the longitudinal fibrous layer (fenestrated membrane, Henle). c and d, the middle coat; c, the external coarse stratum of the longitudinal fibrous layer ; d, a small portion of the circular fibrous tunic; most of the fibres are cut across, but a few which take an oblique course, are seen in their whole length, and their penniform branching is slightly indicated. (Longi- tudinal section.) 2. The middle coat of large arteries (Fig. 333) consists of plates of elastic tissue, of collagenous tissue, fine elastic networks, and smooth muscular fibres; the last constituting ouly one-fourth to one-third 502 THE TISSUES. of the whole tunic, and being in a merely embryonic state of de- velopment. They therefore probably manifest but little contractile power. Its innermost stratum, the annular fibrous layer, contains the peculiar elastic membranes or plates, of T2oVxr to t^tto or" an inch, and 50 to 60 in number, regularly alternating, at distances of ?^T to -g^v of an inch, with transverse layers of smooth muscular fibres, pervaded by areolar tissue. These plates are, however, not mere -concentric tubes, but are connected with each other, and with the firm elastic network pervading the muscular tissue. (Fig. 333.) In the middle coat of the medium-sized arteries the elastic plates just described are absent, and the smooth muscular fibres are far more abundant; though there is here and there a disposition to the formation of elastic layers, alternating with the muscular. Its muscular fibres, therefore, preponderate, and doubtless manifest a considerable degree of contractile force. It is thinner than the external coat. The small arteries have their middle coat composed exclusively of smooth muscular fibres; and it is stronger or weaker, according to the size of the vessel, down to 7^ of an inch. In vessels of T2tf to 3^ of an inch, they are still united into lamellae presenting two or three layers, and a thickness of ^otr to T5V an inch, they have become so numerous as clearly to represent the epithelium, and now the external layer has received also the addition of a nu- cleated lamina, the tunica advenlitia, and the vessel has become a vein. (Fig. 337, c.) The older anatomists have also assumed the existence of still finer vessels than the capillaries, never admitting the blood-corpus- cles, called vasa serosa; and recently Hyrtl has admitted their ex- istence in the cornea. If any such vessels exist in the cornea, they must be regarded as atrophied capillaries; the latter having formed an abundant plexus in the foetus. It cannot be admitted that such vessels exist in the adult in any other part, at any rate (p. 281). The finest capillaries above-mentioned have a less diameter than the smallest blood-corpuscles; but the latter easily adapt themselves by their extensibility and elasticity to traverse the former. C The Veins. The veins also present three tunics—the advenlitia (external), the media, and the inlima; and may also be divided into the small, the medium-sized, and the large. Their walls are always thinner than those of the arteries, there being less of both the muscular and the elastic element. The external coat is usually the thickest of the three; its relative and absolute thickness usually increasing with the size of the vessel. The inner coat is often not thicker in large veins than in those of medium size. 1. The smallest veins may be said to consist of a nucleated indis- tinctly fibrous or homogeneous areolar tissue, lined by a scaly epithelium. A muscular membrane, and generally a layer of an- nular fibres are first seen in veins above g J0 of an inch in diameter; the contractile cells being at first oval, placed transversely (Fig. 337, c), and widely apart, but which afterwards become longer and more numerous; and, finally, in vessels of T2Vtt uP to T*^ of an inch, constituting a continuous layer, but always less developed than the middle coat of the small arteries. Afterwards, elastic networks gradually make their appearance in this muscular layer, and in the external coat; the muscular layers also multiplying, and admitting areolar tissue among their elements. THE BLOODVESSELS — VEINS. 507 2. The medium-sized veins (1 to 3 lines in diameter) have an ex- ternal tunic almost always thicker than the middle coat, often twice as thick, though rare- ly as strong. It is composed of areolar tissue, except in some visceral veins whose trunks contain longitudinal muscular fibres, and into whose branches also the muscular elements extend for some distance.—The middle coat has a considerable development of the annular fibrous layer, of a yellowish-red color, as in the arteries. It, however, is never more than 5^7 to T4x of an inch thick. Unlike that of the arteries, it consists of longitudinal as well as transverse layers. (Fig. 338.) The latter are composed of undeveloped areolar tissue and a large amount of smooth muscular fibres. In the popliteal, saphena major and minor, and the profunda femoris vein, there is a transverse layer of muscular fibres with areolar tissue, immediately in contact with the tunica intima, external to which is a regular alternation of longitudinal elastic membranes and transverse muscular fibres; so that the mid- dle coat presents a laminated aspect somewhat like that of the largest arteries. There are from five to ten of these elastic laminae; their interspaces being from 3 oVo to T2'oo °f an inch.—The inner coat of the medium-sized veins is T2'oTT to g'g of an inch. These are covered by a thick epithelial coat, drawn out into a number of long, thin, fine, and subdivided processes, resembling a fine brush, and sometimes ^ to TV of an inch long. The whole mass somewhat resembles a hair (Fig. 344), and is liable to be covered with mucedinous fungi. (Fig. 155.) Each filiform papilla has an artery giving a capillary loop to each of the simple papillae upon it. Nerves also can be found in most, but not all, of them; there being in the base of the papilla one or two small trunks with five to ten dark-bordered nerve-fibres, becoming finer as they approach the point. They probably terminate in loops. - (Kolliker) (Fig. 345.) 2. The fungiform papillae abound particularly on the anterior part of the tongue. They consist of a clavate primary papilla, ^ to T'5 of an inch long, to g'<, to ^ of an inch broad, covered with closely' placed, conical, secondary papillae, TJT to T^7 of an inch long, and covered by a simple epithelium, only s^^ to ^V o of an inch thick, over their points. (Fig. 346.) The vessels are arranged as in the 516 THE TISSUES. Fig. 344. a, I A c <* A. Vertical section near the middle of the dorsal surface of the tongue : a, a, fungiform papillae ; b, filiform papillae, with their hair-like processes; c, similar ones, deprived of their epithelium. (Magnified 2 diameters), b. Filiform papillse : a, artery ; v, vein ; c, capillary loops of the secondary papillae; 6, line of basement-membrane; d, secondary papillae, deprived of their (e,e) epithelium; /, hair-like processes like epithelium, capping the simple papillae (magnified 25 diameters); g, sepa- rated nucleated particles of epithelium (magnified 300 diameters). 1, 2. Hairs found on the surface of the tongue. 3, 4, 5. Ends of hair-like epithelium process, showing varieties in the imbricated arrangement of the particles, but in all a coalescence of the particles towards the point. 5. Incloses a soft hair. (Magnified 160 diameters.) papillae filiformes, except that they are far more numerous. (Fig. 346, B.) One or two larger nervous trunks also (-5 oVtt to y^Vu 0I"an inch) enter every fungiform papilla, besides many minute filaments, which, repeatedly anastomosing, spread out like a brush towards the secondary papillae and their axile corpuscles. They probably terminate both in loops and in free extremities. (Kolliker) 3. The papilloz circumvallatce are situated at the base of the tongue, are six to twelve in number, and consist of a central round papilla, flattened at the end, ^ to y^ of an inch in diameter, and Jg to even ^g of an inch high; with a lower uniform wall, ^ to -$$ of an inch MUCOUS MEMBRANE OF THE ORAL CAVITY. 517 Fig. 345. a. Secondary papilla of the conical class treated with acetic acid: a, its basement-membrane ; 6, its nerve-tube, forming a loop; c, its curly elastic tissue. The epithelium in this instance is not abundant, but the vertical arrangement of its particles over the apex of the papilla is well seen (d), and illustrates the mode of formation of the hair-like processes described in the text. (Magnified 160 diameters.) b. A similar papilla, deprived of its epithelium: a, basement-membrane ; b, tubular (nerve) fibre, probably forming a loop, but its arch not clearly seen ; c, c, elastic fibrous tissue at its base and in its interior. (Magnified 320 diameters.) c. Nerves of a compound papilla near the point of the tongue, in which their loop-like arrangement is distinctly seen. (Magnified 160 diameters.) Fig. 346. a. Fungiform papilla, showing the secondary papillae on its surface, and at a, its epithelium cover- ing them over. (Magnified 35 diameters.) b. The capillary loops of the simple papillae of a, injected: n, artery ; v, vein. The groove around the base of some of the fungiform papillae is here represented, as well as the capillary loops (c, c) of some neighboring simple papillae. (Magnified 18 diameters.) broad, closely surrounding the papilla, especially at its base. They are arranged so as to correspond to the letter V, the point being 518 THE TISSUES. constituted by the foramen cozcum, which is a depression containing fungiform papillae. The papilla itself is, in structure, to be regarded as a flattened fungiform papilla, except that it contains no elastic tissue; and the wall is a simple elevation of the mucous membrane, with a smooth epithelium, under which its upper border is pro- duced into many rows of simple conical secondary papillae. (Fig. Fig. 347. Papilla circumvallata of man, in section. A. Proper papilla. B. Wall. a. Epithelium, c. Second- ary papillae, b, b. Nerves of the papilla and of the wall.—Magnified about 10 diameters. (Kolliker.) 347.) Far more nerves are distributed to these than to the fungi- form papillae; the walls also being abundantly provided with them. Uses of the Lingual Papilla}.—The filiform papillae are neither the seat of the sense of taste, nor delicate tactile organs; but are the analogues of the lingual spines of animals (Todd and Bowman), and hence aid in mastication, and in protecting the tongue. The two other kinds of papillae subserve the sense of taste, and are also the seat of touch, temperature, &c. The sense of touch is most acute at the point of the tongue where the fungiform papillae are most abundant; the sense of taste at the root of the tongue, pro- bably because the circumvallate papillae possess more nerves in the same space. The nerve-fibres are also finer, or more nearly reduced to isolated axis-fibres. Certain pathological appearances of the tongue are easily under- stood from the data just afforded. The gastric furred tongue is produced principally by the growth of the epithelial processes of the filiform papillae, which projecting backwards apparently form a peculiar white coating. If they become longer, so that the pa- pillas measure | to % of an inch, the appearance called the villous tongue, not uncommon in various disorders, is produced. At length, indeed, the tongue may seem to be covered with hairs 4 to 6 lines long. In old people, the tongue may present no papillae at all; they being small and imbedded in the epithelium. Finally, the mucedinous fungi collecting on the papillae filiformes may produce a thick white coat, as shown by Fig. 155. GLANDS OF THE ORAL CAVITY. 519 The Glands of the Oral Cavity. The submucous areolar tissue of the mouth presents no peculiari- ties, except that it is thin and yielding on the fraena of the lips, tongue, and epiglottis, and the floor of the mouth; while it is more solid where mucous glands occur; and is firmly fixed on the root of the tongue, and the soft palate, where there are also large masses of fat in it. The glands are of three classes: the mucous, the fol- licular, and the salivary glands. 1. The 'mucous glands are racemose, yellowish, or whitish, of a rounded form, and J to \ of an inch in diameter. (Fig. 348.) Their terminal vesicles, or caeca, precisely resemble a simple Flg- 348, sebaceous gland. They ge- nerally lie in the submu- cous areolar tissue. On the lips they form a ring about 2\ of an inch broad round the oval aperture, com- mencing \ of an inch from the red edge of the lips. They are very numerous in the cheeks, but smaller. Those of the hard palate cover only its anterior half; while those of the soft pa- late are abundant, but di- minish towards the free edge of the uvula. Smaller glands also exist on its pos- terior surface. There are no glands upon the gums. The mucous glands of the root of the tongue are 2\j to \ of an inch in diameter. They form a stratum in some parts very thick, extending almost from one tonsil to the other. They, however, never extend forwards beyond the middle of the tongue. The ducts of some of these glands which lie in the extremity of the genio-glossus muscle, are even half an inch long. Other small glands lie on the margin of the root of the tongue; and two elongated glandular masses J to § of an inch long, i to \ of an inch thick, and \ to ^ of an inch broad, lie under the Human racemose mucous gland from the floor of the oral cavity, a. Investment of areolar tissue, b. Ex- cretory duct. c. Glandular vesicles (cseca). d. Ducts of the lobes.—Magnified 50 diameters. (Kolliker.) 520 THE TISSUES. point of the tongue each side of the fraenum, where five or six ex- cretory ducts open close to the latter. All these glands are abundantly supplied with bloodvessels, each of the caeca and vesicles being usually in contact with three or four capillaries. Nerves also exist abundantly upon the excretory ducts, and occasionally fine fibres are found in the glands them- selves. The mucus, secreted by these glands, has already been described (p. 198). 2. The simple follicular glands are, when dissected out, 2'T to \ of an inch in diameter, and are found at the root of the tongue lying under the mucous membrane, but above the mucous glands; and so superficially that their position is seen externally. Indeed, the excretory ducts of the mucous glands, before described, open into the bottom of these follicles or sacs. Each of these is a cavity lined by the mucous membrane of the tongue, with its papillae and epithelium; with a number of large completely closed capsules rl^ to j5 of an inch in diameter, and with walls g^Vir to 4uW OI" an inch thick, lying immediately under the membrane in a delicate fibrous and vascular matrix. (Fig. 349.) Their contents are gray- ish-white, consisting of a clear fluid, cells ^Vtt to 54V0 °? an incn in diameter, and free nuclei, g^Vo to 5Vtf of an inch in diameter, diminish below to goW 0I> an inch, or less; and the most common form terminates in a flask-shaped enlargement of 4-5^ to T^-g of an inch. Each tube is lined through its upper third by a simple conoidal epithelium; but in the rest of its extent the tube is entirely filled with pale, finely granular, nucleated cells, 2tto~tt to izvjj of an inch in diameter, which do not seem to constitute a dis- tinct epithelium. They are termed the peptic cells; and these are the simple pep- tic glands occurring in the middle zone of the stomach. The compound peptic glands (Fig. 352, c) occur in the narrow cardiac zone of the stomach. They resemble the preceding, except that they divide into two or three, and then into four to seven equally long cylindrical tubules, also lined by the peptic cells; in which oil-globules are frequently observed. The terminal lobules have a twisted appearance dependent on numerous lateral dilata- tions. Smooth muscular fibres are also found between these glands. Still, other compound tubular glands also exist in the pyloric zone, resembling the last, except that they are larger and lined throughout by a conoidal epithelium, and therefore contain no peptic .cells. (Fig. 352, b.) It is pretty certain that the true gastric juice is afforded only by the two forms of peptic glands just described; while the last men- Fig. 351. Perpendicular section through the tunics of the pig's stomach, from the pylorus, a. Glands. 6. Muscular layer of mucous membrane, c. Sub- mucous tissue (tunica nervea) with divided vessels, d. Transverse mus- cular layer, e. Longitudinal mus- cular layer. /. Serous membrane.— Magnified 30 diameters. (KMiker.) STRUCTURE OF THE STOMACH. 525 tioned secrete mucus alone. The pepsin is, therefore, afforded only by the cardiac and middle zone of the stomach, and not by the pyloric. Fig. 352. A and c. Peptic gastric glands, from the middle of the stomach, b. Mucous gland from pyloric region, a, trunk of the glands ; 6, branches ; c, terminal caeca ; d, termination of mucous gland, b, lined with conoidal epithelium, d. Portion of C8eca of c, magnified 350 diameters, e. The same, transverse section, a, basement membrane ; 6, large cells ; c, small epithelial cells. A and b, from the dog—200 diameters ; c, 60 diameters. (Kolliker.) The bloodvessels of the gastric mucous membrane are very numerous, and their distribution quite characteristic. Fig. 353 represents those of the large intestine, which are very similar. The arteries, beginning to divide in the submucous areolar tissue, break up into capillaries of BoVo to ?tjVtj- °f an mcn> which ascend between, and form a network around the tubular glands, extending as far as their apertures, and forming polygonal meshes around the latter g£T to 3^ of an inch in diameter. From this network the veins rise by many radicles, and penetrating the glandular layer further apart than the arteries, enter a venous network with partly horizontal vessels, in the submucous tissue. 526 THE TISSUES. Fig. 353. The lymphatic vessels of the gastric mu- cous membrane form two networks; a fine, superficial, and a deep, coarse one. The nerves, derived from the pneumogastric and the sympathetic, have been seen to enter the muscular layer of the mucous mem- d brane, but have not been traced further. 2. Structure of the Small Intestine. The small intestine is divided into the duodenum, the jejunum, and the ileum.— Throughout, the mucous membrane has a simple conoidal epithelium; and its corium has a layer of smooth muscular fibres both longitudinal and transverse (described by Briicke), like that of the gastric mucous membrane; and, at most, ^ of an inch thick. Where certain glands exist, there is but little submucous tissue, the corium be- ing closely connected with the muscular tunic of the intestine. It is more compli- cated in structure, though thinner than the membrane of the stomach; pre- senting, as it does, the villi and several varieties of glands. I. The villi (Fig. 351) ex- tend throughout the small intes- tine from the pylorus to the sharp edge of the ileo-caecal valve, being most numerous (50 to 90 upon a square line) in the duodenum and jejunum; while there are but 40 to 70 on the same surface in the ileum. They are whitish elevations of the corium of the mucous mem- section of the mucous membrane of the small brane, easily seen bv the unaid- mtestine of the dog, showing Lieberkuhn's folli- j cles and the villi, a. Villi, b. Lieberkuhn's folli- ed eye, and are Set SO close to- cles. c. Other coats of the intestine. gether upQn and between the Vessels of the large intestine of a dog, the mucous membrane being cut through perpendicu- larly, a. Artery, b. Capillary network of the surface with glandular apertures, e. Vein. d. Capillary network round the glandular tubules in the thick- ness of the mucous membrane.— (Kolliker.) Fig. 354. STRUCTURE OF THE SMALL INTESTINE. 527 valvuloz conniventes as to give to the membrane its velvety appear- ance. In the duodenum they are broader and less elevated, resem- bling folds and laminae Tlv to ^ of an inch high, and ^2 to even Txs of an inch broad. In the jejunum they are mostly conical and flattened, and often cylindrical, clavate, or filiform ; being g1^ to 2'3 of an inch long, 7!2 to T2Tr of an inch, or less, in breadth, and ^fa of an inch (in the flattened forms) thick. The epithelium of the villi is the simple conoidal variety. The proper villus itself is sim- ply a solid process of the corium whose matrix is undeveloped col- lagenous tissue, in which a variable number of roundish free nuclei are scattered; containing bloodvessels, lymphatics, and smooth muscular fibres. The bloodvessels are very numerous. Two or three small arteries (tsW to 7^o of an inch) give off a close net- work of capillaries, 40V0 to 2?V(T oi" an incn i*1 diameter, which lies immediately beneath the basement membrane on the outer surface of the proper villus itself. From the gradual confluence of these capillaries a vein arises which carries the blood into the larger trunks of the submucous Fig. 355. Fig. 355. Vertical section of the coats of the small in- testine of a dog, showing only the commencing por- tions of the portal veins, and the capillaries. The injection has been thrown into the portal vein, but has not penetrated to the arteries, a. Vessels of the villi. 6. Of Lieberkiihn's tubes, c. Of the muscular coat. Fig. 356. Two villi without epithelium, and with the lacteals in their interior (from the calf) ; treated with a dilute solution of caustic soda.—(Kolliker.) (Fig. 355.) The lympha- 528 THE TISSUES. tics of the villi are usually called lacteals. These traverse the axis of the villus, commencing in a caecal and frequently enlarged end. (Fig. 356.) They have a much greater diameter than the capilla- ries, and, according to Professor Briicke, are mere excavations in the villi without walls, while the true chyliferous vessels commence in the deeper parts of the membrane. In some broad villi, two lacteal cavities, a long and a short, appear. The smooth muscular fibres of the villi are arranged longitudinally, forming a thin layer, not always distinct in man, placed centrally around the lacteals. They produce contractions, and thus influence the propulsion of the chyle and the venous blood in the villi.— Nothing is known of any nerves in them. Function of the Villi.—The villi are the principal agents of ab- sorption of the nutritive elements resulting from the digestion of the food. But Briicke shows that absorption also occurs on the surfaces between them, and particularly from between the glands of Lieberkuhn. It is generally asserted that the lacteals alone absorb fat, while the minute bloodvessels absorb the other elements. Briich, however, found that the bloodvessels absorb fat as well as the lacteals; the former sometimes being half filled with fat, instead of blood alone. Both these observers also show that the epithelium of the villi is not cast off during normal digestion, as stated by Mr. Goodsir. Briicke asserts that the epithelial cells are mere tubes, closed externally by a layer of mucilaginous substance easily per- meable by fluids, and that the fat therefore finds an easy admission into them, and to the surface and into the substance of the proper villus itself, in the form of oil-drops. This observation needs con- firmation. In cholera, the epithelium of the villi, and sometimes of the whole intestine, is thrown off. II. The glands of the small intestine are of two kinds, the tubular and the racemose. Certain closed follicles are, however, also to be described in this connection. 1. The tubular, or Lieberkuhn's, glands are distributed over the whole small intestine, as straight, narrow caeca (Fig. 357), extending completely through the mucous membrane, and occupying almost all the space left between the villi; and, in a vertical section (Fig. 359 and 362), resembling palisades. They are, however, not found over the centre of the closed follicles, as will be seen. Their leuo-th equals the thickness of the mucous membrane (g^ to g'? of an inch); STRUCTURE OF THE SMALL INTESTINE. 529 their breadth is ^g to -5-^3 of an inch; and their aperture is g^ to 4^ of an inch. They contain a simple conoidal epithelium, whose cells Fig. 357. Fig. 358. Fig. 357. A. Transverse section of Lieberkuhn's tubes or follicles, showing the basement-mem- brane and the sub-conoidal epithelium of their walls, with the areolar tissue connecting the tubes : o, basement-membrane and epithelium constituting the wall of the tube ; b, cavity or lumen of the tube. (Magnified 200 diameters.) b. A single Lieberkuhn's tube, highly magnified; an accidental section in the oblique direction displays very distinctly the form and mode of packing of the epithe- lial cells, the cavity of the tube, and the mosaic pavement of its exterior: a, basement-membrane ; c, internal surface of the wall of the tube. (Magnified 200 diameters.) Fig. 358. Distribution of capillaries around follicles of mucous membrane. during digestion never contain fat, like those of the villi; the lumen of the tube being filled by a clear fluid secretion—the intestinal fluid—already described on page 201. The vessels of these glands follow the type of those of the stomach. (Figs. 358, 355, and 353.) 2. The racemose glands—Brunner's glands—rmost abundant in the duodenum, resemble those of the oral cavity and the salivary glands, in structure, and their vessels have the same arrangement as those of the latter. (Fig. 348.) Thus the vessels whence the secretion of these and the preceding glands is obtained are next to the arteries, while those concerned in absorption (those of the villi) are further from them, and nearer to the veins. (Fig. 355.) 3. The closed follicles are found scattered simply or in groups over the walls of the small intestine. In groups, they constitute the Peyer's patches, or glanduloz agminatoz. Each closed follicle is ^ to i,\ or even ^ of an inch in diameter, rounded or conical towards the intestinal cavity, and lying partly in the corium of the mucous membrane, and partly under it; extending from a point B£T to 4^ of an inch beneath its surface to the muscular tunic, which is here more closely united with the corium. (Fig. 359.) On the surface of the mucous membrane are roundish depressions, ■£$ to T*2 of an inch apart, corresponding to the separate follicles, and presenting 34 530 THE TISSUES. Fig. 359. Fig. 360. Vertical section through a patch of Peyer's glands in the dog. a. Villi. 6. Glands of Lieberkiihn, with the apices of Peyer's glands, c. Submucous tissue, with the glands of Peyer imbedded in it. d. Muscular and peritoneal coats, e. Apex of one of Peyer's glands projecting among the tubes of Lieberkiihn. *. Its contents. The glands are seen laid open by the section. (Magnified about 20 diameters.) no villi. When, however, the follicles are isolated (glandulae soli- tariae), they usually present a convex surface, and support villi. (Fig. 360.) Each follicle has a completely'closed, thick, and strong coat of indistinctly fibrillated collagenous tis- sue, with interposed nuclei; within which are the soft grayish contents, consisting of a little fluid, and innumerable nuclei and round cells, 3UOT5 to -jVo-xj °f an iacb in diameter. Very fine bloodvessels ramify, like those of the closed follicles of the tonsils, on the exterior of these follicles (Fig. 350), and penetrate to their inte- rior. (Frei and Ernst.) Lymphatics also form networks around them; but do not enter them, as Briicke asserted. (Kolliker) The patches of Peyer are from 20 to 30 in number, when confined, as usual, to the ileum and lower part of the jejunum; from 50 to 60 when extending nearly to, or even into, the duodenum. They are rounded or elliptical in form, always situated on the portion of intestine opposite the mesentery, and are | of an inch to even 1 inch long, and \ to even £ of an inch broad. They are mere aggregations of the closed follicles just described, each A solitary gland from the small intestine of the hu- man subject. — Magnified. (After Boehm.) MUCOUS MEMBRANE OF THE LARGE INTESTINE. 531 follicle being surrounded by the apertures of Lieberkuhn's glands, 6 to 10 in number, as shown Fig. 361. by Fig. 361. We have as yet no certain knowledge of the functions of the closed follicles of the small intestine. They become ulcer- ated in typhoid fever, and are subject to various other patho- logical conditions. 3. Mucous Membrane of the Large Intestine. This agrees mainly in struc- ture with the mucous mem- brane of the small intestine. Its peculiarities, therefore, will alone be specified. It presents no villi, but, aside from occasional wart-like elevations, it is level and smooth. The muscular layer is difficult to detect, except in the mucous membrane of the rectum. The glands of the large intestine are: 1. Lieberkuhn's glands, precisely resembling those of the small intestine, except that they are longer and broader, to cor Portion of one of the patches of Peyer's glands, from the end of the ilium ; moderately magnified. The villi and Lieberkuhn's glands are also displayed. respond with the greater thick- ness of the membrane (^g to 5*5 of an inch, by Ti5 to jl^). They are distributed over the whole surface from the ileo- caecal valve to the anus. 2. The solitary closed follicles are very frequent in the colon and rectum, and usually more abun- dant in the latter than in the small intestine. They are larg- er than in the latter locality (Jg to even § of an inch in dia- meter), and upon each of the little prominences to which the follicles give rise there is a Fie. 362. Solitary follicle from the colon of a child, a. Lieberkiihn's glands, b. Muscular layer of the mu- cous membrane, c. Submucous tissue, d. Trans- verse muscular fibres, e. Serous membrane. /.De- pression of mucous membrane above the follicles g.—Magnified 45 diameters. (Kolliker.) 532 THE TISSUES. small, pit-like, elongated or rounded aperture, T£5 to T^7 of an inch in diameter, in the mucous membrane. (Fig. 362.) The function of these closed follicles is also unknown. The bloodvessels of the preceding glands have the same rela- tions as in the small intestine. (Fig. 353.) Nothing is known of either the lymphatics or the nerves of the mucous membrane of the large intestine. The Appendages to the Alimentary Canal. 1. The Liver. Referring to the works on descriptive anatomy for all other par- ticulars in regard to the liver, such only will be specified here as are necessary to give an idea of its minute structure. The vena portae, the hepatic artery, and the hepatic duct enter the transverse fissure of the liver, and, subdividing, at last termi- nate—the first two in a capillary plexus from which the hepatic vein commences, and the last in immediate contact with the plexus. In the pig, and some other animals, the minute structures just men- tioned are so inclosed as to constitute distinct lobules, and it is the lobules in this animal which Kiernan first accurately described and figured. In man, however, nothing of the kind occurs, as E. H. Weber first demonstrated • the various structural elements being intimately connected throughout the whole organ. Still, the distribution of the capillaries and ducts is such as to give rise to little islets in the liver, somewhat analogous to the lo- bules above mentioned. These are masses of the hepatic sub- stance, gTg to.^j of an inch in diameter, containing some of the minutest branches of the vena portae and the hepatic artery ex- ternally, and giving off in their centre a small twig of the hepa- tic vein. Between these vessels the portal hepatic plexus of ca- pillaries is found. (Fig. 363.) The hepatic ducts arise in the meshes between the vessels of Fig. 363. Horizontal section of three superficial lobules of the liver, showing the two principal systems of bloodvessels. 1, 1. interlobular veins proceeding from the hepatic veins. 2, 2. Interlobular (portal- hepatic) plexus, formed by branches of the portal vein. (Pig.) APPENDAGES TO THE ALIMENTARY CANAL. 533 the plexus, and accompany the finest ramifications of the portal vein, so that the bile flows in a direction opposite to that of the blood. Finally, the spaces in the islets left between the elements just described are occupied by the so-called hepatic cells. Thus, in general, is an islet in the human liver composed; the capillary plexus, however, being common to all the contiguous islets, and continuous between them. The capsule of Glisson, composed of areolar tissue, invests the vena portae, hepatic artery, and hepatic duct, as far as to the branches going to the islets; but it extends between, and isolates the latter into distinct lobules, only in the pig, so far as has yet been ascertained. The passages in the liver containing Glisson's capsule with the vessels just mentioned, are called the portal canals. (Fig. 364.) Fig. 364. Fig. 365. Fig. 364. A transverse section of a small portal canal and its vessels; after Kiernan. 4. Portal vein. 9. Interlobular branches. 5. Branches of the vein, also giving off interlobular branches (vaginal branches, Kieman.) 7. Hepatic duct. 6. Hepatic artery. 2. Hepatic vein. The lobules are seen in outline. Fig. 365. Hepatic cells of man. a. Normal cells. 6. With pigment, c. With fat —Magnified 400 diameters. (KiHiker.) More particularly, the hepatic cells (Fig. 365) are described by Kolliker as averaging ygVo" t° tt/oti oi> an ^ncn in diameter, the ex- tremes being 2TJVw an(^ 750 0I> an inch. Their membrane is smooth and delicate, and their normal contents are—ls^, a yellowish, gran- ular, semi-fluid substance; Idly, a round, vesicular, nucleolated nu- cleus, 4 A(7 to gtfVcT of an inch in diameter (and sometimes two of these). Besides these (Sdly) fat-drops, and (^thly) pigment-granules are frequently to be met with. The last hardly exceed T2tr^Tr °f an inch in diameter, are of a yellow or brownish-yellow color, and appear to be chemically identical with the coloring' matter of the bile (p. 101). 534 THE TISSUES. These cells are so arranged in the islets as to appear to form a network by the mere apposition of their flat surfaces, without any intermediate substance or investing coat. The meshes of the net- work are mere perforations and passages for the capillary plexus and the commencement of the hepatic vein, and are of course con- formed to their diameters. The cells are generally arranged in from one to three rows (rarely four or five), to form the network itself (Fig. 118), so that the meshes are thus y^^ to B^ of an inch apart. Their true relation to the minute hepatic ducts will be specified on page 536. The hepatic ducts had been traced to the margin of the hepatic islets by Kolliker, but not into them; and he suggests that the finest ducts are open at their extremity, and abut on the hepatic cells, as shown by Fig. 118. Far more probable, however, was the view of Prof. Leidy on this subject, viz., that the hepatic ducts commence in the substance of the islets as a network of distinct tubules, lined by a basement-membrane and an epithelium.1 (Figs. 366 and 367.) Fig. 306. Fig. 367. Transverse section of a lobule of the human liver, A small portion of the preceding section, showing the reticular arrangement of the bile-ducts ; more highly magnified, showing the secret- wlth some of the branches of the hepatic vein in the ing cells within the tubes. (Leidy.) centre, and those of the portal system at the periphery. But Dr. Beale's recent investigations on this point seem quite con- clusive. He finds the hepatic cells to be arranged in lines radiating from the centre of the lobule, as shown in Fig. 368; though pre- cisely this appearance is presented only when the section is made at right angles to the small twig of the hepatic vein in the centre of 1 Researches into the Comparative Structure of the Liver, American Journal of the Medical Sciences, Jan. 1848. THE LIVER. 535 Fig. 368. Transverse section of hepatic islets (horse), showing the secreting cells forming lines radiating from the hepatic vein (a) in the centre, towards the circumference (6). Inj ected with vermilion. (Dr. Beale.) the islet. There is usually but one row (sometimes two) of cells between the capillary vessels. He further ascertained that these rows of cells are contained within tubes formed of simple membrane; which is sometimes incorporated with the walls of the capillaries, and sometimes distinct from them. (Fig. 369.) These cell-con- taining tubes, therefore, form the network in the substance of the islet. Fig. 369. Tubes of simple membrane containing the liver-cells (pig), a. An injected specimen, the shades Bhowing the injection, b. Cells and free oil-globules within the tube. c. Tube in which the cells have been disintegrated.—Magnified 200 diameters. (Dr. Beale.) 536 THE TISSUES. The precise connection of the ducts between the lobules, and the tubes just mentioned, is as follows: Numerous finer branches leave the small trunk of the duct, in the spaces between the islets, and pass towards the secreting cells, without branching or anastomosing with each other; and, pursuing a tortuous course around the branches of the portal vein, pass at once to the cell-containing net- work of tubes just described, and with which they are continuous. Near to the point where the duct joins the network of cell-contain- ing tubes, it becomes very much narrowed; being frequently ^^ Fig. 370. Communications of interlobular ducts, a. With the cell-containing tubular network. 6. Part of tubes containing cells filled with oil and free oil-globules, c. Narrowest portions of the ducts (pig.) The shaded parts are filled with injection.—Magnified 215 diameters. (Dr. Beale.) of an inch, or even less, in diameter in the uninjected state. Fig. 370 represents the narrowest ducts in the pig, and Fig. 371 those in the human liver. The epithelium lining the minute ducts between the islets (T2C^ of an inch in diameter) is of the simple scaly variety; its cells being far smaller than the secreting cells in the network before described, or only about 5oV an mcn in diameter. Fig. 372 shows their size compared with that of the former. It terminates abruptly where the secreting cells begin. In the ducts 3^ to 2^ of an inch in diameter, the epithelium is more conoidal; and it becomes com- pletely so in those above T2TJ of an inch. 'The latter also have a dense layer of areolar tissue (corium) externally to the epithelium and basement-membrane. The ductus communis choledochus, and the cystic duct, have both a mucous layer and a submucous areolar layer; the former containing a few smooth muscular fibres, but no THE LIVER. 537 special muscular coat. The gall-bladder has a layer of smooth mus- cular fibres beneath its peritoneal covering. That of the ox may be made to diminish its capacity one-fourth by a powerful galvanic Fig. 371. Fig. 372. Fig. 371. Narrowest portions of bile-duct, lined by its epithelium, continuous into the tubes con- taining the hepatic cells. A venous capillary and a small branch of the artery are seen in section, close to the narrow duct. The liver-cells have been destroyed by the reagents used in preparing the specimen. (Human.)—Magnified 215 diameters. (Dr. Beale.) Fig. 372. Terminal portion of interlobular duct, containing its epithelium, with four hepatic cells to show the comparative size. battery. (Dr. Mayer) Its mucous membrane presents many reticu- lated, more or less prominent, folds, containing a capillary network exactly like that of the foliaceous intestinal villi. It has also a conoidal epithelium.—Finally, the mucous membrane of the hepatic ducts above T2g of an inch in diameter contains a multitude of small, racemose, yellowish mucous glands (Kolliker) or sacculi (Dr. Beale); while there are but few in the cystic duct, and usually none at all in the gall-bladder. Dr. Beale finds these generally to be simple oval pouches, arranged in two rows on opposite sides of the duct, and connected with its cavity by a very narrow neck, often not 5TrVtf of an inch in diameter. In the larger ducts they are, however, branched, and often run for some distance in the coats of the duct. Occasionally the branches of one gland anastomose with those of another. Fig. 373 shows the more simple, and Fig. 374 the complicated forms of these pouches in the pig; where they are arranged completely around the duct. Many of the smaller ducts, about ■£$ of an inch in diameter, have numerous caecal pouches, arranged pretty closely together, and giving off branches of simple membrane only. These are very numerous in the transverse fissure of the liver, where they form an intricate network connected with the larger branches of the duct. They were first noticed, and named vasa aberrantia, by Weber; and who also described the anastomosis between the right and left 538 THE TISSUES. Fig. 373. A small lobule, showing the duct branching upon the capsule (pig). The sacculi of the ducts are seen as injected. A branch of the portal vein accompanies the duct. hepatic ducts in the transverse fissure, by the intervention of their irregular branches. Fig. 374. Large sacculi or glands in the coats of the ducts (pig). The largest and most complicated at c, where a smaller branch is coming off from the main trunk, a. Portion of large duct. 6. A small branch without glands.—Magnified 10 diameters. (Dr. Beale.) Dr. Beale considers these cavities or irregular branches "as little reservoirs in which the bile in the thick-coated ducts is brought into closer proximity with the numerous vessels surrounding them; THE LIVER. 