IMAGE EVALUATION TEST TARGET (MT-3) / m ^/ ^ ss> nd pour dtre reproduit en un seul clichd, il e& fiimd d partir de Tangle eupdrieur gauche, de gauche d droite, et de haut en bas, en prenant le nombre d'images n6cessaire. Les diagrammes suivants illustrent la m6thode. 1 2 3 1 2 3 4 5 6 Jjy XjfoJr^\^j^ r ^riJCTrJZo ' lo - ^ - o ir TEXT BOOK OF PHYSIOLOGY p TEXT BOOK OF I iJ Or S v) a. .. u- PHYSIOLOGY, BY J. FULTON, M.D., M.R.C.S., Eng.; L.R.C.P., Lon. TROKKSSOR OP PIIYHIOtiOQY AND bANITARY SCIBNCE IN TRINITY MKDICAL COLLEGK, TORONTO ; 8UR0E0N TO THE TOROSTO OKNKRAli HOHl'ITAL, AND PHYSICIAN TO THE IIO.MK KOR INCl'RABLKS, TORONTO. t i SECOND EDITION, REVISED AND ENLARGED, WITH NUMEROUS ILLUSTRATIONS. "labor omnia vincit. ' I'lIILAUELrillA: LINDSAY & BLAKISTON TORONTO : WILLING & WILLIAMSON 1879. Property of the Library University of Waterloo- Entered according to Act of the Parliament of Canada, in the Year One Thousand Eight Hiinilred and Seventy-nine, by J. FrLTON, M.D., in the Office of the Mi:iisterof Agri- cultinu, at Ottawa, D.C. Entered according to Act of Congress, in the Year One Tliousand Eight Hundred and Seventy-nine, by A. L. Eti/roN, M.D., in the Office of tlie Librarian of Congress, at Washington, D.C. Dudley & Birxs, Printers, 11 Colhornc Street, Toronto. PREFACE TO THE SECOND EDITION, The science of Physiology has been so much advanced in almost every department of the subject, since the issue of the first edition, that the preparation of the present one has been no easy matter. The very favorable reception, however, which was accorded the first edition, has induced me willingly to undertake the self-imposed task. Many of the chapters have been re-written, and much new matter added ; but while every part has received careful revision, the original plan of arrangement has been rigidly adhered to, as that best adapted to the wants of those for whom it Wivs written. My experience as a teacher in the department of Physiology during the last fifteen years, formerly in Victoria Medical College, and latterly in the University of Trinity College, has led me to the conclusion that Physiology can be best taught in connection with Histo- logy, and with this view I have endeavored to supply a prevailing want in the ordinary text books, by the intro- duction of a concise history of this interesting subject. It has been truly said that a knowledge of Anatomy is the keystone to Medicine, and it is equally true that a knowledge of Histology is the keystone to Physiology. Illustrations have been introduced wherever they ap- peared desirable, and in order to prevent the volume from being too expensive, such illustrations as did not appear necessary to the elucidation of the text have been omitted. j VI. The illustrations are partly new and partly borrowed from recognized authorities, and special acknowledgment must be made of those obtained from jAMES CAMPBELL, Pub- lisher, Boston, U.S. It was not considered desirable, as a rule, in a work of this kind, to quote authorities for the statements in the text, as it would have required numerous references to home and foreign books and periodical litera- ture, which would have been not only useless, but confusing to the generality of readers. Notwithstanding the number of most excellent works on Physiology published, a well digested te :t book on this subject, adapted to the wants of the advanced medical student and the general practitioner, is still a desideratum in medical literature. This work is chiefly intended for medical students, but it is hoped that it may also prove serviceable to medical practitioners, more especially those who have students under their instruction. J. FULTON. £i.oi.N PiiACK, .'iiK! Cliiuvli St., Toronto. m St b- a he us a- tig ks liis :al im for )ve Dse CONTENTS. PAGE INERODUCTION II CHAPTER I. Proximate Principles 14 Definition of a Proximate Principle 14 Classification of Proximate Principles IS Proximate Principles of the First Class 16 Water 16 Sodium Chloride 17 Potassium Chloride ... 18 Lime Phosphate 19 Lime Carbonate 19 Sodium and Potassium Carbonates 20 Sodium and Potassium Sulphates 20 Magnesium Phosphate and Carbonate 21 Gases 22 Proximate Principles of the Second Class 22 Starch 23 Glycogen 25 Sugars 26 Oils and Fats 29 Proximate Principles of the Third Class 33 Albumen 35 Albuminose or Peptone 37 Fibrin 38 Casein 40 Globuline 41 Pepsine , , . 41 Pancreatine 42 Ptyaline 42 Mucosine 42 Musculine 42 Cartilagine 42 Collagen 43 Elasticine 43 Keratine 43 Coloring Matters 43 Hemoglobine 43 Melanine 44 Bilirubine and Biliverdine 44 Urosacine or Urochrome 45 Luteine 45 €rvstallizable Nitrogenous Mattees 45 Lecithine 45 Cerebine 46 Leucine 47 I Vlll. CHAPTER II. I'AOE Elementary or Primary Forms ok Tissue 46 Protoplasm 47 Cells, shape, size and structure 47 Cytogenesis 5' Conditions necessary to Cell growth 53 Permanent Change in the Shape of Cells. . S3 Temporary Change in the Shape of Cells 54 Cause of Organization 55 Function of Cells 56 Manifestations of Cell Life 57 Granules 57 Simple Fibres 57 Simple Membranes 58 CHAPTER HI. Tissues 60 White Fibrous or Connective Tissue 60 Yellow Fibrous or Elastic Tissue 62 Areolar Tissue 64 Adipose Tissue 65 Cartilage 66 Gelatinous and Reticular Tissue 71 Bone 72 Teeth 79 Muscle 83 CHAPTER IV. Membranous Expansions 96 Epithelium 97 Serous Membranes loi Synovial Membranes 102 Mucous Membranes 103 Appendages of the Mucous Membrane 105 ^ Integument 1 12 Appendages of the Integument 116 CHAPTER V. Digestion 125 Prehension 1 32 Mastication 132 Insalivation 134 Deglutition 137 Chymification 1 39 Chylification 144 Defecation 156 CHAPTER VI. Absorption 158 Villi and Lacteals 158 Lymphatic Vessels and Glands 159 Mechanism of Absorption 162 Absorption by the Villi and Lacteals 165 Absorption by the Blood Vessels 166 Absorption by the Lymphatics 167 Glandulse Solitariae ^, . . 167 IX. CHAPTER vir. TAOE Blood i68 Physical Character of the IMood i68 Microscopical Appearance of tlie Blood 169 Chemical and Structural Characters of the Blood 176 Difference i)etween Arterial and Venous Blood 180 Conditions which Influence the Ciiaracter of the Blood 183 Coagulation and Vital Properties of the Blood 188 Circumstances which Promote Coagulation 191 Circumstances which Retard Coagulation 192 Function of the Constituents of the Blood 194 Relation of the Blood to the Living Organism 198 CHAPTER VIII. Circulation 200 The Heart and Circulation 200 Proofs of the Circulation 203 Action of the Heart 206 Arteries 212 Veins 219 Capillaries 222 Velocity f.f the Circulation 225 Fa'tal Circulation 227 CHAPTER IX. KliSPIRATION 230 The Lungs 230 Meclinnism of Respiration 233 Influence of the Nerves in Respiration 237 Modification of the Respiratory Movements 238 Changes in the Respired Air 239 Changes in the Blood during Respiration 242 Elfects of the Arrest of Respiration 243 CHAPTER X. Animal Heat, Light and Electricity 244 Heal 244 Theory of the Production of Heat 245 Regulation of the Temperature of the Body 247 Light 248 Electricity 248 CHAPTER XL Secreting Glands and their Skcretions 252 The Liver 252 The Kidney , 256 Secretion of Urine 259 The Mammary Glands , 266 Milk 267 CHAPTER XII. Ductless or Vascular Glands 270 The Spleen 270 The Supra-renal Capsules 273 The Thymus Gland 274 The Thyroid Gland 275 X. CHAPTER XIII. PACK The Nervous Systkm 276 Structure of the Nervous System 28 1 Ganglia of Nerves 284 Chemical Composition of Nerve Tissue 284 ■ Origin and Termination of Nerves 286 Function of Nerve Fibres 289 Develop'v.ent of Nerve Tissue 292 Function of the Nervous Centres 293 Rellcx Action 295 Nerve force 295 The Spinal Cord 296 Function of the Spinal Cord 299 Encephalon S^S- y. ;;lulla Oblongata 303 Pons Varolii 3°^ Cerebellum 3°7 . Cerebrum 3'° The Mind and its relation to the body 324 Cranial Nerves 329 Sympathetic Nervous System 336 CHAPTER XIV. The SPEC! Ai, Senses 340' Smell 340 Sight 343 Phenomena of Vision 35 1 Accommodation of the Eye to Vision 352 Defects of Vision 35^ Hearing 35^ The Mechanism of Hearing 362 Sense of Taste 3^4 Sense of Touch 3^6 CHAPTER XV. ■ The Voice 37° Larynx 37° Compass of the Voice 373 Ventriloquism and Stammering 374 CHAPTER XVI. Reproduction 375 Action of the Male 377 Action of the Female 37^ Corpus Luteum 3^0 Action of the Oviducts 3^1 Development of the Ovum 3^2 Formation of the Amnion and Allantois 386 Formalism of the Chorio'i 3^^ Preparation of the Uterus