539 by which it loses some of its water, and probably undergoes other changes." Thus the secreting cells at the surface of the islets probably take the most active part in the secretion of bile, being first reached by the portal blood, and while it also circulates more slowly. These cells also first show an increase of oil-drops in cases of fatty de- generation. The bile is formed by each individual cell, and trans- ferred, by the tube inclosing the row of cells, to the ducts between the islets. The very close contact in which the cells sometimes lie, is accounted for by the great changes in bulk they are known so readily to undergo. Hence the liver is a true gland, like the other racemose glands; and not essentially distinct from them in struc- ture, as has generally been asserted. The capillary network of the islets completely fills the interspaces of the tubular network, before described (Fig. 118). The capilla- ries average about 3^^ to 22Vtt °f an inon iR diameter; being somewhat less than the rows of the cells in the tube-network. The meshes between the vessels of course correspond in diameter with that of the columns of the cells, being 2^V^ *° zhu of an inch. A transverse section of the islets (in the pig), is shown by Fig. 363, where the formative radicles of the intra-insiilar hepatic vein is seen in the centre, and the capillary communications on the other hand with the vena portae, in the perimetral portion. The latter, however, even in the pig, does not form a complete ring round each lobule. The blood probably moves more slowly in the outer part of the capillary network; where it is more richly charged with the constituents of the bile. The external cells also usually contain the most fat; the central the most colored granules. The hepatic artery also terminates in the outer part of the capil- lary plexus of each islet, with the vena portae, it having previously supplied the walls of the vessels, and the intra-insular spaces (the capsules of the lobules, in the pig). In regard to the lymphatics and nerves of the liver, the works on descriptive anatomy may be con- sulted. That some twigs from the diaphragmatic nerve are sent to this organ, was first announced by Luschka. Dr. Beale finds the chemical composition of the liver to be as fol- lows :— Water.......68.58 Solid residue......31.42 540 THE TISSUES. Fatty matter 3.82 ' Albumen .... 4.67 Alkaline salts . . 1.17 .33 ' Earthy salts Extractive matter 5.40 Vessels, &c, insoluble in water 16.03 J Function of the Liver.—1. The liver secretes the bile, whose pro- perties have already been specified (p. 212). And all analogy war- rants the idea that it is secreted by the true hepatic cells lying in the meshes of the portal-hepatic plexus, and which are contained in the tubes which have been described. It is also very certain that the bile is formed in the cells and not merely eliminated from the blood (p. 211). 2. But the liver also forms sugar, as has already been shown (p. 71); and probably its parenchymal cells are the agents employed in its formation. 3. Again, the liver produces a change in the alimentary substances (albumen, &c), while traversing it from the vena portae, after being first absorbed into the vessels of the intestinal villi. It even forms fat as well as sugar, when neither are contained in the food; and thus becomes a sort of equilibrator of the function of hozmatosis, or the development of blood. Of its pathological conditions, fatty degeneration has already been described at some length (p. 311, 5). In cirrhosis of the liver, there is an enormous increase of the areolar tissue inclosing the vascular trunks (except the hepatic vein) and. the hepatic ducts; and the individual islets may become prominent, or even form isolated lobules. Since also this increase of the connective tissue is consequent upon the organization of plasma exuded by an inflammation of Glisson's capsule, and the new for- mation subsequently contracts—the liver is thus rendered more solid and smaller; the true hepatic substance also becoming atro- phied, or in part disappearing. In jaundice, the pigment-granules are abnormally increased in the hepatic cells; they sometimes completely filling the latter. For its other pathological conditions, reference must be had to the treatises on pathological anatomy. 2. The Pancreas. The pancreas is a compound racemose gland, so similar in its minute structure to the salivary glands, that only its peculiarities will be here described. The terminal caeca of the pancreatic duct are g^ to 3^0 of an inch in diameter, and usually rounded, and are lined by a simple scaly epithelium whose cells are frequently THE URINARY APPARATUS. 541 remarkable for their number of fat-granules. The pancreatic duct is lined by a mucous membrane, an offset from that of the duode- num, with a simple conoidal epithelium; and presenting many small racemose glands—probably analogous to the mucous glands of the bile-ducts. (Kolliker) The bloodvessels are distributed precisely as those of the parotid gland; while the lymphatics are more numerous. The nerves only accompany the vessels, and rise from the great sympathetic. The secretion of the pancreas is of the greatest importance to the function of digestion, as has been explained on page 213. CHAPTEB XIV. THE URINARY APPARATUS. The urinary organs are the kidneys, the ureters, the bladder, and the urethra. The mucous membrane lining the last three, forms the urinary passages; while that of the uriniferous tubes of the kid- neys is the seat of the secretion itself. The urinary passages will be first described, and then the substance of the kidney. 1. The urethra of the male will be described with the sexual organs (p. 550). That of the female has a reddish mucous membrane, with a compound scaly epithelium, and a quite vascular corium. The latter also contains, especially near the bladder, a certain number of racemose mucous glands (Littre's glands, Fig. 380), like those of the bladder, except that ihey are larger (sometimes even T'g of an inch in diameter), and more closely placed. It has a tunic of lon- gitudinal and transverse smooth muscular fibres, intermixed with areolar tissue; and outside of this, the musculus urethralis (Kolliker), consisting principally of transverse fibres. In the submucous areo- lar tissue is a plexus of veins, which has been incorrectly described as a corpus spongiosum. 2. The bladder has, externally to its lining mucous membrane, two layers of smooth muscular fibres: 1, an internal, consisting of oblique and transverse fasciculi, incompletely covering the mucous membrane from their reticular arrangement, but constituting a strong circular layer at the neck of the bladder (the sphincter ve- 542 THE TISSUES. siege); and 2, an external layer of parallel longitudinal fasciculi (the detrusor urina}). The mucous membrane is pale, smooth, and rather thick, except where the vesical triangle is situated; and most vascular at the fun- dus and the neck of the bladder. Its nerve-fibres are principally confined to the same parts, are dark-bordered, and both fine and of medium size. Its epithelium generally approaches the compound scaly kind, and, like that of the pelvis of the kidney, is remarkable for the diversity in form and size, of its cells—the deeper being usually elongated, and the superficial rounded, polygonal, or flat- tened. A conoidal epithelium, however, exists near the urethra and the orifices of the ureters. The corium is level (presenting no papillae), and shows isolated or aggregated simple racemose mucous glands in the neck of the bladder and towards the fundus. These are _i.^ to fa of an inch in diameter, and their orifices are g£o to 5!^ of an inch. They have a conoidal epithelium. In pathologi- cal conditions these are sometimes enlarged and filled with whitish mucous plugs. (Virchow) There is an abundant submucous layer of areolar tissue, except over the vesical triangle; and which is thrown into numerous folds when the bladder contracts. 3. The ureters, including also the pelvis and the calices of the kidney, are composed of an external fibrous coat, a middle mus- cular coat, and a mucous membrane. 1. The fibrous coat is com- posed of areolar tissue, and where the calices surround the papilla}, is continuous with the fibrous coat of the kidney. 2. The muscular tunic consists of an external longitudinal, and an internal trans- verse layer of smooth fibres; longitudinal fibres being also added to the inner layer towards the bladder. The two muscular layers are as thick in the pelvis of the kidney as in the ureters lower down; becoming thinner in the calices, and ceasing where the latter are inserted into the papillae. 3. The mucous membrane is thin throughout, tolerably vascular, without glands or papillae, and is continued upon the renal papillae. Its epithelium is the compound scaly variety like that of the bladder, and is g£7 to 3^ of an inch thick. The cells frequently contain two nuclei. Structure of the Kidney. The kidney is made up of 8 to 15 lobules (pyramids of Malpighi), each inclosed in an investment of areolar tissue; and which are all invested together by the fibrous capsule of the kidney. Outside of • STRUCTURE OF THE KIDNEY. 543 the latter is a layer of loose areolar tissue abounding in fat-cells, improperly termed the adipose capsule. The structure of the kid- ney is, therefore, but the repetition of that of each lobule. Each lobule is of a pyramidal form, the base presenting on the surface of the kidney, and the apex at the hilus; the outer por- tion, about half an inch thick, being more vascular, and constituting the cortical portion of the kidney, while the remaining part con- tains no Malpighian bodies, but consists principally of the urinifer- ous tubes, and is termed the medullary or tubular portion. The vascular portion, however, also gives off processes inward, ex- tending even to the hilus (the columns of Bertini). 1. The tubuli uriniferi of the kidney commence in the papillae of each lobule (i. e. the prominent part constituting the apex of the lobule), by from 200 to 500 orifices -g^ to T^ of an inch in dia- meter, scattered over its surface; and traverse the pyramids in close contiguity (tubes of Bellini). Each tubule in its course divides at least as many as ten times, and usually at very acute angles, into two, or more rarely into three or four smaller branches, diverging from each other, somewhat like the dentinal tubuli; and thus giving a greater diameter to the lobules towards the exterior. Vessels are also interpolated between them at regular distances as they pro- ceed outwards. Arriving in the cortical substance they become curved in their course (tubuli contorti), appearing at first sight to be inextricably interwoven, but ultimately terminating, as discovered by Bowman,1 in a dilated extremity jfa-Q of an inch in diameter, containing a vascular plexus of a peculiar kind—the Malpighian body. (Figs. 375, 130, and 377.) The tubuli contorti (or convoluted portions of the tubes) are, how- ever, actually arranged in columnar masses fa to fa of an inch wide (the pyramids of Ferrein), extending through the entire cortical substance; and here they freely anastomose with each other. The number of the tubuli contorti corresponds with that of the Mal- pighian bodies. Huschke calculates that each " pyramid of Fer- rein" contains 200 tubuli, and that there are 700 of these pyramids in a single lobule, or pyramid of Malpighi. Assigning 15 of the latter to each kidney, it would contain 2,100,000 tubuli contorti, and as many Malpighian bodies. Todd and Bowman maintain that the urine is secreted only in these convoluted portions of the tubes. (Figs. 375, m, and 130, 1 and 2.) 1 In 1842. 544 THE TISSUES. Fig. 375. The tubuli uriniferi are everywhere composed of a simple co- noidal epithelium resting upon a strong basement-membrane, ivhvTf to tsW of an inch thick, external to which is no distinct corium but merely the stroma, consisting of a firm transparent substance containing small gra- nular cells (Todd and Bowman); which, everywhere in the lobule, connects its various structural elements together. (Fig. 376.) Being at the commencement in the papillae -gfa to T2C of an inch in diameter, their branches are soon but Tfao to gg8 of an inch; but in the pyramids of Ferrein they again expand to g£0 to zfa, and in the cortical substance to •jgg of an inch or less; though again somewhat constricted just before they end in the dilatation receiving the Malpighian bodies, 2 &i> to T2V^ of an inch wide. The nucleated epithelial cells are also larger in the tubuli contorti {jfas to ToV(j of an inch wide, and -gfajf to 24W °f an inch thick); while in the straight portion of the tubules they are only one-half as wide, and sfaj. Vertical section through a portion of a pyramid and the cortical substance belonging to it, of an injected rabbit's kidney. The figure is half diagrammatic. The vessels are represented on the left side, and on the right the course of the tubuli uriniferi. a. Arteriae interlobulares with the Mal- pighian bodies (6), and their vasa afferentia. c. Vasa efferentia. d. Cortical capillaries, e. Vasa efferentia of the outermost bodies, proceeding to the superficial capillaries. /. Vasa efferentia of the innermost tufts continuous with the arteriole rectse (g, g, g). h. Capillaries of the pyramids which are formed out of the latter, i. A venula recta, commencing at the papilla, k. Commencement of a straight canal at the papilla. I. Divisions of the same. m. Convoluted tubes in the cortex, their whole course not shown, n. The same at the surface of the gland, o. Their continuation in the straight tubules of the cortex, p. Their connection with the Malpighian capsules.—Magnified 30 diameters. (Kolliker.) STRUCTURE OF THE KIDNEY. 545 of an inch thick. Thess cells have also clear, non-granular con- tents; while those of the tubuli contorti contain, besides the usual Fig 376. Soction of the cortical substance of the human kidney, a, a. Tubuli uriniferi divided trans- versely, showing the subconoidal epithelium in their interior. B. Malpighian capsule; a, its affer- ent branch of the renal artery; 6, its tuft of capillaries ; c, c, secreting plexus (of vessels) formed by its efferent vessels ; d, d, fibrous stroma. round nuclei, a finely granular albuminous (Kolliker) substance in the fluid contents, and generally some dark oil-drops, and more rarely, granules of yellow pigment. (Fig. 132, A k B.) The last cells alone probably secrete the urine. (Todd and Bowman) 2. The vascular (cortical) portion of each lobule consists of the tubuli contorti, just described, the Malpighian bodies, the vessels carrying blood to and from the latter, and the stroma of embryonic areolar tissue connecting all these elements together. The Malpi- ghian bodies extend to within g^ of an inch of the surface of the kidney on the one hand, and in the columns of Bertini even to the hilus of the kidney on the other. Each of these is a rounded mass (glomerulus), consisting of a close convolution or tuft of capillaries st/oo to T5V^ of an inch in diameter; inclosed in a capsule and sup- plied by an artery (vas afferens), ifao to g^ of an inch in diameter. This convolution Jf vessels is received into the dilated extremity of a tubulus contortus ; and its capsule is apparently the continuous basement-membrane of the tubulus, somewhat thickened. Thus the Malpighian body is virtually inclosed in the extremity of the tubulus; and it amounts to the same thing, practically, if it be said that the tubulus ends like the larger closed extremity of a retort, after having first inclosed the Malpighian body. (Figs. 377, and 131.) A vessel also emerges from the tuft within, through the capsule (the vas efferens)—not a vein, however, as might be expected; the pre- 35 546 THE TISSUES. Fig. 377. cise arrangement of the ves- sels being as follows: The artery divides at once on entering the coil into from 5 to 8 branches, and each of these into a bundle of capillaries, which, though much interlaced and convo- luted, do not anastomose; and ultimately merge into the vas efferens in the way in which they were first formed. Generally, the two vessels enter and quit the glomerulus near together, and opposite the commence- ment of the tubulus; and the capillary loops and con- volutions are always situat- ed exactly at its commence- ment. The vas efferens after emerging from the capsule of the Malpighian body, proceeds as an artery for a short distance, and then di- vides into two sets of capil- laries—the one going to the cortical portion to encom- pass the tubuli contorti on all sides in a rich network which is continuous through the whole cortical substance—and the other taking a straight course and with but few branches, between the straight tubes, and in the whole cir- cumference of the pyramids, even to the papillae, in which they are continuous with the proper capillaries of these parts. (Fig. 378.) Kolliker describes the epithelium of the tubuli contorti as in- closing the glomerulus; while at the same time the projecting free portion of the glomerulus is covered by epithelium. This has also been recently demonstrated in a very ingenious manner by Dr. Isaacs, of this city; though Todd and Bowman still believe that Relations of Malpighian tufts to the arterial branches and the cortical portion of the uriniferous tubes (man). a. Arterial branch with its terminating twigs, the injec- tion having only partially filled the tuft at a.. It has entirely filled, g, and passed out through the efferent vessel, e, f. It has burst into the capsule at y, entered the tube, t, and filled the efferent vessel, e, f. At (T it has extravasated, and passed along the tube. At to the injection has escaped from the capsule to a limited ex- tent. (Magnified 45 diameters.) VESSELS AND NERVES OF THE KIDNEYS. 547 the " vessels are bare within the capsule."1 Kolliker describes the epithelium as existing everywhere between the Malpighian tuft and its capsule, except where the affer- ent and efferent arteries penetrate. The Fi&- 378- ciliary motion, described by Bowman, at the junction of the Malpighian bodies and the tubuli contorti, exists in reptiles and fishes; but not in man or other mammalia. Vessels and Nerves of the Kidney. The branches of the renal artery enter the cortical substance interposed between the pyramids (columns of Bertini), and in the boundaries of the latter repeatedly dividing, form a delicate ramification without anastomoses around each pyra- mid. From this on the side towards the cortical substance, smaller arteries arise, mostly at right angles, which, after seve- ral divisions, give off the interlobular ar- teries (^hu to T27 of an inch in diameter), which run outwards in a straight course between the cortical fasciculi, or pyra- mids of Ferrein. And, finally, the last give off on one, two, three, or four sides, a great number of the arteria afferentia of the Malpighian bodies already described. In- deed, except a few branches to the capsule of the kidney, all the interlobular arteries terminate in the formation of the vascular tufts. (Figs. 130 and 377.) The renal veins commence in two situations: 1st, at the surface of the kidney; and, Idly, at the apices of the papillas. In the first situation, minute veins are formed from the outermost part of the capillary plexus of the cortical substance, and surround each bundle of Ferrein; and, between the latter, unite in a stellate manner into larger roots, or, extending over several bundles, connect into larger trunks. These, however, all unite to form the interlobular veins which accompany the arteries of that name, before described; and Malpighian tuft from near the base of one of the medullary cones. a. Arterial branch; af. afferent ves- sel, to. Malpighian tuft. ef. Effer- ent vessel; 6, its branches, entering the medullary cone. (Magnified 70 diameters.) 1 The Physiological Anatomy and Physiology of Man. Part IV., sect. 2, p. 4S9. 548 THE TISSUES. larger branches finally terminate in the wider arched venous rami- fications encompassing the pyramids (lobules). The veins of the latter commence in a beautiful plexus surrounding the orifices of the uriniferous tubes on the papillae, and, ascending with the arte- ries of the pyramids between the tubuli recti, also terminate in the ramifications just named. There are, proportionally, but few lymphatics in the kidney, ac- companying the bloodvessels as far as the interlobular branches. The nerves also (from the cardiac plexus) form a plexus around the arteries, to their interlobular subdivisions. How and where they terminate is unknown. Of the chemical composition of the kidney but little is known. Frerichs found from 72 to 73.70 per cent, of water, and 28 to 26.30 of solid matter. The fat amounted to from .63 to 1 per cent., or even 1.86 (Owen Rees); but the greater part of the solid residue is probably albumen from the epithelial cells (p. 114, 1). Dr. Beale finds 76.45 of water, and 23.55 of solid matter; viz., fatty matter containing much cholesterine, .939; watery extractive, 5.84; fixed alkaline salts, 1.01; earthy salts, .396; albumen, vessels, &c, 15.365. Function of the Kidney. The kidney secretes the urine; for an account of which see pages 214-22. It is pretty certain that much of the water in the urine is merely a transudation from the Malpighian bodies; while the peculiar ele- ments of this secretion are secreted by the epithelial cells of the uriniferous tubes, and mainly at least of the contorted portion. It is, however, not probable that a rupture of the epithelial cells is necessary, that their contents may become free in the straight por- tion of the uriniferous tubes; and hence the same cell may continue to secrete longer than has usually been supposed. (T. and B)1. Development of the Kidney. The urinary passages are developed as an offset from the lower extremity of the intestine; the kidneys being solid at first, like the salivary glands. The tubuli are at first composed solely of a solid series of cells, without any basement-membrane. Subsequently the 1 Dr. Isaacs, of this city, has recently read a paper before the New York Academy of Medicine, maintaining that the urine is secreted also by the Malpighian bodies. As it is not yet published, we cannot state the grounds of this opinion. PATHOLOGICAL STATES OF THE KIDNEY. 549 latter appears, and the tubuli become rapidly longer and convoluted. The Malpighian bodies are originally merely the solid thickened extremities of the tubuli, the interior cells of which subsequently become the capillary coil. In the new-born infant, the tubuli are one-third as large as in the adult, and the whole kidney one-half as large. (Harting) Therefore no tubules are formed after birth. The suprarenal glands will be described in connection with the blood-vascular glands (p. 592), since they appear to have no phy- siological connection with the kidneys. Pathological States of the Kidney. 1. The epithelial cells may contain abnormal contents; e.g. an increased amount of fat-drops, constituting fatty degeneration of the kidney (p. 310, 4), with or without pigment-granules; also colloid- like bright-yellow masses are sometimes found in the cells, when they generally dilate into slender cysts, ^ to T^ of an inch long, and which at length burst and discharge the colloid substance into the tubuli, and then into the urine. Cysts may also be formed by partitions of the tubuli contorti, finally separating their extremities from the portions below in the pyramids. The epithelial cells be- come detached in acute desquamative nephritis. 2. The basement-membrane sometimes becomes much thickened (t° ts^o to $fao of an inch), and presents close transverse striae on its inner surface. 3. The Malpighian bodies may expand into cysts containing the atrophied glomerulus and a clear fluid. 4. As abnormal contents (p. 215), the tubuli may contain blood, fibrine, the colloid substance before mentioned, concretions in the straight tubuli, principally of carbonate and phosphate of lime; and of uric acid salts, in the new-born infant, giving the pyramids a bril liant gold-yellow color. In Bright's disease, exudations into the tubuli first remove the epithelium, after which they become atro- phied, or altogether disappear; or become filled with a fatty broken- up exudation, and dilated into minute nodosities or granulations. 5. In inflammation of the kidney, the stroma often becomes so much condensed by the exudation as more or less to compress the tubuli. Often, also, the exudation becomes organized into embry- Fig. 379. A. Uriniferous tube containing a homogeneous cast. 550 THE TISSUES. onic areolar tissue; producing atrophy of the Malpighian bodies by its pressure, and thus interfering with the functions of the gland. 6. The casts of the uriniferous tubes, occurring in various con- ditions of the kidney, have already been noticed (Figs. 123-4, and p. 215). Another form is also shown by Fig. 379. CHAPTER XY. THE SEXUAL ORGANS. I. Sexual Apparatus of the Male. The male sexual organs are: 1. The testes; 2. The vasa defe- rentia; 3. The vesiculae seminales and ejaculatory ducts; 4. The penis, including the urethra and the accessory glands (Cowper's and the prostate). The mucous membrane of the urethra, prolonged through the vesicula seminalis and the vasa deferentia to the semi- niferous tubes of the testis, constitutes the genital passages of the male. 1. The urethra is a canal of mucous membrane, supported through- out its spongy portion by the corpus spongiosum urethra}, and in the prostatic by the prostate gland; while the membranous portion, so called, is an independent canal. The corpus spongiosum is essen- tially of the same structure as the corpus cavernosum penis, next to be described; except that its investing fibrous membrane is much thinner and has more elastic fibres, the intertrabecular spaces are smaller, and the trabeculae are smaller and richer in elastic fibres beneath their epithelium. It is also invested externally by a layer of smooth muscular fibres, and expands into the glans penis at its free extremity. The mucous membrane of the prostatic and membranous por- tions contains smooth muscular fibres, both longitudinal and trans- verse, though less developed in the membranous portion; and outside of these, in the latter, are the striated fibres' of the accelerator urinoz muscle. Smooth fibres also exist here and there in the sub- mucous tissue of the spongy portion, and a complete muscular tunic formed of them lies in contact with the corpus spongiosum on its fc SEXUAL APPARATUS OF THE MALE. 551 inside, towards the mucous membrane, and which meets the external muscular layer at the lips of the penis. (Hancock) The epithelium of the urethra is^the compound conoidal, consist- ing of two or three layers of cells. In the anterior half of the fossa Malpighii are papilla? ?^ of an inch long, and a scaly epithelium 3^ of an inch thick. Racemose mucous glands are found (Littre's glands) in the spongy and membranous portions, of g*g to fa of an inch (Fig. 380); while in the prostatic portion are minute mucous follicles, like those of the neck of the bladder (p. 542). The epithelium both of the caeca of Littre's glands and of the ex- cretory ducts (fa to fa of an inch long) is the simple conoid- al, approaching the scaly in the first position. The minute in- constant fossa? of the mucous membrane, called lacuna}, con- tain nothing of a glandular na- ture. (Kolliker) Cowper's glands are also compound racemose "filand °!J'1":'!''', t?,.the fossa Morgagnii in r man.—Magnified 500 diameters. (Kolliker.) mucous glands, and hence have a structure like the salivary glands. The delicate membrane in- vesting them, as well as the fibrous stroma in their interior and their excretory ducts fa of an inch wide, are well supplied with smooth muscular fibres. A simple conoidal epithelium lines the ducts, and a scaly, the terminal caeca. The penis is essentially made up—1st, of the urethra, as described, with its spongy body invested by a layer of smooth muscular fibres; and, 2dly, the two corpora cavernosa—with its investing fascia, skin, vessels, nerves, &c. The corpora cavernosa are two cylindrical bodies rising from the rami of the ischium, and uniting under the sym- physis pubis, though there is between them an incomplete septum; and consisting of a special fibrous membrane and the internal spongy tissue. The former is composed of white fibrous tissue with numerous elastic fibres, and is fa of an inch thick; investing the cavernous bodies externally, and giving off the' septum between them, as a thin lamella, partially broken up into separate fibres and laminas. Within it lies the reddish spongy substance, consisting of innumerable fibres, bars, and laminae, united into a fine meshwork 552 THE TISSUES. (the trabecular); and the minute rounded angular cavities bounded by the latter, and communicating on all sides. These cavities (the venous sinuses of the cavernous body) are all lined by a delicate scaly epithelium, which often does not admit of being detached; and are naturally filled with venous blood. The trabecules are composed of collagenous and elastic tissue in nearly equal proportions, toge- ther with smooth muscular fibres; and in many of them larger or smaller arteries and nerves are inclosed. The fascia penis incloses the corpora cavernosa from the root of the penis to the glans, abounds in elastic tissue, and contributes to the formation of the suspensory ligament of the penis; extending from its dorsum to the symphysis pubis, and containing much elastic tissue. External to this is the subcutaneous areolar tissue, containing a layer of smooth muscular fibres continued from the dartos to the prepuce; and finally the very delicate skin, whose peculiarities, so far as its glands are concerned, have already been specified (p. 487). The arteries of the penis need description here only in regard to the manner in which they supply the corpora cavernosa. Very small branches run in a convoluted manner, except at the time of erection, in the axis of the trabeculae, ramify in them, and ultimately open into the venous spaces by ramuscules ^fa^ to jfa-Q of an inch in diameter. (Fig. 381, c) In the posterior part of the penis there are numerous minute arterial trunks (3^ to yi^ of an inch), lying from 3 to 10 together, and being convoluted in a peculiar tendril- like manner (arteriae helicinae); though not terminating in caecal ends, in most instances certainly, as they were sup- posed to do by J. Muller. (Fig. 381.) The arterial ramification is precisely similar in the corpus spongiosum urethra}. The veins commence in the venous spa- ces, which intercommunicate through- out; from which short efferent veins carry the blood to the superficial ones. The lymphatics form very close plexuses in the corium of the glans, and the prepuce, and the remainder of the integument, and commu- nicate with the superficial inguinal glands. There are also lymph- Fig. 381. Small artery of the corpus caverno- sum, giving off a lateral hranch divid- ing into helicine arteries; terminating in very small vessels, which are con- tinued into the trabecular tissue, a. Arterial sheath of trabecular tissue. 6. Wall of the arteries, c. Capillary arteries. PROSTATE GLAND — VESICULAE SEMINALES. 553 atics in the glans around the urethra, and running backwards on that canal to the pelvic glands. The nerves of the penis from the internal pudic, go to the skin and the mucous membrane of the urethra, and, in very small amount, to the corpora cavernosa; while all those from the sympathetic are destined to the latter. The former nerve-fibres terminate like those of the skin generally; of the terminations of the latter, nothing is known. There is an expansion of the corpus spongiosum of the urethra opposite the root of the penis, called the bulb of the urethra; and behind this is the membranous and then the prostatic portion of the urethra—the last being encompassed by the prostate gland. The prostate consists partly (one-third to one-half) of glandular substance, and the rest mainly of smooth muscular fibres. 1. The glandular portion consists of 30 to 50 compound racemose glands, generally conical or pyriform, situated principally in the more ex- ternal parts of the organ. The numerous excretory ducts penetrate between the longitudinal and transverse fibres, and open into the urethra on both sides of the caput gallinaginis, which also consists in part of smooth muscular fibres. The caeca of the prostate gland are lined by a simple scaly epithelium; their ducts by a conoidal one. 2. The muscular portion of the prostate consists—1st, of an external layer of circular fibres continuous with the sphincter ve- sicae, extending as far as the caput gallinaginis; Idly, of a layer between this and the urethra, composed about equally of areolar tissue and smooth muscular fibres, extending from the vesical tri- angle to the caput gallinaginis. The fibrous coat which invests the prostate also abounds in fasciculi of smooth muscular fibres.—The secretion of the prostate resembles that of the vesiculoz seminales, next to be described. 2 and 3. The vesicula} seminales (Fig. 382), with the ejaculatory ducts, and the vasa deferentia, have essentially the same structure; consisting of an external fibrous tunic, then a layer of smooth mus- cular fibres, and internally a mucous membrane. The walls of the vesiculae seminales are much thinner than those of the vasa defe- rentia; the latter being fa to fa of an inch thick, while their whole diameter is fa to y of an inch, and their cavity, or lumen, fa to fa of an inch. The ejaculatory ducts commence from the prostatic portion of the urethra on each side of the caput gallinaginis, and become continuous on the one hand with the vesiculae seminales, and on the 554 THE TISSUES. Fig. 382. other with the vasa deferentia. Since the vesicular seminales are mere appendages of the vasa deferentia, furnished with saccular or branched processes (Fig. 382), their mu- cous membrane is also similar; and the last remark may be applied also to the ejacu- latory ducts.—The fluid secreted by the ve- siculae seminales is clear, rather viscid, and contains an albuminous compound identical with that contained in the ejaculated semen. Since spermatozoids are so generally con- tained in it, we must assign to these append- ages the double office of secreting a peculiar secretion, and of being a receptacle for the semen. The vasa deferentia have a muscular coat fa to fa of an inch thick, consisting of an external layer of longitudinal fibres, a middle one of transverse and oblique fibres, and an internal one, constituting not more than one- fourth of the whole thickness, of longitudinal fibres. The mucous membrane is T^ of an inch thick, yellowish white, longitudinally plicated, and in the widest portions of the canal presents numerous larger and smaller fossae, disposed in a reticular manner. The deeper two-thirds of the corium is a very closely filled structure of elastic fibres, while the remainder is more transparent. The epithelium is of the simple scaly variety,, the cells almost invariably containing some brownish pigment-granules. The vessels and nerves of these three portions of the genital pass- ages require no particular description. 4. The testes are glands inclosed in a fibrous tunic (the tunica albuginea), which also sends processes into the interior from a thicker portion called the corpus Highmorianum. (Fig. 177.) But for the particulars respecting this and the other tunics, as well as the vessels and nerves, we refer to the works on descriptive anatomy. The glandular substance of the testes consists of 100 to 250 pyri- form lobules—not everywhere separated, however—the apices all converging towards the corpus Highmorianum. Each of these lobules is formed of from one to three seminal tubes T?u to Thtt of Vesicula seminalis. a. Eja- culatory duct. 6. Vas deferens. e. Vesicula seminalis. d. Ter- minal diverticula. (E. H. We- ber.) VS TSU an inch in diameter; which, much convoluted, frequently dividing, STRUCTURE OF THE TESTIS. 555 and perhaps also anastomosing, form a compact substance, and ter- minate at the base of the lobule, either in caecal extremities or in Fig. 383. Structure of the testis and epididymis, a, a. Seminiferous tubes, a*, a*. Their anastomoses. a. Lobules formed of the seminiferous tubes, b. Eete testis, c. Vasa efferentia. d. Flexures of the efferent vessels (cones) passing into the head (e, e) of the epididymis. /. Body of the epididymis. g. Appendix (vasculum aberrans). h. Tail of epididymis, i. Vas deferens. loops. (Fig. 383.) Their origin in caecal extremities is shown by Fig. 384. Though joined together by some areolar tissue and ves- Fig. 384. a. Blind extremities and branches of human seminal tubes, b. One of the caeca more highly magnified. sels, the tubes in each lobule may be separated, and their length, according to Lauth, is from 13 to 33 inches. Estimating the ave- rage number of lobules in each testis at 175, it would contain from 556 THE TISSUES. 189 J to 481 feet of tubing. Out at the apex of each lobule a single tube, y^ of an inch in diameter (tubuli recti), passes into the base of the corpus Highmorianum. These form a very close plexus (the rete testis), from the upper end of which proceed 7 to 15 efferent canals (vasa efferentia testis), fa to fa of a line in diameter, which traverse the tunica albuginea, and are continued into the epididy- mis. Here, contracting to ^g to f ^ of an inch, they are convoluted in precisely the same way as in the lobules, but without dividing or anastomosing; and thus form the spermatic cones. These, united by connective tissue, constitute the head (globus major) of the epididymis; at the upper and posterior border of which their canals gradu- ally coalesce, and thus a simple duct is formed, fa to fa of an inch in diameter. (Fig. 385.) This duct is so convoluted as to form the body and tail (globus minor) of the epididy- mis; and, after giving off usually, a cascal prolongation at its inferior extremity (vas aberrans), is ultimately continuous with the vas deferens, already described. Structure of the Seminiferous Tubes. The tubuli testis consist of an external fibrous coat, a basement-membrane, and an epithelium, these together being jfa-Q to jfa^ of an inch thick. The first averages -^fa-^ to pVo of an inch in thickness, is tolerably firm and extensible, contains no smooth muscular fibres, and rarely any indications of elastic tissue. The epithelium is simple conoidal, approaching to the scaly variety. In young subjects the cells are pale and finely granular; but as age increases, a continually increasing quantity of fatty granules is collected in them, giving the seminal tubes a light yel- lowish, partially brownish color. The tubes in the rete testis, how- ever, appear to be mere passages in the dense tissue of the corpus Highmorianum, lined by an epithelium. But in the cones the fibrous coat again appears, and to it is added a coat of smooth muscular fibres, continuous upon the vasa deferentia, as before described. Fig. 385. A view of the minute struc- ture of the testis. 1, 1. Tu- nica albuginea. 2, 2. Corpus Highmorianum. 3,3. Tubuli seminiferi convoluted into lo- bules. 4. Vasa recta. 5. Eete testis. 6. Vasa efferentia. 7. Coni vasculosi constituting the globus major of the epi- didymis. 8. Body of the epididymis. 9. Its globus minor. 10. Vas deferens. 11. Vasculum aberrans, or blind duct. STRUCTURE OF THE SEMINIFEROUS TUBES. 557 The contents of the seminal tubes vary according to age. Pre- viously to puberty, they contain nothing but minute clear cells, resembling epithelial cells. At this period, however, the tubes increase in size, and when the formation of semen has commenced, they become clear, round cells and cysts, ^fa^ to ^^ of an inch in diameter, inclosing from 1 to 10, or even 20, clear nucleolated nuclei, sfa-Q to -gfajf of an inch in diameter. At this time, also, the epithelium is not manifest, the cells in question appearing en- tirely to fill the tubes (Fig. 386); though at other times, especially Fig. 386. Seminal tube (man), with contained cells, a. Wall of tube. b. Nuclei of fibrous coat. c. Base- ment-membrane, d. Cells removed from the tube. The latter figure shows the action of acetic acid. (Magnified 220 diameters.) in advanced years, the epithelium appears, containing fat, or pig- ment-cells, surrounding the other elements. The cells and cysts (spermatophori) just mentioned are the precursors of the semen; for in each nucleus a spermatic filament (spermatozoid) is developed on the inner wall, as a spiral corpuscle with two or three turns. (Figs. 387 and 117.) This development commences in the tubuli testis, but it is not completed so that the spermatozoids become liberated, till they reach the rete testis and the coni vasculosi. The nuclei first bursting, the spermatozoids remain for a time in the cysts or spermatophori, the heads and tails together when numerous (10 to 20); but subsequently the spermatophori also burst, in the epididy- mis, and the dense entangled crowd thus liberated entirely fill its 558 THE TISSUES. tubes, some of them still being collected in bundles. The process of development is usually concluded in the lower part of the epididymis, though transitional forms are sometimes found in the vas deferens. The pure semen, as found in the vas defe- rens, consists of a very small quantity of a viscid fluid, together with the spermatozoids just spoken of; and for a description of which we refer to page 207, and Fig. 116. Semen, as emitted, contains the secretions of the vesiculas seminales, and of Cowper's and the prostate gland, in addition to the two elements before mentioned. The movements of the spermatozoids are not exhibited, or slightly if at all, in the pure semen of the vasa deferentia; but are first seen in the less concentrated contents of the vesiculae seminales.