for the Ovum 389 Formation of the Placenta 39° Umbilical Cord and Amniotic Fluid 39' Parturition 392 General Development of the Embryo 392 HUMAN PHYSIOLOGY. INTRODUCTION. Physiology, from 7 Teeth loo Bones 130 Tendons 500 Cartilage 550 Muscles 750 Ligaments 768 !1 ^ Blood 795 Bile 880 Milk 887 Pancreatic Juice 900 Urine 936 Gastric Juice 975 Perspiration 986 Saliva 995 Origin and Discharge of Water. — It is introduced with the fluid and solid elements of the food. It is also be- lieved to be formed in the body from the union of oxygen and hydrogen, as they are liberated from organic combinations. The amount of water taken into the system by an adult, in the course of 24 hours, varies from 3i to 4 pounds. It is dis- charged from the body in four different ways — by the urine, faeces, perspiration, and breath — about 50 per cent, being dis- charged by the urine and faeces, 30 per cent, by the per- spiration and 20 per cent, by the lungs. These proportions will vary according to circumstances ; for example, in warm weather, when the skin is more active, and the perspiration more abundant, the quantity of urine is diminished. The PROXIMA TE PAVXC/PLES. 17 quantity of water discharged b}' the lungs varies also, with the state of the atmosphere and the pulmonary circulation. The water is not discharged pure, but is mingled with various salts, animal matters, and odoriferous subs-tances. Function.— It holds in solution different salts and sub- stances of excretion, and gives fluidity to , the blood and secretions. It is a most important article of diet, and is necessary both for the introduction of substances into the body, and their elimination from it. It gives to cartilage its elasticity, and to tendons their toughness and pliability, for, if water be expelled from a piece of cartilage by evaporation, it becomes dark in colour, semi-transparent, hard and inelastic. The same thing is true of musJes, tendons, etc. Sodium Chloride, NaCl. — Sodium chloride is next in importance, and is found in all parts of the body except the enamel of the teeth. The entire quantity in the body has been estimated b}' Dr. Laukester, at one-quarter of a pound, avoirdupois. It exists in the greatest quantity in the fluids. In blood, for example, it is more abundant than all the other salines taken together. The following is a list of the quantities in the most important solids and fluids.: — QUANTITY OF SODIUM CHLORIDE IN 1,000 PARTS. Muscles. Bones. . Milk.... Saliva. . Urine. . . Bile.... ■7 •3 .1.5 5-5 .^1 Lymph 5. Blood 3.3 Chyle 5-3 Mucus 6 Aqueous Humor 11 Vitreous 14 Origin and Discharge. — It is introduced with the dif- ferent kinds of animal and vegetable food and fluids, and as a condiment. Being soluble, it is taken up by absorption from the intestines, and is deposited in different parts of the body. About | is discharged from the body in the urine, fiieces, perspiration and mucus, the remaining J being sup- posed to be changed in the body by double-decomposition lA 18 riiOXIMA riC PRIACIPLES. with ])ota.s,siuni phosphate, resulting in the formation of sodium phosphate and potassium chloride. It is also sup- posed to furnish the sodium to all the salts of that metal. ^U^XTIUN. — It rejjulates, to a certain extent, the process of osmosis, for we know that a solution of sodium chlo- ride i)ermeates an animal membrane nnich less readily than pure water. In tlie blood it holds in solution the albu- men and earthy phosphates, and preserves the integrity of the blood corpuscles. As an article of diet, it stimulates the secretion of saliva and gastric juce, and aids in digestion. The importance of sodium chloride in this respect has been demonstrated by Boussingault in the fattening of animals. A small herd of animals were experimented upon, all of the same age, size and vigor. They were divided into two lots and all su])plied with an abundance of nutritious food. One of these lots was deprived of this salt (except what was con- tained in the food), while the other received about oOO grains per day. No difi'erence was observable for four or five months ; from that time to the end of the year a marked difference was noticed. Those animals which received the sodium chloride had a fine, sleek, healthy aspect, contrast- ing strongly with the listless and inanimate appearance of the others. The animals of the forest, as the buffalo and deer have their " salt-licks " to which they resort from time, to time. Potassium Chloride, KCl. — This substance is found in the muscleSjliver, milk, chyle, blood, gastric juice, bile, saliva, mucus and urine, as,sociated with .sodium chloride. It is quite soluble in the fluids, and is more abundant in muscle and milk, than sodium chloride, less so in blood, gastric juice and perspiration. Origin and Discharge. — It is introduced with the food and is also supposed to be formed in the interior of the body by double-decomposition as previously stated. Potassium chloride is discharged in the urine, mucus and perspiration. Function. — Its function is probably identical with sodium chloride. PROXIMA TK PRhXClPLKS. 10 Lime Phosphate, Ca^P^Og. — Lime phosphate is found in all the solids and fluids of the body, but is more abun- 3 In genous. There are two divisions, the carbo-hydrates and fatty matters. In the former the hydrogen and oxygen are in the proportion to form water, and in the latter the carbon and hydrogen arc in much larger quantity than the oxygen. Stauch, CjHioOs- — This substance, tliough not crystal- lizable, is so closely allied to the others in its general pro- perties, and so easily converted into sugar, which is crystallizable, that it is naturall}' included in the proximate principles of the second class. It is not amorphous, but pos- sesses a distinct granular form. It is found in nearly all the flowering plants, and is the principal ingredient in sago, tapioca, arrowroot, &c. (.)UANTITY OF STARCH IN 100 PARTS. In Rice 88 " Maize 67 ' ' Barley Meal 66 "Rye " 64 " Oat " 60 Wheat P'lour 57 Iceland Moss 44 Beans 33 Peas 37 Potatoes 20 Physical Appearance of Starch. — It is a white pow- der, consisting of solid granules, which vary in shape, size, and physical appearance, in different vegetables. It pro- duces a crackling sensation when rubbed between the tiu- gers. Each starch granule consists of two substances niin- gled together, Oleate of Glyceryl. ( Glyceryl (C3 lis ) ( Palmiilc Acid (Cia H32 O2 ) ) Palmitine < and > Palmitate of Glyceryl. ( Glyceryl (C3 H5 ) ! Stearic Acid {C18 H36 O2 ) ) and > Stearate of Glyceryl. Gylceryl C3 H5 ) ) These may be separated from each other by the process of saponification. When oleine, palmitine, or stearine, is boiled in a solution of caustic alkali, it is decomposed into a fat acid, as oleic, palmitic, or stearic, and a sweetish viscid fluid t \ fa s h I I- [ tt € Si. 30 PROXIMA TE PRINCIPLED . the hydrate of glyceryl, or glycerine. The acid unitea with the alkali and forms soap, and glycerine (C^H^SHO.) is set free. The fat acid may also be separated from the base, gly- ceryl, by passing steam through fat at a temperature of 300** (572° F.) The human body, when immersed in water for a length of time, becomes changed into a substance called adipocere, or saponified fat. This is supposed to be a pro- cess of saponification, caused by the union of palmitic^ stearic, and oleic acids with ammonia, which is developed during the ])rocess of decomposition. Physical Appearance and Properties of Fat, — It ex- ists in two forms in the body. First, in the form of large cells or vesicles, varying in diameter from ^?,,. to ^?,o of an inch (31 to 83 mmm.), as in adipose tissue, (Fig. 9.) Secondly^ in the form of oil globules, varying from ito.'mmt to jo'oo of an inch, (1.2 to G mmm.) as in the chyle, in which it is said to be emul^ ified, (Fig 7.) This is a mechanical subdivision of the fat Fiu-, Fig. 8. Fa': globules of chyle. Fat globules of cow 's milk. cells, and is the only form in which it can be absorbed. Fats may be emulsified by means of alkalies, serum of blood, muci- lage, or white of egg. The fat cell is characterized by a dark border surrounding a bright centre; usually no nucleus is seen,, but it may occasionally be found attached to the cell wall. It is generally rounded in shape, but is found irregular in outline, depending on pressure. The small globules appear as minutely dark granules, so as to give the fluid in which they float an opalescent appearance. In cow's milk, the oil globules are ^^'o^y of an inch (6.25 mmm.) in diameter, have a pasty consistence, due to the palmitine they contain ; PROXIMATE PRINCIPLES. 