—In the semen of patients who have suffered attacks of double epididymitis, the spermatozoids have remained absent for months, and even years. (Gosselin) In those broken down by seminal losses, they are im- perfectly developed, the tails being rough, irregular, and indistinct. (Lallemand) Henle states that the spermatozoids move at the rate of 1 inch in 7J minutes. The ejaculation of the semen is principally secured by the strong muscular layer of the vasa deferentia, their action being also con- tinued by the vesiculae seminales, the very muscular prostate, and the layers of smooth muscle inclosing the urethra; to which must also be added the action of the striated muscles, levator ani, accele- rator urinae, &c. The erection of the penis is caused, Kolliker main- tains, by the relaxation of the smooth muscular fibres contained in the trabeculae of that organ, and the consequent flaccid state of the venous sinuses and their distension with blood. This is not, how- ever, a satisfactory explanation. The distension of the sinuses of the corpora cavernosa and the corpus spongiosum with blood is, apparently, the immediate cause of erection; this, doubtless, over- coming the contractile force of the smooth muscular fibres in the walls of the trabeculae for the time being. Development of spermato- zoids in the spermatophori of the rabbit, a. Parent cell with five nuclei, b. Each nucleus containing a spermatic fila- ment (spermatozoid). c. Nu- cleus with spermatozoid. d. A parent cell with several spermatozoids set free from the nuclei, or cells of develop- ment, and coiled together in a bundle. SEXUAL ORGANS OF THE FEMALE. 559 II. Sexual Organs of the Female. The sexual organs of the female are: 1, the vulva ; 2, the vagina; 8, the uterus and oviducts; and 4, the ovaries. To these the lacteal glands must also be added. 1. Of the external genital organs of the female, together consti- tuting the vulva, the clitoris with its two corpora cavernosa and glans, presents, on a small scale, precisely the same conditions as the corresponding parts and corpora cavernosa of the male; the mus- cular elements being even more readily isolated. The mucous membrane of the vulva has a submucous layer of a spongy, highly vascular, areolar tissue; and a compound scaly epi- thelium, -j J^ to jIjj of an inch thick. Its corium fa to fa of an inch thick, is everywhere furnished with much developed papillae, T2^ to %fa of an inch long on the labia minora, and 5|5 to -j^g of an inch on the clitoris. It also contains sebaceous glands on the labia majora (of fa to fa of an inch), in connection with hair-sacs; and still more abundantly, and mostly without the latter, on the labia minora, T^ to fa of an inch in diameter; and sometimes also round the orifice of the urethra, and laterally at the entrance of the vagina. Common racemose mucous glands fa to £ of an inch in diameter, with excretory ducts either short, or even \ an inch long, exist around the orifice of the urethra, in the vestibule and the lateral portions of the entrance of the vagina. The two glands of Bartholini (Duverney1 s), corresponding to Cowper's glands in the male, and situated at the inferior extremity of the bulbi vestibuli, are common racemose mucous glands J an inch in diameter, with pyri- form casca lined with a scaly epithelium. Their ducts are 7 to 8 lines long, and J a line wide, having a longitudinal layer of smooth muscular fibres external to their mucous membrane, and a conoidal epithelium Tfa-Q of an inch thick. The labia majora contain com- mon adipose tissue in their interior. 2. The walls of the vagina, fa of an inch thick, consist of an external fibrous coat, a middle muscular layer, and a mucous mem- brane. 1. The external tunic is a layer of areolar tissue, contain- ing plexuses of veins, and passing without any line of demarcation into the middle redder layer, consisting of areolar tissue, numerous veins, and some muscular fibres. 2. The latter increase during pregnancy, and becoming -^ to 1fa of an inch long, constitute a true muscular membrane. 3. The mucous membrane is pale red, 560 THE TISSUES. presents numerous folds and elevations (columnar), and has a com- pound scaly epithelium T4T to T^ of an inch thick,.like that of the oesophagus; its scales being the largest in the body. Its corium is very firm, and yet very extensible, and presents numerous conical or filiform papillae (Fig. 389, c), 2£ whose cilia vibrate towards the uterus—or in a direction contrary to those of the uterine cavity itself. They may aid in the passage of the ovum into the latter; but cannot carry the semen in an opposite direction. The round ligaments of the uterus contain longitudinal bundles of smooth muscular fibres, surrounded by areolar tissue; with which are associated at the internal abdominal ring, many striated muscu- lar fibres, often extending nearly to the uterus. The ligaments of the ovaries also contain a small amount of smooth muscular fibres; and between the two folds of the peritoneum constituting the broad ligaments of the uterus, a small amount of these fibres is continued from the uterus. Except that the veins are large and very thin-walled (uterine sinuses), the bloodvessels of the unimpregnated uterus present no- thing for special description. The lymphatics, probably commenc- ing in the mucous membrane, are very numerous, and proceed in part to the pelvic and partly to the lumbar glands. The nerves, from the hypogastric plexus and the pudendal branches, reach the uterus by the broad ligaments, and ramify from the body to the cervix, being most abundant in the latter. Those spread out upon the surface of the uterus are but few in number. (Dr. Beck) They are not in the uterus furnished with any ganglia (Kolliker), contrary to the assertion of Dr. Lee, of London; and their condition in the mucous membrane, and their terminations elsewhere, are unknown. Changes in the Uterus at the Menstrual Period, and in Pregnancy. At the menstrual period the whole uterus enlarges and its tex- ture expa"hds; principally, doubtless, from the distension of its ves- sels. No change occurs, apparently, in the muscular coat; but the mucous membrane becomes thicker (to 1 or even 3 lines, or in its projecting folds to 5 or 6 lines) and softer, and presents easily iso- lated uterine glands, 1 to 3 lines long, and ^^ to 3^ of an inch broad—and many immature round and pyriform cells. The blood- vessels throughout the uterus, and especially of the fundus and the body, are much distended with blood. This is especially the case with the superficial capillary plexus, and hence the bright red color of the mucous membrane. The menstrual fluid consists of blood poured out in consequence of rupture of some of these capillaries, with cells of the epithelium, which is in great measure thrown off; CHANGES IN THE UTERUS IN PREGNANCY. 565 but which is again rapidly restored after the catamenial period has passed (p. 176, e.) In pregnancy, changes of a very different character occur; the increased bulk of the organ being, however, the subject of main interest here. The principal changes occur in the muscular struc- ture of the uterus; and these have already been described on page 388. But the mucous membrane also undergoes manifold changes; it being also first affected. As early as the second week in preg- nancy it becomes 2 to 3 lines thick, is softer, redder, has more pro- minent plica}, and is more distinct from the muscular coat. The uterine glands become 2 to 3 lines long; and a new formation of areolar tissue has taken place in the corium. These peculiari- ties become more marked as time advances; and the greater part of the hypertrophied mucous membrane is transformed into the decidua vera, while that corresponding to the attachment of the ovum is converted into the placenta uterina, and a growth from the border of this produces the reflexa around the ovum. No epithe- lium exists on the decidua after the first month. The mucous mem- brane of the cervix takes no part in this formation, and retains its epithelium (without cilia), during the whole period of pregnancy. The serous coat of the uterus also increases in thickness during pregnancy, but less than the mucous. The smooth muscular fibres also, and probably the striated, increase in the round ligaments. The bloodvessels and lymphatics also increase in length and calibre, and the nerves appear to become thickened (though it is doubtful whether any new fibres are produced in them), and may be traced further into the organ than at other times. The return of the uterus after parturition to a state similar to, but not precisely identical with, its condition previously to that state, is effected (1,) by an atrophy of the muscular structure, so that in -three weeks after parturition the fibres are as short as in the virgin uterus (p. 389); and (2,) by the complete removal after par-, turition of the placenta and decidua, so that the membrane has to be formed anew. 4. The ovaries consist of two coats, the peritoneal and the fibrous (tunica albuginea), and the stroma. The last is a grayish-red, tolerably firm substance, composed of embryonic areolar tissue, which contains the ovisacs, or Graafian follicles, and the vessels. The ovisacs are entirely closed round cavities J to 3 lines in dia- meter, and imbedded in the more peripheral parts of the stroma. 566 THE TISSUES. There are from 30 to 100 in each ovary, and often even 200; while in old women only 2 to 10, or even none at all, are to be found. Each mature ovisac consists of a membrane and contents. The former resembles a mucous membrane, consisting of (1,) a highly vascular fibrous layer (tunica fibrosa), and (2,) an epithelium. Baer distinguished the outer portion of the fibrous layer, which is united to the stroma by a loose connective tissue, from the internal thicker, softer, and reddish portion. The epithelium (membrana granulosa), lies upon a basement-membrane, is rfas to tttVtt °^ an inch thick, lines the whole sac, and on the side of it towards the surface of the ovary, presents a wart-like thickening, the germinal eminence (cumu- lus proligerus). This is fa of an inch broad, and envelops the ovum to be described further on. (Fig. 392.) Its cells are polygonal, with large nuclei and frequently yellowish fatt}?- granules disposed in several layers. (Fig. 145.) The contents of the ovisac within the membrana granulosa are (1,) a clear light yellowish fluid of the density of the serum of the blood (liquorfolliculi); al- most always containing (2,) isolated granules, nuclei, and cells detached from the mem- Graaflan foiiicie of the sow. brana granulosa. a External, b, internal layer To retum tQ the Qy QT rp^ Heg of the fibrous membrane of the ' °° foiiicie. c. Membrana granulosa, close upon the fibrous membrane of the ovi- i^T T^Lrn^T£ sac> on the side of the latter looking to the eminence, a projection ot the ' o membrana granulosa. /. Ovum surface of the ovary, and imbedded in the with a zona pellucida, vitellus, ■.•. i. ., 1 • in l and germinal vesicie.-Magni^ °ells of the germinal eminence before de- fied about io diameters. (Kan- scribed. When the ovisac bursts, the ovum escapes, completely inclosed by the cells of the eminence and the contiguous portion of the epithelium, consti- tuting the germinal disk (discus proligerus). The ovum itself is a spherical vesicle, fa to T^o of an inch in diameter, possessing the nature and constitution of a simple cell, though in some respects peculiar. The cell wall (vitelline membrane), is a simple mem- brane, is usually 30W to jifas of an inch thick, very elastic and firm, and, surrounding the contents as a clear transparent ring, is called zona pellucida. (Fig. 393.) The cell is completely filled by the light-yellowish yolk. This is a viscid fluid having many minute pale granules dispersed in it, and fatty granules; besides—in thefully THE OVUM—CORPORA LUTEA. 567 formed ovum—a well-marked vesicular nucleus, the germinal vesicle. This is gi«j of an inch in diameter with clear contents; and a ho- mogeneous round nucleolus (of %fa^ of an inch) on its surface— the germinal spot. (Figs. 55 and 393.) The arteries of the ovary enter from its inferior border, and terminate partly in the stroma, and partly in the walls of the ovisacs, where is an inner finer plexus of capillaries extending to the basement-membrane under the mem- brana granulosa. A few lymphatics come out from the hilus ovarii, and pro- ceed to the lumbar and pelvic glands. The nerves come from the spermatic plexus, and enter the ovary with the arteries. Their ultimate distribution is not yet ascertained. The ovisacs are constantly becoming matured, and then burst as above men- tioned, from the commencement of pu- berty till menstruation ceases; this oc- curring principally, but not exclusively, at the menstrual period. As they ap- proach the time of bursting, they ac- quire a diameter of 4 to 6 lines, and at length project beyond the surface of the ovary. Meantime the tunica albu- ginea and the peritoneal coat become thinner, and at length give way; when the ovum, being situated at the point of rupture as before ex- plained, escapes, surrounded by the germinal disk, and makes its way into the uterus through the Fallopian tube. The empty ovisac is now termed a corpus luteum. (Fig. 394.) Occurring in the ordinary course of menstruation they are termed false corpora lutea; and true corpora lutea, if in connection with impregnation of an ovum. Fig. 395 represents three corpora lutea of pregnancy, at two days and at twelve weeks after delivery and in the sixth week after conception; but a particular description of them is out of place here. The yellow plicated appearance in the interior is due to the thickened condition of the fibrous membrane of the ovisac; and Fig. 393. Mammalian ova. Upper figure an immature, and the lower a mature ovum. a. Zona pellucida. b. Yolk. c. Germinal vesicle, d. Germinal spot. In the lower figure, the zona pellucida, a, is ruptured, and the yolk granules, 6, and the germinal vesicle have escaped through the opening. (Coste.) . 568 THE TISSUES. the contents are the blood poured out upon the rupture of the ovi- sac, with some remains of its original liquid contents.1 Fig. 394. Human ovary, a. Graafian follicle (ovisac) with opening. 6. Inner lining of follicle (membrana granulosa), c. Outer portion of the same. d. Ovum. e. Vascular wall of ovisac. (Coste.) Fig. 395. Corpora lutea of different periods, b. Corpus luteum of about the sixth week after Impregnation, showing its plicated form at that period. 1. Substance of the ovary ; 2, substance of the corpus luteum ; 3, a grayish coagulum in its cavity. (After Dr. Patterson.) a. Corpus luteum two days after delivery. D. In the twelfth week after delivery. (After Dr. Montgomery.) In respect to the function of the female genital organs, it may be here remarked merely that the Fallopian tubes, as well as the uterus and the vagina, manifest motor phenomena. The application of the Fallopian tubes to the ovaries to receive the ovum into their fim- briated extremity, is doubtless secured by the action of their mus- 1 For the most satisfactory account of the corpus luteum, see Prof. J. C. Dalton's Prize Essay, Transactions of Amer. Med. Association, vol. iv. THE LACTEAL GLAND. 569 cular fibres. The muscular structure of the uterus may act all at once, or only a part at a time; as during parturition, the os and cervix are at first at rest, while the fundus and body are contract- ing. In convulsions, the whole uterus contracts firmly round the child (Kolliker); in retention of the placenta, the contraction is con- fined to the fundus. The author is convinced that during the or- gasm a descent of the uterus, an opening of the os, and a dilatation of the canal of the cervix take place. The sensibility of the interior of the uterus is very slight; care- ful sounding of its cavity usually causing no pain, and intra-uterine instruments being worn by many patients in the treatment of ute- rine displacements, with very little inconvenience. The vagina also has but little sensibility internally. The most sensitive parts of the vulva are the clitoris, and the entrance to the vagina at the orifice of the glands of Duverney. The mucous secretions from the genital passages of the female have already been specified (p. 198). For the changes undergone by the impregnated ovum during its development in utero, consult the works on Embryology. The original development of the fe- male genital organs—very analogous to that of the male organs during the first part of embryonic life—will also be omitted here. 5. The Lacteal Glands. The lacteal glands are of the compound racemose variety, cor- responding in all essential particulars with the parotid and the pan- creas. Each gland consists of 15 to 24 or more flattened lobes | to 1 inch wide, and which are composed of lobules connected by areolar tissue, containing many fat-cells. The terminal casca of the lobules are rounded or pyriform, and 2fa to t4t of an inch in diameter. (Figs. 398, and 115.) The smallest ducts leading from these have a simple scaly epithelium; and these uniting, form the larger trunks. Each of the latter running towards the nipple, dilates beneath the areola into an elongated sac, ^ to J of an inch wide;1 then con- tracting to 1 or even J a line, it bends into the nipple, and finally opens at its apex in a separate orifice, -g'g to gV of an inch in dia- meter, between the papillae which exist there. (Figs. 306, 307, 308.) These ducts, about 20 in number, are lined by a so-called mucous membrane, longitudinally plicated in the largest, and, deep in the 1 These reservoirs in the cow hold even a quart. 570 THE TISSUES. gland, containing longitudinal smooth muscular fibres. (Henle) The epithelium is conoidal in the larger ducts, and scaly in the smaller. Fig. 396. Six milk-tubes of the lacteal gland, injected from the nipple, a. The straight tubes proceeding to the apex of the nipple. 6. Reservoirs, or dilatations of the ducts, c. Branches of the ducts, d. Terminal lobules. (Sir A. Cooper.) The nipple and areola con: tain many smooth muscular fibres (p. 477), and which are much increased in pregnancy. Its compound papillae are rfa t° 39s °f an mcn l°no5 and their direction is from the base towards the apex of the nipple. The cuticle is not more than zfa-Q of an inch thick; while the Malpighian layer is ^-J„ of an inch thick, and colored in the deeper portion. Over the gland itself, the papillae are small and simple, and the epi- thelium still finer. In the areola, but not on the nipple, there are large sebaceous folli- Fig. 397. Terminal lobule of lacteal gland with ducts; from a puerperal woman.—Magnified 70 diameters. (Lun- ger.) THE LACTEAL GLAND. 571 cles, with fine hairs often visible on the exterior; and sudoriparous glands, often with peculiar contents. Fig. 398. Terminal follicles (caeca) of lacteal gland and ducts ; from a woman not pregnant. Numerous elastic fibres appear on the wall of the ducts, and the caeca are separated from each other by a consi- derable amount of areolar tissue. (Magnified 150 diameters.) The bloodvessels present nothing pe- FiS- 399- culiar, except the venous circle in the areola (circulus venosus Halleri).— Lymphatics abound in 'the skin, but are not found in the gland. The same remark also applies to the nerves; ex- cept that a few fine twigs are found accompanying the vessels. The secretion of the lacteal glands, the milk, has already been described (pp. 202-5). In their development the lacteal follow the same course as the cutaneous glands, being at first merely a solid projection of the stratum Mal- pighii. The structure of the lacteal gland in the new-born child is shown by Fig. 399. Lacteal gland of a new-born child. The rudimentary follicles are very well shown. (Langer.) 572 THE TISSUES. CHAPTER XVI. THE RESPIRATORY ORGANS. The respiratory apparatus consists of the nasal passages; the upper part of the pharynx; the larynx; the trachea; and the lungs. The mucous membrane lining all these constitutes the air-passages. 1. The mucous membrane alone of the nasal passages, needs to be described here. It is continuous with the skin of the nose at the entrance of the nostrils, and with the mucous membrane of the eye through the lachrymal passages. It is intimately connected with the periosteum of the nasal passages, in the sinuses and some other parts; but on the spongy bones and the septum, forming the direct passages to the pharynx, it is thicker, having a submucous layer of areolar tissue containing plexuses both of arteries and veins. The corium presents papillae resembling those of the skin, just within the nostrils. Its epithelium is of the compound scaly variety, like that of the skin, to the distance of about f of an inch within the nostrils, where it becomes the compound conoidal cili- ated epithelium, there being two layers of cells (Fig. 400); and Fig. 400. Section of the ciliated epithelium of the nasal passages, a. Superficial cells clothed with cilia. b. Deeper series becoming elongated vertically, c. Various shapes of the perfect ciliated cells. (Magnified 180 diameters.) thus continues through the nasal passages, except over the olfac- tory region (p. 449). The same epithelium also extends, over the upper portion of the pharynx, posteriorly to the level of the larynx, and in front over the posterior surface of the velum—this portion constituting a part of the air-passages, as already stated (p. 522). THE RESPIRATORY ORGANS — LARYNX AND TRACHEA. 573 This part also of the mucous membrane of the pharynx, abounds in glands. 1. Racemose mucous glands fa to T'2 of an inch in diameter, form a perfectly continuous layer on the posterior wall around the Eustachian tubes, and on the posterior surface of the velum. 2. Closed follicular glands, simple as well as compound, are met with on the vault of the pharynx, where the mucous membrane is closely attached to the base of the cranium. A glandular mass extending from one Eustachian opening to the other, and 1 to 4 lines thick, is constantly found here. This, in aged persons, frequently presents large cavi- ties filled with puriform masses. Other glands also exist upon the sides of the pharynx, and on the posterior surface of the velum, which probably have the same structure as the mucous sacs on the base of the tongue (p. 520). 2. The larynx and trachea, with the continuations of the latter into the lungs (bronchial subdivisions), resemble in form the excre- tory ducts of the compound racemose glands, which the lungs may, in fact, be regarded as being. The larynx has a framework of car- tilages with their connecting ligaments; the thyroid, cricoid, and two arytenoid being true (hyaline) cartilages. The epiglottis, how- ever, and the cartilages of Santorini and Wrisberg, are reticular cartilages (p. 314); and the cartilago triticea is common fibro-carti- lage. Of the ligaments, the middle crico-thyroid, and the inferior thyro-arytenoid (chordce vocales) contain a preponderance of elastic fibres, and are of a yellow color. The other ligaments and the hyo-thyroid membrane, also contain an abundance of this element. To the cartilages and ligaments just mentioned, the striated muscles of the larynx are attached; but which present nothing peculiar to the histologist. The mucous membrane of the larynx, continuous with that of the mouth and pharynx, is smooth and whitish-red, and above the chordae vocales, has an abundant layer of areolar tissue under it. The membrane is very closely adherent to the vocal cords, and where it lines the larynx below them; and is prolonged into its ventri- cles. Its corium presents no papillae, and its outer portion abounds in elastic networks. The epithelium on the epiglottis is compound scaly, like that of the oral cavity. At its base and above the upper vocal ligaments, commences the compound conoidal ciliated epithelium, lining the air-passages throughout. It is here com- posed of several layers of cells, and is y£T to 3^ of an inch thick. The external (ciliated) cells are gfo to SU of an inch long, by -gfa-^ 574 THE TISSUES. t0 Wtto 0I> an incn broad, on the average, with elongated round nuclei, and occasionally a few fat-granules. The cilia are fine transparent processes of the cell-membrane, -gfa-Q to $fa of an inch long, rising in a broader basis and terminating in a pointed extre- mity. They have been described on page 243; their motion some- times continuing 72 hours after death. It should be, however, re- marked that the epithelium on the vocal cords is a scaly, and not a conoidal ciliated one; as discovered by H. Rheiner. The mucous membrane of the larynx also contains a large num- ber of minute racemose glands (^^o to fa of an inch), like those of the mouth, pharynx, &c, with caeca lined by a scaly, and ducts by a conoidal, epithelium. They occur sparsely on the posterior sur- face of the epiglottis. At the entrance of the larynx in front of the arytenoid cartilages, they form a large mass, a horizontal por- tion of which envelops the cartilage of Wrisberg, while another dips down into the laryngeal cavity. Glands also abound in the external wall of the ventricles of the larynx, behind and above the sacciform ligaments. All these glands secrete pure mucus. The bloodvessels of the larynxare numerous, but require no spe- cial description. The numerous lymphatics are received by the deep cervical glands. Of the nerves, the more sensitive superior laryngeal contains more fine fibres; while the inferior laryngeal has more thick fibres. (Bidder, Volckmann). They terminate in the muscles, the perichondrium, and especially in the mucous mem- brane. The branches going to the epiglottis are furnished with mi- croscopic ganglia. 3. The trachea contains a series of rings of true cartilage, each completing about § of a circle; and between their separated extre- mities is a transverse layer of smooth muscular fibres. On the outer aspect of this, are isolated longitudinal muscular fasciculi, rising by minute tendons of elastic tissue partly from the inner surface of the ends of the tracheal rings, and partly from the ex- ternal fibrous membrane; which covers the cartilages as a perichon- drium, and at the same time the muscular layer, and connects the different cartilages together. The mucous membrane of the trachea has a layer of close areolar tissue, x^cr of an inch thick beneath it, and its corium consists of two layers: 1, an external, of areolar tissue, T^ of an inch thick, and, 2, an internal, yellow, fa to T^-0- of an inch thick, almost en- tirely composed of longitudinal elastic fibres. The epithelium is RESPIRATORY ORGANS—THE LUNGS. 0(0 ciliated as in the larynx, and differs in no respect from the latter. The glands in the mucous membrane of the trachea are numerous; the larger occurring more in the posterior wall, externally to the muscles and the whole mucous membrane, while the smaller are more numerous on the anterior wall, and just exterior to the elastic layer of the membrane.' The larger have a scaly epithelium in their caeca; while the smaller, being only simple or bifurcated follicles in the thickness of the membrane itself, have a conoidal epithelium. The bloodvessels have their larger branches running longitudi- nally, while the superficial capillary plexus is close beneath the basement-membrane.—The lymphatics are abundant; commencing (in one case) in wide meshed plexuses, T5^^- to -^fa^ of an inch broad, of thin-walled vessels giving off caecal processes. (Kolliker) 4. The lungs are, structurally, to be regarded as two compound racemose glands; and an accurate knowledge of the structure of one of the lobules, therefore, implies that of a whole lung., The lungs are invested, however, externally, by a serous membrane, the pleura; which, like the peritoneum, forms a closed cavity, and con- sists of two portions—the pleura costalis lining the thoracic cavity, and the pleura pulm&nalis, directly adherent to the lung. In struc- ture, also, the pleura entirely corresponds with the peritoneum (see p. 523); the parietal layer being the thicker and most adherent, and its epithelium being the simple scaly variety. The pulmonary layer is, however, the more vascular.—Nerves, with fine and coarser fibres, are sent to the parietal layer, from the phrenic and the sym- pathetic (Luschka); and Kolliker has seen medium and thick nerve- fibres accompanying the branches of the bronchial arteries in the pleura costalis, and occasionally, large scattered ganglion-cells also. The lung proper consists—1st, of the continuations of the trachea (the bronchi and their subdivisions) into the air-cells; Mly, the ves- sels and nerves; and, Mly, the connective tissue binding all these elements together in the lobules. 1. The bronchi and their subdivisions in the lung have the same structural elements as' the trachea, on a diminished scale; except that the cartilaginous rings entirely disappear in the finer subdi- visions (under fa of an inch), and in the finest the fibrous tunic coalesces with the mucous. The smooth muscular fibres constitute a completely continuous layer in the smaller subdivisions, and ter- minate i of an inch short of the last air-cells to which they lead. 576 THE TISSUES. Fig. 401. Small bronchial tube laid open, showing the transverse plexiform ar- rangement of the mus- cular layer, and its dis- position at the orifice of a branch. From a man aged 50. (Magnified 2 diameters.) Their appearance in twigs y^ to T|T of an inch in diameter is shown by Fig. 401. Finally the bronchi end in the lobular passages. The mucous membrane lining the bronchi and their subdivisions is at first like that of the tra- chea, but gradually becomes extremely thin in tubes of less than fa of an inch. It everywhere consists of a layer of elastic fibres, a basement- membrane gAtf to 7fas of an inch thick, and a ciliated epithelium. The last, even down to tubes 1 line in diameter, contains several layers of cells; but is finally reduced to a single layer of conoidal ciliated cells, -zfa-Q of an inch long. In the larger branches, racemose mucous glands are also found, but these are wanting in tubes of less than 1 to 1J line in diameter. The subdivisions of the bronchial tubes do not anastomose. The air-cells will be described in speaking more particularly of the lobules. 2. The pulmonary arteries enter the substance of the lung in company with the bronchi, and follow their subdivisions also, though more frequently dividing dichotomously, and hence more rapidly diminishing in size. Finally, the terminal branches occa- sionally, but not regularly, anastomosing, merge exclusively into the capillary plexus of the air-cells in each lobule—to be described further on—except a few fine branches to the pleura. (Henle) The pulmonary veins rise from this plexus, in radicles more superficial than the arteries, and more external in the smallest lobules; and unite to form larger trunks, proceeding, in great part isolated from the arteries, through the pulmonary substance.—The bronchial arte- ries are distributed—1st, to the larger bronchial tubes; Idly, to the pulmonary veins and arteries, as their vasa vasorum (to the latter even fa of an inch in diameter); and, Bdly, to the pleura pulmonalis. They do not go to the mucous membrane at all, and do not anasto-: mose with the pulmonary artery or vein.—The lymphatics are nume- rous, but require no distinct description. The bronchial lymphatic glands are both numerous, and colored dark brown or black by a carbonaceous deposit. The nerves, from the pneumogastric and the sympathetic, are furnished in the interior of the lung with micro- scopic ganglia, and may be traced nearly to the termination of the THE RESPIRATORY ORGANS — LUNGS. 577 bronchial subdivisions. They accompany the pulmonary artery, and occasionally the veins and the bronchial arteries. 3. The interlobular connective tissue of the lungs, everywhere existing very sparingly, is the common areolar, containing in the adult a quantity of blackish pigment in the form of irregular minute granules, aggregations of granules, or crystals, but which are never inclosed in cells. They also frequently exist in the walls of the air-cells themselves (p. 132). The pulmonary lobules are far more distinct in the infant and child than in the adult. In the latter, they are so intimately united that even on the surface of the lung their outlines are but imper- fectly perceived. They are fa to y^ of an inch in diameter. The secondary lobules, however—£ to 1 inch in diameter—are very apparent, being bounded by streaks of pigmentary matter. Each lobule is of a more or less conical or pyramidal form, and consists of—A, a terminal bronchial tube; B, the air-cells; and C, the capillary plex- us; besides the nerves and some con- nective tissue. A. The terminal air-tubes are from Fig. 402. are T^ to fa (fa to fa of an inch—Todd and Bowman) of an inch in diameter. They enter at the apex of the lobule, and, passing nearly in its axis, termi- nate in the lobular passages and infun- dibula (the former being 2£^ to r^ of an inch in diameter), as shown in Fig. 402. The air-cells open into the in- fundibula, and their appearance in the lobule, as seen from without, is shown by Fig. 403. b. The air-cells are grouped around and open directly into the infundibula. A few, indeed, open thus into the air- tube before it divides. (Fig. 403.) Thus a honey-comb appearance is afforded by the cells, as seen in their relations 37 Termination of the bronchi in the lung of the dog. a. Terminal tube, and its branches (lobular passages), and the infundibula. b. One of the last. c. Septa projecting inwards on the infundibular wall, and forming the alveoli or cells. (From Rossignol.) Fig. 403. Two small pulmonary lobules (a, a), with the air-cells (6, b), and the finest bronchial twigs (c, c); upon which air- cells are also placed. From a new-born child. Half diagrammatic.—Magnified 25 diameters. (Kolliker.) 578 THE TISSUES. Fig. 404. Fig. 405. Thin slice from the pleural surface of a cat's lung, considerably magnified. At the thin edge (6, c, d), cells (alveoli) are seen. In the centre (at a), where the slice is thicker, cells are seen on the walls of infundibula, and opening into the latter. (From Rossignol.) to the infundibula, in sections of the latter. (Fig. 404.) There are about 18,000 air-cells in communication with each terminal air- tube, and the number of cells in both lungs is estimated at 600 millions. (Rochoux) The size of the cells varies considerably; they being after death, and when not distended with air, from 5Tg to fa of an inch in diameter. They mayrhowever, be dis- tended to two or three times this diameter without rup- turing ; and are, probably, at least one-third larger during life than after death. In a collapsed lung, they are usu- ally of a rounded oval form; when inflated, they are round- ed angular; and those on the surface of the lung are inva- riably polygonal, and their external sides almost always plane. In structure, they present merely a wall (fibrous mem- brane) and an epithelium. waiis of the air-ceiis. a. Epithelium, b. Elastic Tne former has been regard- trabeculse.c. Membranous walls with fine elastic fibres. ed as the attenuated mUCOUS THE RESPIRATORY ORGANS — AIR-CELLS. 579 membrane and fibrous tunic of the bronchial tubes (Kolliker); but it is, in fact, made up of elastic tissue and vessels, in a homogeneous matrix. The elastic fibres present the form, chiefly, of separate trabeculae and filaments, running between the epithelial linings of the air-cells, and supporting the capillary vessels. (Fig. 405.) By anastomosing with each other, they constitute a firm frame, on which the softer vessels are stretched, while over them the epithe- lium is laid. These elastic trabeculae mutually coalesce, so that, for the most part, the boundaries of the separate air-cells cannot be recognized where the latter abut upon each other. The epithelium of the air-cells is the simple scaly variety, com- posed of pale, polygonal, granular cells, averaging ^fa-Q of an inch in width, and sfajj of an inch in thickness. It lies immediately on the fibrous walls (just described) of the air-cells. C. The capillary plexus of the lobules is one of the closest in the human body, presenting rounded or oval meshes %fa-Q to jfa-Q of Fig. 406. Fig. 407. Fig. 406. Arrangement of the capillaries of the air-cells of the human lung. Fig. 407. Slightly oblique section through a bronchial tube. a. The cavity of the tube. b. Its lining membrane, containing bloodvessels with large areolae, c, c. Perforations in this membrane, where it ceases, at the orifice of the lobular passages, d, d. e, e. Spaces between contiguous lobules, containing the terminal pulmonary arteries and veins supplying the capillary plexus (/,/), to the meshes of which the air gains access by the lobular passages. an inch wide, and vessels ^Vtt to ^fa^ of an inch in diameter.1 It lies in the wall of the air-cells, about T3i™ of an inch from the 1 Todd and Bowman make the capillaries so large (j^Vo- of an inch) as to secure a free circulation, and intimate that the blood traversing them moves If inch per minute. Each capillary extends over 8 to 10 air-cells, and the air remains in con- lact with the blood li second. (Rainey.) 580 THE TISSUES. epithelium; some of the vessels also projecting fairly into the cells, since they are sometimes thicker than the walls of the latter. It continues not only over all the air-cells of the same lobule, but also anastomoses with the plexuses of the contiguous lobules. A great portion of the capillaries are also situated between, and in relation with, two air-cells at the same time. Fig. 406 shows the capillary plexus seen on the walls of, and between, the air-cells, after the epithelium is removed.—There is also a capillary plexus on the surface of the smallest air-tubes, and even extending to the trachea, in continuation with the preceding, characterized by the elongated form of its meshes (Heale1), and formed of vessels almost as fine as those of the air-cells (3 fa-$ to ^fa-Q of an inch). (Fig. 407.) Only the pure aerated blood enters this plexus, since it has previously circulated through the capillaries of the air-cells. Function of the Respiratory Apparatus. The air-tubes merely conduct the air to and from the air-cells of the lungs. It is not probable that the epithelium becomes desqua- mated to any considerable extent in disease. At least, it is certain that in croup an exudation may occur through the epithelium with- out detaching its cells, and which may subsequently be coagulated into a " false membrane," falsely so called, or undergo degeneration into pus (pp. 497 and 189). The lungs are the aerating organs of the blood; i. e. they secrete carbonic acid gas from the blood in the capillary plexus in the walls of the air-cells, and absorb oxygen at the same time into the blood. The layers interposed between the air in the cells, and the capillary vessels, are but %fajf of an inch thick on an average. The whole amount of surface presented to the air by the six hundred million air-cells in the lungs, has been estimated at 132 square feet, or more than eight times as great as the cutaneous surface of the body ;a and all the blood in the body traverses the capillary plexus spread out on the air-cells, probably, within the space of two minutes. Development of the Lungs. The lungs appear a little after the liver, as two hollow protru- sions of the anterior wall of the pharynx; into the composition of which the epithelium and the corium of the pharynx equally enter. 1 American Medical Monthly, vol. ii. p. 302. 2 Lindenau computed the whole surface of the air-cells and the air-tubes at 2642 square feet!!! PATHOLOGICAL STATES OF THE LUNGS. 581 A continually increasing number of arborescent hollow processes spring from the extremities of the original protrusions, and in the 6th month the air-cells are developed from the dilated extremities. New cells are, however, continually added, up to birth, but not sub- sequently. Before they are filled with air in the new-born child, they are ,fo of an inch, and after breathing, ^ to 2fo of an inch in diameter. The subsequent increase of the lungs consists in an expansion of all their parts. Pathological States of the Lungs. * 1. In emphysema, the air-cells become permanently dilated to two or three times their normal diameter; or become even ruptured, so that the cells of the same, or even of different lobules, become con- fluent. Their wall becomes very thin. The bronchial arteries become dilated in cases where the circula- tion through the pulmonary arteries is interrupted; the former re- placing branches of the latter, and becoming aerating vessels. 2. Hypertrophy of the air-cells occurs in hypertrophy of the lungs from increased functional action. 3. The air-cells become obliterated by exudation or deposit (e. g. tubercular), in the cavities or their walls, or into the interlobular areolar tissue. Red hepatization is produced by a complete filling of the air-cells by the exudation of pneumonitis; in gray hepatiza- tion the walls of the cells and the interstitial tissue become softened and undergo a fatty metamorphosis. (Kolliker.1) Fig- 408. Fig. 409. Fig. 40S. Section of gray granulations, after addition of acetic acid ; showing the air-cells filled with tubercle nuclei. Fig. 409. Cretaceous transformation of tubercle, with crystals of cholesterine. 1 See also p. 193, 2. 582 THE TISSUES. Deposits of pigment occur as a consequence of hepatization, or from a simple congestion of the lungs. Tubercle (gray granula- tions) is most frequently deposited in the air-cells (Fig. 408); cancer, in the interstitial tissue. The former is liable to cretaceous trans- formation (Fig. 409). 4. In oedema of the lung, serum is effused into the air-cells; in apoplexy, blood is extravasated into the interstitial tissue. 5. The epithelial cells undergo a fatty degeneration in portions of the lung encompassed by a pleuritic effusion, in atelectasis (Rein- hardt), and in splenization. 6. New formations (bone and cartilage), and cysts, are generally noticed in the interstitial tissue. 