31 ftnd when churned, are converted into butter, from their tendency to cohere. Oleine, palmitine, and stearine, are . to n 1 I 1 I 32 PROXIMATE PRINCIPLES. FiK'. 10. Origin and Function. — It is found in all parts of the body except in the compact tissue of the bones, teeth, ten- dons, beneath mucous membranes, in the cutis, between the rectum and bladder, beneath the epicranial aponeurosis, iti the ligaments, scrotum and eyelids. It is introduced in the food, and is emulsified by the pancreatic juice during diges- tion and previous to absorption. It is also formed in the interior of the body. This has been proved by experiments on geese, the re- sult of which showed more fat in the body than could be accounted for by that which existed in the food. Another proof is, that it has been found in the form of globules in the interior of the costal, laryngeal, and tracheal cartilage cells, and also in the muscular fibre cell of the uterus during involution (Fig. 10,) It also exists in the form of globules in uterine muscular fibre cells. *^6 ^^P^^^« ^^^^^^ ^^^S' ^^^ SebaCCOUS two weeks after piirturitioii glauds, corpus luteum and uriniferous tubes of the carnivora. In the marrow of bones, it exists both in the form of oil globules, and fat cells forming adipose tissue. In some parts, it is formed from blastema supplied by the blood vessels, as in adipose tissue; in others it is formed as the result of a retrograde metamorphosis, as in the muscular fibre cell of the uterus. It accumulates in excess in cer- tain diseased conditions, as in fatty degeneration of the heait, liver, kidney. Its function in the foim of adipose tissue, is to give rotundity to the body ; form a nidus for delicate organs; fill up spaces other- wise unoccupied, and from being a bad conductor, to prevent the too rapid escape of the animal heat of the body. As an article of diet, it is necessary in the process of nutrition. It Fijf. U. Hepatic culls. PROXIMATE PRINCIPLES. 83 supplies animal heat, and is a store of food in case of emer- gency, as in the hybernating animals. Certain kinds of food favor the formation of fat ; for example, negroes employed in making sugar grow fat from the quantity of sugar they eat. It is said to accumulate more rapidly when the animal is fattened in a darkened room. Fat is absorbed from the body in some diseases, and its place supplied with serum, as in consumption. It is discharged by the sebaceous glands of the skin, and in the milk of the female during lactation. CholesteuinEjCojjH^^O. — Thissubstance may be described among the oils and fats. It is found in bile, blood, liver, nervous tissue, crystalline lens, and meconium. It differ? from ordinary fat in the fact that it is not capable of saponi- fication, is volatile at a high temperature and rotates a ray of polarized light to the left. It crystallizes in thin trans- parent rhomboidal plates, is insoluble in water, but soluble in ether, chloroform, hot alcohol, and volatile and fatty acids. When treated with sulphuric acid and chloroform it produces a peculia..^ red color, which soon changes on exposure to air to violet, blue, green and finally fades away. It melts at 14.5° (293°F) and distils at 3G0°. (G8()^ F). PROXIMATE PRINCIPLES OF THE THIRD CLASS. The substances belonging to this class are very important as they have an intimate connection with the active phe- nomena of living bodies. They are not crystallizable, and are not definite in their chemical composition ; that is, they do not always contain the same proportions of oxygen, hydro- gen, carbon, and nitrogen, but the relative quantities of these elements may vary, within certain limits, in different individuals, and in the same individual at different times, without changing in any material degree the peculiar pro- perties of the substance which they form. This is charac- teristic of organic substances. They all closely resemble albumen, hence called " albuminoid substances". Their re- action is neutral. They were regarded by Mulder as com- t C I. \ 1: % V C C 34 PROXIMA TE PRINCIPLES. pounds of a theoretical radical, which he called protein. This gave them the name of " protein compounds". The albuminoid substances are all hygroscopic. In some parts of the body they are fluid, and in others semi-solid, or solid, depending upon the amount of water which they contain. When subjected to evaporation they lose water, and may be leduced to a solid state. Advantage is taken of this fact in the preservation of eggs,, milk etc , by evaporating at a low temperature and hermetically sealing in cans. When water is added, they again absorb it, and return nearly to their original condition. They are all capable of being coagulated. Fibrin coagu- lates spontaneously, when removed from the vessels ; albu- men, on the application of a temperature of 71° (1G0°F.) ; and casein on the- addition of an acid. An organic sub- stance, once coagulated, cannot be restored to its original condition. It may be dissolved by certain re-agents, as e. g., the caustic alkalies ; but in this it only suffers a still further alteration ; nevertheless it is necessary to resort to coagula- tion to remove an organic substance from the other proxi- mate principles with which it is associated. FiVjrin is obtained by switching freshly-drawn blood with a bundle of twigs. Thus obtained it is an unnatural condition, having lost its original character of fluidit}^ These organic substances, when the vital force is removed, are liable to putrefaction. This process is peculiar to organic nitrogenized substances, and distinguishes them from all other proximate principles. When in a state of putrefac- tion, they are capable of inducing in certain other substances a process of fermentation, as for example, the decaying or- ganic matters of the grape give rise to fermentation of the sugar, converting it into alcohol and carbonic acid. The putrescent body is called a ferment, and acts by catalysis, or by its mere presence, having nothing to do chemically with the process. The conditions necessary to putrefaction are, the presence of oxygen, heat, and moisture. If oxygen PROXIMATE PRINCIPLES. 85 be excluded by boiling, and the substance be placed in her- metically sealed vessels, in an atmosphere of carbonic acid, or nitrogen, putrefaction will not take place. The same is the case if the substan ',e be dried, or if the temperature bo kept near the freezing or boiling points respectively. During the process of putrefaction, there will be observed swarms of minute microscopic organisms floating about in the fluid, called bacteria and micrococci, ^"i'■' 12 (Fig. 12) ; the former are so named from their rod-like form, and consist of two small cells placed end to end ; the latter are so called because of their minuteness, and appear like small specks. Both are in a state of inces- sant and rapid motion. Bacteria are in- creased by spontaneous subdivision of A.-Bactcrin. n. -Micrococci. the cell into two, each of them again subdividing, and so on. The variety found in putrefying infusions is known as the hacteriwni termo. They are believed by some to be vegetable organisms, which are spontaneously developed in the albuminoid substance, and cause putrefaction to take place. By others, they are supposed to be derived from germs floating in the air, and which become developed in putrefying substances. Albuminous matters are found in most substances used as food, the proportion according to Payen being as follows : QUANTITY OF ALBUMINOUS MATTER IN 100 PARTS. Beans 24.40 Mackerel 24.30 Peas 23.80 Beefsteak 19-50 Wheat 18.00 Oats 14-30 Oysters 14.00 Salmon 1 3- So Indian corn 12.50 Eggs 12.30 lUce 7.50 Potatoes 2. 