7. The parenchyma of the lung is destroyed by inflammation, gangrene, tubercle, or cancer; the elastic fibres usually being well preserved, while the remaining elements are infiltrated with fine fatty molecules. For the pathological states of the air-passages, reference may be made to the works on pathological anatomy. CHAPTER XVII. THE BLOOD-VASCULAR GLANDS. This class includes a series of organs possessing a glandular structure, but no excretory ducts; and which are supposed to ela- borate substances from the blood to be again applied to some pur- pose in the organism, after resorption from their tissue. As they derive their designation from a mere hypothesis, it were doubtless better to abolish it altogether. "Ductless glands" (Todd and Bowman) is a better designation. The following organs are referred at the present time to this class; all of which have been described in connection with other parts and organs, except the last four. The anterior lobe of the pituitary body (p. 465); the solitary follicles of the stomach and intestine, and the aggregated follicles of the small intestine (p. 530); the follicular glands in the root of the tongue, the tonsils, and the pharyngeal follicles (p. 573), and the lymphatic glands (p. 510). The spleen, the thyroid body, the thymus, and the supra-renal glands—still remain to be described. THE SPLEEN. 583 I. The Spleen. The spleen consists of a serous and a fibrous coat, and a soft parenchyma. 1. The serous coat is the peritoneal investment, and adheres so firmly to the fibrous coat that it can be dissected off only in frag- ments. 2. The fibrous coat is composed of areolar tissue, and completely invests the spleen, and, at the hilus, sends sheaths into the interior around the vessels, like Glisson's capsule.1 3. The parenchyma is principally composed of (1,) the trabeculae, inclosing (2,) the pulp, in which (3,) the Malpighian corpuscles are found. 1. The trabeculoe are white, shining, flattened or cylindrical bars, averaging T^ to fa of an inch, of are- olar tissue, attached to the inner sur- face of the fibrous coat, and sometimes to the outer surface of the sheath of the vessels, and which unite to form a network extending through the whole organ. The interstices in it freely communicate, and contain the red pulp and the Malpighian corpuscles. Be- sides the collagenous and elastic ele- ments, the trabecular also contain many peculiar spindle-shaped fibres g^ to 4^ of an inch long, and ^fa^ of an inch wide, with undulated ends and prominent enlargements, containing rounded nuclei. Kolliker at first mis- took them for smooth muscular fibres. Their nature is not fully understood. They are sometimes found coiled up in cell-like bodies. (Fig. 410.) 2. The interspaces of the trabeculae are filled by the pulp, in which the Malpighian bodies are lodged. The pulp is a soft, reddish sub- stance, consisting of three elements: 1, the smallest bloodvessels; 2, microscopic fibres and trabeculae; and 3, peculiar cells. The oc- Peculiar fibres from the pulp of the human spleen. A. The same, free b. One inclosed in a cell.—Magnified 350 diameters. (Kolliker.) 1 In the ox, dog, pig, ass, and cat, it contains smooth muscular fibres also. 584 THE TISSUES. currence of extra vasated blood in various stages of metamorphosis is also so frequent as to be almost regarded as a normal constituent. The vessels will be described further on. The fine trabeculae are also composed of areolar tissue, and are ?fao to Tfas of an inch in diameter. The minute fibres are very numerous, and of collagenous tissue; some of them being the terminations of the vascular sheaths. The cells of the pulp (parenchymal cells) (Fig. 411), are round, uni-nucleated, -^fas to 54-Vo OI*an inca iQ diameter, and apparently Fig. 411. Pulp of human spleen, a, a. Blood-corpuscles. 6,6. Dotted nuclei, c, c. Nucleated vesicles, d, d. Colored masses of haematine. (Gray.) like those of the Malpighian bodies, soon to be described. More than in the latter also, free nuclei are mixed with them. Pale, round, homogeneous bodies also are found, somewhat larger than blood-corpuscles, resembling free nuclei, or homogeneous nuclei surrounded by a delicate investment; pale larger cells, up to -r^u of an inch in diameter, with one or more nuclei—and cells with dark colorless fat-granules. These elements also exist, but in less extent, in the Malpighian corpuscles. The cells are united by a reddish-yellow fluid; and, together with the latter, constitute about THE SPLEEN. 585 Fig. 412. one-half the mass of the spleen. There are no special investments around these parenchymal cells. They lie in direct contact with the sheaths of the vessels, the trabeculae, and the sheaths of the Malpighian bodies. The red pulp of the spleen presents different shades at different times, as they depend on the blood-corpuscles in its vessels; and which present all the various stages of metamorphosis. Kolliker and Gray1 describe round cells ^fa^ to H^ of an inch in diameter, holding more or less metamorphosed blood-corpuscles, and con- taining 1 to 10 or even 20 of them. These, with other masses of corpuscles without an investment, finally become converted into pigment-masses and pigment-cells, after undergoing various changes in color. Finally, however, the last pass into perfectly colorless cells. The more recent investigations, however, of Remak and T. Wharton Jones, throw doubt upon the existence of these red-corpuscle-inclosing cells; especially in the normal state. Reddish crystalline forms (haematine) are also occasion- ally found in the pulp. (Gray.) 3. The Malpighian bodies are white, rounded masses im- bedded in the red substance of the spleen, and connected with the smallest arteries.— Kolliker states that they are constant only in healthy subjects, and are found rare- ly, or not at all, in those dy- ing of disease, or after long fasting. Gray, however, as- serts that they are always present in the mammalia, though not always visible to the naked eye. They are Ti « to fa (average fa) of an inch in dia- meter ; being larger after food has been taken. Though imbedded in the red pulp, and hardly separable from it, they are always at- A portion of the splenic artery, its ramifications be- ing studded with Malpighian corpuscles (dog). (Mag- nified 10 diameters.) 1 On the Structure and Use of the Spleen. London, 1854. 586 THE TISSUES. Fig. 413. tached to an arterial twig, and either rest upon it laterally, or are situated at its angle of division, or transfixed by the artery itself. (Fig. 412.) Arteries of fffo to ikv of an incl1 nave 5 to 10 corpus- cles ; and each cubic line appears, on an average, to contain one of them (Kolliker), they constituting ^ to £ of the whole pulp. (Gray.) Gray describes the Malpighian bodies as consisting of—1st, a closed capsule intimately connected with the sheath of the vessel, formed of simple membrane, and T5?i53 t0 sxn.0- of an inch thick (Kolliker) (Fig. 413); and, 2dly, its contents, a viscid grayish substance, consisting of—1st, an amorphous, finely granular matter, containing dispersed nuclei; 2dly, nuclei like those of the red pulp, -gfao to 3^Vo of an inch in diameter; and, Sdly, a few nucleated cells, %fajj of an inch in diameter. No blood-cor- either free or in cells, met with. Remak and the artery.-Magnified 150 diameters. (KoUi, J^kly, however, have not found the ker.) J' ' distinct capsule above described; but assert that the Malpighian corpuscles pass, in man at least, into the red pulp. The external surface of the closed capsule is covered by a plexus of capillaries. (Gray) Kolliker's idea, of a clear fluid within the capsule, is contradicted by most recent observers. Vessels.—The subdivisions of the splenic artery are very nume- rous, and assume the peculiar arrangement shown in Fig. 412; and finally merge into capillaries ifau to ^fa-$ of an inch in diameter, constituting a network throughout the pulp and around the Malpi- ghian corpuscles (Fig. 414), and traversing the substance of the latter also. (Drs. Sanders and Huxley) The veins present no peculiarity requiring mention here. The lymphatics are, comparatively, very few; and the lymph of the deep-seated ones contains blood-cor- puscles, perhaps from rupture of minute bloodvessels (p. 148). In diseased spleens, no trace of the superficial lymphatics (those be- tween its two coats) can usually be detected. The nerves, consisting of many fine and a few thick fibres, are derived from the splenic * plexus, and accompany the branches of the artery into the interior of the organ. A Malpighian corpuscle from the spleen of rjuscleS an ox. • a. Wall of the corpuscle, b. Con- ■ tents, d. Sheath of the artery, e. Wall of an inch thick, and presents no pecu- liarities. The epithelium con- sists of a single layer of po- lygonal, finely granular cells, sfajs t0 2fan 0I" an incn in diameter, with simple nuclei. (Fig. 415.) The fluid con- tained in the cells is clear, somewhat viscous, with a tinge of yellow, and highly albu- minous. If, however, the organ be changed from its normal state, different conditions are presented. Frequently no epithelium is met with, but only a fluid mixed with minute granules, and free nuclei. The vesicles are also more or less filled with a colloid substance in the form of transparent, amor- phous, light-yellowish, soft masses. This, filling the vesicles, trans- forms the latter into cysts of T^ to fa of an inch, in which the epithelium is no longer distinct; and which, causing the stroma to disappear by their pressure, ultimately coalesce into larger sinuous cavities. (Fig. 416.) Some gland-vesicles from the thyroid gland of a child, a. Connective tissue between them. b. Mem- brane of the gland-vesicles, c. Their epithelium. (Kolliker.) THE THYROID GLAND. 589 Fig. 416. The vesicles of the thyroid gland, filled with colloid matter —Magnified 50 diameters. (Kolliker.) The following is Dr. Beale's analysis of the thyroid body :— Water.......70.60 Fibrinous and albuminous matter, vessels, and fat.......26.384 Extractive matter . . . . . 1.70 Alkaline salts...... .50 Earthy salts...... .816 The bloodvessels of the thyroid are disproportionally numerous. The terminal arteries are distributed in the stroma between the vesicles, and end in a capillary plexus around each of them, resem- bling that of the air-cells of the lungs, except that it is less close. The veins only partially accompany the arteries, much exceeding them in number. Of the considerable number of lymphatics, the relations in the interior are unknown. The few nerves contain only vascular nerve-fibres from the cervical portions of the sympathetic. (Kolliker) The function of the thyroid is unknown. It is probably a diver- ticulum to the cerebral circulation; and is developed from an offset from the anterior wall of the pharynx. Pathological enlargements of the thyroid (bronchocele) are very common. These may be due—1st, to numerous dilatations of the smaller vessels, the bursting of which may also produce apoplectic cysts, to which fresh extravasations, or exudations and cretification of the vessels may be added • or, Idly, to an actual hypertrophy of the glandular elements, or a production of new gland-vesicles. 590 THE TISSUES. III. The Thymus Gland. The thymus is an organ more especially of fcetal and infantile life. It consists of lobules grouped around a central canal, which is generally spirally convoluted. The lobules are collected into lobes; while the latter, invested by areolar tissue, constitute the whole organ. The lobules are, however, composed of smaller hollow subdivi- sions, and the latter of rounded corpuscles, like gland-vesicles, which give the exterior of the lobules a delicate mosaic aspect, not unlike that of the lungs. (Fig. 417.) These corpuscles are, how- Fig. 417. A section of the thymus gland at the eighth month, showing its structure ; from a preparation of Sir A. Cooper. 1. The cervical portions of the gland ; the independence of the two lateral glands is well marked. 2. Secretory follicles seen upon the surface of the section ; these are observed in all parts of the section. 3, 3. The pores or openings of the secretory follicles and pouches are seen covering the whole internal surface of the great central cavity reservoir. The continuity of the reservoir, in the lower or thoracic portion of the gland, with the cervical portion, is seen in the figure. ever, not vesicles, but solid bodies, cohering intimately towards the cavities, though separated from each other on the outer side. Each lobule is inclosed in a thin, almost homogeneous, mem- brane, 54&7n$ to yijcnyo 0I> an inca thick. "Within this, and between it and the cavity of the lobule, lies a grayish-white soft substance, fa to ^g of an inch thick, consisting of free nuclei and minute cells, among which bloodvessels and a small amount of white fibrous tissue are sent; and thus a structure is presented resembling that of the contents of the follicles of Peyer (p. 530). The cells and nuclei, however, of the thymus-lobules, with a small quantity of a connecting fluid, constitute the main bulk. The THE THYMUS GLAND. 591 2400" / 3t»0"TT Of cells are much less numerous than the free nuclei, and from t0 ifajj 0I* an iQCh m diameter; the latter being sfa^ to an inch. The arteries (Fig. 418) are sent from the external surface through to the internal cavity, and there ramify in a delicate expansion of areolar tissue lining it. From this arterial plexus, branches enter the ca- vity of each lobule, and form a capillary plexus in their external portion, or the gland-corpuscles, entirely filling them, but never extending further than to the inner surface of the homogeneous membrane investing them.—The fibres above mentioned support the capilla- ries just described, and require no spe- cial description.—The lymphatics are numerous; and nerves accompany the arteries, though not yet traced to their terminations. The cavities of the thymus inclose a grayish-white or milky, faintly acid, albuminous fluid, containing numerous nuclei, isolated cells, and sometimes concentric corpuscles, next to be de- scribed. Between the ages of 12 and 20 years, involution of the thymus com- mences. During this, peculiar spheri- cal bodies are found in the substance of the lobules, called the con- centric corpuscles. These (first noticed by Hassall and Virchow) are: 1. Simple, ^q^ to jfajj of an inch in diameter, with a thick concentrically striated membrane and a granular substance within, appearing sometimes as a nucleus, at others as a cell; 2. Compound, fas t0 t£u °f an incn i11 diameter, and consisting of several simple corpuscles inclosed in a common laminated envelop. By the 40th year, the thymus is usually entirely removed. The function of the thymus is not certainly known. Mr. Simon considers it " a sinking fund in the service of respiration." It is developed by two tubular offsets from the larynx, containing blas- tema. It is not stationary after birth, as sometimes stated, but grows Transverse section of an injected lob- ule of the thymus of a child, a. Mem- brane of the lobule. 6. Membrane of the gland-corpuscles, c. Cavity of the lobule from which the larger vessels branch out into the corpuscles, on the surface of which they terminate, occa- sionally forming loops. (30 diameters.) 592 THE TISSUES. considerably up to the 2d year. Subsequently it becomes atrophied, and finally disappears, as above mentioned. IV. The Supea-Eenal Glands. These bodies are usually classed with the blood vascular glands, though they do not strictly belong to this class. They consist (1,) of a fine, but thin coat of areolar tis- sue, and (2,) the proper parenchyma. The former needs no special descrip- tion. The parenchyma is divisible into two parts, the cortical and the medullary portions. (Fig. 419.) 1. The former is of a whitish-yellow color (more nearly brown in its innermost third), fa to fa of an inch thick; easily torn in the direction of its thickness, and when torn, presenting a fibrous aspect. 2. The medullary substance is of a brighter color than the cortical, being grayish-white with a tinge of red, though it may become darker when its veins are full of blood. It is softer than the-cortical substance, and only fa to ^e °f an inch thick at their bor- ders; while it is 1 to 1J line in the middle, and the lower and inner half of these organs. In their intimate structure the cor- tical and the medullary portions are entirely dissimilar. The cortical substance consists of very nu- merous compartments (cortical cylinders, Kolliker), 1\J5 to even y^ of an inch across, formed by interlacements of areolar tissue, and extending through the entire thickness of the cortex; contain- ing a granular substance, subdivided by delicate, oblique, or trans- verse dissepiments. (Fig. 420.) These generally contain nothing but rounded angular cells, ^fau to ru^v °f an inch in diameter. In the inner brown layer of the cortex, the cells are entirely filled with brown pigment-granules. The medullary substance also has a stroma of areolar tissue pro- Fig. 419. Transverse section of the supra-renal body of the calf, treated with soda. a. Cortex, b. Medulla, c. Central vein, surrounded1, with some cortical sub- stance, d. Three entering nerves, e. Nerves and their distribution in the in- terior. (Magnified about 15 diameters.) THE SUPKA-RENAL GLANDS. 593 Fig. 420. Portion of a vertical section through the cortex of the supra-renal body in man. a. Septa of connective tissue. 5. Cortical cylinder whose composition from cells is more or less distinctly manifest. (Magnified 300 diameters.) longed from the cortical lamellae, and pervading the whole interior, forming a network with rather wide meshes. This is filled by a pale, finely granular substance, contain- ing pale cells, Tfa-^ to ^^g of an inch in diameter, resembling the nerve-cells of the central organs, though they cannot be definitely declared to be such. (Kol- liker) The bloodvessels of the supra-renal glands are very numerous. Some- times even twenty arterial trunks enter one of thesl glands. A capillary plexus with elongated meshes exists in the cortical substance, and one with round- ed interstices in the medullary. Thus the cortical cylinders are surrounded by blood on all sides; and this capil- lary plexus joins that of the medul- lary substance, formed principally by arteries penetrating at once into the latter. A few lymphatics are found on the surface of the organ, but more in its interior. The nerves of the supra-renal glands are very numerous; being derived from the semi-lunar ganglion, and the renal plexus; and also, to a small extent, from the pneumogastric and the diaphragm- atic. (Bergmann). Kolliker has counted 33 trunks entering the right supra-renal gland, varying from g1^ to g^ of an inch in diameter; and found that almost without exception, they were constituted of dark-bordered, finer, and medium-sized, or even thick, nerve-fibres; and were furnished with isolated larger or smaller ganglia. They appear to be all destined for the medullary substance, where there is an extremely rich nervous plexus; the terminations of the fibres being, however, nowhere perceptible. The supra-renal glands are developed simultaneously with the kidneys, but independently of them; and are originally larger than they. The first appearance and growth of the blastema where they are found is unknown. Of the function of the supra-renal glands, nothing positive is known. They, however, have pretty certainly no physiological connection with the kidneys. Kolliker thinks that while the cor- tical portion may belong to the class of blood-vascular glands, the 38 594 THE TISSUES. medullary portion is physiologically distinct from the former, and must be regarded as an apparatus pertaining to the nervous system, as Bergmann suggested. And Ley dig's recent investigations in t regard to the structure of these organs in fishes and reptiles, have led him to conclude that they have the same relation to the gan- glia of the sympathetic nerves, that the pituitary body bears to the brain (p. 465). CHAPTEB XVIII. < THE ORGANS OF THE SENSES. The histological elements of the organs of the senses have already been mostly described. I. The organ of touch—the skin—in Chap. XL (pp. 476—494.) II. The organ of taste—the mucous membrane of the tongue— pp. 515-18, and Figs. 344 to 347. Fie 421. General view of the external, internal, and middle ear, as seen in a prepared section through a, the auditory canal; b, the tympanum or middle ear; c, Eustachian tube, leading to the pharynx: d, cochlea; e, semicircular canals, and vestibule, seen on their exterior as brought into view by dissecting away the surrounding petrous bone. The styloid process projects below; and the inner surface of the carotid canal is seen above the Eustachian tube. (From Scarpa.) THE MEMBRANOUS LABYRINTH. 595 III. The organ of smell—the olfactory nerves and the mucous membrane of the nasal passages—p. 448, and Figs. 290-2. IV. The organ of hearing—so far as the acoustic nerve, and the distribution of its cochlear branch are concerned—has been de- scribed on p. 453, Figs. 300 and 301. Fig. 422. The soft parts of the vestibule taken out of their bony case, so as to show the distribution of the terves in the ampullae. 1. The superior semicircular membranous canal or tube. 2. The external semicircular tube. 3. The inferior semicircular tube. 4. The tube of union of the superior and in- ferior canals. 5. The sacculus ellipticus. 6. The sacculus sphericus. 7. The portio dura nerve. ?. The anterior fasciculus of the auditory nerve. 9. The nerve of the sacculus sphericus. 10, 10. The nervous fasciculi to the superior and external ampullae. 11. The nerve to the sacculus ellipticus. 12. The posterior fasciculus of the auditory nerve furnishing (13), the filaments of the sacculus sphericus, and 11, the filaments of the cochlea, cut off. Fig. 423. The ampulla of the external semicircular membranous canal, showing the mode of termination of its nerve. 59 3 THE TISSUES. A section of both the external and internal ear is shown by Fig. 421. The membranous labyrinth, and the terminations of the vesti- bular nerve, are shown by Figs. 422, 423. Fig. 424. A view of the labyrinth of the left side, laid open in its whole extent so as to show its structure. Magnified about 12 diameters. 1. The thickness of the outer covering of the cochlea. 2, 2. The scala vestibuli, or upper layer of the lamina spiralis. 3, 3. The scala tympani or lower layer of the lamina spiralis. 4. The hamulus cochlea. 5. Centre of the infundibulum. 6. Foramen opening into the tympanum. 7. The thickness of the outer layer of the vestibule. 8. The foramen rotund- urn. 9. The fenestra ovalis. 10. The orifice of the aqueduct of the vestibule. 11. The inferior semicircular canal. 12. The superior semicircular canal. 13. The external semicircular canal. 14. The ampulla of the inferior canal. 15. The ampulla of the superior canal. 16. The common orifice of the superior and inferior canals. 17. The ampulla of the external canal. Fig. 425. An anterior view of the external ear, as well as of the meatus auditorius, labyrinth, &c. 1. The opening of the ear at the bottom of the concha. 2. The meatus auditorius externus, or carti- laginous canal. 3. The membrana tympani stretched upon its ring. 4. The malleus. 6. The stapes. The labyrinth, MEMBRANES OF THE EYE. 597 The whole labyrinth (internal ear), consisting of the cochlea and semicircular canals, laid open, is shown by Fig. 424. Its relations to the external and middle ear are seen in Fig. 425. V. The Eye. Some of the structural elements of the eye have already been spoken of (pp. 449-53); and the rest will be described here. I. Membranes of the Eye. A section of the eyeball is shown by Fig. 426. The three mem- branes of its posterior seven-eighths, or more, are the tunica scle- rotica, the choroid, and the retina; while the cornea is seen project- ing in front, and the iris is represented by 6, in the figure. 1. The sclerotic coat is composed of white fibrous tissue and a few elastic fibres (p. 279); and is shown, together with the choroid, by Fig. 427. 2. The choroid coat is continuous in front with the iris; a narrow ring of white fibrous tissue—the ciliary ligament— connecting them Fig. 423. A longitudinal section of the globe of the eye. 1. The sclerotic, thicker behind than in front. 2. The cornea apparently received within the anterior margin of the sclerotic, and connected with it by means of a bevelled edge, though really continuous with it. 3. The choroid, connected anteriorly with (4), the ciliary ligament and (5), the ciliary processes. 6. The iris. 7. The pupil. 8. The third layer of the eye, the retina, terminating anteriorly (ora serrata) at the commencement of the ciliary processes. 9. The canal of Petit, which encircles the lens (12) ; the thin layer in front of this canal is the zonula ciliaris, a vascular prolongation of the retina to the lens. 10. The anterior chamber of the eye containing the aqueous humor ; the lining membrane by which the humor is secreted is represented. 11. Posterior chamber. 12. The lens more convex behind than before, and inclosed in its proper capsule. 13. The vitreous humor inclosed in the hyaloid membrane, and its cells formed in its interior by that membrane. 14. A tubular sheath of the hyaloid membrane, which serves for the passage of the artery of the capsule of the lens. 15. Perineurium of the optic nerve. 16. The arteria centralis retinze, imbedded in its centre. 598 THE TISSUES. firmly at their union, with the sclerotica. (Figs. 427-8.) The choroid itself is essentially a thin lamina of capillaries, with arteries and veins external to it, and lined on its internal surface by a single layer of nucleated pigment-cells of a pentagonal or hexagonal shape. (Fig. 69.) Between the capillary network and the arteries and veins, as well as among the veins themselves, there is also an abun- dance of pigment-cells. The internal plexus of capillaries is termed the tunica Ruyschiana. (Fig. 429.) The veins Of the choroid are arranged in beautiful curves, and are termed vasa vorticosa. For ^ of an inch behind the ciliary ligament, the choroid coat is sepa- rated from the sclerotic by the ciliary muscle, consisting of smooth muscular fibres. (Fig. 428.) The last is covered externally by the ciliary processes, which are projecting folds of the choroid, lodged in similar folds upon the vitreous body—the ciliary zone. They also are very vascular (Fig. 430), and contain an abundance of ir- regular pigment-cells. The ciliary nerves are seen on their way to the iris in Fig. 427. Fig. 427. Choroid and iris exposed by turning aside the sclerotica, c, c. Ciliary nerves branching in tL.> iris. d. Smaller ciliary nerve, e, e. Vasa vorticosa. h. Ciliary ligament and muscle, k. Con- verging fibres of the greater circle of the iris. I. Looped and knotted form of these near the pupil, with the converging fibres of the lesser circle of the iris within them. o. The optic nerve. (From Zinn.) 3. The retina has already been described (pp. 450-3, and Figs. 295 to 299). The relations of the crystalline lens and the vitreous body are shown by Fig. 431. 4. The cornea has already been described at length (pp. 280-1, and Figs. 178 to 180). MEMBRANES OF THE EYE, 599 5. The iris is a process of the choroid, and continuous behind with the ciliary processes; though modified in structure. For it Fie. 428. Fig. 429. Fig. 428. Diagram to show the position and action of the ciliary muscle, a. Sclerotic. 6. Cornea. e. Choroid, separated a little from the sclerotic, d. Situation of the ciliary ligament, and point from which the ciliary muscle radiates, e. Iris. n. Lens connected with the ciliary processes of the anterior wall of the canal of Petit, the situation of which is marked by the *. (Magnified 3 dia- meters.) Fig. 429. Capillary network in choroid coat of the eye. has, 1, a stroma, mostly of collagenous tis- Fig. 430. sue; 2, smooth muscular fibres; and 3, a layer of cells on both its anterior and its posterior surface. The muscular fibres form (1,) a distinct occlusor of the pupil (sphincter pupillce) in the .form of a smooth ring fa of an inch wide, close to the edge of the iris. There is, besides, another very narrow ring ,§T of a line wide. (2.) They also form numerous slender fasciculi, but not a distinct layer, extending from the outer margin of the iris to the sphincter pupillce, into the border of which they are inserted, constituting the dilator pupillce. The layer of cells on the posterior sur- face of the iris, constitutes the uvea; they being closely filled pigment-cells. The anterior layer of cells is a simple scaly epithelium Without pigment-granules.---' processes, and iris ; inner surface. ....... , j a. Portion of the capillary net- The color of the iris in blue eyes depends work> or tunica Ruysehiana. 6. merelv upon the pigment in the uvea, seen ciliary processes. c. Portion of j tr ro .... , the iris. From an infant. (After thrOU^h the Substance Of the ins; in hazel Arnold.—Magnified 14 diameters. Vessels of the choroid, ciliary fiOQ THE TISSUES. and black eyes, the pigment also exists in the stroma and among the other elements of the iris itself. Fig. 431. Position of the lens (b) in the vitreous humor, shown by an imaginary section. The dark triangular space on each side of the lens is intended to indicate the position of the canal of Petit. The bloodvessels and the nerves of the iris are numerous. The ciliary branches of the latter are shown by Fig. 430. II. Humors of the Eye. The three humors of the eye are the crystalline lens, and the vi- treous, and the aqueous humor. Fig. 431 shows the relation of the vitreous body and the crystalline lens. The aqueous humor fills up the spaces between the crystalline lens and the iris,1 and (extending through the pupil) between the iris and the cornea (Fig. 426); these spaces being termed the posterior and the anterior chambers of the eye. (Figs. 426 and 428.) The aqueous humor is so called from its resemblance to pure water. It is afforded by the epithelial cells covering the anterior and the posterior chambers of the eye, and is very readily repro- duced if removed experimentally in the lower animals. It is one of the three refracting media of the eye. The crystalline lens and the vitreous body require a special de- scription. 1. The Crystalline Lens. The crystalline lens consists of concentric lamina? arranged like the coats of an onion (Fig. 432), which are composed of elongated, flat, hexahedral tubes {not fibres), ^fa-Q to sfajf of an inch broad, and la'gj to g^7 of an inch thick, perfectly transparent, and con- taining a clear, viscous, albuminous fluid. Each tube is slightly 1 It is very doubtful if any space naturally exists between the iris and the lens. THE CRYSTALLINE LENo. 601 Fig. 432. n. Cells connecting the body of the lens to its capsule (human), b. Tubes of the lens, with slightly sinuous edges, c. Tubes from the ox, with finely serrated edges, d. Tubes from the cod; the teeth much coarser. (Magnified 320 diameters.) serrated at its edges (Fig. 432), and, as it enters into the formation of a lamina, is surrounded by six others. Thus their transverse section resembles a wall built of hexagonal bricks. (Fig. 433.) The serrations are much more beautifully marked in the lower Tubes of the lens. 1. From the ox, with slightly toothed borders. 2. Transverse section of the lenticular tubes of man —Magnified 350 diameters. (Kolliker.) animals, especially fishes. (Fig. 432, d.) The tubes are more solid, slender, and opaque in the central part of the lens. The tubes lie with their sides parallel to the surface of the lens, 602 THE TISSUES. and, being here less coherent than on their largest surfaces, they are more easily separated into laminae in this direction. In the separate lamellae, both the superficial and the deeper tubes generally radiate from the centre of the lens towards the margin, and then curve round upon the other surface, anterior or posterior; but never extend through the entire semi-circumference of the lens. Indeed, a peculiar appearance called the "star" is produced where they terminate on both surfaces of the lens, as shown by Lens of the adult (after Arnold), to show the "star." 1 Anterior aspect. 2. Posterior aspect.' (Kolliker.) Fig. 434. In these there are no tubes, but a substance partly clear and partly finely granular. The capsule of the lens is formed of simple membrane, and is perfectly transparent and very elastic. It admits neither vessels nor nerves to the completely inclosed lens. It is, however, readily permeable to fluids; and it is the transmission through it, after death, of the aqueous humor of the eye, that mainly gives rise to the "liquor Morgagni"—this not being a normal condition, as has been supposed. A single layer of clear, polygonal, epithelial cells, however, covers the anterior half of the inner surface of the cap- sule; and these, disintegrated, also help to form the "liquor." Chemical analysis (of the lens) detects the presence of crystalline, described on page 97. It contains about 58 per cent, of water. The crystalline lens is not vascular at any period of its develop- ment. The capsule is so, however, during early fcetal existence; the central artery of the retina expanding upon its posterior layer (after having traversed the vitreous humor), and sending branches THE VITREOUS BODY. 603 round its margin to unite with twigs from the ciliary processes upon the anterior surface. The loops of the latter gradually retire from the centre towards the margin, and finally the posterior layer also ceases to be vascular. In inflammatory conditions, however, the vascularity may return. Uses.—The crystalline lens is of the highest importance as one of the refracting media of the eye. The fibres of the crystalline lens are, apparently, developed ori- ginally from cells like those shown in Fig. 432. The growth of the lens is, probably, secured by the absorption, through its capsule, of the aqueous or the vitreous humor. (Kol- liker) The crystalline lens has been, though very rarely, regenerated, in very young subjects, after its entire extraction. An opacity of the crystalline lens, or its capsule, or both at the same time, constitutes cataract. 2. The Vitreous Body. This body (Figs. 426 and 431) is a close web of transparent fibres, enveloping a transparent fluid in its meshes; and is inclosed in a simple membrane (membrana hyaloidea), on the exterior of which vessels are distributed. (Todd and Bowman) The central artery of the retina passes through the centre of the vitreous body, but does not give off any branches to it. Its nourishment is pro- bably in part sustained by the plexiform arrangement of vessels constituting the ciliary processes. (Fig. 430.) The fluid of the vitreous humor is a weak, watery solution of salts and albumen. During fcetal life, this body is supplied with vessels in its inte- rior also. Use.—This is also one of the refracting humors of the eye. The eyeball is covered anteriorly by the conjunctiva, which is essentially a mucous membrane; though the portion in front of the cornea is merely a compound scaly epithelium, without a corium. This also continues over the sclerotica, where there is a pale, thin corium, without any papillae, and attached to the sclerotic by a loose and abundant areolar tissue containing fat-cells. The mem- 604 THE TISSUES. brane is reflected from the selerotica above and below, and lines the lids. The latter also have a compound scaly epithelium. Pa- pillae occur on the palpebral conjunctiva, especially towards the line of reflection, where they are T^ of an inch long. At the line of reflection they are sometimes even g1^ of an inch. (Krause.) Their enlargement constitutes the granular lid, so called; the lower lid being most frequently affected, since they are most abundant there. The eyelids consist of—1st, the mucous membrane just described; Idly, the fibres of the levator palpebral superioris, and the orbicu- laris palpebrarum; and, Sdly, the skin, only fa to fa of an inch thick; all these elements being connected together by a lax con- nective tissue. The skin is furnished throughout with minute sweat-glands (T^ to yi^ of an inch), and generally with minute hairs and sebaceous glands. The free borders of the lids are bounded by the tarsi, improperly termed tarsal cartilages. They consist merely of fasciculi of white fibrous tissue, though occasion- ally containing a few minute cartilage-cells. Into their free edges the cilia (eyelashes) are inserted, immediately in relation with the Meibomian glands. (Fig. 133.) But for a full description of the remaining appendages of the eye (the muscles and the lachrymal passages, &c.) the works on descriptive anatomy may be consulted, since they present no pecu- liar histological elements. For the very numerous pathological conditions to which this organ is liable, reference must be had to the special treatises on this subject. INDEX. A Absorption by cells, 128 Acarus folliculoram, 226 Accessory organs of skin; sebaceous and sweat glands, 486-92 Acid, carbonic, 44; hippuric, 64; lactic, 60 ; pneumic, 67; uric, 61 Acne, 135 Acoustic nerve, 453-54 Adhesions, 497. Adipose cells, 286 Adipose tissue, 295-312 ; fat-cells, peculiari- ties, 296 ; intercellular areolar tissue, 296 ; vessels, 297; crystals in cells, 297; pecu- liarities in lower animals, 298 ; chemical composition, 298; distribution, 299 ; pe- culiarities in distribution, 300 ; circum- stances modifying its amount, 302 ; distri- bution in lower animals, 303 ; uses of fat, 304; development, 305; growth, 306; pathological states, 306; stearosis, or fatty degeneration, 309-12 Aerating process, its object, 44 Age, effects on composition of blood, 173 Air-cavities in hairs, 254 Air-cells, 577; hypertrophy of, 581; oblitera- tion of, 581 Air-passages, 572; function of, 580 Albinoes, 132-3 Albumen, 84-7; physical and chemical pro- perties, 84; occurrence, origin, uses, 85, 120; remarks, 86 ; pathological relations, 87 ; albuminuria in various states, 87 ; al- bumen in various secretions, 87 ; antidote to corrosive sublimate, 86; the pabulum of the tissues, 86, 120, 158; amount in blood-serum, 153; uses, 158; in what dis- eases increased, 179 ; in what diminished, 179 Albuminuria in various pathological states, 87, 220 ; the blood in, 178 Albuminose, 87 ; uses, 88 ; results from diges- tion, 200 Alimentary canal and appendages, 514-41; oral cavity, 514-22; pharynx, 522 ; oeso- phagus, 522 ; stomach, 523-26 ; duodenum, 527; jejunum, and ileum, 527-31; large intestine, 531-2; liver, 532-40; pancreas, 540 Alternating calculus, 66 Ammonia free in the blood, 95, note; hydro- chlorate of, 51; carbonate in blood in dis- ease, 155 Ammonio-magnesian phosphate, 56; forms of its crystals, 57 Amphiarthrosis, 346 Anaemia, the blood in, 178 Analysis, histological, of body, 32 ; chemical, of liquor sanguinis, 152; do. of blood-cor- puscles, 163 ; dry blood, 167 ; bone, 332-5 ; diseased do., 334; nervous centres, 473; muscular fibre, 396 ; milk, 204 ; urine, 217 ; dentine, 368; enamel, 372; cementum, 373; liver, 539; thyroid gland, 589 Anasarca, 294 Anastomosing fibres of heart, 394 Aorta of whale, 272 Apolar nerve-cells, 436 Aponeurosis, structure of, 278 Apoplexy of lungs, 582 Appendages of alimentary canal, 532-40 ; of skin, 249-55 Arachnoid, 469 Arcus senilis, 282 Areola darker in pregnancy, 136 ; its struc- ture, 570 Areolae of areolar tissue, 285 ; their contents, 286 Areolar tissue, 284-95; its two kinds of fibres, its areolae, 285 ; their contents; emphy- sema, 286 ; chemical composition ; proper- ties; vessels, 287; uses; distribution, 288; peculiarities, 289; subcutaneous areolar tissue, 289-90 ; development, 291-3; re- generation, 293; pathological states of, 294; new formations, 295 Areolitis, 294 Arrectores pili, 267, 477 Arterial blood compared with venous, 174 Arteries, 500-504 ; external tunic, 500; mid- dle do., 501; inner do., 502; vasa vaso- rum, 503; development of arteries, 511; arteries of bone, 337 Articular cartilages, 342-4; peculiarities; the bone under them, 343; pathological states, 344 Ascites, 496 Ass, milK of, 206 Atelectasis pulmonum, 582 Atheroma, 312; of arteries. 513 Atrophy of cells, 130 ; of white fibrous tissue. EX. 606 ini 283 ; areolar tissue, 293; adipose tissue, 306 ; cartilage, 320; bone, 365 ; smooth muscular fibre, 392 ; striated do. do., 406; tendons and aponeuroses. 