50 Albumen. — This substance is named albumen from "Al- bus," white, on account of its appearance when coagulated. It exists both in the fluid and solid state in the body — fluid in the blood, lymph, chyle, cerebro-spinal fluid, serous and t e L I C f i b m Hi mt... 1 il PROXIMATE PRINCIPLES. synovial fluids, and milk, — solid in tho brain, spinal cord and nerves. It is also found in mucous membranes, muscu- lar tissue, and in tho a(iueons and vitreous humors of the eye. It exists in tho white of Qgg, and can bo easily coagulated or ma•> V Br an «'< ni :38 PROXIMATE PRINCIPLES. ^ition of the re-agents, and when boiled, the color changes from red to yellow, but no copper suboxide is thrown down. This test may be made to apply, by evaporating the solution to dryness, and making an alcoholic extract, then a watery solution of the sugar contained in the extract will respond as usual. It also interferes with the mutual reac- tion of starch and iodine, no blue color beiug produced. Origin and Function. — It is formed from the organic nitrogenized elements of the food, as fibrin, albumen, and casein, etc., by the action of the gastric juice during the process of digestion. It is absorbed in this state, and is converted into albumen in the blood. It is much more easily absorbed than albumen, on account of its superior osmotic properties. It is the soluble principle of fibrin, albumen, casein, &c. Fibrin. — Fibrin exists in the blood, lymph, and chyle as found in the lacteals. When blood is removed from the ves- sels, it soon separates into a solid portion, or clot, and a fluid portion, or serum. The clot consists Fig. 13. of coagulated Coaj,'ulatetl fibrin containing: white blood corpuscles. i fibrin, containing red and white corpuscles entangled in its meshes. When inflammation is present, the red corpuscles have a tendency to cohere, and sink to the bottom of the vessel, hence the fibrin is more abundant at the top, and from the PROXIMATE PRINCIPLES. SD- peculiar color it presents, is called the " buffy coat." Fibrin is difficult to obtain free from corpuscles. It may be ob- tained nearly pure, by switching freshly-drawn blood with a bundle of twigs. It coagulates on the twigs, and may be freed from impurities by washing. It is first washed with water, to remove the salts, then with alcohol, to remove the pigment, and ether, to remove fatty matters. Another mode is to filter frogs' blood, the corpuscles of which, being large, are kept back ; but the liquor sanguinis passes through, and the fibrin coagulates, and may be washed as above. A little thin syrup, or a weak solution of an alkali, should be added to retard coagulation during filtration. It is some- times found in a tolerably pure state, in the cavities of the heart and large arteries after death. It is also found arranged in lamina3, in the sacs of aneurisms. It is regarded by some as formed by the union of two substances in the blood, fibrinogen and fibrinojilastin, and by others as resulting from the decomposition of a substance called plasmine. Physical Appearance and Properties. — Fibrin is a greyish- white, tough, elastic and stringy substance, composed of microscopic fibrils. It possesses the property of " spon- taneous coagulation," or fibrillation. It is insoluble in water, alcohol, and ether, but is soluble in the alkalies. Three-fourths of its weight is water. When treated with acetic acid, it swells out, becomes soft and gelatinous, and slightly soluble in water. It may be dissolved in cold con- centrated hydrochloric acid, and after a time the solution ac- quires a blue color. When dissolved in the potash salts, it resembles albumen in its properties and reactions. When boiled in water, it forms binoxide and teroxide of protein. When boiled in hydrochloric acid, it yields " leucine " and " tyrosine." It is held in solution in the blood by the alka- line chlorides and carbonates. Coagulation. — The coagulation of fibrin is a process of fibrillation. When the process of coagulation is viewed with a microscope, a granular appearance is first noticed ; some of E •*. M I c. m Cv ki, CI 40 PROXIMATE PRINCIPLES. the granules become star-shaped by the addition of other granules, the arms being directed towards the corpuscles which are ultimately included in the meshes. When fully organized it is distinctly fibrous in structure, ooagulation of the fibrin takes place more slowly in the absence of the corpuscles, as in filtered blood. Certain vegetable sub- stances as wheat flour, contain an albuminous matter very similar to fibrin, called gluten, or vegetable Jlbrin. Origin and Function. — Fibrin is formed from albumen, by the influence of the corpuscles and oxygen ; in other words, it is albumen in a higher state of organization. It gives to the blood its property of coagulation, and it is through this property that " natural hsemostasis" is effected. It gives to the blood its viscidity, and prevents it from, exuding through the coats of the vessels. It was formerly supposed to be the material which was thrown out, and sub- sequently became organized, in the repair of wounds, and in inflammation, under the name of " coagulable lymph" Lymph is now generally believed to be the product of the white corpuscles, which have passed through the coats of the vessels by virtue of their amoeboid movement, supplemented by the proliferation of connective tissue elements in the wounded or inflamed parts. Fibrin was by some considered as effete matter, formed from the worn out elements of the blood and tissues, and the argumcniis adduced in favour of that view were, that it was increased in bleeding and starvation ; that there was none found in the renal veins, having been discharged by the kidneys ; that there was very little in the blood of the foetus ; none in the egg ; none in the chyle until it entered the lacteals, and then only as the result of the additions made to it from the blood or lymph. Casein. — This is an albuminous principle found only in milk. It is held in solution by the alkaline carbonates, and when any of the organic or mineral acids, or magnesium tiulphate is added, the alkali is neutralized, and coagulation of PROXIMATE PRINCIPLES. 41 of the casein follows. It is also coagulated by a solution of rennet, the abomasus, or fourth stomach, of the young of ruminants. The pepsine contained in the stomach has the power of converting the sugar of milk into lactic acid, which neutralizes the alkali, and causes a precipitate of casein. This is a catalytic process. Casein is also coagu- lated during a thunder storm ; a substance called ozone is developed in the atmosphere, which acts on the casein and decomposes it. The decaying casein acts as a ferment, and converts the sugar of milk into lactic acid, which precipi- tates the casein. Casein differs from albumen ; it is not coagulated by heat, and is precipitated by organic acids. The precipitate of casein may be re-dissolved by a solution of caustic alkali. It is insoluble in water and alcohol. An albuminous substance called vegetable casein is found in beans, peas, &c. Origin and Function. — It is formed from the albumen of the blood by a catalytic process in the mammary gland. It has been found in the blood of puerperal women. Casein may be obtained in a nearly pure state, by precipitating it with acetic acid, and then washing the precipitate witli alcohol and water. It is the chief aliment of the young of the mammalia, and the substance from which all the tissues are formed. Globuline. — This is a semi-solid substance found in the crystalline lens, in the blood globules, and in the structure of cells generally. It is coagulated by heat, alcohol, and the mineral acids. It is soluble in water, but not in the liquor sanguinis of the blood. The coagulum of globuline is partly jjoluble in hot alcohol ; this distinguishes it from albumen. Acetic acid causes it to swell out and become transparent. The globuline of the crystalline lens is called by some " Crystalline" It is more easily coagulated than globuline. Pepsine. — This is the organic principle of the gastric juice. It is coagulated by heat and alcohol, and is with L mi t r c £ 42 PROXIMATE PRINCIPLES. difficulty distinguished from albumen. It exists in the gastric juice in the proportion of fifteen parts per thousand, from which it may be precipitated and extracted by means of alcohol. The solvent power of the gastric juice depends on the presence of pepsine. This will be discussed in the chapter on digestion. Pancreatine. — This substance exists in the proportion of ninety parts per thousand in pancreatic juice. It is a viscid fluid, coagulable by heat, alcohol, and strong acids. It is coagulated by magnesium sulphate ; this distinguishes it from albumen. It has the property of emulsifying oils and fats, and of converting starch iiiiu sugar during the pro- cess of digestion. It is formed from the albumen of the blood in the pancreas. Ptyaline is an ingredient in saliva, and gives it the pro- perty of converting starch into sugar. It is not coagulated by nitric acid or acidulated potassium ferrocyanide. This distinguishes it from albumen. It is precipatated by alco- hol and boiling, and in the latter case loses its power of con- verting starch into sugar. Mucosine. — The organic substance of mucus is termed mucosine. In some of its properties it resembles albumen. It is coagulated by alcohol and acids, but not by heat, or the metallic salts. It lubricates the free surface of mucous membranes, and is formed from the blood by the agency of the cells, which line the free surface of the membrane and its follicles. Musculine or Myosine is a semi-solid substance peculiar to muscular tissue. It is insoluble in water, but is soluble in a mixture of ten parts of water with one of hydrochloric acid, and may be precipitated again by neutralizing with an alkali. It is a most important element of animal food, and is the great source of albumen and fibrin. Cartilagine is the organic ingredient of cartilage. By prolonged boiling, it is transformed into a substance called mal gi. PROXIMATE PRINCIPLES. 43 COLLAGEN- liganients, etc. mal matter. " L'elatine " or " chondrine." It is precipitated by acids and some of the metallic salts ; this distinguislies it from " gelatine." This substance is peculiar to bones, tendons, It constitutes the principal part of the ani- By prolonged boiling, it is converted into " glue," and is then soluble in water. Elasticine. — This is the organic principle of the yellow elastic tissue. It is not soluble in water, alcohol, ether, or acetic acid, but is dissolved and decomposed in nitric, sul- phuric and hydrocliloric acids, and these solutions are not preci))itated by alkalies. Keratine. — This is an organic substance, found in the epidermis, nails and hair. It is not affected by boiling in water, alcohol, ether and dilute acids, except by continuous boiling in a Papin's digester at 150° (:302°F). COLORING MATTERS. The substances of this group give to the tissues and fluids their distinctive coloration. They are all supposed to bo crystal lizable, and formed from the coloring matter of the blood. The coloring matter may be removed from the fluids of the body by filtering through animal charcoal, which has the ])roperfy of removing coloring matter from any fluid. Animal charcoal will also remove albuminous matter from any fluid containing it. The most abundant and important of the coloring matters is Hemogi^ohine. — It is analogous in manj'' respects to chlo- rophyl in the vegetable kingdom, for while hemoglobine is the agent on the one hand by which oxygen is carried into the system, chlorophyl, on the other, is the agent by which carbonic acid and water are decomposed and oxygen set free in the vegetable. It exists in the blood corpuscles in the proportion of 25 to 30 per cent., and also in muscular tissue. It is soluble in water, dilute alcohol, and alkaline salts, but is insoluble in strong alcohol, ether and oils. It crystallizes out in rhombic or hexagonal plates or prisms* 3 c r L mi r i Br •*. •U *'i Ri 1 I U A 44 PROXIMATE PRINCIPLES. differing in different species, and also in the same species under different circumstances. It is easily decompojed. Its characteristic property is its great power of absorbing oxy- gen, which it holds in a free state, until it yields it up to the tissues. When charged with oxygen it becomes bright red, and is called "oxidized" or scarlet hemoglohine ; whendeoxi- dized,it assumes a purple color,and is called "reduced" or pur pie hemoglohine. It contains 4.2 parts iron per thousand, which is essential to the blood. This is not in the form of an oxide, but is combined with carbon, hydrogen, nitrogen, and oxygen of which it is composed. Iron is also found in the coloring matter of the hair, bile and urine. The blood of an ordinary sized man is said to contain 2.8 grammes (43 grs.) of iron. When the red blood corpuscles are broken down from any cause, the hemoglohine is set free, and the walls of the vessels and tissues are stained. This has been mistaken for arteritis. When the hemoglohine is deficient in the blood, as in anemia, etc., it may be restored by the administration of iron. Melanine is a brownish-colored substance, found in those parts of the body where pigment exists, as in the choroid coat of the eye, iris, epidermis and hair. It is very abun- dant in the epidermis of the negro. It is formed from hemoglohine, but contains less iron. The coloring matter is the same in all situations, the different shades being pro- duced by the arrangement of the pigment cells among the fibres and capillaries of the tissue. In some cases it is entirely absent, as in the " albino." It is insoluble in water alcohol, ether and dilute acids, but is soluble in caustic potassa. BiLiRUBiNE is formed from hemoglohine in the liver, and constitutes the yellowish-red coloiing matter of the bile. It is crystal lizable, insoluble in water, but soluble in alcohol, ether, chloroform, and alkaline fluids. It responds readily to " Gmelin's bile test," — nitroso-nitric acid. If a small quan- tity of nitric acid be dropped into a solution of bilirubine PROXIMATE PRINCIPLES. 45 to w^hich nitrous acid is previously added, a play of colors is produced in order as follows, — green, blue, violet, red, arul yellow. Bilirubine, if rendered alkaline, and exposed to tlie air becomes changed into biliverdine. BiLiVERDiNE is the greenish coloring matter of the bile. It is more abundant in animals that feed upon vegetable food. It is insoluble in water, ether and chloroform, but is soluble in dilute alkaline solutions, alcohol, and acetic acid. It is believed to be formed from bilirubine. It is discharged from the body in the faeces. It is often found in gall stones. Urochrome or Urosacine is a yellowish-red coloring matter peculiar to the urine. It is found, also, in urinary calculi. It is probably the worn-out hemoglobine of the blood, which is being discharged by the kidney. Urosa- cine and the coloring of bile arc both discharged from the body, the one in the urine, and the other in the fieces. It is soluble in water and in ether, but only slightly so in alcohol. LUTEINE is a yellow coloring matter found in yolks of eggs and the corpus luteum. It is crystallizable, insolu- ble in water, but soluble in alcohol, ether, chloroform, and oils. It is easily decomposed, and nitric acid added to it gives a blue color. CRYSTALLIZABLE NITROGENOUS MATTERS. The substances of this group are crystallizable, and with one or two exceptions are derived from the nitrogenous mat- ters of the body as the result of retrograde changes. They are lecithine, cerebrine, leucine, and the substances found in urine and bile, as urea, creatine, creatinine, urates and hippu- rates of soda, glycocholate and taurocholate of soda. The latter will be described with urine and bile respectively. Lecithine, formerly described as a phosphorized fat is found in blood, (.4 parts per thousand), bile, spermatic fluid, yolk of egg and nerves, also in certain vegetables. It is c t L »; ■» I I an icr MS Wi t J I J 46 PRIMARY FORMS OF TISSUE. Holuble in alcohol, ether, chloroform, and oils, and is easily decomposed. Water swells it up into a pasty mass, and j^ives rise to so-called " niyeline forms," an appearance resembling " myeline " or medullary layer of nerve fibre. It contains phosphorus. CLiREniiiNE exists only in brain and nerves, and is more abundant in the white than the gray substance. It is a whitish substance, insoluble in water and ether, but is solu- ble in boiling alcohol and deposits again on cooling. Heated in the air it turns brown and burns readily. Leucine is found in small quantities in the kidneys, si)leen, liver, pancreas, brain and glandular system. It crys- tallizes in whitish glistening laminus and is soluble in water and alcohol, but insoluble in ether. Little is known regarding the origin and physiological relation of these sub- stances. CHAPTER IL ELEMENTARY OR PRIMARY FORMS OF TISSUE. The elementary or primary forms of tissue are cells, granules, simple fibres, and simple or basement membranes. Of these, the cells are the most important, since they are the active agents in the performance of aiJ the functions of the animal body, as digestion, absorption, selection, assimi- lation, respiration, secretion, excretion and reproduction. They also constitute the fundamental elements of all the tis- sues, and are the active agents in all the catalytic and chemico-vital changes which take place in the animal eco- nomy. The agency of cells is not only exhibited in the healthy actions of the body, but may also be seen in the de- velopment of various morbid growths, as fibroid tumors, cancer, etc. The form which organic matter takes when it passes from the condition of a proximate principle to that of an organized structure, is that of a cell, a simple fibre, or a simple membrane. PRIMARY FORMS OF TISSUE. 