422; mucous membrane, 495 Axile-corpuscles, 483 Axis-fibre, 425 B Bat, hair of, 257 Beard, uses of, 265 Belly of muscles, 410 Bile, from fat of the blood, 77; properties, 210 ; amount, origin, 211; uses, 212 ; patho- logical states, 213 Biliary calculi, 213 Bladder, 541-2 Blastema, 120, note Blood, 151-70; properties, specific gravity, coagulation, 151; liquor sanguinis, analy- sis of, 152 ; amount of fibrine, water, and albumen in, 153; blood serum, 153; fats in serum ; glucose ; mineral constituents, 155 ; origin and uses of each constituent, 156-59 ; uses of fibrine; albumen the pabu- lum of the tissues; colorless corpuscles, 159-61; colored do., 162-72; quantity of blood, 172 ; composition in various physio- logical states, 173; normal differences in different vessels, 174; changes in various diseases, 176 ; the life of the blood, 170 Blood-corpuscles, colorless (see Colorless cor- puscles, , M. D., F. R. S., Examiner in Physiology and Comparative Anatomy in the University of London. (Just Issued, 1856.) THE MICROSCOPE AND ITS REVELATIONS. With an Appendix con- taining the Applications of the Microscope to Clinical Medicine, &:c. By F. G. Smith, M. D Illustrated by four hundred and thirty-four beautiful engravings on wood. In one large and vef handsome octavo volume, of 724 pages, extra cloth, $4 00 ; leather, $4 50. Dr. Carpenter's position as a microscopist and physiologist, and his great experience as a teacher eminently qualify him to produce what has long been wanted—a good text-book on the practical use of the microscope. In the present volume his object has been, as stated in his Preface, "to combine, within a moderate compass, that information with regard to the use of his ' tools,' which is most essential to the working microscopist, with such an account of the objects best fitted for his study, as might qualify him to comprehend what he observes, and might thus prepare him to benefit science, whilst expanding and refreshing his own mind " That he has succeeded in accom- plishing this, no one acquainted with his previous labors can doubt. The srreat importance of the microscope as a means of diagnosis, and the number of microsco- pists who are also physicians, have induced the American publishers, with the author's approval, to add an Appendix, carefully prepared by Professor Smith, on the applications of the instrument to clinical medicine, together with an account of American Microscopes, their modifications and accessories. This portion of the work is illustrated with nearly one hundred wood-cuts, and, it is hoped, will adapt the volume more particularly to the use of the American student. Every care has been taken in the mechanical execution of the work, which is confidently pre- sented as in no respect inferior to the choicest productions of the London press. The mode in which the author has executed his intentions may be gathered from the following condensed synopsis of the CONTENTS. Introduction—History of the Microscope. Chap. I. Optical Principles of the Microscope. Chap. II. Construction of the Microscope. Chap. III. Accessory Apparatus. Chap. IV. Management of the Microscope Chap. V. Preparation, Mounting, and Collection of Objects. Chap. VI. Microscopic Forms of Vegetable Life—Protophytes. Chap. VII. Higher Cryptoga- mia. Chap. VIII. Phanerogamic Plants. Chap. IX. Microscopic Forms of Animal Life—Pro- tozoa—Animalcules. Chap. X. Foraminifera, Polycystina, and Sponges. Chap. XI. Zoophytes. Chap. XII. Echinodermata. Chap. XIII. Polyzoa and Compound Tunicata. Chap. XIV. Molluscous Animals Generally. Chap. XV. Annulosa. Chap. XVI. Crustacea. Chap. XVII. Insects and Arachnida. Chap. XVIII. Vertebrated Animals. Chap. XIX. Applications of the Microscope to Geology. Chap. XX. Inorganic or Mineral Kingdom—Polarization. Appendix. Microscope as a means of Diagnosis—Injections—Microscopes of American Manufacture. Those who are acquainted with Dr. Carpenter's previous writings on Animal and Vegetable Physio- logy, will fully understand how vast a store of know- ledge he is able to bring to bear upon so comprehen- sive a subject as the revelations of the microscope j and even those who have no previous acquaintance with the construction or uses of this instrument, will find abundance of information conveyed in clear and simple language.—Med. Times and Gazette. Although originally not intended as a strictly medical work, the additions by Prof. Smith give it a positive claim upon the profession, for which we doubt not he will receive their sincere thanks. In- deed, we know not where the student of medicine will find such acomplete and satisfactory collection of microscopic facts bearing upon physiology and practical medicine as is contained in Prof. Smith's appendix; and this of itself, it seems to us, is fully worth the cost of the volume.—Louisville Medical Review, Nov. 1856. BY THE SAME AUTHOR. ELEMENTS (OR MANUAL) OF PHYSIOLOGY, INCLUDING PHYSTO- LOG1CAL ANATOMY. Second American, from a new and revised London edition. With one hundred and ninety illustrations. In one very handsome octavo volume, leather, pp. 566. S3 00. In publishing the first edition of this work, its title was altered from that of the London volume, by the substitution of the word " Elements" for that of " Manual," and with the author's sanction the title of "Elements" is still retained as being more expressive of the scope of the treatise. Those who have occasion for an elementary trea- tise on Physiology, cannot do better than to possess themselves of the manualof Dr. Carpenter.—Medical Examiner. The best and most complete expose- of modern Physiology, in one volume, extant in the English language.—St. Louis Medical Journal. To say that it is the best manual of Physiology now before the public, would not do sufficient justice to the author.—Buffalo Medical Journal. In his former works it would seem that he had exhausted the subjectof Physiology. In the present, he gives the essence, as it were, of the whole.—N. Y. Journal of Medicine. BY the same author. (Preparing.) PRINCIPLES OF GENERAL PHYSIOLOGY, INCLUDING ORGANIC CHEMISTRY AND HISTOLOGY. With a General Sketch of the Vegetable and Animal Kino-dom. In one large and very handsome octavo volume, with several hundred illustrations. The subject of general physiology having been omitted in the last editions ol the author's '< Com- parative Physiology" and "Human Physiology," he has undertaken to prepare a volume which shall present it more thoroughly and fully than has yet been attempted, and which may be regarded as an introduction to his other works. BY THE SAME AUTHOR. A PRIZE ESSAY ON THE USE OF ALCOHOLIC LIQUORS IN HEALTH AND DISEASE. New edition, with a Preface by D. F. Condie, M. D., and explanations of scientific words. In one neat 12mo. volume, extra cloth, pp. 178. 50 cents. BLANCHARD & LEA'S MEDICAL CONDIE (D. F.), M. D., &c. A PRACTICAL TREATISE ON THE DISEASES OF CHILDREN. Fourth edition, revised and augmented. In one large volume, 8vo., leather, of nearly 750 pages. $3 00. From the Author's Preface. The demand for another edition has afforded the author an opportunity of again subjecting the entire treatise to a careful revision, and of incorporating in it every important observation recorded since the appearance of the last edition, in reference to the pathology and therapeutics of the several diseases of which it treats. In the preparation of the present edition, as in those which have preceded, while the author has appropriated to his use every important fact that he has found recorded in the works of others, having a direct bearing upon either of the subjects of which he treats, and the numerous valuable observations—pathological as well as practical—dispersed throughout the pages of the medical journals of Europe and America, he has, nevertheless, relied chiefly upon his own observations and experience, acquired during a long and somewhat extensive practice, and under circumstances pe- culiarly well adapted for the clinical study of the diseases of early life. Every species of hypothetical reasoning has, as much as possible, been avoided. The author has endeavored throughout the work to confine himself to a simple statement of well-ascertained patho- logical facts, and plain therapeutical directions—his chief desire being to render it what its title imports it to be, a practical treatise on the diseases of children. Dr. Condie's scholarship, acumen; industry, and practical sense are manifested in this, as in all his numerous contributions to science.—Dr. Holmes's Report to the American Medical Association. Taken as a whole, in our judgment, Dr. Condie's Treatise is the one from the perusal of which the practitioner in this country will rise with the great- est satisfaction.—Western Journal of Medicine and Surgery. One of the best works upon the Diseases of Chil- dren in the English language.—Western Lancet. Perhaps the most full and complete work now be- fore the profession of the United States; indeed, we may say in the English language. It is vastly supe- rior to most of its predecessors.—Transylvania Med. Journal, We feel assured from actual experience that no physician's library can be complete without a copy of this work.—N. Y. Journal of Medicine. A veritable pediatric encyclopaedia, and an honor to American medical literature.—Ohio Medical and Surgical Journal. We feel persuaded that the American medical pro- fession will soon regard it not only as a very good, but as the very best "Practical Treatise on the Diseases of Children."—American Medical Journal. We pronounced the first edition to be the best work on the diseases of children in the English language, and, notwithstanding all that has been published, we still regard it in that light.—Medical Examiner. CHRISTISON (ROBERT), M. D., V. P. R. S. E., &.C. A DISPENSATORY; or, Commentary on the Pharmacopoeias of Great Britain and the United States; comprising the Natural History, Description, Chemistry, Pharmacy, Ac- tions, Uses, and Doses of the Articles of the Materia Medica. Second edition, revised and im- proved, with a Supplement containing the most important New Remedies. With copious Addi- tions, and two hundred and thirteen large wood-engravings. By R. Eglesfeld Griffith, M. D. In one very large and handsome octavo volume, leather, raised bands, of over 1000 pages. $3 50. It is not needful that ws should compare it with the other pharmacopoeias extant, which enjoy and merit the confidence of the profession : it is enough to say that it appears to us as perfect as a Dispensa- tory, in the present state of pharmaceutical science, could be made. If it omits any details pertaining to this branch of knowledge which the student has a right to expect in such a work, we confess the omis- sion has escaped our scrutiny. We cordially recom- mend this work to such of our readers as are in need of a Dispensatory. They cannot make choice of a better.—Western Journ. of Medicine and Surgery. COOPER (BRANSBY BJ, F. R. S. LECTURES ON THE PRINCIPLES AND PRACTICE OF SURGERY. In one very large octavo volume, extra cloth, of 750 pages. $3 00. COOPER ON DISLOCATIONS AND FRAC- TURES OF THE JOINTS —Edited by Bransby B. Cooper, F. R. S., &c. With additional Ob- servations by Prof. J. C. Warren. A new Ame- rican edition. In one handsome octavo volume, extra cloth, of about 500 pages, with numerous illustrations on wood. $3 25. COOPER ON THE ANATOMY AND DISEASES OF THE BREAST, with twenty-five Miscellane- ous and Surgical Papers. One large volume, im- perial 8vo., extra cloth, with 252 figures, on 3G plates. $2 50. COOPER ON THE STRUCTURE AND DIS- EASES OF THE TESTIS, AND ON THE THYMUS GLAND. One vol. imperial 8vo., ex- tra cloth, with 177 figures on 29 plates. $2 00. COPLAND ON THE CAUSES, NATURE, AND TREATMENT OF PALSY AND APOPLEXY. In one volume, royal 12mo., extra cloth, pp. 326. 80 cents. CLYMER ON FEVERS: THEIR DIAGNOSIS, PATHOLOGY, AND TREATMENT In one octavo volume, leather, of 600 pages. $1 50. COLOMBAT DE L'ISERE ON THE DISEASES OF FEMALES, and on the special Hygiene of their Sex. Translated, with many Notes and Ad- ditions, by C. D. Meigs, M. D. Second edition, revised and improved. In one large volume, oc- tavo, leather, with numerous wood-cuts. pp. 720. 83 50. CARSON (JOSEPH), M. D., Professor of Materia Medica and Pharmacy in the University of Pennsylvania. SYNOPSIS OF THE COURSE OF LECTURES ON MATERIA MEDICA AND PHARMACY, delivered in the University of Pennsylvania. Second and revised edi- tion. In one very neat octavo volume, extra cloth, of 208 pages. $] 50. AND SCIENTIFIC PUBLICATIONS. 9 CHURCHILL (FLEETWOOD), M. D., M. R. I. A. ON THE THEORY AND PRACTICE OF MIDWIFERY. A new American, from the last and improved English edition. Edited, with Notes and Additions, by D. Francis Condie, M. D., author of a "Practical Treatise on the Diseases of Children," &c. With 139 illustrations. In one very handsome octavo volume, leather, pp. 510. $3 00. To bestow praise on a book that has received such marked approbation would be superfluous. We need only say, therefore, that if the first edition was thought worthy of a favorable reception by the medical public, we can confidently affirm that this will be found much more so. The lecturer, the practitioner, and the student, may all have recourse to its pages, and derive from their perusal much in- terest and instruction in everything relating to theo- retical ;md practical midwifery.—Dublin Quarterly Journal of Medical Science. A work of very great merit, and such as we can confidently recommend to the study of every obste- tric practitioner.—London Medical Gazette. This is certainly the most perfect system extant. It is the best adapted for the purposes of a text- book, and that which he whose necessities confine him to one book, should select in preference to all others.—Southern Medical and Surgical Journal. The most popular work on midwifery ever issued from the American press.—Charleston Med. Journal. Were we reduced to the necessity of having but one work on midwifery, and permitted to choose, we would unhesitatingly take Churchill.—Western Med. and Surg. Journal. It is impossible to conceive a more useful and elegant manual than Dr. Churchill's Practice of Midwifery.—Provincial Medical Journal. Certainly, in our opinion, the very best work on the subject which exists.—N. Y. Annalist. No work holds a higher position, or is more de- serving of being placed in the hands of the tyro, the advanced student, or the practitioner.—Medical Examiner. Previous editions, under the editorial supervision of Prof R. M. Huston, have been received with marked favor, and they deserved it; but this, re- printed from a very late Dublin edition, carefully revised and brought up by the author to the present time, does present an unusually accurate and able exposition of every important particular embraced in the department of midwifery. * * The clearness, directness, and precision of its teachings, together with the great amount of statistical research which its text exhibits, have served to place it already in the foremost rank of works in this department of re- medial science.—N. O. Med. and Surg. Journal. In our opinion, it forms one of the best if not the very best text-book and epitome of obstetric science which we at present possess in the English lan- guage.—Monthly Journal of Medical Science. The clearness and precision of style in which it is written, and the great amount of statistical research which it contains, have served to place it in the first rank of works in this department of medical science. —N. Y. Journal of Medicine. Few treatises will be found better adapted as a text-book for the student, or as a manual for the frequent consultation of the young practitioner.— American Medical Journal. BY the same author. (Just Issued.) ON THE DISEASES OF INFANTS AND CHILDREN. Second American Edition, revised and enlarged by the author. Edited, with Notes, by W. V. Keating, M. D. In one large and handsome volume, extra cloth, of over 700 pages. $3 00, or in leather, $3 25. In preparing this work a second time for the American profession, the author has spared no labor in giving it a very thorough revision, introducing several new chapters, and rewriting others, while every portion of the volume has been subjected to a severe scrutiny. The efforts of the American editor have been directed to supplying such information relative to matters peculiar to this country as might have escaped the attention of the author, and the whole may, there- fore, be safely pronounced one of the most complete works on the subject accessible to the Ame- rican Profession. By an alteration in the size of the page, these very extensive additions have been accommodated without unduly increasing the size of the work. A few notices of the former edition are subjoined:— The present volume will sustain the reputation acquired by the author from his previous works. The reader will find in it full and judicious direc- tions for the management of infants at birth, and a We regard this volume as possessing more claims to completeness than any other of the kind with which we are acquainted. Most cordially and ear- nestly, therefore, do we commend it to our profession- al brethren, and we feel assured that the stamp of their approbation will indue time be impressed upon it. After an attentive perusal of its contents, we hesitate not to say, that it is one of the most com- tice without calling attention to the author's style, prehensive ever written upon the diseases of chil dren, and that, for copiousness of reference, extent of research, and perspicuity of detail, it is scarcely to be equalled, and not to be excelled, in any lan- guage.—Dublin Quarterly Journal. After this meagre, and we know, very imperfect notice of Dr. Churchill's work, we shall conclude by saying, that it is one that cannot fail from its co- piousness, extensive research, and general accuracy, to exalt still higher the reputation of the author in this country. The American reader willbenarticu- larly pleased to find that Dr. Churchill has done full justice throughout his work to the various American authors on this subject. The names of Dewees, Eberle, Condie, and Stewart, occur on nearly every page, and these authors are constantly referred toby the author in terms of the highest praise, and with the most liberal courtesy.—The Medical Examiner. compendious, but clear account of the diseases to which children are liable, and the most successful mode of treating them. We must not close this no- which is perspicuous and polished to a degree, we regret to say, not generally characteristic of medical works. We recommend the work of Dr. Churchill most cordially, both to students and practitioners, as a valuable and reliable guide in the treatment of the diseases of children.—Am. Journ. of the Med. Sciences. We know of no work on this department of Prac- tical Medicine which presents so candid and unpre- judiced a statement or posting up of our actual knowledge as this.—N. Y. Journal of Medicine. Its claims to merit both as a scientific and practi- cal work, are of the highest order. Whilst we would not elevate it above every other treatise on the same subject, we certainly believe that very few are equal to it, and none superior.—Southern Med. and Surgical Journal. BY THE SAME AUTHOR. ESSAYS ON THE PUERPERAL FEYER, AND OTHER DISEASES PE- CULIAR TO WOMEN. Selected from the writings of British Authors previous to the close of the Eighteenth Century. In one neat octavo volume, extra cloth, of about 450 pages. $2 50. 10 BLANCHARD & LEA'S MEDICAL CHURCHILL (FLEETWOOD), M. D., M. R. I. A., &c. ON THE DISEASES OF WOMEN; including those of Pregnancy and Child- bed. A new American edition, revised by the Author. With Notes and Additions, by D Fran- cis Condie, M. D., author of "A Practical Treatise on the Diseases of Children." With nume- rous illustrations. In one large and handsome octavo volume, leather, of 768 pages. (Now Ready, May, 1857.) $3 00. This edition of Dr. Churchill's very popular treatise may almost be termed a new work, so thoroughly has he revised it in every portion. It will be found greatly enlarged, and thoroughly brought up to the most recent condition of the subject, while the very handsome series of illusira- tions introduced, representing such pathological conditions as can be accurately portrayed, present a novel feature, and afford valuable assistance to the young practitioner. Such additions as ap- peared desirable for the American student have been made by the editor, Dr. Condie, while a marked improvement in the mechanical execution keeps pace with the advance in all other respects which the volume has undergone, while the price has been kept at the former very moderate rate. A few notices of the former edition are subjoined :— larity. This fifth edition, before us, is well calcu- lated to maintain Dr. Churchill's high reputation. It was revised and enlarged by the author, for hie We now regretfully take leave of Dr. Churchill's book. Had our typographical limits permitted, we should gladiyhave borrowed more from its richly stored pages. In conclusion, wc heartily recom- mend it to the profession, and would at the same time express our firm conviction that it will not only add to the reputation of its author, but will prove a work of great and extensive utility to obstetric practitioners.—Dublin Medical Press. Former editions of this work have been noticed in previous numbers of the Journal. The sentiments of high commendation expressed in those notices, have only to be repeated in this; not from the fact that the profession at large are not aware of the high merits which this work really possesses, but from a desire to see the principles and doctrines therein contained more generally recognized, and more uni- versally carried out in practice.—N. Y. Journal of Medicine. We know of no author who deserves that appro- bation, on "the diseases of females," to the same extent that Dr. Churchill does. His, indeed, is the only thorough treatise we know of on the subject; and it may be commended to practitioners and stu- dents as a masterpiece in its particular department. The former editions of this work have been com- mended strongly in this journal, and they have won their way to an extended, and a well-deserved popu- American publishers, and it seems to us that there is scarcely any species of desirable information on its subjects that may not be found in this work.—Tht Western Journal of Medicine and Surgery. We are gratified to announce a new and revised edition of Dr. Churchill's valuable work on the dis- eases of females We have ever regarded it as one of the very best works on the subjects embraced within its scope, in the English language; and the present edition, enlarged and revised by the author, renders it still more entitled to the confidence of the profession. The valuable notes of Prof Huston have been retained, and contribute, in no small de- gree, to enhance the value of the work. It is a source of congratulation that the publishers have permitted the author to be, in this instance, his own editor, thus securing all the revision which an author alone is capable of making.—The Western Lancet. Asa comprehensive manual for students, or a work of reference for practitioners, we only speak with common justice when we say that it surpasses any other that has ever issued on the same sub- ject from the British press.—The Dublin Quarterly Journal. DICKSON (S. H.), M. D., Professor of Institutes and Practice of Medicine in the Medical College of South Carolina. ELEMENTS OF MEDICINE; a Compendious View of Pathology and Thera- peutics, or the History and Treatment of Diseases. In one large and handsome octavo volume, of 750 pages, leather (Lately Issued.) $3 75. As an American text-book on the Practice of Medicine for the student, and as a condensed work of reference for the practitioner, this volume will have strong claims on the attention of the profession. Few physicians have had wider opportunities than the author for observation and experience, and few perhaps have used them better. As the result of a life of study and practice, therefore, the present volume will doubtless be received with the welcome it deserves. This book is eminently what it professes to be; a distinguished merit in these days. Designed for " Teachers and Students of Medicine," and admira- bly suited to their wants, we think it will be received, on its own merits, with a hearty welcome.—Boston, Med. and Surg. Journal. Indited by one of the most accomplished writers of our country, as well as by one who has long held a high position among teachers and practitioners of medicine, this work is entitled to patronage and careful study. The learned author has endeavored to condense in this volume most of the practical matter contained in his former productions, so as to adapt it to the use of those, who have not time to devote to more extensive works.—Southern Med. and Surg. Journal. We can strongly recommend Dr. Dickson's work to our readers as one of interest and practical utility, well deserving of a place in their libraries as a book of reference ; and we especially commend the first part as presenting an admirable outline of the princi- ples of medicine.—Dublin Quarterly Journal, Feb. 1850. This volume, while as its title denotes it is a compendious view, is also a comprehensive system of practice, perspicuously and pleasantly written, and admirably suited to engage the interest, and in- struct the reader.—Peninsular Journal of Medicine, Jan. 1856. Prof. Dickson's work supplies, to a great extent, a desideratum long felt in American medicine.—N. 0. Med. and Surg. Journal. Estimating this work according to the purpose for which it is designed, we must think highly of its merits, and we have no hesitation in predicting for it a favorable reception by both students and teachers. Not professing to be a complete and comprehensive treatise, it will not be found full in detail, nor filled with discussions of theories and opinions, but em- bracing all that is essential in theory and practice, it is admirably adapted to the wants of the Arperican student. Avoiding all that is uncertain, it presents more clearly to the mind of the reader that which is established and verified by experience. The varied and extensive reading of the author is conspicuously apparent, and all the recent improvements and dis- coveries in therapeutics and pathology are chroni- cled in its pages.— Charleston Med. Journal. In the first part of the work the subject of gene- ral pathology is presented in outline, giving a btau- tiful picture of its distinguishing features, and throughout the succeeding chapters we find that he has kept scrupulously within the bounds of sound reasoning and legitimate deduction. Upon the whole, we do not hesitate to pronounce it a superior work in its class, and that Dr. Dickson merits a place in the first rank of American writers.—Western Lancet. AND SCIENTIFIC PUBLICATIONS 11 DRUITT (ROBERT), M.R. C.S., &c. THE PRINCIPLES AND PRACTICE OF MODERN SURGERY. A new American, from the improved London edition. Edited by F. W. Sargent, M. D., author of " Minor Surgery," &c. Illustrated with one hundred and ninety-three wood-engravings. In one very handsomely printed octavo volume, leather, of 576 large pages. $3 00. Dr. Druitt's researches into the literature of his subject have been not only extensive, but well di- rected; the most discordant authors are fairly and impartially quoted, and, while due credit is given to each, their respective merits are weighed with an unprejudiced hand. The grain of wheat is pre- served, and the chafF is unmercifully stripped off. Tlir arrangement is simple and philosophical, and liie style, though clear and interesting, is so precise, that the book contains more information condensed into a few words than any other surgical work with which we are acquainted.—London Medical Times and Gazette. No work, in our opinion, equals it in presenting bo much valuable surgical matter in so small a compass.—St. Louis Med. and Surgical Journal. Druitt's Surgery is too well known to the Ameri- can medical profession to require its announcement anywhere. Probably no work of the kind has ever been more cordially received and extensively circu- lated than this. The fact that it comprehends in a comparatively small compass, all the essential ele- ments of theoretical and practical Surgery—that it is found to contain reliable and authentic informa- tion on the nature and treatment of nearly all surgi- cal affections—is a sufficient reason for the liberal patronage it has obtained. The editor, Dr. F. W. Sargent, has contributed much to enhance the value of the work, by such American improvements as are calculated more perfectly to adapt it to our own views and practice in this country. It abounds everywhere with spirited and life-like illustrations, which to the young surgeon, especially, are of no minor consideration. Every medical man frequently noeds just such a work as this, for immediate refer- ence in moments of sudden emergency, when he has not time to consult more elaborate treatises.—The Ohio Medical and Surgical Journal. The author has evidently ransacked every stand- ard treatise of ancient and modern times, and all that is really practically useful at the bedside will be found in a form at once clear, distinct, and interest- ing.—Edinburgh Monthly Medical Journal. Druitt's work, condensed, systematic, lucid, and practical as it is, beyond most works on Surgery accessible to the American student, has had much currency in this country, and under its present au- spices promises to rise to yet higher favor.—The Western Journal of Medicine and Surgery. The most accurate and ample resume of the pre- sent state of Surgery that we are acquainted with.— Dublin Medical Journal. A better book oh the principles and practice of Surgery as now understood in England and America, has not been given to the profession.—Boston Medi- cal and Surgical Journal. An unsurpassable compendium, not only of Sur- gical, but of Medical Practice.—London Medical Gazette. This work merits our warmest commendations, and we strongly recommend it to young surgeons as an admirable digest of the principles and practice of modern Surgery.—Medical Gazette. It maybe said with truth that the work of Mr. Druitt affords a complete, though brief and con- densed view, of the entire field of modern surgery. We know of no work on the same subject having the appearance of a manual, which includes so many topics of interest to the surgeon ; and the terse man- ner in which each has been treated evinces a most enviable quality of mind on the part of the author, who seems to have an innate power of searching out and grasping the leading facts and features of the most elaborate productions of the pen. It is a useful handbook for the practitioner, and we should deem a teacher of surgery unpardonable who did not recommend it to his pupils. In our own opinion, it is admirably adapted to the wants of the student.— Provincial Medical and Surgical Journal. DUNGLISON, FORBES, TWEEDIE, AND CONOLLY. THE CYCLOPAEDIA OF PRACTICAL MEDICINE: comprising Treatises on the Nature and Treatment of Diseases, Materia Medica, and Therapeutics, Diseases of Women and Children, Medical Jurisprudence, &c. &c. In four large super-royal octavo volumes, of 3254 double-columned pages, strongly and handsomely bound, with raised bands: $12 00. *** This work contains no less than four hundred and eighteen distinct treatises, contributed by sixty-eight distinguished physicians, rendering it a complete library of reference for the country practitioner The most complete work on Practical Medicine extant; or, at least, in our language.—Buffalo Medical and Surgical Journal. For reference, it is above all price to every prac- titioner.—Western Lancet. One of the most valuable medical publications of the day—as a work of reference it is invaluable.— Western Journal of Medicine and Surgery. It has been to us, both as learner and teacher, a work for ready and frequent reference, one in which modern English medicine is exhibited in the most advantageous light.—Medical Examiner. We rejoice that this work is to be placed within the reach of the profession in this country, it being unquestionably one of very great value to the prac- titioner. This estimate of it has not been formed from a hasty examination, but after an intimate ac- quaintance derived from frequent consultation of it during the past nine or ten years. The editors are practitioners of established reputation, and the list of contributors embraces many of the most eminent professors and teachers of London, Edinburgh, Dub- lin, and Glasgow. It is, indeed, the great merit of this work that the principal articles have been fur- nished by practitioners who have not only devoted especial attention to the diseases about which they have written, but have also enjoyed opportunities for an extensive practical acquaintance with them, and whose reputation carries the assurance of their competency justly to appreciate the opinions of others, while it stamps their own doctrines with high and just authority.—American Medical Journ. DEWEES'S COMPREHENSIVE SYSTEM OF MIDWIFERY. Illustrated by occasional cases and many engravings. Twelfth edition, with the author's last improvements and corrections In one octavo volume, extra cloth, of 600pages. $320. DEWEES'S TREATISE ON THE PHYSICAL AND MEDICAL TREATMENT OF CHILD- REN. Tenth edition. In one volume, octavo, extra cloth, 548 pages. $2 80. DEWEES'S TREATISE ON THE DISEASES OK FEMALES. Tenth edition. In one volume, octavo, extra cloth, 532 pages, with plates. $3 00. DANA ON ZOOPHYTES AND CORALS. In one volume, imperial quarto, extra cloth, with wood- cuts. $15 00. Also, AN ATLAS, in one volume, imperial folio, with sixty-one magnificent colored plates. Bound in half morocco. $30 00. DE LA BECHE'S GEOLOGICAL OBSERVER. In one very large and handsome octavo volume, ex- tra cloth, of 700 pages, with 300 wood-cuts. $i 00. FRICK ON RENAL AFFECTIONS; their Diag- nosis and Pathology. With illustrations. One volume, royal 12mo., extra cloth. 75 cents. 12 BLANCHARD & LEA'S MEDICAL DUNGLISON (ROBLEY), M.D., Professor of Institutes of Medicine in the Jefferson Medical College, Philadelphia. NEW AND ENLARGED EDITION, Now Ready. MEDICAL LEXICON; a Dictionary of Medical Science, containing a concise Explanation of the various Subjects and Terms of Anatomy, Physiology, Pathology, Hygiene, Therapeutics Pharmacology, Pharmacy, Surgery, Obstetrics, Medical Jurisprudence, Dentistry, ore. Notices of Climate and of Mineral Waters; Formulae for Officinal, Empirical, and Dietetic Preparations, &c. With French and other Synonymes. Fifteenth edition, revised and very greatly enlarged. In one very large and handsome octavo volume, of 992 double-columned pages, in small type; strongly bound in leather, with raised bands. Price $4 00. No care, labor, or expense has been spared in the preparation of this edition to render it in every respect worthv a continuance of the very remarkable favor which it has hitherto enjoyed. The rapid sale of Fifteen large editions, and the constantly increasing demand, show that it is regarded by the profession as the standard authority. Stimulated by this lact, the author has endeavored in the present revision to introduce whatever might be necessary to render it a complete exposition of Medical Terminology in the advanced condition of all the collateral sciences. To accomplish this, large additions have been found requisite, and ihe extent of the author's labors may be estimated from the fact that about Six Thousand subjects and terms have been introduced throughout, ren- dering the whole number of definitions about Sixty Thousand. To accommodate these additions, the number of pages has been increased by nearly a hundred, notwithstanding an enlargement in the size of the pane, and the author trusts that he has succeeded in the endeavor to render it a com- plete and accurate lexicon, presenting clear and satisfactory definitions of all the terms which have been legitimated in medical science. By the unanimous verdict of the medical press, both in this country and in England, the work has been pronounced indispensable to all medical students and practitioners, and the present improved edition will not lose that enviable reputation. The publishers have endeavored to render the mechanical execution worthy of a volume of such universal use in daily reference. The greatest care has been exercised to obtain the typographical accuracy so necessary in a work of the kind. By Ihe small but exceedingly clear type employed, an immense amount of matter is condensed in its thousand ample pages, while the binding will be found strong and durable. With all these improvements and enlargements, the price has been kept at Ihe former very moderate rate, placing it within the reach of all. readers to its peculiar merits; and we need do little more than state, in reference to the present reissue, that, notwithstanding the large additions previously made to it, no fewer than four thou- sand terms, not to be found in the preceding edi- tion, are contained in the volume before us.— We welcome it cordially; it, is an admirable work, and indispensable to all literary medical men. The labor which has been bestowed upon it is something prodigious. The work, however, has now been done, and we are hnppy in the thought that no hu- man being will have again to undertake the same gigantic task. Revised and corrected from time to time, Dr. Dunglison's " Medical Lexicon" will last for centuries.—British and Foreign Med.-Chirurg. Review. The fact that this excellent and learned work has passed through eight editions, and that a ninth is rendered necessary by the demands of the public, affords a sufficient evidence of the general apprecia- tion of Dr. Dunglison's labors by the medical pro- fession in England and America. It is a book which will be of great service to the student, in teaching him the meaning of all the technical terms used in medicine, and will be of no less use to the practi- tioner who desires to keep himself on a level with the advance of medical science.—London Medical Times and Gazette. In taking leave of our author, we feel compelled to confess that his work bears evidence of almost incredible labor having been bestowed upon its com- position.—Edinburgh Journal of Med. Science. A miracle of labor and industry in one who has written able and voluminous works on nearly every branch of medical science. There could be no more useful book to the student or practitioner, in the present advancing age, than one in which would be found, in addition to the ordinary meaning and deri- vation of medical terms—so many of which are of modern introduction—concise descriptions of their explanation and employment; and all this and much more is contained in the volume before us. It is therefore almost as indispensable to the other learned professions as to our own. In fact, to all who may have occasion to ascertain the meaning of any word belonging to the many branches of medicine. From a careful examination of the present edition, we can vouch for its accuracy, and for its being brought quite up to thedate of publication ; the author states in his preface that he has added to it about four thou- sand terms, which are not to be found in the prece- ding one. — Dublin Quarterly Journal of Medical Sciences. On the appearance of the last edition of this valuable work, we directed the attention of our Whilst it is a wonderful monument of its author's erudition and industry, it is also a work of great practical utility, as we can testify from our own experience; for we keep it constantly within our reach, and make very frequent reference to it, nearly always finding in it the information we seek. —British and Foreign Me&.-Chirurg. Review. It has the rare merit that it certainly has no rival in the English language for accuracy and extent of references. The terms generally include short physiological and pathological descriptions, so that, as the author justly observes, the reader does not possess in this work a mere dictionary, but a book, which, while it instructs him in medical etymo- logy, furnishes him with a large amount of useful information. The author's labors have been pro- perly appreciated by his own countrymen ; and we can only confirm their judgment, by recommending this most useful volume to the notice of our cisat- lantic readers. No medical library will be complete without it.—London Med. Gazette. It is certainly more complete and comprehensive than any with which we are acquainted in the English language. Few, in fact, could be found better qualified than Dr. Dunglison for the produc- tion of such a work. Learned, industrious, per- severing, and accurate, he brings to the task all the peculiar talents necessary for its successful performance; while, at the same time, his fami- liarity with the writings of the ancient and modern " masters of our art," renders him skilful to note the exact usage of the several terms of science, and the various modifications which medical term- inology has undergone with the change of theo- ries or the progress of improvement. — American Journal of the Medical Sciences. One of the most complete and copious known to the cultivators of medical science.—Boston Med. Journal. The most comprehensive and best English Dic- tionary of medical terms extant.—Buffalo Medical Journal. BY THE SAME AUTHOR. THE PRACTICE OF MEDICINE. A Treatise on Special Pathology and The- rapeuties. Third Edition. In two large octavo volumes, leather, of 1,500 pages. $6 25. AND SCIENTIFIC PUBLICATIONS. 13 DUNGLISON (ROBLEY), M.D., Professor of Institutes of Medicine in the Jefferson Medical College, Philadelphia. HUMAN PHYSIOLOGY. Eighth edition. Thoroughly revised and exten- sively modified and enlarged, with five hundred and thirty-two illustrations. In two large and handsomely printed octavo volumes, leather, of about 1500 pages. (Just Issued, 1856.) $7 00. In revising this work for its eighth appearance, the author has spared no labor to render it worthy a continuance of the very great favor which has been extended to it by the profession. The whole contents have been rearranged, and to a great extent remodelled ; the investigations which of late years have been so numerous and so important, have been carefully examined and incorporated, and the work in every respect has been brought up to a level with the present state of the subject. The object of the author has been to render it a concise but comprehensive treatise, containing the whole body of physiological science, to which the student and man of science can at all times refer with the certainty of finding whatever they are in search of, fully presented in all its aspects; and on no former edition has the author bestowed more labor to secure this result. A similar improvement will be found in the typographical execution of the volumes, which, in this respect, are superior to their predecessors. A large number of additional wood-cuts have been introduced, and the series of illustrations has been greatly modified by the substitution of many new ones for such as were not deemed satisfactory. By an enlargement of the page, these very considerable additions have been accommodated without increasing the size of the volumes to an extent to render them unwieldy. We believe that it can truly be said, no more com- plete repertory of facts upon the subject treated, can anywhere be found. The author has, moreover, that enviable tact at description and that facility and ease of expression which render him peculiarly acceptable to the- casual, or the studious reader. This faculty, so requisite in setting forth many praver and less attractive subjects, lends additional charms to one always fascinating.