47 In all animal and vegetable tissues, there exists a soft gelatinous or albuminous substance called 'protoplaHrrit sarcode, cytoplasm or " (jervtlnal mattev." It is transparent, of the same consistence in all parts of the body, and by the action of the vital forces may be formed into small rounded masses or cells, or thin hyaline membranes. It possesses properties and exhibits phenomena which are called vital, such as the movement of molecules in its substance, and the changes in the shape of the mass itself. CELLS. A cell may be defined to be a semi-solid rcjunded mass of protoplasm, or it may assume the form of a membranous sac enclosing proto[)lasmic or other contents. In the in- terior of most animals cells will be seen a small body termed the nucleus,jai,nd within the nucleus, a. nucleolus ; or there may be two or more nuclei,each containing one or more nucleoli. Vakiation in Shape. — Cells are generally globular, but may as- sume various shapes, depending on internal and extei'ual circumstances, and the growth of the cell ; for ex- ample, fat cells which are round when formed, may become poly- gonal as the result of mutual pressure (Fig. 9.) The specific gra- vity of the contents will also atfect i^} the shape to a considerable extent, clear -'ianrco When water is added they have a ^gSef'^ '^'"'"^ corpuscle, (k) Fat tendency to swell out and finally burst. When evaporation or desiccation takes place, they become flattened and hard- ened, as in the epidermis. The shape of the cell may also be changed by the absorption of gases and vapors, e.g., the blood corpuscles present a distinctly biconcave disk under the influence of oxygen, and become rounded again when Fits. 14. Xcrve cell. (h) -NucleoluB. (d) Oaiiiflion corpus- nuclei, (e) Multiiui- ccU from bone marrow. )— Nucleus. c 91 f ■T t 48 PRIMARY FORMS OF TISSUE. riu'int-iit Cells. exposed to the influence of carbonic acid gas. The vapor of ether, when inhaled, produces an irregular appearance of the blood corpuscles. Chloroform vapor causes a serrated out- line, and alcohol renders them oval, with an indentation on one side. KiK. 1"'. Cells may also assume different shapes, depending on their growth ; for example, the pigment cell, which is at first spheroidal, throws out arms or projections in different directions, and becomes stellate during its growth. The nerve cell becomes unipolar, bipolai-, or multi- polar ; nonstriated muscular cell, fusiform. Epithelial cells are either cylindrical (columnar), or squamous (tesselatcd or pavement.) In some instances, hair-like growths take ])lace on the free surfaces or ex- tremities of cells, as is seen in thc| cilia of epithelial cells. Some cells undergo a spontancoufi change in^^J,,,,,,^^ „,,i„.^,i„,„ ^^ t,,e shape, as the amuilinj, white corpus- ^^^^ ^,;-'^;;^|;;;r^,iatc.) qntueiium cles, etc. "' ^'•'-' "•""''• Variation in Size. — Cells vary in size from ^i^ of an inch (83.5 mmm.) in diameter, the size of the largest fat cell, to ^ooo.) of an inch, (1.25 mmm.) the size of the fat globule. Some are so large as to be called giant cells, as those of bone marrow (Fig. 14, e.), and abnormal tumors, as cancer, sarcoma, etc. The average diameter of the red blood corpuscle is about ^-aVo of an inch, (7 mmm). Nerve cells vary from ^i^ toxoioo of an inch (83.5 to 2.5 mmm; muscular fibre cells Tfy'jnr to -^rhr^ of an inch, (5.5 to 10 mmm.) in diameter. The cell may be divided into a cell wall, nucleus, nucleolus and contents. Cell Wall. — The cell wall, when present, is substan- tially the same in all cells, and is formed by the consolida- tid a an int sor un iti vie PRIMARY h\ RMS OF TISSUE. 49 tion of the outer surface of tlio mass of protoplasm. It is a simple homogeneous membrane, composed oi globuline, and although no pores can be seen by the highest magnify- ing power, yet it possesses the property of osmosis. In some instances it is extremely thin ; in others dense and unyielding. When the cell-wall is acted on by acetic acid, it swells out and becomes transparent, so as to bring into view the nucleus, when that body exists. Nucleus. — In the interior of most animal cells is seen a small body, which is called the nuckus. It exists either in the form of a small vesicle, or as a small mass of proto- plasm, containing one or more minute particles termed nucleoli. The nucleus is generally situated in or near the centre of the cell, but may be attached to the wall, or imbedded in it, as in the fat cell. It is generally rounded in form, but may be found elongated, as in the nonstriated muscular fibre cell. The size of the nucleus varies from Tir'oTs to oT,V() of an inch (6 to 4 mmm.) in diameter. It is more regular, both in shape and size, than the cell itself. In most instances each cell contains but one nucleus ; cartilage cells frequently contain two or more. When two or more nuclei are found in one cell, it is generally an evidence of rapid growth, as in fibro-cellular tumors, cancer, pus, etc. In giant cells there may be a multitude of nuclei in each cell (Fig. 14 e.). They are, in these cases, formed by the subdivision of the original nucleus. The nucleus resists the action of acids and alkalies better than any other part of the cell. It is readiiy stained by ammoniacal solution of carmine, and hence is regarded by Beale as gevminal ^matter in contra- distinction to the outer portion of the cell, which he calls formed matter. Nuclei are sometimes found disconnected from the cells, when they are said to be free. They may be found floating in fluid as in certain secretions, or imbedded in a homogen- eous pellucid substance, as in rudimental cellular tissue, or c c t I C: I Kit so PRIMARY FORMS OF TISSUE. on tho surface of fibres, as in muscle and nerve fibres, in which they are either upon or inunediately beneath the investing membrane. The nucleus is a most persistent little body, and retains its original form in many cases after the cell to which it belongs has ceased to exist as such. Nucleolus. — This is situated. in the interior of the nu- cleus, and may consist of a single molecule, or a number united together. In some instances it is highly refracting, and not readily acted upon by most chemical re-agents. There may be one or more in each cell. Contents. — The contents of all cells consist of a certain amount of protoplasm mingled with other substances. Each cell has the power of generating in its interior a sub- stance peculiar to itself, which is the result of its own se- cretion ; one secretes bile, another milk, another mucus, another gastric juice, etc. The contents of the cell may be either solid, as in bone, nails, epidermis, etc., or fluid, as in blood, chyle, mucus, etc. The contents of all cells are fluid when formed, but become hardened by secondary deposit, as in bone, dentine, etc. This takes place by the deposition of solid particles in the interior of the cell.' Color. — Cells are generally colorless ; a few only have color which depends partly on their refracting power, and partly on the hemoglobine, melanine, or pigment which they contain, as the red blood corpuscles, pigment cells, etc. Protoplasm, or Cijtohlastema. — This is the name given to the substance from which the cells spring, and is derived either from the fluid in which they float, as blood, chyle, lymph; or from the capillaries near the seat of growth. When the cells are situated on a basement membrane, as the epithelium of mucous and serous membranes, it is found surrounding them, having passed through the basement membrane from the capillaries immediately beneath. In all these cases the cytoblastema contains material not only to supply the wants of the present brood of cells, but also for the development of the new brood which is destined to take the place of the old. the bt)ui and For PRIMARY FORMS OF TISSUE. 