—Boston Med. and Surg. Journal, Sept. 1856. The most complete and satisfactory system of Physiology in the English language.—Amer. Med. Journal. The best work of the kind in the English lan- guage.—Silliman's Journal. The present edition the author has made a perfect mirror of the science as it is at the present hour. As a work upon physiology proper, the science of the functions performed by the body, the student will find it all he wishes.—Nashville Journ. of Med. Sept. 1S56. That he has succeeded, most admirably succeeded in his purpose, is apparent from the appearance of an eighth edition. It is now the ereat encyclopedia on the subject, and worthy of a place in every phy- sician's library.— Western Lancet, Sept. 1S56. BY the same author. (Now Ready.) GENERAL THERAPEUTICS AND MATERIA MEDICA; adapted for a Medical Text-book. With Indexes of Remedies and of Diseases and their Remedies. Sixth Edition, revised and improved. With one hundred and ninety-three illustrations. In two large and handsomely printed octavo vols., leather, of about 1100 pages. $6 00. From the Author's Preface. " Another edition of this work being called for, the author has subjected it to a thorough and careful revision: It has been gratifying to him that it has been found so extensively useful by those for whom it was especially intended, as to require that a sixth edition should be issued in so short a time afier the publication of a fifth. Grateful for the favorable reception of the work by the profession, he has bestowed on the preparation of the present edition all those cares which were demanded by the former editions, and has spared no pains to render it a faithful epitome of General Therapeutics and Materia Medica. The copious Indexes of Remedies and of Diseases and their Remedies can- not fail, the author conceives, to add materially to the value of the work." This work is too widely and too favorably known to require more than the assurance that the author has revised it with his customary industry, introducing whatever has been found necessary to bring it on a level with the most advanced condition of the subject. The number of illustrations has been somewhat enlarged, and the mechanical execution of the volumes will be found to have undergone a decided improvement. by the same author. (A new Edition.) NEW REMEDIES, WITH FORMULA FOR THEIR PREPARATION AND ADMINISTRATION. Seventh edition, with extensive Additions. In one very large octavo volume, leather, of 770 pages. (Just Issued.) $3 75. Another edition of the " New Remedies" having been called for, the author has endeavored to add everything of moment that has appeared since the publication of the last edition. The chief remedial means which have obtained a place, for the first time, in this volume, either owing to their having been recently introduced into pharmacology, or to their having received novel applications—and which, consequently, belong to the category of " New Remedies"—are the fol- lowing :— Apiol, Caffein, Carbazotic acid, Cauterization and catheterism of the larynx and trachea, Cedron, Cerium, Chloride of bromine, Chloride of iron, Chloride of sodium, Cinchonicine, Cod-liver olein, Congelation, Eau de Pagliari, Galvanic cautery, Hydriodic ether, Hyposulphite of soda and silver, Inunction, Iodide of sodium, Nickel, Permanganate of potassa, Phosphate of lime, Pumpkin, Quinidia, Rennet, Saccharine carbonate of iron and manganese, Santonin, Tellurium, and Traumaticine. The articles treated of in the former editions will be found to have undergone considerable ex- pansion in this, in order that the author might be enabled to introduce, as far as practicable, the results of the subsequent experience of others, as well as of his own observation and reflection; and to make the work still more deserving of the extended circulation with which the preceding editions have been favored by the profession. By an enlargement of the page, the numerous addi- tions have been incorporated without greatly increasing the bulk of the volume.— Preface. One of the most useful of the author's works.— Southern Medical and Surgical Journal. This elaborate and useful volume should be found in every medical library, for as a book of re- ference, for physicians, it is unsurpassed by any other work in existence, and the double index for diseases and for remedies, will be found greatly to enhance its value.—New York Med. Gazette. The great learning of the author, and his remark- able industry in pushing his researches into every source whence information is derivable,have enabled him to throw together an extensive mass of facts and statements, accompanied by full reference to authorities; which last feature renders the work practically valuable to investigators who desire to examine the original papers.—The American Journal of Pharmacy. 14 BLANCHARD & LEA'S MEDICAL ERICHSEN (JOHN), Professor of Surgery in University College, London, &c. THE SCIENCE AND ART OF SURGERY; being a Treatise on Surgical Injuries, Diseases, and Operations. Edited by John H. Brinton, M. D. Illustrated with three hundred and eleven engravings on wood. In one large and handsome octavo volume, of over nine hundred closely printed pages, leather, raised bands. $4 25. rarely encounter cases requiring surgical manage- ment.—Stethoscope. Embracing, as will be perceived, the whole surgi- cal domain, and each division of itself almost com- plete and perfect, each chapter full and explicit, each subject faithfully exhibited, we can only express our estimate of it in the aggregate. We consider it an excellent contribution "to surgery, as probably the best single volume now extant on the subject, and with great pleasure we add it to our textbooks — Nashville Journal of Medicine and Surgery. Prof. Erichsen's work, for its size, has not been surpassed; his nine hundred and eight pages, pro- fusely illustrated, are rich in physiological, patholo- gical, and operative suggestions, doctrines, details, and processes; and will prove a reliable resource for information, both to physician and surgeon, in the hour of peril.— N. 0. Med. and Surg. Journal. We are acquainted with no other work wherein so much good sense, sound principle, and practical ^lferences, stamp every page.—American Lancet. Il is, in our humble judgment, decidedly the best book of ihe kind in the English language. Strange that just such books are notoftener produced by pub lie teachers of surgery in 1his country and Great Britain Indeed, it is a matterof great astonishment. but no less true than astonishing, that of the many works on surgery republished in this country within the last fifteen or twenty years as text books for medical students, this is the only one that even ap- proximates to the fulfilment of the peculiar wants of young men just entermar upon the study of this branch of the profession.— Western Jour.of Med. and Surgery. Its value is greatly enhanced by a very copious well-arran?ed index. We regard this as one of the most valuable contributions to modern surgery. To one entering his novitiate of practice, we regard it th° mo" serviceable guide which he can consult. He will find a fulness of detail leadinghim through every siep of the operation, and not deserting him until the final issue of the case is decided. For the same rea- son we recommend it to those whose routine of prac- tice lies in such parts of the country that they must ELLIS (BENJAMIN), M.D. THE MEDICAL FORMULARY: heing a Collection of Prescriptions, derived from the writings and practice of many of the most eminent physicians of America and Europe. Together with the usual Dietetic Preparations and Antidotes for Poisons. To which is added an Appendix, on the Endermic use of Medicines, and on the use of Ether and Chloroform. The whole accompanied with a few brief Pharmaceutic and Medical Observations. Tenth edition, revised and much exfended by Robert P. Thomas, M. D., Professor of Materia Medica in the Philadelphia College of Pharmacy. In one neat octavo volume, extra cloth, of 296 pages. (Lately Issued.) $1 75. After an examination of the new matter and the alterations, we believe the reputation of the work built up by the author, and the late distinguished editor, will continue to flourish under the auspices of the present editor, who has the industry and accu- racy, and, we would say, conscientiousness requi- site for the responsible task.—Am. Jour, of Pharm. It will prove particularly useful to students and young practitioners, as the most important prescrip- tions employed in modern practice, which lie scat- tered through our medical literature, are here col- lected and conveniently arranged for reference.— Charleston Med. Journal and Review. FOWNES (GEORGE), PH. D., &.C. ELEMENTARY CHEMISTRY; Theoretical and Practical. With numerous illustrations. Edited, with Additions, by Robert Bridges, M. D. In one large royal 12mo. volume, of over 550 pages, with 181 wood-cuts. In leather, $1 50; extra cloth, $ 1 35. We know of no better text-book, especially in the difficult department of organic chemistry, upon which it is particularly full and satisfactory. We would recommend it to preceptors as a capital 1' office book" for their students who are beginners in Chemistry. It is copiously illustrated with ex- cellent wood-cuts, and altogether admirably "got up."—A". J. Medical Reporter. A standard manual, which has long enjoyed the reputation of embodying much knowledge in a small space. The author has achieved the difficult task of condensation with masterly tact. His book is con- cise without being dry, and brief without being too dogmatical or general.— Virginia Med. and Surgical Journal. The work of Dr. Fownes has long been before the public, and its merits have been fully appreci- ated as the best text-book on chemistry now in existence. We do not, of course, place it in a rank superior to the works of Brande, Graham, Turner, Gregory, or Gmelin, but we say that, as a work for students, it is preferable to any of them.—Lon- don Journal of Medicine. A work well adapted to the wants of the student. It is an excellent exposition of the chief doctrines and facts of modern chemistry. The size of the work, and still more the condensed yet perspicuous style in which it is written, absolve it from the charges very properly urged against most manuals termed popular.—Edinburgh Journal of Medical Science. FERGUSSON (WILLIAM), F. R. S., Professor of Surgery in King's College, London, &c. A SYSTEM OF PRACTICAL SURGERY. Fourth American, from the third and enlarged London edition. In one large and beautifully printed octavo volume, of about 700 pages, with 393 handsome illustrations, leather. $3 00. The most important subjects in connection with practical surgery which have been more recently brought under the notice of, and discussed by, the surgeons of Great Britain, are fully and dispassion- ately considered by Mr. Fergusson, and that which was before wanting has now been supplied; so that we can now look upon it as a work on practical sur- gery instead of one on operative surgery alone. Medical Times and Gazette. No work was ever written which more nearly comprehended the necessities of the student and practitioner, and was more carefully arranged to that single purpose than this.—A'. Y. Med. Journal. The addition of many new pages makes this work more than ever indispensable to the student and prac- titioner.—Ranking's Abstract. Among the numerous works upon surgery pub- lished of late years, we know of none we value more highly than the one before us. It is perhaps the very best we have for a text-book and for ordi- nary reference, being concise and eminently practi- cal.—Southern Med. and Surg. Journal. AND SCIENTIFIC PUBLICATIONS 15 FLINT (AUSTIN), M. D., Professor of the Theory and Practice of Medicine in the University of Louisville, &c. (An Important New Work.) PHYSICAL EXPLORATION AND DIAGNOSIS OF DISEASES AFFECT- ING THE RESPIRATORY ORGANS. In one large and handsome octavo volume, extra cloth, 636 pages. $3 00. AVe can only state our general impression of the | the results of his study and experience. These ex- high value of this work, and cordially recommend pectations we are confident will not be disappointed. it to nil. We regard it, in pointboth of rirrnngement ! Forour own part, we have been favorably impressed and of the marked abilitv of its treatment of the sub- I by a perusal of the book, and heartily recommend it jeets, as destined to take the first rank in works of | to all who are desirous of acquiring a thorough ac- this class. So far as our information extends, it has quaintance with the means of exploring the condi- at present no equal. To the practitioner, as well as tions of the respiratory organs by means of auscul- the student, it will be invaluable in clearing up the diagnosis of doubtful cases, and in shedding light upon difficult phenomena.—Buffalo Med. Journal. This is the most elaborate work devoted exclu- sively to the physical exploration of diseases of the lungs, with which we are acquainted in the English tation and percussion. — Boston Med. and Surg. Journal. A. work of original observation of the highest meri t. We recommend the treatise to every one who wishes to become a correct auscultator. Based to a very larsre extent upon cases numerically examined, it language. From the high standing of the author as carries the evidtnce of careful study and disonmina- a clinical teacher, and his known devotion, during i tion upon every pane. It does credit to the author, many years, to the study of thoiacic diseases much and, through him, to the profusion in this country. was to be expected from the announcement of his i It is, what we cannot call every book upon auscul- determination to embody in the form of a treatise, ! tation, a readable book.—Am. Jour. Med. Sciences. FISKE FUND PRIZE ESSAYS. THE EFFECTS OF CLIMATE ON TUBERCULOUS DISEASE. By Ebwin Lee, M. R. C. S., London. THE INFLUENCE OF PREGNANCY ON THE DEVELOPMENT OF TUBERCLES. By Edward Warren, M. D., of Edenton, N. C. Together in one neat octavo volume, extra cloth. $1 00. (Just Ready.) These two valuable Essays on Tuberculosis are reprinted by request of the Rhode Island Medi- cal Society, from the " American Journal oftlie Medical Sciences" for April and July, 1S57. GRAHAM (THOMAS), F. R. S., Professor of Chemistry in University College, London, &c. THE ELEMENTS OF CHEMISTRY. Including the application of the Science to the Arts. With numerous illustrations. With Notes and Additions, by Robert Bridges, M. D., &c. &c. Second American, from the second and enlarged London edition. PART I. (Lately Issued) large 8vo., 430 pages, 185 illustrations. $1 50. PART II. (Preparing) to match. _________________ GRIFFITH (ROBERT E.), M. D., &c. A UNIVERSAL FORMULARY, containing the methods of Preparing and Ad- ministering Officinal and other Medicines. The whole adapted to Physicians and Pharmaceu- tists. Second Edition, thoroughly revised, with numerous additions, by Robert P. Thomas, M D., Professor of Materia Medica in the Philadelphia College of Pharmacy. In one lars-e end handsome octavo volume, extra cloth, of 650 pages, double columns. (Just Issued.) $3 00; or bound in sheep, $3 25. It was a work requiring much perseverance, and [ tioner can possibly have in his possession.—Medical when published was looked upon as by far the best Chronicle. work-of its kind that had issued from the American | The amount of useful, every-da\ matter, for a prat. press. Prof Thomas has certainly "improved." as well as added othis Formulary, and has rendered it additionally deserving of the confidence of pharma- ceutists and physicians.—Am. Journal of Pharmacy We are happy to announce a new and improved edition of this, one of the most valuable and useful works that have emanated from an American pen. It would do credit to any country, and will be found of daily usefulness to practitioners of medicine; it is better adapted to their purposes than the dispensato- ries. — Southern Med. and Surg. Journal. A new edition of this well-known work, edited by R. P. Thomas. M. D.. affords occasion for renewing our commendation of so useful a handbook, which ouffht to be universally studied by medical men of every class, and made use of by way of reference by- office pupils, as a standard authority. It has been much enlarged, and now condenses a vast amount of needful and necessary knowledge in small com- pass The more of such books the better for the pro- fession and the public-AT. F. Med. Gazette. It is one of the most useful books a country practi- ticins physician, is really immense.— Boston Mid. and Surg. Journal. This is a work of six hundred and fifty one pages, embracing all on the sul>.it-ct of preparing and admi- nistering medicines thai can be desired by ihe physi- cian and pharmaceutist.— Western Lancet. In short, it is a full and complete work of the kiudj and should be in the hands of every physician and apothecary. O. Med. and Surs. Journal We predict a great sale for this work, and we espe- ciallv recommend it to all medical teachers.—Rich- mond Stethoscope. This edition of Dr Griffith's work hns been greatly improved by the revision and ample additions of Dr. Thomas, and is now. we believe, one of the most complete works of its kind in any laiiguage. The additions amount to about seventy pages, and no effort has been spared to include in them all the re- cent improvemenls which have been published in medical journals, and systematic treatises. A. work of this kind appears to us indispensable to the physi- cian, and lh^reis none -.v« can more cordially recom- mend.— iV. y. Journal of Medicine. BY THE SAME AUTHOR. MEDICAL BOTANY; or, a Description of all the more important Plants used in Medicine, and of their Properties, Uses, and Modes of Administration. In one large octavo volume, extra cloth, of 704 pages, handsomely printed, with nearly 350 illustrations on wood. S3 00. 16 BLANCHARD & LEA'S MEDICAL GROSS (SAMUEL DJ, M. D., Professor of Surgery in the Jefferson Medical College of Philadelphia, &c. New Edition (Now Ready.) ELEMENTS OF PATHOLOGICAL ANATOMY. Third edition, thoroughly revised and greatly improved. In one large and very handsome octavo volume, with about three hundred and fifty beautiful illustrations, of which a large number are from original drawings. Price in extra cloth, $4 75; leather, raised bands, $5 25. The very rapid advances in the Science of Pathological Anatomy during the last few years have rendered essential a thorough modification of this work, with a view of making it a correct expo- nent of the present state of the subject. The very careful manner in which this task has been executed, and the amount of alteration which it has undergone, have enabled the author to say that " with the many changes and improvements now introduced, the work may be regarded almost as a new treatise," while the efforts of the author have been seconded as regards the mechanical execution of the volume, rendering it one of the handsomest productions of the American press. A very large number of new and beautiful original illustrations have been introduced, and the work, it is hoped, will fully maintain the reputation hitherto enjoyed by it of a complete and practical ex- position of its difficult and important subject. We most sincerely congratulate the author on the successful manner in which he has accomplished his proposed object. His book is most admirably cal- culated to fill up a blank which has long been felt to exist in this department of medical literature, and as such must become very widely circulated amongst all classes of the profession. — Dublin Quarterly Journ. of Med. Science, Nov. 1857. We have been favorably impressed with the gene- ra.] manner in which Dr. Gross has executed his task of affording a comprehensive digest of the present state of the literature of Pathological Anatomy, and have much pleasure in recommending his work to our leaders, as we believe one well deserving of diligent perusal and careful study.—Montreal Med. Chron., Sept. 1857. BY THE SAME AUTHOR. A PRACTICAL TREATISE ON THE DISEASES, INJURIES, AND MALFORMATIONS OF THE URINARY BLADDER, THE PROSTATE GLAND, AND THE URETHRA. Second Edition, revised and much enlarged, with one hundred and eighty- four illustrations. In one large and very handsome octavo volume, of over nine hundred pages, (Just Issued.) In leather, raised bands, $5 25; extra cloth, $4 75. A volume replete with truths and principles of the utmost value in the investigation of these diseases.— American Medical Journal. On the appearance of the first edition of this work, the leading English medical review predicted that it would have a." permanent place in the literature of surgery worthy to rank with the best works of the present age." This prediction has been amply ful- filled. Dr. Gross's treatise has been found to sup- ply completely the want which has been felt ever since the elevation of surgery to the rank of a science, of a good practical treatise on the diseases of the bladder and its accessory organs. Philosophical in its design, methodical in its arrangement, ample and sound in its practical details, it may in truth be said to leave scarcely anything to be desired on so im- portant a subject, and with the additions and modi- fications resulting from future discoveries and im- provements, it will probably remain one of the most valuable -works on this subject so long as the science of medicine shall exist.—Boston Med. and Surg. Journal. Whoever will peruse the vast amount of valuable practical information it contains, and which we have been unable even to notice, will, we think, agree with us, that there is no work in the English language which can make any just pretensions to be its equal.—N. Y. Journal of Medicine. BY THE SAME AUTHOR. (Just Issued). A PRACTICAL TREATISE ON FOREIGN BODIES IN THE AIR-PAS- SAGES. In one handsome octavo volume, extra cloth, with illustrations, pp. 468. $2 75. A very elaborate work. It is a complete summary of the whole subject, and will be a useful book of reference.—British and Foreign Medico-Chirurg. Review. A highly valuable book of reference on a most im- portant subject in the practice of medicine. We conclude by recommending it to our readers, fully persuaded that its perusal will afford them much practical information well conveyed, evidentlv de- rived from considerable experience and deduced from an ample collection of facts. — Dublin Quarterly Journal, May, 1855. BY the same author. (Preparing.) A SYSTEM. OF SURGERY j Diagnostic, Pathological, Therapeutic, and Opera- tive. With very numerous engravings on wood. GLUGE (GOTTLIEB), M. D., Professor of Physiology and Pathological Anatomy in the University of Brussels, &c AN ATLAS OF PATHOLOGICAL HISTOLOGY. Translated, with Notes and Additions, by Joseph Leidy, M. D., Professor of Anatomy in the University of Pennsylva- nia. In one volume, very large imperial quarto, extra cloth, with 320 figures, plain and colored, on twelve copperplates. $5 00. GARDNER'S MEDICAL CHEMISTRY, for the use of Students and the Profession. In one royal ISmo. vol., ex. cloth, pp. 396. with illustrations. SI 00. HARRISONS ESSAY TOWARDS A CORRECT THEORY OF THE NERVOUS SYSTEM. In one octavo volume, leather, 292 pages. $1 50. HUGHES' CLINICAL INTRODUCTION TO THE PRACTICE OF AUSCULTATION AND OTHER MODES OF PHYSICAL DIAGNOSIS, IN DISEASES OF THE LUNGS AND HEART! Second American, from the second London edition. 1 vol. royal 12mo., ex. cloth, pp. 304. $1 00. HUNTER'S COMPLETE WORKS, in 4 vols. 8vo., leather, with plates. $10. AND SCIENTIFIC PUBLICATIONS. 17 HOBLYN (RICHARD D.), M. D. A DICTIONARY OF THE TERMS USED IN MEDICINE AND THE COLLATERAL SCIENCES. By Richard D. Hoblyn, A. M., &c. A new American from the last London edition. Revised, with numerous Additions, by Isaac Hays, M. D., editor of the " American Journal of the Medical Sciences." In one large royal 12mo. volume, leather, of over 500 double columned pages. (Just Issued, 1856.) $1 50. If the frequency with which we have referred to this volume since its reception from the publisher, two or three weeks ago, be any criterion for the future, the binding will soon have tobe renewed, even with careful handling. We find that Dr. Hays has done the profession great service by his careful and industrious labors. The Dictionary has thus become eminently suited to our medical brethren in this country. The additions by Dr. Hays are in brackets, and we believe there is not a single page but bears these insignia; in every instance which we have thus far noticed, the additions are really needed and ex- ceedingly valuable. We heartily commend the work to all who wish to be au courant in medical termi- nology.— Boston Med. and Surg. Journal. To both practitioner and student, we recommend this dictionary as being convenient in size, accurate in definition, and sufficiently full and complete for ordinary consultation.—Charleston Med. Journ. and Reviexo. Admirably calculated to meet the wants of the practitioner or student, who has neither the means nor desire to procure a larger work. — American Lancet. Hoblyn has always been a favorite dictionary, and in its present enlarged and improved form will give greater satisfaction than ever. The American editor, Dr. Hays, has made many very valuable additions. —N.J. Med. Reporter. To supply the want of the medical reader arising from this cause, we know of no dictionary better arranged and adapted than the one bearing the above title. It is not encumbered with the obsolete terms of a bygone age, but it contains all that are now in use ; embracing every department of medical science down to the very latest date. The volume is of a convenient size to be used by the medical student, and yet large enough to make a respectable appear- ance in the library of a physician.—Western Lancet. Hoblyn's Dictionary has long been a favorite with us. It is the best book of definitions we have, and ought always to be upon the student's table.— Southern Med. and Surg. Journal. HOLLAND (SIR HENRY), BART., M.D..F. R. S., Physician in Ordinary to the Queen of England, &c. MEDICAL NOTES AND REFLECTIONS. From the third London edition. In one handsome octavo volume, extra cloth, (Now Ready.) $3 00. As the work of a thoughtful and observant physician, embodying the results of forty years' ac- tive professional experience, on topics of the highest interest, this volume is commended to the American practitioner as well worthy his attention. Few will rise from its perusal without feel- ing their convictions strengthened, and armed with new weapons for the daily struggle with disease. HABERSHON (S. O.), M. D., Assistant Physician to and Lecturer on Materia Medica and Therapeutics at Guy's Hospital, &c. PATHOLOGICAL AND PRACTICAL OBSERVATIONS ON DISEASES OF THE ALIMENTARY CANAL, OESOPHAGUS, STOMACH, CECUM, AND INTES- TINES. With illustrations on wood. In one handsome octavo volume. (Republishi?ig in the Medical News and Library for 1858.) HORNER (WILLIAM E.), M. D., Professor of Anatomy in the University of Pennsylvania. SPECIAL ANATOMY AND HISTOLOGY. Eighth edition. Extensively revised and modified. In two large octavo volumes, extra cloth, of more than one thousand pages, handsomely printed, with over three hundred illustrations. $6 00. HAMILTON (FRANK H.), M. D., Professor of Surgery, in Buffalo Medical College, &c. A TREATISE ON FRACTURES AND DISLOCATIONS. octavo volume, with numerous illustrations. (Preparing.) In one handsome JONES (T. WHARTON), F. R. S., Professor of Ophthalmic Medicine and Surgery in University College, London, &c. THE PRINCIPLES AND PRACTICE OF OPHTHALMIC MEDICINE AND SURGERY. With one hundred and ten illustrations. Second American from the second and revised London edition, with additions by Edward Hartshorne, M. D., Surgeon to Wills' Hospital, &c. In one large, handsome royal 12mo. volume, extra cloth, of 500 pages. (Now Ready.) $1 50. We are confident that the reader will find, on perusal, that the execution of the work amply fulfils the promise of the preface, and sustains, in every point, the already high reputation of the author as an ophthalmic surgeon as well as a physiologist and pathologist. The book is evidently the result of much labor and research, and has been written with the greatest care and attention; it possesses that best quality which a general work, like a sys- tem or manual can show, viz: the quality of having all the materials whencesoever derived, so thorough- ly wrought up, and digested in the author's mind, as to come forth with the freshness and i repressive- ness of an original production. We entertain little doubt that this book will become what its author hoped it might become, a manual for daily reference and consultation by the student and the general prac- titioner. The. work is marked by that correctness, clearness, and precision of style which distinguish all the productions of the learned author.—British and For. Med. Review. 18 BLANCHARD & LEA'S MEDICAL JONES (C. HANDFIELD), F. R. S., &. EDWARD H. SI EV EKING, M.D., Assistant Physicians and Lecturers in St. Mary's Hospital, London. A MANUAL OF PATHOLOGICAL ANATOMY. First American Edition, Revised. With three hundred and ninety-seven handsome wood engravings. In one large and beautiful octavo volume of nearly 750 pages, leather. $3 75. Asa concise text-book, containing, in a condensed form, a complete outline of what is known in the domain of Pathological Anatomy, it is perhaps the best work in the English language. Its great merit consists in its completeness and brevity, and in this respect it supplies a great desideratum in our lite- rature. Heretofore the student of pathology was obliged to glean from a great number of monographs, and the field was so extensive that but few cultivated it with any degree of success. As a simple work of reference, therefore, it is of great value to the student of pathological anatomy, and should be in every physician's library.— Western Lancet. Tn offering the above titled work to the public, the authors have not attempieil to intrude new views on their professional brethren, but simply to lay before them, what has long been wanted, an outline of the present condition of pathological anatomy. In this they have been completely successful. The work is one of the best compilations which we have ever perused.—Charleston Medical Journal and Review. We urge upon our readers and the profession gene- rally the importance of informing themselves in re- gard to modern views of pathology, and recommend to them to procure the work before us as the bes means of obtaining this information.—Stetkoscop e. From the casual examination we have given we are inclined to regard it as a text-book, plain, ra- tional, and intelligible, such a book as the practical man needs for daily reference. For this reason it will be likely to be larg-ely useful, as it suits itself to those busy men who have little time for minute investigation, and prefer a summary to an elaborate tieatise.—Buffalo Medical Journal. KIRKES (WILLIAM SENHOUSE), M.D., Demonstrator of Morbid Anatomy at St. Bartholomew's Hospital, &c. A MANUAL OF PHYSIOLOGY. A new American, from the third and improved London edition. With two hundred illustrations. In one large and handsome royal 12mo. volume, leather, pp. 58G. $2 00. (Now Ready, 1857.) In again passing this work through his hands, the author has endeavored to render it a correct exposition of the present condition of the science, making such alterations and additions as have been dictated by further experience, or as the progress of investigation lias rendered desirable. In every point of mechanical execution the publishers have sought to make it superior to former edi- tions, and at the very low price at which it is offered, it will be found one of the handsomest and cheapest volumes before the profession. In making these improvements, care has been exercised not unduly to inerease its size, thus maintaining its distinctive characteristic of presenting within a moderate compass a clear and con- nected view of its subjects, sufficient for the wants of the student. This is a new and very much improved edition of Dr. Kirkes' well-known Handbook of Physiology. Oi iginally constructed on the basis of the admirable treatise of Miller, it has in successive editions de- veloped itself into an almost original work, though no change has been made in the plan or arrangement. It combines conciseness with completeness, and is, therefore, admirably adapted for consultation by the busy practitioner.—Dublin Quarterly Journal, Feb. 1857. Its excellence is in its compactness, its clearness, and its carefully cited authorities. It is the most convenient of text-books. These gentlemen, Messrs Kirkes and Paget, have really an immense talent for silence, which is not so common or so cheap as prat- ing people fancy. They have the gift of telling us what we want to know, without thinking it neces- sary to tell us all they know.—Boston Med. and Surg. Journal, May 14, 1857. One of the very best handbooks of Physiology we possess—presenting just such an outline of the sci- ence, comprising an account of its leading facts and generally admitted principles, as the student requires during his attendance upon a course of lectures, or for reference whilst preparing for examination.— Am. Medical Journal. We need only say, that, without entering into dis- cussions of unsettled questions, it contains all the recent improvements in this department of medical science. For the student beginning this study, and the practitioner who has but leisure to refresh his memory, this book is invaluable, as it contains all that it is important to know, without special details, which are read with interest only by those who would make a specialty, or desire to possess a criti- cal knowledge of the subject.—Charleston Medical Journal. KNAPP'S TECHNOLOGY ; or, Chemistry applied to the Arts and to Manufactures. Edited, with numerous Notes and Additions, by Dr. Edmund Ronalds and Dr. Thomas Richardson. First American edition, with Notes and Additions, by Prof. Walter R. Johnson. In two handsome octavo volumes, extra cloth, with aboutSOO wood- engravings. $6 00. LALLEMAND ON SPERMATORRHOEA. Trans- lated and edited by Henry J. McDougal. In one volume, octavo, extra cloth, 320 pages. Second American edition. $1 75. LUDLOW (J. L.), M. D. A MANUAL OF EXAMINATIONS upon Anatomy, Physiology, Surgery, Practice of Medicine, Obstetrics, Materia Medica, Chemistry, Pharmacy, and Therapeutics. To which is added a Medical Formulary. Designed for Students of Medicine throughout the United States. Third edition, thoroughly revised and greatly extended and enlarged. With three hundred and seventy illustrations. In one large and handsome royal 12mo. volume, leather, of over 800 closely printed pages (Now Ready.) $2 50. The s;reat popularity of this volume, and Ihe numerous demands for it during the two years in which it has been out of print, have induced the author in its revision to spare no pains to render it a correct and accurate digest of the most recent condition of all ihe branches of medical science. In many respects it may, therefore, be regarded rather as a new book than a new edition, an entire section on Physiology having been added, as also one on Organic Chemistry, and many portions having been rewritten. A very complete series of illustrations has been introduced, and every care has been taken in the mechanical execution to render it a convenient and satisfactory book for study or reference. The arrangement of the volume in the form of question and answer renders it especially suited for the office examination of students and for those preparing for graduation. We know «f no better companion for the student I crammed into his head by the various professors to during the hours spent in the lecture room, or to re- whom he is compelled to listen.— Western Lancet, fresh, at a glance, his memory of the various topics Mav. 1857. AND SCIENTIFIC PUBLICATIONS. 19 LEHMANN (C. G.) PHYSIOLOGICAL CHEMISTRY. Translated from the second edition hy George E. Day, M. D., F. R. S., Arc, edited by R. E. Rogers, M. D., Professor of Chemistry in the Medical Department of the University of Pennsylvania, with illustrations selected from Funke's Atlas of Physiological Chemistry, and an Appendix of plates. Complete in two large and handsome octavo volumes, extra cloth, containing 1200pages, with nearly two hundred illus- trations. (Just Issued.) $6 00. This great work, universally acknowledged as the most complete and authoritative exposition of the principles and details of Zoochemistry, in its passage through the press, has received from Professor Rogers such care as was necessary to present it in a correct and reliable form. To such a work additions were deemed superfluous, but several years having elapsed between the appear- ance in Germany of the first and last volume, the latter contained a supplement, embodying nume- rous corrections and additions resulting from the advance of the science. These have all been incor- porated in the text in their appropriate places, while the subjects have been still furtner elucidated by the insertion of illustrations from the Atlas of Dr. OttoFunke. With the view of supplying the student with the means of convenient comparison, a large number of wood-cuts, from works on kindred subjects, have also been added in the form of an Appendix of Plates. The work is. therefore, pre- sented as in every way worthy the attention of all who desire to be familiar with the modern facts and doctrines of Physiological Science. The most important contribution as yet made to Physiological Chemistry.—Am. Journal Med. Sci- ences, Jan. 1856. The present volumes belong to the small class of medical literature which comprises elaborate works of the highest order of merit.—Montreal Med. Chron- icle, Jan. 1856. The work of Lehmann stands unrivalled as the most comprehensive book of reference and informa- tion extant on every branch of the subject on which it treats.—Edinburgh Monthly Journal of Medical Science. Already well known and appreciated by the scien- tific world, Professor Lehmann's great work re- quires no laudatory sentences, as, under a new garb, it is now presented to us. The little space at our command would ill suffice to set forth even a small portion of its excellences.—Boston Med. and Surg. Journal, Dec. 1855. by the same author. (Just Issued, 1856.) MANUAL OF CHEMICAL PHYSIOLOGY. Translated from the German, with Notes and Additions, by J. Cheston Morris, M. D., with an Introductory Essay on Vital Force, by Samuel Jackson, M. D., Professor of the Institutes of Medicine in the University of Pennsylvania. With illustrations on wood. In one very handsome octavo volume, extra cloth, of 336 pages. $2 25. From Prof. Jackson's Introductory Essay. In adopting the handbook of Dr. Lehmann as a manual of Organic Chemistry for the use of the students of the University, and in recommending his original work of Physiological Chemistry for their more mature studies, the high value of his researches, and the great weight of his autho- rity in that important department of medical science are fully recognized. The present volume will be a very convenient one I densed form, the positive facts of Physiological for students, as offering a brief epitome of the more Chemistry.—Am. Journal Med. Sciences, April, 1856. elaborate work, and as containing, in a very con- | LAWRENCE (W.), F. R. S., &.C. A TREATISE ON DISEASES OF THE EYE. A new edition, edited, with numerous additions, and 243 illustrations, by Isaac Hays, M. D., Surgeon to Will's Hospi- tal, &c. In one very large and handsome octavo volume, of 950 pages, strongly bound in leather with raised bands. $5 00. This work is so universally recognized as the standard authority on the subject, that the pub- lishers in presenting this new edition have only to remark that in its preparation the editor has carefully revised every portion, introducing additions and illustrations wherever the advance of science has rendered them necessary or desirable, constituting it a complete and thorough exponent of the most advanced state of the subject. This admirable treatise—the safest guide and most comprehensive work of reference, which is within the reach of the profession.—Stethoscope. This standard text-book on the department of which it treats, has not been superseded, by any or all of the numerous publications on the subject heretofore issued. Nor with the multiplied improve- ments of Dr. Hays, the American editor, is it at all likely that this great work will cease to merit the confidence and preference of students or practition- ers. Its ample extent—nearly onq| thousand large octavo pages—has enabled both author and editor to do justice to all the details of this subject, and con- dense in this single volume the present state of our knowledge of the whole science in this department, whereby its practical value cannot be excelled. We heartily commend it, especially as a book of refer- ence, indispensable in every medical library. The additions of the American editor very greatly en- hance the value of the work, exhibiting the learning and experience of Dr. Hays, in the light in which he ought to be held, as a standard authority on all sub- jects appertaining to this specialty.