51 Tliocoll has alno tho power of choosinjj and ret'u.siii*j from the particles of nutrient fluid or cytohhisteina in its neigh- bourliood, incorporating some of them into its substance, and converting others into new substances in its interior. For example, the blood cori)usele has the power of forming globuline and hemoglobine from the albumen and fibrin of the blood. It is Cv^iitended by some physiologists that this power resides solely in the nucleus ; but it must be borne in mind that this property belongs alsc to those cells which are entirely destitute of a nucleus, as the blood corpuscle, germ cells of the vegetable kingdom, etc. Cytooenesis. — KwTor "cell" and '^iitui "generation." evils have their j^eriod of birth, growth, maturity,aud decline. They spiiug up, ])erform their ottice, and then pass away. Some do so witli great rapidity, while others are slower in their progress, or are longer lived. They are governed by certain laws, two of which we may here formulate. Xst Law. — In all tissues composed of cells, the new cells which are being developed must resemble the ]jarent cells in all their distinctive features and properties. When the young cell deviates in its character from the parent cell, abnormal growth may be said to have commenced. ^nd Law. — Cell growth can only take place in or near its appropriate pabulum, and on living surfaces. The mode of origin of cells takes place in several ways. Schleiden and Schwann, as far back as 1838, asserted that cells were developed de novo in an organizable blastema. According to this theory the cell was developed by the foi-- matiou of granules in the blastema, their subsecjuent ar- rangement to form the nucleolus, around which at a certain distance was formed the nucleus, and lastly the cell wall and contents ; or the order might be reversed by the for- mation, first of the cell wall, and subse(iuently the nucleus and nucleolus. This theory oi free cell formation still has its advocates among many French physiologists, especially Robin. c c 1^ c 1. 1* ■: •*t «i t .1 *» 1 r 1 c. £ «.• •»* m B« H-> «' 1 M»r.4 52 PKIMAKV FORMS OP TISSUE. According to the modern doctrine, which was first advo- cated by Virchow in 1852, every cell must originate from a pre-existing or parent cell {omnis cellula e cellula.) There are three difi'erent modes by which cells may bo produced in this way. 1st. By Midfi plication by suh-divif^ion,^ss\on, orfis.sip- arous multiplication of the cell. This process has been seen in the anui4)a, and in the blood corpuscles of the lower animals. The cartilage coll also fmnishes a good example. The cell is originally rounded ; but when the process of subdivision commences, it becomos oval, and subsequently ]>resents a sort of hour-glass contiaction, first of the nu- cleus, and afterwards of the cell. This continues until Fiji. 17. there is a complete separ- ation, first of the nucleus i uto two parts, and then the cell, each ]iart of the nu- cleus drawing a })ortion of the coll or cell- wall around it. This process may be A ifll midoi'Ljoiiij;' till" lUMfoss of multiiilioiitioii . •. . , i.y siiii.iiviMoii. ^iO ()n,i;inai ivii. (1.) Oval, agaiu repeated in each (c)— Uinir-j;liis» ooiitnu'tion and division of tlie . , . ., tiucii'ii!,. ^d) Division of the loii into two. y)art, Cither lu tliG .sauio direction or transversely, so as to form four now cells, and so on until a number have been produced. This is the mode by which segmentation of the vitellus takes place. 2nd. By subdivision of the nucleus or contents of the cell only, the so-called ondojjfonous mode. In this mode the ' '^ '^ nucleus a[)pears to sc})arate into two or mora parts, each of which is developed into a new coll, and in this way the parent cell may be filled by a wb.olo brood of young cells, the so- This variety of cell development may be observed in bone cells, (Frey) also m structures of very rapid growth, as in cancerous tissue. 3rd. By gemmation or budding. In this case a node or swelling is setu on one side of the cell which gradually in- A cell containing a called daughter cells, number of joung oells. o PRIMARY FORMS OP TISSUE. $5 creasing, finally drops off by constriction at the base. The yeast cell is propagated in tliis manner. Dr. Bealo accepts the modern doctrine, and the term "pro- toplasm " as the substance from which cells are formed, but makes a distinction between the nucleus, which is readily stained with carmine, and the rest of the cell. Ho terms the nucleus " germinal " or living matter, in contra- distinction to the outer ])ortions of the cell, which he calls "formed matter," designating by the latter, the various tis- sues formed from cells. Conditions nkckssar\ to Ckll Gkowth. — The condi- C! tions necessary to cell growth are the pjesonce of protoplasm C upon a living surface, a certain degree of animal licat, a re- S^ quisite amount of water, oxygen, light and electricity. The |, dynamic agency of heat cannot be dispensed with ; too juiich r* would be injurious. The mysterious iulluence of light is necessary to healthy action, and a certain amount of water is required to preserve the integrity and piomote the growtli ■ 'J of the cell; but too much would destroy it. ranes, because they furnish the germs of these cells. They are also called hyaline.membranes, because of theirstructureless appearance. Basement membrane is found on all the free surfaces of the body, giving support to the epithelial cells. It forms the outer layer of the true skin, and the inner layer of mucous serous and synovial membranes, blood-vessels and lym- phatics. It is also prolonged into ali th? ducts, follicles and tubuli connected with the mucous membranes. In all these examples its free surface is covered with cells, which receive their nutriment by osmosis, through the membrane, from the capillaries on its attached surface. Its office is to limit osmosis of the nutrient fluid, and to modify it in its passage. It also supports the cells, and probably determines the formation of all the cells which are developed on its surface. In all probability, the spots, or nuclei, seen in the basement membrane are the germs of cells, which spring from them as from a centre. r c c I. I- m m\ J ■ ( I CO TISSUES. CHAPTER III. TISSUES. There are seven distinct tissues in the body viz : white fibrous or connective, yellow elastic, adipose, cartilage, bone (including dentine and enamel), muscle and nerve tissue, to which may be added gelatinous tissue and reticular con- nective tissue of modern histologists. All other tissues are made up of a combination of two or more of these. All, ex- cept muscular and nerve tissues are considered by some to be modified forms of connective tissue, and are described as the connective tissue group. WHITE FIBROUS, OR CONNECTIVE TISSUE. This tissue enters into the formation of ligaments, tendons aponeuroses and membranes. 1st. As ligaments, it connects the bones together and pre- serves the integrity of the joints in their various move- ments. The ligaments assume three different forms : Fu- nicular, which consists of rounded cords of fibrous tissue, as the ligamentum teres. Fascicular, which consists of flattened bands, as the ligaments of the ankle, knee, and elbow ; and Capsular, which forms tubular expansions, as in the shoulder and hip joints. 2nd. As tendons, it serves to connect the muscles to the bones and other structures to which they are occasionally attached ; some of these are round — Funicular, as the ten- don of the semi-tendinosus ; others flattened — Fascicular, as the semi-membranosus. The tendons, at their insertion in- to the bones, blend with the periosteum. 3rd. As aponeuroses. These are tendinous expansions of considerable extent, as in the abdominal muscles. They serve to enclose cavities, and protect the contained organs. 4 vari peri driu are P beai neoi whi inte foun mm ous Com (b)Elt deoli, (1.6 rate( CONNECTIVE TISSUE. 