—N.Y. Med. Gaz. LARDNER (DIONYSIUS), D. C. L., &c. HANDBOOKS OF NATURAL PHILOSOPHY AND ASTRONOMY. Revised, with numerous Additions, by the American editor. First Course, containing Mecha- nics, Hydrostatics, Hydraulics, Pneumatics, Sound, and Optics. In one large royal 12mo. volume, of 750 pages, with 424 wood-cuts. $1 75. Second Course, containing Heat, Electricity, Magnetism, and Galvanism, one volume, large royal 12mo., of 450 pages, with 250 illustrations. $1 25. Third Course f now ready), containing Meteorology and Astronomy, in one large volume, royal 12mo. of nearly 800 pages, with 37 plates and 200 wood-cuts. $2 00. 20 BLANCHARD & LEA'S MEDICAL LA ROCHE (R.), M. D., &c. YELLOW FEVER, considered in its Historical, Pathological, Etiological, and Therapeutical Relations. Including a Sketch of the Disease as it has occurred in Philadelphia from 1699 to 1854, with an examination of the connections between it and the fevers known under the same name in other parts of temperate as well as in tropical regions In iwo large and handsome octavo volumes of nearly 1500 pages, extra cloth. (Just Issued.) $7 00. arduous research and careful study, and the result is such as will reflect the highest honor upon the author and our country.—Southern Med. and Surg. Journal. From Professor S. H. Dickson, Charleston, S. C, September 18, 1855. A monument of intelligent and well applied re- search, almost without example. It is, indeed, in itself, a large library, and is destined to constitute the special resort as a book of reference, in the subject of which it treats, to all future time. We have not time at present, engaged as we are, by da,y and by night, in the work of combating this very disease, now prevailing in out city, to do more than give this cursory notice of what we consider as undoubtedly the most able and erudite medical publication our country has yet produced But in view of the startlin? fact, that this, the most malig- nant and unmanageable disease of modern times, has for several years been prevailing in our country to a greater extent than ever before; that it is no longer confined to either large or small cities, but penetrates country villages, plantations, and farm- houses; that it is treated with scarcely better suc- cess now than thirty or forty years ago; that there is vast mischief done by ignorant pretenders to know- ledge in regard to the disease, and in view of the pro- bability that a majority of southern physicians will be called upon to treat the disease, we trust that this able and comprehensive treatise will be very gene- rally read in the south.—Memphis Med. Recorder. This is decidedly the great American medical work of the day—a full, complete, and systematic treatise, unequalled by any other upon the all-important sub- ject of Yellow Fever. The laborious, indefatigable, and learned author has devoted to it many years of The genius and scholarship of this great physician could not have been better employed than in the erection of this towering monument to his own fame, and to the glory of the medical literature of his own country. It is destined to remain the great autho- rity upon the subject of Yellow Fever. The student and physician will find in these volumes a rtsumi. of the sum total of the knowledge of the world upon the awful scourge which they so elaborately discuss. The style is so soft and so pure as to refresh and in- vigorate the mind while absorbing the thoughts of the gifted author, while the publishers have suc- ceeded in bringing the externals into a most felicitous harmony with the inspiration that dwells within. Take it all in all, it is a book we have often dreamed of, but dreamed not that it would ever meet our waking eye as a tangible reality.—Nashville Journal of Medicine. We deem it fortunate that the splendid work of Dr. La Roche should have been issued from the press at this particular time. The want of a reliable di- gest of all that is known in relation to this frightful malady has long been felt—a want very satisfactorily met in the work before us. We deem it but faint praise to say that Dr. La Roche has succeeded in presenting the profession with an able and complete monograph, one which will find its way into every well ordered library.— Va. Stethoscope. BY THE SAME AUTHOR. PNEUMONIA; its Supposed Connection, Pathological and Etiological, with Au- tumnal Fevers, including an Inquiry into the Existence and Morbid Agency of Malaria. In one handsome octavo volume, extra cloth, of 500 pages. $3 00. A more simple, clear, and forcible exposition of Thiswork should becarefully studied by Southern the groundless nature and dangerous tendency of physicians, embodying as it does the reflections of certain pathological and etiological heresies, has an original thinker and close observer on a subject seldom been presented to our notice.—N. Y. Journal peculiarly their own.— Virginia Med. and Surgical of Medicine and Collateral Science. Journal. LAYCOCK (THOMAS), M. D., F. R. S. E., Professor of Practical and Clinical Medicine in the University of Edinburgh, &c. LECTURES ON THE PRINCIPLES AND METHODS OF MEDICAL OBSERVATION AND RESEARCH. For the Use of Advanced Students and Junior Prac- titioners. In one very neat royal 12mo. volume, extra cloth. Price $1 00. (Just Published, 18570 A review of the book cannot now be attempted ; I cuniarily) successful practice who would be very and our desire is simply to recommend it to all—not | much benefited by a close study of its precepts and merely the class for which it was designed; since principles.—Va. Med. Journal, March, 1857. there are many senior practitioners in full and (pe- ] MULLER'S PRINCIPLES OF PHYSICS AND METEOROLOGY. Edited, with Additions, by R. Eglesfeld Griffith, M. D. In one larse and handsome octavo volume, extra cloth, with 550 wood-cuts, and two colored plates, pp. 636. $3 50. MILLER (HENRY), M. D., Professor of Obstetrics and Diseases of Women and Children in the University of Louisville. PRINCIPLES AND PRACTICE OF OBSTETRICS, &c.; including the Treat- ment of Chronic Inflammation of the Cervix and Body of the Uterus considered as a frequent cause of Abortion. With about one hundred illustrations on wood. In one very handsome oc- tavo volume, of over 600 pages. (Now Ready.) $3 75. The reputation of Dr. Miller as an obstetrician is too widely spread to require the attention of the profession to be specially called to a volume containing the experience of his long and extensive practice. The very favorable reception accorded to his " Treatis^ on Human Parturition," issued some years since, is an earnest that the present work will fulfil the author's intention of providing within a moderate compass a complete and trustworthy text-book for the student, and book of re- ference for the practitioner. Based to a certain extent upon the former work, but enlarged to more than double its size, and almost wholly rewritten, it presents, besides the matured experience of the author, the most recent views and investigations of modern obstetric writers, such as Dubois, Cazeaux, Simpson, Tyler Smith, &c, thus embodying the results not only of the American, but also of the Paris, the London, and the Edinburgh obsteti ic schools. The author's position for so many years as a teacher of his favorite branch, has given him a familiarity with the -wants of stu- dents and a facility of conveying instruction, which canuot fail to render the volume eminently adapted to its purposes. AND SCIENTIFIC PUBLICATIONS. 21 MEIGS (CHARLES D.), M.D., Professor of Obstetrics, &c. in the Jefferson Medical College, Philadelphia. OBSTETRICS: THE SCIENCE AND THE ART. Third edition, revised and improved. With one hundred and twenty-nine illustrations. In one beautifully printed octavo volume, leather, of seven hundred and fifty-two large pages. $3 75. The rapid demand for another edition of this work is a sufficient expression of the favorable verdict of the profession. In thus preparing it a third time for the press, the author has endeavored to render it in every respect worthy of the favor which it has received. To accomplish this he has thoroughly revised it in every part. Some portions have been rewritten others added, new illustrations have been in many instances substituted for such as were not deemed satisfactory, while, by an alteration in the typographical arrangement, the size of the work has not been increased, and the price remains unaltered. In its present improved form, it is, therefore, hoped that the work will conlinue to meet the wants of the American profession as a sound, practical, and extended System of Midwifery. Though the work has received only five pages of | The best American work on Midwifery that is enlargement, its chapters throughout wear the im- accessible to the student and practitioner—N. W. press of careful revision. Expunging and rewriting, j Med. and Surg. Journal, Jan. Ir57. remodelling its sentences, with occasional new ma- | This is a stiindard work by a srreat American Ob- tenal, all evince a lively desire that it shall deserve ' stetrici:in. It is the third and "last edition, and, in to be regarded as improved in manner as well as the lar ua e of the prefaCP tne author has "brought matter. In the matter, every stroke of the pen has , the subject up to the latest dates of real improve- in creased the value of the book, both in expungings : ment in ()ur art and Science."—Nashville Journ. of and additions —II estern Lancet, Jan. 1S5,. | md, and Surg-] MaV) lfe57 BY THE same author. (Lately Issued.) WOMAN: HER DISEASES AND THEIR REMEDIES. A Series of Lec- tures to his Class. Third and Improved edition. In one large and beautifully printed octavo volume, leather. pp. 672. $3 60. The gratifying appreciation of his labors, as evinced by the exhaustion of two large impressions of this work within a few years, has not been lost upon the author, who has endeavored in every way to render it worthy of the favor with which it has been received. The opportunity thus afforded for a second revision has been improved, and the work is now presented as in every way superior to its predecessors, additions and alterations having been made whenever the advance of science has rendered them desirable. The typographical execution of the work will also be found to have undergone a similar improvement, and the work is now confidently presented as in every way worthy the position it has acquired as the standard American text-book on the Diseases of Females. It contains a vast amount of practical knowledge, by one who has accurately observed and retained the experience of many years, and who tells the re- sult in a free, familiar, and pleasant manner.—Dub- lin Quarterly Journal. There is an off-hand fervor, a glow, and a warm- heartedness infecting the effort of Dr. Meigs, which is entirely captivating, and which absolutely hur- ries the reader through from beginning to end. Be- sides, the book teems with solid instruction, and it shows the very highest evidence of ability, viz., the clearness with which the information is pre- sented. We know of no better test of one's under- standing a subject than the evidence of the power of lucidly explaining it. The most elementary, as well as the obscurest subjects, under the pencil of such bold relief, as to produce distinct impressions upon the mind and memory of the reader. — Tht Charleston Med. Journal. Professor Meigs has enlarged and amended this great work, for such it unquestionably is, having passed the ordeal of criticism at home and abroad, but been improved thereby ; for in this new edition the author has introduced real improvements, and increased the value and utility of the book im- measurably. It presents so many novel, bright, and sparkling thoughts; such an exuberance of new ideas on almost every page, that we confess our- selves to have become enamored with the book and its author; and cannot withhold our congratu- lations from our Philadelphia confreres, that such a teacher is in their service.—N. Y. Med. Gazette. Prof. Meigs, are isolated and made to stand out in by the same author. (Lately Published.) ON THE NATURE, SIGNS, AND TREATMENT OF CHILDBED FEVER. In a Series of Letters addressed to the Students of his Class. *In one handsome octavo volume, extra cloth, of 365 pages. $2 50. This book will add more to his fame than either of those -which bear his name. Indeed we doubt The instructive and interesting author of this work, whose previous labors in the department of medicine which he so sedulously cultivates, have placed his countrymen under deep and abiding obli- gations, again challenges their admiration in the fresh and vigorous, attractive and racy pages before us. It is a delectable book. * * * This treatise upon child-bed fevers will have an extensive sale, being destined, as it deserves, to find a place in the library of every practitioner who scorns to lag in the rear.—Nashville Journal of Medicine and Surgery. BY THE SAME AUTHOR ; WITH COLORED PLATES. A TREATISE ON ACUTE AND CHRONIC DISEASES OF THE NECK OF THE UTERUS. With numerous plates, drawn and colored from nature in the highest style of art. In one handsome octavo volume, extra cloth. $4 50. whether any material improvement will be made on the teachings of this volume for a century to come, since it is so eminently practical, and based on pro- found knowledge of the science and consummate skill in the art of healing, and ratified by an ample and extensive experience, such as few men have the industry or good fortune to acquire.—N. Y. Med. Gazette. MAYNE'S DISPENSATORY AND THERA- PEUTICAL REMEMBRANCER. Comprising the entire lists of Materia Medica, with every Practical Formula contained in the three British Pharmacopoeias. Edited, with the addition of the Formulae of the U. S. Pharmacopoeia, by R. E. Griffith, M.D. 112mo. vol. ex. cl.,300pp. 75 c. MALGAIGNE'S OPERATIVE SURGERY, based on Normal and Pathological Anatomy. Trans- lated from the French by Frederick Brittan, A. B.,M.D. With numerous illustrations on wood In one handsome octavo volume, extra cloth, of nearly six hundred pages. $2 25. 22 BLANCHARD & LEA'S MEDICAL MACLISE (JOSEPH), SURGEON. SURGICAL ANATOMY. Forming one volume, very large imperial quarto. With sixty-eight large and splendid Plates, drawn in the best style and beautifully colored. Con- taining one hundred and ninety Figures, many of them the size of life. Together with copious and explanatory letter-press. Strongly and handsomely bound in extra cloth, being one of the cheapest and best executed Surgical works as yet issued in this country. $11 00. %* The size of this work prevents its transmission through the post-office as a whole, but those who desire to have copies forwarded by mail, can receive them in five parts, done up in stout wrappers. Price $9 00. One of the greatest artistic triumphs of the age in Surgical Anatomy.—British American Medical Journal. . Too much cannot be said in its praise ; indeed, we have not langange to do it justice.—Ohio Medi- cal and Surgical Journal. The most admirable surgical atlas we have seen. To the practitioner deprived of demonstrative dis- sections upon the human subject, it is an invaluable companion.—N. J. Medical Reporter. The most accurately engraved and beautifully colored plates we have ever seen in an American book—one of the best and cheapest surgical works ever published.—Buffalo Medical Journal. It is very rare that so elegantly printed, so-well illustrated, and so useful a -work, is offered at so moderate a price.—Charleston Medical Journal. Its plates can boast a superiority which places them almost beyond the reach of competition.—Medi- cal Examiner. Every practitioner, we think, should have a work of this kind -within reach.—Southern Medical and Surgical Journal. No such lithographic illustrations of surgical re- gions have hitherto, we think, been given.—Boston Medical and Surgical Journal. As a surgical anatomist, Mr. Maclise has proba- bly no superior.—British and Foreign Medico-Chi- rurgical Review. Of great value to the student engaged in dissect- ing, and to the surgeon at a distance from the means of keeping up his anatomical knowledge.—Medical Times. The mechanical execution cannot be excelled.— Transylvania Medical Journal. A work which has no parallel in point of accu- racy and cheapness in the English language.—iV. Y. Journal of Medicine. To all engaged in the study or practice of their profession, such a work is almost indispensable.— Dublin Quarterly Medical Journal. No practitioner whose means will admit should fail to possess it.—Ranking's Abstract. Country practitioners -will find these plates of im- mense value.—N. Y. Medical Gazette. We are extremely gratified to announce to the profession the completion of this truly magnificent work, which, as a whole, certainly stands unri- valled, both for accuracy of drawing, beauty of coloring, and all the requisite explanations of the subject in hand.—The New Orleans Medical and Surgical Journal. This is by far the ablest work on Surgical Ana- tomy that has come under our observation. We know of no other work that would justify a stu- dent, in any degree, for neglect of actual dissec- tion. In those sudden emergencies that so often arise, and which require the instantaneous command of minute anatomical knowledge, a work of this kind keeps the details of the dissecting-room perpetually fresh in the memory.—The Western Journal of Medi- cine and Surgery. B®*" The very low price at which this work is furnished, and the beauty of its execution, require an extended sale to compensate the publishers for the heavy expenses incurred. MOHR (FRANCIS), PH. D., AND REDWOOD (TH EOPH I LUS). PRACTICAL PHARMACY. Comprising the Arrangements, Apparatus, and Manipulations of the Pharmaceutical Shop and Laboratory. Edited, with extensive Additions, by Prof. William Procter, of the Philadelphia College of Pharmacy. In one handsomely printed octavo volume, extra cloth, of 570 pages, with over 500 engravings on wood. $2 75. MACKENZIE (W.), M.D., Surgeon Oculist in Scotland in ordinary to Her Majesty, &c. &c. A PRACTICAL TREATISE ON DISEASES AND INJURIES OF THE EYE. To which is prefixed an Anatomical Introduction explanatory of a Horizontal Section of the Human Eyeball, by Thomas Wharton Jones, F. R. S. From the Fourth Revised and En- larged London Edition. With Notes and Additions by Addinell Hewson, M. D., Surgeon to Wills Hospital, &c. &c. In one very large and handsome octavo volume, leather, raised bands, with plates and numerous wood-cuts. $5 25. The treatise of Dr. Mackenzie indisputably holds the first place, and forms, in respect of learning and research, an Encyclopaedia unequalled in extent by any other work of the kind, either English or foreign. —Dixon on Diseases of the Eye. Few modern books on any department of medicine or surgery have met with such extended circulation, or have procured for their authors a like amount of European celebrity. The immense research which it displayed, the thorough acquaintance with the subject, practically as well as theoretically,and the able manner in which the author's stores of learning and experience were rendered available for general use, at once procured for the first edition, as well on the continent as in this country, that high position as a standard work which each successive edition has more firmly established, in spite of the attrac- tions of several rivals of no mean ability. This, the fourth edition, has been in a great measure re-writ- ten ; new matter, to the extent of one hundred and fifty pages, has been added, and in several instances formerly expressed opinions have been modified in —Dublin Quarterly Journal accordance with the advances in the science which have been made of late^ years. Nothing worthy of repetition upon any branch of the subject appears to have escaped the author's notice. We consider it the duty of every one who has the love of his profes- sion and the welfare of his patient at heart, to make himself familiar with this the most complete work in the English language upon the diseases of the eye. —Med. Times and Gazette. The fourth edition of this standard work will no doubt be as fully appreciated as the three former edi- tions. It is unnecessary to say a word in its praise, for the verdict has already been passed upon it by the most competent judges, and " Mackenzie on the Eye" has justly obtained a reputation which it is no figure of speech to call world-wide.—British and Foreign Medico-Chirurgical Review. This new edition of Dr. Mackenzie's celebrated treatise on diseases of the eye, is truly a miracle of industry and learning. We need scarcely say that he has entirely exhausted the subject of his specialty. AND SCIENTIFIC PUBLICATIONS. 23 MILLER (JAMES), F. R. S. E., Professor of Surgery in the University of Edinburgh, &c. PRINCIPLES OF SURGERY. Fourth American, from the third and revised Edinburgh edition. In one large and very beautiful volume, leather, of 700 pages, with two hundred and forty exquisite illustrations on wood. (Just Issued, 18-56.) $3 75. The extended reputation enjoyed by this work will be fully maintained by the present edition. Thoroughly revised bv the author, it will be found a clear and compendious exposition of surgical science in its most advanced condition. In connection with the recently issued third edition of the author's " Practice of Surgery," it forms a very complete system of Surgery in all its branches. putation, or seeks the interests of his clients, can acquit himself before his God and the world without making himself familiar with the sound and philo- sophical views developed in the foregoing book.— New Orleans Med. and Surg. Journal. Without doubt the ablest exposition of the prin- ciples of that branch of the healing art in any lan- guage. This opinion, deliberately formed after a careful study of the first edition, we have had no cause to change on examining the second. This edition has undergone thorough revision by the au- thor; many expressions have been modified, and a mass of new matter introduced. The book is got up in the finest style, and is an evidence of the progress of typography in our country.—Charleston Medical Journal and Review. The work of Mr. Miller is too well and too favor- ably known among us, as one of our best text-books, to render any further notice of it necessary than the announcement of a new edition, the fourth in our country, a proof of its extensive circulation among us. As a concise and reliable exposition of the sci- ence of modern surgery, it stands deservedly hisrh— we know not its superior.—Boston Med. and Surg. Journal. It presents the most satisfactory exposition of the modern doctrines of the principles of surgery to be found in any volume in any language.—N. Y. Journal oj Medicine. The work takes rank with Watson's Practice of Physic; it certainly does not fall behind that great work in soundness of principle or depth of reason- ing and research. No physician who values his re- bt the same author. (Now Ready.) THE PRACTICE OF SURGERY. Fourth American from the last Edin- burgh edition. Revised by the American editor. Illustrated by three hundred and sixty-four engravings on wood. In one large octavo volume, leather, of nearly 700 pages. $3 75. his works, both on the principles and practice of surgery have been assigned the highest rank. If we were limited to but one work on surgery, that one should be Miller's, as we regard it as superior to all No encomium of ours could add to the popularity of Miller's Surgery. Its reputation in this country is unsurpassed by that of any other work, and, when taken in connection with the author's Principles of Surgery, constitutes a whole, without reference to which no conscientious surgeon would be willing to practice his art. The additions, by Dr. Sargent, have materially enhanced the value of the work.— Southern Medical and Surgical Journal. It is seldom that two volumes have ever made so profound an impression in so short a time as the "Principles" and the "Practice" of Surgery by Mr. Miller—or so richly merited the reputation they have acquired. The author is an eminently sensi- ble, practical, and -well-informed man, who knows exactly what he is talking about and exactly how to talk it.—Kentucky Medical Recorder. By the almost unanimous voice of the profession, others.—St. Louis Med. and Surg. Journal. The author, distinguished alike as a practitioner and writer, has in this and his " Principles," pre- sented to the profession one of the most complete and reliable systems of Surgery extant. His style of writing is original, impressive, and engaging, ener- getic, concise, and lucid. Few have the faculty of condensing so much in small space, and at the same time so persistently holding the attention; indeed, he appears to make the very process of condensation a means of eliminating attractions. Whether as a text-book for students or a book of reference for practitioners, it cannot be too strongly recommend- ed.—Southern Journal of Med. and Phys. Sciences. MONTGOMERY (W*. F.), M. D., M. R. I. A., &.c, Professor of Midwifery in the King and Queen's College of Physicians in Ireland, &c. AN EXPOSITION OF THE SIGNS AND SYMPTOMS OF PREGNANCY. With some other Papers on Subjects connected with Midwifery. From the second and enlarged Eno-lish edition. Wilh two exquisite colored plates, and numerous wood-cuts. In one very handsome octavo volume, extra cloth, of nearly 600 pages. (Now Ready, 1857.) $3 75. The present edition of this classical volume is fairly entitled to be regarded as anew work, every sentence having been carefully rewritten, and the whole increased to more than double the original size. The title of the work scarcely does justice to the extent and importance of the topics brought under consideration, embracing, with the exception of the operative procedures of mid- wifery almost everything connected with obstelries, either directly or incidentally ; and there are few physicians who will not find in its pages much that will prove of great interest and value in their daily practice. The special Essays on the Period of Human Gestation, the Signs of Delivery, and the Spontaneous Amputation and other Lesions of the Foetus in Utero present topics of the highest interest fully treated and beautifully illustrated. Iu every point of mechanical execution the work will be found one of the handsomest yet issued from the American pre^s. A book unusually rich in practical suggestions.— Am Journal Med.'Sciences, Jan. 1857. These several subjects so interesting in them- selves, and so important, every one of them, to the most delicate and precious of social relations, con- trolling often the honor and domestic peace of a family, the legitimacy of offspring, or the life of its parent, are all treated with an elegance of diction, lulness of illustrations, acutenessand justice of rea- soning, unparalleled in obstetrics, and unsurpassed in medicine. The reader's interest can never flag, so fresh, and vigorous, and classical is our author's st\le'; and one forgets, in the renewed charm of every'page, that it,'and every line, and every word has been weighed and reweighed through years of preparation; that this is of all others the book of Obstetric Law, on each of its several topics ; on all points connected with pregnancy, to be everywhere received as a manual of special jurisprudence, at once announcing fact, affording argument, establish- ing precedent, and governing alike the juryman, ad- vocate, ami judge. It is not merely in its legal re- lations that we find this work so interesting. Hardly a page but that has its hints or facts important to the general practitioner; and not a chapter without especial matter for the anatomist, physiologist, or pathologist.—N. A- Mcd.-Chir. Review, March, lt-57. 24 BLANCHARD & LEA'S MEDICAL NEILL (JOHN), M. D., Surgeon to the Pennsylvania Hospital, &c.; and FRANCIS GURNEY SMITH, M. D., Professor of Institutes of Medicine in the Pennsylvania Medical College. AN ANALYTICAL COMPENDIUM OF THE VARIOUS BRANCHES OF MEDICAL SCIENCE ; for the Use and Examination of Students. A new edition, revised and improved. In one very large and handsomely printed royal 12mo. volume, of about one thousand pages, with 374 wood-cuts. Strongly bound in leather, with raised bands. $3 00. The very flattering reception which has been accorded to this work, and the high estimate placed upon it by the profession, as evinced by the constant and increasing demand which has rapidly ex- hausted two large editions, have stimulated the authors to render the volume in its present revision more worthy of the success which has attended it. It has accordingly been thoroughly examined, and such errors as had on former occasions escaped observation have been corrected, and whatever additions were necessary to maintain it on a level with the advance of science have been introduced. The extended series of illustrations has been still further increased and much improved, while, by a slight enlargement of the page, these various additions have been incorporated without increasing the bulk of the volume. The work is, therefore, again presented as eminently worthy of the favor with which it has hitherto been received. As a book for daily reference by the student requiring a guide to his more elaborate text-books, as a manual for preceptors desiring to stimulate their students by frequent and accurate examination, or as a source from which the practitioners of older date may easily and cheaply acquire a knowledge of the changes and improvement in professional science, its reputation is permanently established. The best work of the kind with which we are acquainted.—Med. Examiner. Having made free use of this volume in our ex- aminations of pupils, we can speak from experi- ence in recommending it as an admirable compend for students, and as especially useful to preceptors who examine their pupils. It will save the teacher much labor by enabling him readily to recall all of the points upon which his pupils should be ex- amined. A work of this sort should be in the hands of every one who takes pupils into his office with a view of examining them; and this is unquestionably the best of its class.—Transylvania Med. Journal. In the rapid course of lectures, where work for the students is heavy, and review necessary for a« examination, a compend is not only valuable, but it is almost a sine qua non. The one before us is, in most of the divisions, the most unexceptionable of all books of the kind that we know of. The newest and soundest doctrines and the latest im- provements and discoveries are explicitly, though concisely, laid before the student. There is a class to whom we very sincerely commend this cheap book as worth its weight in silver—that class is the gradu- ates in medicine of more than ten years' standing, who have not studied medicine since. They wiil perhaps find out from it that the science is not exactly now what it was when they left it off.—The Stetho- scope. NEILL (JOHN), M. D., Professor of Surgery in the Pennsylvania Medical College, &c. OUTLINES OF THE VEINS AND LYMPHATICS. With handsome colored plates. 1 vol., cloth. $1 25. OUTLINES OF THE NERVES. With handsome plates. 1 vol., cloth. $1 25. NELIGAN (J. MOORE), M. D., M. R. I.A., &c. (A splendid work. Just Issued.) ATLAS OF CUTANEOUS DISEASES. In one beautiful quarto volume, extra cloth, with splendid colored plates, presenting nearly one hundred elaborate representations of disease. $4 50. This beautiful volume is intended as a complete and accurate representation of all the varieties of Diseases of the Skin. While it can be consulted in conjunction with any work.on Practice, it has especial reference to the author's " Treatise on Diseases of the Skin," so favorably received by the profession some years since. The publishers feel justified in saying that few more beautifully exe- cuted plates have ever been presented to the profession of this country. The diagnosis of eruptive disease, however, under all circumstances, is very difficult. Nevertheless Dr. Neligan has certainly, "as far as possible," given a faithful and accurate representation of this class of diseases, and there can be no doubt that these plates will be of great use to the student and practitioner in drawing a diagnosis as to the class, order, and species to which the particular case may belong. While looking over the " Atlas" we have been induced to examine also the " Practical Trea- tise," and we are inclined to consider it a very su- perior work, combining accurate verbal description, with sound views of the pathology and treatment of eruptive diseases.—Glasgow Med. Journal. placed within its reach and at a moderate cost a most accurate and well delineated series of plates illus- trating the eruptive disorders. These plates are all drawn from the life, and in many of them the daguer- reotype has been employed with great, success. Such works as these are especially useful to country prac- titioners, who have not an opportunity of seeing the rarer forms of cutaneous disease, and hence need the aid of illustrations to give them the requisite infor- mation on the subject. With these plates at hand, the inexperienced practitioner is enabled to discri- minate with much accuracy, and he is thus, com- paratively speaking, pat on an equal footing with those who have had the opportunity of visiting the large hospitals of Europe and America.—Va. Med. Journal, June, 1856. The profession owes its thanks to the publishers of Neligan's Atlas of Cutaneous Diseases, for they have BY THE SAME AUTHOR. A PRACTICAL TREATISE ON DISEASES OF THE SKIN. Second American edition. In one neat royal 12mo. volume, extra cloth, of 334 pages. $1 00. The two volumes will be sent by mail on receipt of Five Dollars. OWEN ON THE DIFFERENT FORMS OF I THE SKELETON, AND OF THE TEETH. One vol. royal 12mo., extra cloth, with numerous illustrations. I Just Issued.) SI 25. AND SCIENTIFIC PUBLICATIONS. 25 (Now Complete.) PEREIRA (JONATHAN), M. D., F. R. S., AND L. S. THE ELEMENTS OF MATERIA MEDICA AND THERAPEUTICS. Third American edition, enlarged and improved by the author; including Notices of most of the Medicinal Substances in use in the civilized world, and forming an Encyclopfedia of Materia Medica. Edited, with Additions, by Joseph Carson, M. D., Professor of Materia Medica and Pharmacy in the University of Pennsylvania. In two very large octavo volumes of 2100 pages, on small type, with about 500 illustrations on stone and wood, strongly bound in leather, with raised bands. $9 00. Gentlemen who have the first volume are recommended to complete their copies without delay. The first volume will no longer be sold separate. Price of Vol. II. $5 00. When we remember that Philology, Natural His- tory, Botany, Chemistry, Physics, and the Micro- Bcope, are all brought forward to elucidate the sub- ject, one cannot fail to see that the reader has here a work worthy of the name of an encyclopaedia of Materia Medica. Our own opinion of its merits is that of its editors, and also that of the whole profes- sion, both of this and foreign countries—namely, " that in copiousness of details, in extent, variety, and accuracy of information, and in lucid explana- tion of difficult and recondite subjects, it surpasses all other works on Materia Medica hitherto pub- lished." We cannot close this notice without allud- ing to the special additions of the American editor, which pertain to the prominent vegetable produc- tions of this country, and to the directions of the United States Pharmacopoeia, in connection with all the articles contained in the volume which are re- ferred to by it. The illustrations have been increased, and this edition by Dr. Carson cannot well be re- garded in any other light than that of a treasure which should be found in the library of every physi- cian.—New York Journal of Medical and Collateral Science. The third edition of his "Elements of Materia Medica, although completed under the supervision of others, is by far the most elaborate treatise in the English language, and will, while medical literature is cherished, continue a monument alike honorable to his genius, as to his learning and industry.— American Journal of Pharmacy. The work, in its present shape, forms the most comprehensive and complete treatise on materia medica extant in the English langHage. — Dr. Pereira has been nt great pains to introduce into his work, not only all the information on the natural, chemical, and commercial history of medi- cines, which might be serviceable to the physician and surgeon, but whatever might enable his read- ers to understand thoroughly the mode of prepar- ing and manufacturing various articles employed either for preparing medicines, or for certain pur- poses in the arts connected with materia medica and the practice of medicine. The accounts of the physiological and therapeutic effects of remedies are given with great clearness and accuracy, and in a manner calculated to interest as well as instruct the reader.—Edinburgh Medical and Surgical Journal. PEASLEE (E. R.), M. D., Professor of Physiology and General Pathology in the New York Medical College. HUMAN HISTOLOGY, in its relations to Anatomy, Physiology, and Pathology; for the use of Medical Students. With four hundred and thirty-four illustrations. In one hand- some octavo volume, of over 600 pages. (Now Ready.) $3 75. The rapid advances made of late years in our knowledge of the structure and functions of the elements which constitute the human body, have rendered the subject of Histology of the highest importance to all who regard medicine as a science. At the same time, the vast body of" facts covered by Physiology has caused our text-books on that subject to be necessarily resiricted in their treatment"of the portions devoted to Histology. A want has, therefore, arisen of a work de- voted especially to the minute anatomy of the body, giving a complete and detailed account of the structure of the various tissues, as well as the solids and fluids, in all the different organs—their functions in health, and their changes in disease. In undertaking this task, the author has endea- vored to present his extensive subject in the manner most likely to interest and benefit the physician, confident that in these details will be found the basis of true medical science. The very large number of illuslrations introduced throughout, serves amply to elucidate the text, while the typo- graphy of the volume will in every respect be found of the handsomest description. PI RRIE (WILLIAM), F. R. S. E., Professor of Surgery in the University of Aberdeen. THE PRINCIPLES AND PRACTICE OF SURGERY. Edited by John Neill M. D., Professor of Surgery in the Penna. Medical College, Surgeon to the Pennsylvania Hospital, &c. In one very handsome octavo volume, leather, of 780 pages, with 316 illustrations. $3 75. arrived. Prof. Pirrie, in the work before us, has elaborately discussed the principles of surgery, and a safe and effectual practice predicated upon them. Perhaps no work upon this subject heretofore issued is so full upon the science of the art of surgery.— Nashville Journal of Medicine and Surgery. One of the best treatises on surgery in the English language.—Canada Med. Journal. Our impression is, that, as a manual for students, Pirrie's is the best work extant.—Western Med. and Surg. Journal. We know of no other surgical work of a reason- able size, wherein there is so much theory and prac- tice, or where subjects are more soundly or clearly taught.—The Stethoscope. There is scarcely a disease of the bones or soft parts fracture, or dislocation, that is not illustrated by accurate wood-engravings. Then, again, every instrument employed by the surgeon is thus repre- sented These engravings are not only correct, but really beautiful, showing the astonishing degree of perfection to which the art of wood-engraving has PARKER (LANGSTON), Surgeon to the Queen's Hospital, Birmingham. THE MODERN TREATMENT OF SYPHILITIC DISEASES, BOTH PRI- MARY AND SECONDARY; comprising the Treatment of Constitutional and Confirmed Syphi- lis bv a safe and successful method. With numerous Cases, Formulae, and Clinical Observa- tion1* From the Third and entirely rewritten London edition. In one neat octavo volume, extra cloth, of 316 pages. $1 75. 26 BLANCHARD & LEA'S MEDICAL PARRISH (EDWARD), Lecturer on Practical Pharmacy and Materia Medica in the Pennsylvania Academy of Medicine, &c. AN INTRODUCTION TO PRACTICAL PHARMACY. Designed as a Text- Book for the Student, and as a Guide for the Physician and Pharmaceutist. With many For- mulae and Prescriptions. In one handsome octavo volume, extra cloth, of 550 pages, with 243 Illustrations. $2 75. A careful examination of this work enables us to speak of it in the highest terms, as being the best tre>itise on practical pharmacy with which we are acquainted, and an invaluable vade-mecum, not only to the apothecary and to those practitioners who are accustomed to prepare their own medicines, but to every medical man and medical student. Through- out the work are interspersed valuable tables, useful formula?, and practical hints, and the whole is illus- trated by a large number of excellent wood-engrav- ings.—Boston Med. and Surg. Journal. This is altogether one of the most useful books we have seen. It is just what we have long felt to be needed by apothecaries, students, and practitioners of medicine, most of whom in this country have to put up their own prescriptions. It bears, upon every page, the impress of practical knowledge, conveyed in a plain common sense manner, and adapted to the comprehension of all who may read it. No detail has been omitted, however trivial it may seem, al- though really important to the dispenser of medicine. —Southern Med. and Surg. Journal. To both the country practitioner and the city apo- thecary this work of Mr. Parrish is a godsend. A careful study of its contents will give the young graduate a familiarity with the value and mode of administering his presci iptions, which will be of as much use to his patient as to himself.— Va. Med. Journal. Mr. Parrish has rendered a very acceptable service to the practitioner and student, by furnishing this book, which contains the leading facts and principles of the science of Pharmacy, conveniently arranged for study, and with special reference to those features of the subject which possess an especial practical in- terest to the physician It furnishes the student, at the commencement of his studies, with that infor- mation which is of the greatest importance in ini- tiating him into thedomain of Chemistry and Materia Medica; it familiarizes him with the compounding of drugs, and supplies those minutiae which hut few practitioners can impart. The junior practitioner will, also, find this volume replete with instruction. —Charleston Med. Journal and Review, Mar. 1850. There is no useful information in the details of the apothecary's or country physician's office conducted according lo science that is omitted. The young physician will find it an encyclopedia of indispensa- ble medical knowledge, from the purchase of a spa- tula to the compounding of the most learned pre- scriptions. The work is by theablest pharmaceutist in the United States, and must meet with an im- mense sale.—Nashville Journal of Medicine, April, 1856. We are glad to receive this excellent work. It will supply a want long felt by the profession, and especially by the student of Pharmacy. A large majority of physicians are obliged to compound their own medicines, and to them a work of this kind is indispensable.—N. O. Medical and Surgical Journal. We cannot say but that this volume is one of the most welcome and appropriate which has for a long time been issued from the press. It is a work which we doubt not will at once secure an extensive cir- culation, as it is designed not only for the druggist and pharmaceutist, but also for the great body of practitioners throughout the country, who not only have to prescribe medicines, but in the majority of instances have to rely upon their own resources— whatever these may be—not only to compound, but also to manufacture the remedies they are called upon to administer. The author has not mistaken the idea in writing this volume, as it is alike useful and invaluable to those engaged in the active pur- suits of the profession, and to those preparing to en- ter upon the field of professional labors.—American Lancet, March 21, 1856. RICORD (P.), M. D., A TREATISE ON THE VENEREAL DISEASK. By John Hunter, F.R.S. With copious Additions, by Ph. Ricord, M. D. Edited, with Notes, by Freeman J. Bumstead, M. D. In one handsome octavo volume, extra cloth, of 520 pages, with plates. $3 25. secretaries, somelimes accredited and sometimes not. Every one will recognize the attractiveness and value which this work derives from thus presenting the opinions of these two masters side by side. But, it must be admitted, what has made the foriune of the book, is ihe fact that it contains the "most com- plete embodiment of the veritable doctrines of the Hopital du Midi," which has ever been made public. The doctrinal ideas of M. Ricord, ideas which, if not universally adopted, are mcontestably dominant, have heretofore only been interpreted by more or less skilful In the notes to Humer, the master substitutes him- self for his interpreters, and gives his original thoughts to the world in a lucid and perfectly intelligible man- ner. In conclusion we can say that this is incon- testably the best treatise on syphilis with which we are acquainted and, as we do not often employ Ihe phrase, we may be excused for expressing the hope that it may find a place in the library of every phy- sician.— Virginia Med. and Surg. Journal. BY THE SAME AUTHOR. ILLUSTRATIONS OF SYPHILITIC DISEASE. Translated by Thomas F. Betton, M. D. With fifty large quarto colored plates. In one large quarto volume, extra cloth. $15 00. LETTERS ON SYPHILTS, addressed to the Chiel Editor of the Union Medieale. Translated by W. P. Lattimore, M.D. In one neat octavo vol- ume, of 270 pages, extra cloth. $2 00. RIGBY (EDWARD), M. D., Senior Physician to the General Lying-in Hospital, &c. A SYSTEM OF MIDWIFERY. With Notes and Additional Illustrations. Second American Edition. One volume octavo, extra cloth, 422 pages. $2 50. by the same author. (Now Ready, 1857.) ON THE CONSTITUTIONAL TREATMENT OF FEMALE DISEASES. In one neat royal 12mo. volume, extra cloth, of about 250 pages. $1 00. The aim of the author has been throughout to present sound practical views of the important subjects under consideration ; and without entering into theoretical disputations and disquisitions to embody the results of his long and extended experience in such a condensed form as would be easily accessible to the practitioner. ROYLE'S MATERIA MEDICA AND THERAPEUTICS; including the Preparations of the Pharmacopoeias of London, Edinburgh, Dublin, and of the United States. With many new medicines. Edited by Joseph Carson, M. D. With ninety-eight illustrations. In one large octavo volume; extra cloth, of about 700 pages. $3 00. AND SCIENTIFIC PUBLICATIONS. 27 RAMSBOTHAM (FRANCIS H.), M.D. THE PRINCIPLES AND PRACTICE OF OBSTETRIC MEDICINE AND SURGERY, in reference to the Process of Parturition. A new and enlarged edition, thoroughly revised by the Author. With Additions by W. V. Keating, M. D. In one large and handsome imperial octavo volume, of 650 pages, strongly bound in leather, with raised bands; with sixty- four beautiful Plates, and numerous Wood-cuts in the text, containing in all nearly two hundred large and beautiful figures. (Lately Issued, 1856.) $5 00. In calling the attention of the profession to the new edition of this standard work, the publishers would remark that no efforts have been spared to secure for it a continuance and extension of the remarkable favor with which it has been received. The last London issue, which was considera- bly enlarged, has received a further revision from the author, especially for this country. Its pas- sage through the press here has been supervised by Dr. Keating, who has made numerous addi- tions with a view of presenting more fully whatever was necessary to adapt it thoroughly to American modes of practice. In its mechanical execution, a like superiority over former editions will be found. From Prof. Hodge, of the University of Pa. To the American public, it is most valuable, from its intrinsic undoubted excellence, and as being the best authorized exponent of British Midwifery. Its circulation will, I trust, be extensive throughout our country. The publishers have shown their appreciation of the merits of this work and secured its success by the truly elegant style in which they have brought it out, excelling themselves in its production, espe- cially in its plates. It is dedicated to Prof. Meigs, and has the emphatic endorsement of Prof. Hodge, as the best exponent of British Midwifery. We know of no text-book which deserves in all respects to be more highly recommended to students, and we could wish to see it in the hands of every practitioner, for they will find it invaluable for reference.—Med. Gazette. But once in a long time some brilliant genius rears his head above the horizon of science, and illumi- nates and purifies every department that he investi- gates ; and his -works become types, by which innu- merable imitators model their feeble productions. Such a genius we find in the younger Ramsbotham, and such a type we find in the work now before us. The binding, paper, type, the engravings and wood- cuts are all so excellent as to make this book one of the finest specimens of the art of printing that have given such a world-wide reputation to its enter- prising and liberal publishers. We welcome Rams- botham's Principles and Practice of Obstetric Medi- cine and Surgery to our library, and confidently recommend it to our readers, with the assurance that it will not disappoint their most sanguine ex- pectations.—Western Lancet. It is unnecessary to say anything in regard to the utility of this work. It is already appreciated in our country for the value of the matter, the clearness of its style, and the fulness of its illustrations. To the physician's library it is indispensable, while to the studeut as a text-book, from which to extract the material for laying the foundation of an education on obstetrical science, it has no superior.—Ohio Med. and Surg. Journal. We will only add that the student will learn from it all he need to know, and the practitioner will find it, as a book of reference, surpassed by none other.— Stethoscope. The character and merits of Dr. Ramsbotham's work are so well known and thoroughly established, that comment is unnecessary and praise superfluous. The illustrations, which are numerous and accurate, are executed in the highest style of art. We cannot too highly recommend the work to our readers.—St. Louis Med. and Surg. Journal. ROKITANSKY (CARL), M.D., Curator of the Imperial Pathological Museum, and Professor at the University of Vienna, &c. A MANUAL OF PATHOLOGICAL ANATOMY. Four volumes, octavo, bound in two, extra cloth, of about 1200 pages. Translated by W. E. Swaine, Edward Sieve- king, C. H. Moore, and G. E. Day. (Just Issued.) §5 50 To render this large and important work more ea>y of reference, and at the same time less cum- brous and costly, the four volumes have been arranged in two, retaining, however, the separate paging, &c. The publishers feel much pleasure in presenting to the profession of the United States the great work of Prof. Rokitansky, which is universally referred to as the standard of authority by the pa- thologists of all nations. Under the auspices of the Sydenham Society of London, the combined labor of four translators has at length overcome the almost insuperable difficulties which have so long prevented the appearance of the work in an Engli:*h dress. To a work so widely known, eulogy is unnecessary, and the publishers would merely state that it is said to contain the resulls of not less than thirty thousand post-mortem examinations made by the author, diligently com- pared, generalized, and wrought into one complete and harmonious system. The profession is too well acquainted with the re- putation of Rokitansky's work to need our assur- ance that this is one of the most profound, thorough, and valuable books ever issued from the medical press. It is sui generis, and has no standard of com- parison. It is only necessary to announce that it is issued in a form as cheap as is compatible with its size and preservation, and its sale follows as a matter of course. No library can be called com- plete without it.—Buffalo Med. Journal. An attempt to give our readers any adequate idea of the vast amount of instruction accumulated in these volumes, would be feeble and hopeless. The effort of the distinguished author to concentrate in a small space his great fund of knowledge, has so charged his text with valuable truths, that any attempt of a reviewer to epitomize is at once para- lyzed, and must end in a failure.—Western Lancet. As this is the highest source of knowledge upon the important subject of which it treats, no real student can afford to be without it. The American publishers have entitled themselves to the thanks of the profession of their country, for this timeous and beautiful edition.—Nashville Journal of Medicine. As a book of reference, therefore, this work must prove of inestimable value, and we cannot too highly recommend it to the profession.— Charleston Mid. Journal and Review, Jan. 1S.5G. This book is a necessity to every practitioner.__ Am. Med. Monthly. SCHOEDLER (FRIEDRICH), PH.D., Professor of the Natural Sciences at Worms, &c. THE BOOK OF NATURE; an Elementary Introduction to the Sciences of Physics, Astronomy, Chemistry, Mineralogy, Geology, Botany, Zoology, and Physiology. First American edition, with a Glossary and other Additions and Improvements; from the second Engli>h edition. Translated from the sixth German edition, by Henry Medlock, F. C. S., &c In one volume, small octavo, extra cloth, pp. 692, with 679 illustrations. $1 80. 28 BLANCHARD & LEA'S MEDICAL SMITH (HENRY H.), M.D., Professor of Surgery in the University of Pennsylvania, &c, MINOR SURGERY; or, Hints on the Every-day Duties of the Surgeon. Illus- trated by two hundred and forty-seven illustrations. Third and enlarged edition. In one hand- some royal 12mo. volume, pp. 456. In leather, $2 25; extra cloth, $2 00. A work such as the present is therefore highly useful to the student, and we commend this one to their attention.—American Journal of Medical Sciences. And a capital little book it is. . . Minor Surgery, we repeat, is really Major Surgery, and anything which teaches it is worth having. So we cordially recommend this little book of Dr. Smith's.—Med.- Chir. Review. This beautiful little work has been compiled with a view to the wants of the profession in the matter of bandaging, &c, and well and ably has the author performed his labors. Well adapted to give the requisite information on the subjects of which it treats.—Medical Examiner. The directions are plain, and illustrated through- out with clear engravings.—London Lancet. One of the best works they can consult on the subject of which it treats.—Southern Journal of Medicine and Pharmacy. No operator, however eminent, need hesitate to consult this unpretending yet excellent book. Those who are young in the business would find Dr. Smith's treatise a necessary companion, after once under- standing its true character.—Boston Med. and Surg. Journal. No young practitioner should be without this little volume; and we venture to assert, that it maybe consulted by the senior members of the profession with more real benefit, than the more voluminous works.— Western Lancet. BY THE SAME AUTHOR, AND HORNER (WILLIAM E.), M. D., Late Professor of Anatomy in the University of Pennsylvania. AN ANATOMICAL ATLAS, illustrative of the Structure of the Human Body. In one volume, large imperial octavo, extra cloth, with about six hundred and fifty beautiful figures. $3 00. These figures aie well selected, and present a complete and accurate representation of that won- derful fabric, the human body. The plan of this Atlas, which renders it so peculiarly convenient for the student, and its superb artistical execution, have been already pointed out. We must congratu- late the student upon the completion of this Atlas, as it is the most convenient work of the kind that has yet appeared ; and we must add, the very beau- tiful manner in which it is " got up" is so creditable to the country as to be flattering to our national pride.—American Medical Journal. SARGENT (F. W.), M. D. ON BANDAGING AND OTHER OPERATIONS OF MINOR SURGERY. Second edition, enlarged. One handsome royal 12mo. vol., of nearly 400 pages, with 182 wood- cuts. Extra cloth, $1 40; leather, fl 50. This very useful little work has long been a favor- ite with practitioners and students. The recent call for a new edition has induced its author to make numerous important additions. A slight alteration in the size of the page has enabled him to introduce the new matter, to the extent of some fifty pages of the former edition, at the same time that his volume is rendered still more compact than its less compre- hensive predecessor. A double gain in thus effected, which, in a vade-mecum of this kind, is a material improvement.—Am. Medical Journal. Sargent's Minor Surgery has always been popular, and deservedly so. It furnishes that knowledge of the most frequently requisite performances of surgical art which cannot be entirely understood by attend- ing clinical lectures. The art of bandaging, which is regularly taught in Europe, is very frequently overlooked by teachers in this country; the student and junior practitioner, therefore, may often require that knowledge which this little volume so tersely and happily supplies. It is neatly printed and copi- ously illustrated by the enterprising publishers, and should be possessed by all who desire to be thorough- ly conversant with the details of this branch of our art.—Charleston Med. Journ. and Review, March, 1856. A work that has been so long and favorably known to the profession as JDr. Sargent's Minor Surgery, needs no commendation from us. We would remark, however, in this connection, that minor surgery sel- dom gets that attention in our schools that its im- portance deserves. Our larger works are also very defective in their teaching on these small practical points. This little book will supply the void which all must feel who have not studied its pages.—West- ern Lancet, March, 1856. We confess our indebtedness to this little volume on many occasions, and can warmly recommend it to our readers, as it is not above the consideration of the oldest and most experienced.—American Lan- cet, March, 1856. SKEY'S OPERATIVE SURGERY. In one very handsome octavo volume, extra cloth, of over 650 pages, with about one hundred wood-cuts. S3 25. STANLEY'S TREATISE ON DISEASES OF THE BONES. In one volume, octavo, extra cloth, 286 pages. 81 50. SOLLY ON THE HUMAN BRAIN; its Structure, Physiology, and Diseases. From the Second and much enlarged London edition. In one octavo volume, extra cloth, of 500 pages, with 120 wood- cuts. $2 00. SIMQX'S GENERAL PATHOLOGY, as conduc- ive to the Establishment of Rational Principles for the prevention and Cure of Disease. In one neat octavo volume, extra cloth, of 212 pages. ffil 25. STILLE (ALFRED), M.D. PRINCIPLES OF GENERAL AND SPECIAL THERAPEUTICS In handsome octavo. (Preparing.) SIBSON (FRANCIS), M.D., Physician to St. Mary's Hospital. MEDICAL ANATOMY. Illustrating the Form, Structure, and Position of the Internal Organs in Health and Disease. In large imperial quarto, with splendid colored plates. To match "Maclise's Surgical Anatomy." Parti. (Preparing.) AND SCIENTIFIC PUBLICATIONS. 29 SHARPEY (WILLIAM), M.D., JONES QUAIN, M.D., AND RICHARD QUAIN, F. R. S., &.c. HUMAN ANATOMY. Revised, with Notes and Additions, by Joseph Leidy, M. D., Professor of Anatomy in the University of Pennsylvania. Complete in two large octavo volumes, leather, of about thirteen hundred pages. Beautifully illustrated with over five hundred engravings on wood. SO 00. It is indeed a work calculated to make an era in anatomical study, by placing before the student every department of his science, with a view to the relative importance of each ; and so skilfully have the different parts been interwoven, that no one who makes this work the basis of his studies, will hereafter have any excuse for neglecting or undervaluing any important particulars connected with the structure of the human frame; and whether the bias of his mind lead him in a more especial manner to surgery, physic, or physiology, he will find here a work at once so comprehensive and practical as to defend him from exclusiveness on the one hand, and pedantry on the other.— Journal and Retrospect of the Medical Sciences. We have no hesitation in recommending this trea- tise on anatomy as the most complete on that sub- ject in the English language; and the only one, perhaps, in any language, which brings the state of knowledge forward to the most recent disco- veries.—The Edinburgh Med. and Surg. Journal. SMITH (W. TYLER), M. D., Physician Accoucheur to St. Mary's Hospital, &c. ON PARTURITION, AND THE PRINCIPLES AND PRACTICE OF OBSTETRICS. In one royal 12mo. volume, extra cloth, of 400 pages. $1 25. BY THE SAME AUTHOR. A PRACTICAL TREATISE ON THE PATHOLOGY AND TREATMENT OF LEUCORKJEKEA. With numerous illustrations. In one very handsome octavo volume, extra cloth, of about 250 pages. SI 50. We hail the appearance of this practical and invaluable work, therefore, as a real acquisition to our medical literature.—Medical Gazette. TAYLOR (ALFRED S.), M. D., F. R. S., Lecturer on Medical Jurisprudence and Chemistry in Guy's Hospital. MEDICAL JURISPRUDENCE. Fourth American, from the fifth improved and enlarged English Edition. With Notes and References to American Decisions, by Edward Hartshorne, M. D. In one large octavo volume, leather, of over seven hundred pages. (Just Issued, 1856.) S3 00. This standard work has lately received a very thorough revision at the hands of the author, who has introduced whatever was necessary to render it complete and satisfactory in carrying out the objects in view. Tlie editor has likewise used every exertion to make it equally thorough with regard to all matter.- relating to the practice of this country. In doing this, he has carefully ex- amined all that has appeared on the subject since the publication of the last edition, and has incorpo- rated all the new information thus presented. The work has thus been considerably increased in size, notwithstanding which, it has been kept at its former very moderate price, and in every respect it will be found worthy of a continuance of the remarkable favor which has carried it through so many editions on both sides of the Atlantic. A few notices of the former editions are appended. most attractive books that we have met with ; sup- plying so much both to interest and instruct, that we do not hesitate to affirm that after having once commenced its perusal, few could be prevailed upon to desist before completing it. In the last London edition, all the newly observed and accurately re- corded facts have been inserted, including much that is recent of Chemical, Microscopical, and Patholo- gical research, besides papers on numerous subjects never before published .-Charleston Medical Journal and Review. We know of no work on Medical Jurisprudence which contains in the same space anything like the same amount of valuable matter .—N. Y. Journal of Medicine. No work upon the subject can be put into the hands of students either of law or medicine which will engage them more closely or profitably; and none could be offered to the busy practitioner of either calling, for the purpose of casual or hasty reference, that would be more likely to afford the aid desired. We therefore recommend it as the best and safest manual for daily use.—American Journal of Medical Sciences. So well is this work known to the members both of the medical and legal professions, and so highly is it appreciated by them, that it cannot be necessary for us to say a word in its commendation; its.having already reached a fourth edition being the best pos- sible testimony in its favor. The author has ob- viously subjected the entire work to a very careful revision.—Brit, and Foreign Med. Chirurg. Review. This work of Dr. Taylor's is generally acknow- ledged to be one of the ablest extant on the subject of medical jurisprudence. It is certainly one of the BY THE SAME AUTHOR. ON POISONS, IN RELATION TO MEDICAL JURISPRUDENCE AND MEDICINE. Edited, with Notes and Additions, by R. E. Griffith, M. D. In one large octavo volume, leather, of 688 pages. S3 00 TODD (R. B.), M. D., F. R. S., &.C. CLINICAL LECTURES ON CERTAIN DISEASES OF THE URINARY ORGANS AND ON DROPSIES. In one octavo volume. (Now Ready, 1857.) SI 50 The valuable practical nature of Dr. Todd's writings have deservedly rendered them favorites with the pro ession, and the present volume, embodying the medical aspects of a class of diseases not elsewhere to be found similarly treated, can hardly fail to supply a want long felt by the prac- titioner It is not excess of praise to say that the volume before us is the very best treatise extant on Medical Jurisprudence. In saying this, we do not wish-to be understood as detracting from the merits of the excellent works of Beck, Ryan, Traill, Guy, and others; but in interest and value we think it must be conceded that Taylor is superior to anything that has preceded it. The author is already well known to the profession by his valuable treatise on Poisons; and the present volume will add materially to his high reputation for accurate and extensive know- ledge and d'scriminating judgment.—N. W. Medical and Surgical Journal. 30 BLANCHARD & LEA'S MEDICAL Now Complete (April, 1857.) TODD (ROBERT BENTLEY), M. D., F. R. S., Professor of Physiology in King's College, London; and WILLIAM BOWMAN, F. R. S., Demonstrator of Anatomy in King's College, London. THE PHYSIOLOGICAL ANATOMY AND PHYSIOLOGY OF MAN. With about three hundred large and beautiful illustrations on wood. Complete in one large octavo volume, of 950 pages, leather. Price $4 50. The very great delay which has occurred in the completion of this work has arisen from the de- sire of the authors to verify by their own examination the various questions and statements pre- sented, thus rendering the work one of peculiar value and authority. By the wideness of its scope and the accuracy of its facts it thus occupies a position of its own, and becomes necessary to all physiological students. ISP Gentlemen who have received portions of this work, as published in the " Medical News and Library," can now complete their copies, if immediate application be made. It will be fur- nished as follows, free by mail, in paper covers, with cloth backs. Parts I., II., III. (pp. 25 to 552), $2 50. Part IV. (pp. 553 to end, with Title, Preface, Contents, &c), $2 00. Or, Part IV., Section II. (pp. 725 to end, with Title, Preface, Contents, &c), $1 25. In the present part fthird) some of the most diffi- cult subjects in Anatomy and Physiology are handled in the most masterly manner. Its authors have stated that this work was intended " for the use of the student and practitioner in medicine and sur- gery," and we can recommend it to both, confident that it is the most perfect work of its kind. We cannot conclude without strongly recommending the present work to all classes of our readers, recogniz- ing talent and depth of research in every page, and believing, as we do, that the diffusion of such know- ledge will certainly tend to elevate the sciences of Medicine and Surgery.—Dublin Quarterly Journal of Medical Sciences.^ r <— MAN1 ■l. D TANNER (T. H.)f M. D. Physician to the Hospital for Women, L MANUAL OF CLINICAL MEDICINE AND PHYSICAL DIAGNOSIS. To which is added The Code of Ethics of the American Medical Association. Second American Edition. In one neat volume, small 12mo. Price in extra cloth, 87£ cents ; flexible style, for the pocket, 80 cents. Dr. Tanner has, in a happy and successful manner, indicated the leading particulars to which, in the clinical study of a case of disease, the attention of the physician is to be directed, the value and import of the various abnormal phenomena detected, and the several instrumental and accessory means which maybe called into requisition to facilitate diagnosis and increase its certainty.—Am. Journal of Med. Sciences. The work is an honor to its writer, and mu?t ob- tain a wide circulation by its intrinsic merit alone. Suited alike to the -wants of students and practi- tioners, it has only to be seen, to win for itself a place upon the shelves of every medical library. Nor will it be " shelved" long at a time; if we mis- take not, it will be found, in the best sense of the homely but expressive word, " handy." The style is admirably clear, while it is so sententious as not to burden the memory. The arrangement is, to our mind, unexceptionable. The work, in short, de- serves the heartiest commendation.—Boston Med. and Surg. Journal. ■\ * '"' " WATSON (THOMAS), M.D. LECTURES ON THE PRINCIPLES AND PRACTftjE J0F PHYSIC. Third American edition, revised, with Additions, by D. Francis Condie^'M. D., author of " Treatise on' the Diseases of Children," &c. In one octavo volume, of nearly eleven hundred large pages, strongly bound with raised bauds. " To say that it is the very best work on the sub- ject now extant, is but to echo the sentiment of the medical press throughout the country. — N. O. Medical Journal. Of the text-books recently republished Watson is very justly the principal favorite.—Holmes's Rep. to Nat. Med. Assoc. By universal consent the work ranks among the very best text-books in our language.—Illinois and Indiana Med. Journal. Regarded on all hands as one of the very best, if not the very best, systematic treatise on practical medicine extant.—St. Louis Med. Journal. 25. Confessedly one of the very best works on the principles and practice of physic in the English or any other language.—Med. Examiner. Asatext-book it has noequal; as a compendium of pathology and practice no superior.—New York Annalist. We know of no work better calculated for being placed in the hands of the student, and for a text- book; on every important point the author seems to have posted up his knowledge to the day.— Amer. Med. Journal. One of the most practically useful books that ever was presented to the student. — N. Y. Med. Journal. WHITEHEAD ON THE CAUSES AND TREAT-I WALSHE ON DISEASES OF THE HEART MENT OF ABORTION AND STERILITY. | LUNGS, AND APPENDAGES; their Symp- Second American Edition. In one volume, octa vo, extra cloth, pp. 308. $1 75. toms and Treatment. In one handsome volume, extra cloth, large royal 12mo., 512 pages. $1 50. WHAT TO OBSERVE AT THE BEDSIDE AND AFTER DEATH, IN MEDICAL CASES. Published under the authority of the London Society for Medical Observation. Anew American from the second and revised London edition. In one very handsome volume, royal 12mo., extra cloth. $1 00. To the observer who prefers accuracy to blunders and precision to carelessness, this little book is in- valuable.—N. H. Journal of Medicine. One of the finest aids to a young practitioner we have ever seen.—Peninsular Journal of Medicin*. AND SCIENTIFIC PUBLICATIONS 31 WILSON (ERASMUS), M.D., F. R. S., Lecturer on Anatomy, London. A SYSTEM OF HUMAN ANATOMY, General and Special. Fourth Ameri- can, from the last English edition. Edited by Paul B. Goddard, A. M., M D. With two hun- dred and fifty illustrations. Beautifully printed, in one large octavo volume, leather, of nearly six hundred pages. S3 00. In many, if not all the Colleges of the Union, it i It offers to the student all the assistance that can has become a standard text-book. This, of itself, be expected from such a work.—Medical Examiner. is sufficiently expressive of its value. A work very The mogt complete and convenient manual for the desirable to the student; one, the possession of 8tuuent we possess—American Journal of Medical wnich will greatly facilitate his progress in the I Science study of Practical Anatomy.—New York Journal of I ' ,,. Medicine \ every respect, this work as an anatomical | guide for the student and practitioner, merits our Its author ranks with the highest on Anatomy.— warmest and most decided praise.—London Medical Southern Medical and Surgical Journal. I Gazette. by the same author. (Just Issued.) THE DISSECTOR'S MANUAL j or, Practical and Surgical Anatomy. Third American, from the last revised and enlarged English edition. Modified and rearranged, by William Hunt, M. D., Demonstrator of Anatomy in the University of Penn*ylvania. In one large and handsome royal 12mo. volume, leather, of 582 pages, with 154 illustrations. $2 00. The modifications and additions which this work has received in passing recently through the author's hands, is sufficiently indicated by the fact that it is enlarged by more than one bundled pages, notwithstanding that it is printed in smaller type, and with a greatly enlarged page. It remains only to add, that after a careful exami- I ing very superior claims, well calculated to facilitate nation, we have no hesitation in recommending this | their studies, and render their labor less irksome, by work to the notice of those for whom it has been constantly keeping before them definite objects of expressly written—the students—asaguidepossess- | interest.—The Lancet. BY the same author. (Now Ready, May, 1857.) ON DISEASES OF THE SKIN. Fourth and enlarged American, from the last and improved London edition. In one large octavo volume, of 650 pages, extra cloth, $2 75. This volume in passing for the fourth time through the hands of the author, has received a care- ful revision, and has been greatly enlarged and improved. About one hundred and fifty pages have been added, including new chapters on Classification, on General Pathology, on General Thera- peutics, on Furuncular Eruptions, and on Diseases of the Nails, besides exten;-ive addilions through- out the text, wherever they have seemed desirable, either from former omissions or from ihe pro- gress of science and the increased experience of the aulhor. Appended to ihe volume will al>o now be found a collection of Selected Formula, consisting for the most part of piescriptions of which the author has tested the value. In the present edition Mr. Wilson presents us with i the mere manifestations of derangement of internal the results of his matured experience gained after an j organs, is brought under notice, and the book in- exteusivt acquaintance with the pathology and treat- I eludes a mass of information which is spread over a inent of cutaneous affections; and we have cow be- great part of the domain of Medical and Surgical fore us not merely a reprint of his former publica- i Pathology. We can safely recommend it to the lions, but an entirely new ai.d rewritten volume. | profession as the best work on the subject now in Thus, the whole history of the diseases affecting the j existence in the English language.—London Med. skin, whether they originate in that structure or are I Times and Gazette, March 28, 1S57. ALSO, JUST READY, A SERIES OF PLATES ILLUSTRATING WILSON ON DISEASES OF THE SKIN ; consisting of nineteen beautifully executed plates, of which twelve are exquisitely colored, presenting the Normal Anatomy and Palhology of the Skin, and containing accurate re- presentations of about one hundred varieties of disease, most of them the size of nature. Price in cloth $ 1 25. In beauty of drawing and accuracy and finish of coloring these plates will be found superior to anything of the kind as yet issued in this country. The plates by which thiseditition is accompanied ; The representations of the various forms of cutane- leave nothing to be desired, so far as excellence of j ous disease are singularly accurate, and the colorin" delineation and perfect accuracy of illustration are i exceeds almost anything we have met with in point concerned.—Mebico-Chirurgical Review. of delicacy and finish.—British and Foreign Medical Of these plates it is impossible to speak too highly. | Review. BY THE SAME AUTHOR. ON CONSTITUTIONAL AND HEREDITARY SYPHILIS, AND ON SYPHILITIC ERUPTIONS. In one small octavo volume, extra cloth, beautifully printed, with four exquisite colored plates, presenting more than thirty varieties of syphilitic eruptions. $2 25. BY the same author. (Just Issued.) HEALTHY SKIN; A Popular Treatise on the Skin and Hair, their Preserva- tion and Management. Second American, from the fourth London edition. One neat volume, royal 12mo.: extra cloth, of about 300 pages, with numerous illustrations. $1 00; paper cover 75 cents. WILDE (W. R.), Surgeon to St. Mark's Ophthalmic and Aural Hospital, Dublin. AURAL SURGERY, AND THE NATURE AND TREATMENT OF DIS- EASES OF THE EAR. In one handsome octavo volume, extra cloth, of 476 pages, with illustrations. S2 80. This work certainly contains more information on the subject to which it is devoted than any other with which we are acquainted. We feel grateful 10 the author for his manful effort to rescue this depart mentof *urgery from the hands of the empirics wi o nearly monopolize it —la. Med. and Surg. Journal. 32 BLANCHARD & LEA'S MEDICAL PUBLICATIONS. WEST (CHARLES), M. D., Accoucheur to and Lecturer on Midwifery at St. Bartholomew's Hospital, Physician to the Hospital for Sick Children, &c. LECTURES ON THE DISEASES OF INFANCY AND CHILDHOOD. Second American, from the Second and Enlarged London edition. In one volume, octavo, extra cloth, of nearly five hundred pages. $2 00. ligation by this able, thorough, and finished work upon a subject which almost daily taxes to the ut- most the skill of the general practitioner. He has with singular felicity "threaded his way through ail the tortuous labyrinths of the difficult subject he has undertaken to elucidate, and has in many of the darkest corners left a light, which will never be extinguished.—Nashville Medical Journal. We take leave of Dr. West with great respect for his attainments, a due appreciation of his acute powers of observation, and a deep sense of obliga- tion for this valuable contribution to our profes- sional literature. His book is undoubtedly in many respects the best we possess on diseases of children. Dublin Quarterly Journal of Medical Science. Dr. West has placed the profession under deep ob- by the same author. (Nearly Ready.) LECTURES ON THE DISEASES OF WOMEN. In two parts. Part I. 8vo. cloth, of about 300 pages, comprising the Diseases of the Uterus. SI 60. Part II. (Preparing), will contain Diseases of the Ovaries, and of all the parts connected with the Uterus ; of the Bladder, Vagina, and External Organs. The objoct of the author in this work is to present a complete but succinct treatise on Female Diseases, embodying the results of his experience during the last ten years at St. Bartholomew's and the Midwifery Hospitals, as well as in private practice. The characteristics which have se- cured to his former works so favorable a reception, cannot fail to render the present volume a standard authority on its important subject. To show the general scope of the work, an outline of the Contents of Part I. is subjoined. Lectures I, II.—Introductory—Symptoms—Examination of Symptoms—Modes of Examina- tions. Lectures III, IV., V—Disorders of Menstruation, Amenorrhcea, Menorrhagia, Dys- menorrhoea. Lectures VI, VII, VIII.—Inflammation of the Uterus, Hypertrophy, Acute Inflammation, Chronic Inflammation, Ulceration of the Os Uteri, Cervical Leucorrhoea. Lectures IX., X., XI, XII, XIII.—Misplacement of the Uterus, Prolapsus, Anteversion, Retrover- sion, Inversion. Lectures XIV., XV., XVI., XVII.—Uterine Tumors and Outgrowths, Mucous, Fibro-cellular, and Glandular Polypi, Mucous Cysts, Fibrinous Polypi, Fibrous Tumors, Fibrous Polypi, Fatty Tumors, Tubercular Diseases. Lectures XVIII., XIX., XX.—Cancer of the Uterus. Part II. will receive an equally extended treatment, rendering the whole an admirable text-book for the student, and a reliable work for reference by the practitioner. by the same author. (Just Issued) AN ENQUIRY INTO THE PATHOLOGICAL IMPORTANCE OF ULCER- ATION OF THE OS UTERI. In one neat octavo volume, extra cloth. $1 00. WILLIAMS (C. J. B.), M.D., F. R. S., Professor of Clinical Medicine in University College, London, &c. PRINCIPLES OF MEDICINE. An Elementaiy View of the Causes, Nature, Treatment, Diagnosis, and Prognosis of Disease; with brief remarks on Hygienics, or the pre- servation of health. A new American, from the third and revised London edition. In one octavo volume, leather, of about 500 pages. $2 50. (Now Ready, May, 1857.) The very recent and thorough revision which this work has enjoyed at the hands of the au'hor has brought it so completely up to the present state of the subject that in reproducing it no i ddiLons have been found necessary. The success which the work has heretofore met shows that ; s im- portance has been appreciated, and in its present form it will be found eminently worthy a continu- ance of the same favor, possessing as it does the strongest claims to the attention of the medical student and practitioner, from the admirable manner in which the various inquiries in the different branches of pathology are investigated, combined and generalized by an experienced practical phy- sician, and directly applied to the investigation and treatment of disease. We find that the deeply-interesting matter and style of this book have so far fascinated us, that we have unconsciously hung upon its pages, not too long, indeed, for our own profit, but longer than re- viewers can be permitted to indulge. We leave the further analysis to the studenfand practitioner. Our judgment of the work has already been sufficiently expressed. It is a judgment of almost unqualified praise. The work is not of a controversial, but of a didactic character; and as such we hail it, and recommend it for a text-book, guide, and constant companion to every practitioner and every student who wishes to extricate himself from the well-worn ruts of empiricism, and to base his practice of medi- cine upon principles.—London Lancet, Dec. 27,1856. A text-book to which no other in our language is comparable.—Charleston Medical Journal. No work has ever achieved or maintained a more deserved reputation.— Va. Med. and Surg. Journal. YOUATT (WILLIAM), V. S. THE HORSE. A new edition, with numerous illustrations; together with a general history of the Horse; a Dissertation on the American Trotting Horse; how Trained and Jockeyed; an Account of his Remarkable Performances; and an Essay on the Ass and the Mule. By J. S. Skinner, formerly Assistant Postmaster-General, and Editor of the Turf Register. One large octavo volume, extra cloth. $1 50. The attention of all who keep horses is requested to this handsome and complete edition of a work which is recognized as the standard authority on all matters connected with veterinary medi- cine. The very low price at which it is now offered, free by mail, places it within the reach of every one. BY THE SAME AUTHOR. THE DOG. Edited by E. J. Lewis, M. D. With numerous and beautiful illustrations. In one very handsome volume, crown Svo., crimson cloth, gilt. $1 25. ^