61 ^th. As memhranes, it is used to cover, protect, and attach various organs, as the dura mater, sclerotic coat of the eye, pericardium, tunica albuginea testis, periosteum, perichon- drium, fascia lata, &,c. In all the above, a few elastic fibres are found associated with the'white fibres. Physical Appearance and Properties. — It presents a beautiful, silvery- white appearance, when freed from extra- neous substances, and is composed of bundles of fibres, which are parallel to each other in some cases, and cross or interlace in others. Exa 'ned under the microscope, it is found to consist of wavy bands about too of an inch (50 mmm) in diameter (Fig 20, a.) They are formed of numer- ous fibrillse, varying in size from irlinr to tehji^ of an inch Fig. 20. Connective and elastic fibres, (a) Connective fibres, having some embryo. Ac crlobules* (b) Elai^tic fibres, (c) Curly elastic fibres, like horse hair. (d) Nuclei of cells, with nu- cleoli, X 820. (Todd and Buwman.) (1.6 to 1.2 mmm.) The bands are, capable of being sepa- rated into fibrillae, and have a tendency to split up in a r c c I. I* r w tni . t A 1 It » I 62 TISSUES. longitudinal direction. When a portion is exposed to the action of acetic acid, it swells out and becomes semi-trans- parent, the fibrilhc are entirely obliterated, and a number of connective tissue corpuscles make their appearance, showing that it has been developed from cells. At the same time some wavy transverse lines may be seen at regular distances, which somewhat resemble striped muscular fibre. These lines mark the junction or outline of the cells from which the tissue was originally formed. A number of wandering cells (white corpuscles) and connective tissue corpuscles, are always found in connection with fibrous tissue. This tissue is somewhat elastic, and allows of a slight degree of exten- sion from long-continued force. It possesses no contractility, and its force of cohesion is very great. It is said that the tendo-achillis is capable of supporting a weight of nearly 1,000 lbs. It contains few vessels and nerves. The actual presence of nerves has not, as yet, been satisfactorily demon- strated, and its sensibility is very low. The division of a tendon is attended with very little pain. It yields gelatine, on boiling. YELLOW FIBROUS, OR ELASTIC TISSUE. It is -found in the ligamenta subflava, ligamentum nuchte of quadrupeds, internal lateral ligament of the lower jaw, stylo-hyoid and pterygo-maxillary ligaments, chorda3 vo- cales, crico- thyroid and thyro-hyoid membranes, posterior wall of the trachea, arteries, veins, thoracic duct, and in areolar tissue. Physical Appearance and Properties. — This tissue, un- like the preceding, is of a yellowish color, highly elastic and consists of long, single, brittle fibres, with sharply defined dark borders, which show a disposition to curl upon themsel- ves when broken (Fig. 20, b). They vary in size from ^oVw to T50GO of aii inch (5. to 2.5 mmm.) the average diameter being about y^\^^ of an inch (3.5 mmm.) and are round or flattened — depending oij their situation or pressure. They ana! por sue. ELASTIC TISSUE. (J3 anastomose with each other, and are mingleil in varioiis pro- portions witli tlio white, to form areolar or connective tis- sue. It yields a modified form of gelatine on prolonged boil- ing; is not acted on by acetic acid, and is not readily dissolved by the gastric juice. The fibres are stained red, with Millon's re-agent (a solution of proto, and pernitrate of mercury). It resists the approach of disease longer than any other tis- sue in the body ; e. <;., an artery will remain intact in the interior of an abscess after the other structures are destroyed, and when the artery gives way, the walls present a honey- combed appearance.on account of the destruction of the white fibrous and muscular tissues with which it is associated. When dried it becomes dark colored, hard and loses its elasticity. It is sparingly supplied with blood vessels and nerves. The fibres are marked by transverse lines, in the lower animals, which shows that it is developed from cells. Its elasticity is impaired by age. Mode of Development. — This is now believed to be the same in both connective and elastic tissue. They were sup- posed by Heul5 to be developed V)y the process of fibrillation. Their real mode of growth was first pointed out by Schwann, to be from cells. The cells are at first round, and possess a nucleus, nucleolus and granular matter. They then become fusiform, or stellate, surrounded by intercellular substance, and being applied or spliced in a linear manner, coalescence takes place,and fibrillse are formed (Fig.21). At the same time the nuclei become elongated, and finally ^''^- ^^• disappear, until brought into view by means of acetic acid. According to late observers a certain amount of material is formed by the cells, called iissite cement or intercellular sub- stance, in which the cells become im- bedded, and which serves to unite them together. This substance blackened by nitrate of silver (Frey) ^i^p-^ -»«• (b). -ar^eBrauuiar c c r I. 1^ »; m\ I c r 1 I ► *-, »» mi Cells of human connective tis- IS sue. (a), flat stellate or shovel- 64 T/SSl/ES. Arkolar Tissue, (Syn„ cellular, connective or filamen- tous.) This tissue is found in all parts of the body except the brain, compact tissue of bone, teeth, cartilage, hair, nails, epidermis, etc. It consists of a network formed by a combination of white fibrous or connective tissue and yellow elastic tissue, together with a number of connective tissue cor- puscles. Where great strength is required, the connective tissue predominates, and where motion is necer..sary, the elastic, as in the tit'sue of the lungs. The proportion of each may be easily demonstrated by acting on it with acetic acid, whljh dissolves out the whitp, while it produces no change on the yellow. The interstices or meshes (impro- perly called cells) of areolar tissue communicate with each other. This tissue, therefore, may be inflated with air (the butchers take advantage of this circumstance in inflating their meat), or the meshes may be filled with fluid, as in anasarca. The interstices, especially in the subcutaneous areolar tissue, are partially filled with fat cells, and contain a small quantity of serous fluid of an alkaline reaction, composed of water, albumen (.36 in 100) and todium chloride. When the fat is absorbed by the demands of the system, its place is filled with serous fluid, as in phthisis. ^U^X'TION. — Its function is to surround and connect various organs, and retain them at certain distances ; at the same time allowing a certain amount of motion. It also forms a nidus for the vessels and nerves, fills up snaces between different organs, and when the meshes are filled with fat, gives rotundity to the body. In some parts of the body it is very dense, and has received the name of a fibrous membrane, as in the phar3'^nx, sheaths of vessels, etc. It forms sheaths for the muscles, and the bundles and fasciculi of which they are formed. It also forms sheaths for the vessels and nerves. It attaches the membranous expansions as the rcucous, cutaneous, serous and synovial membranes, to the structures M'^hich they surround and embrace, and re- ceives the name of sub-mucous,sub-cutaneous,sub-serous and sub-synovial areolar tissue, respectively. Tl cells in w fouii bon( of muc anc euro ADIPOSE TISSUE. 65 ADIPOSE TISSUE. This was formerly described as areolar tissue, with fat cells imbedded in its meshes. It exists hovr-ever, iu parts in which not the slightest trace of areolar tissue can be found, as, for exam[>lu, in the cancellous tissue and marrow of bones. On the other hand, the areolar tissue in many parts of the body is entirely destitute of fat, as e. (j., beneath mucous membranes, in the cutis vera, between the tectum and bladder, in the cranial cavity, eyelids, epicranial apon- eurosis, scrotum, penis, etc, but in other parts of the body they are associated together. Adipose tissue is found in abundance in the subcutaneous areolar tissue, called panni- cuius adiposua. It is entirely absent in embryonic life. Physical Appearance and Properties. — Itiscompo.ed of cells or vesicles containint; fat, which vary in size from joa to -J J^ J of an inch (83 to 31 mmm) (Fig. 2J ). They are usually deposited in cluisoers, being held together by a mesh of capillaries, which surrounds them, and fi-om which fig. 22. they derive their nutiinnent This constitutes a lobule. When the adipose tissue ex- ists in considerable quan- tity, the lobules are held to- gether by areolar tissue, con- stituting a mass of fatty tis- sue. It is abundantly sup- plied with blood-vessels, but Fat cells of adipose tissue. Donerves or lymphatics have been traced into its substanee. At an early period of its formation, the cell or vesicle possesses a nucleus and nu- cleolus, the nucleus being imbedded in the cell-wall ; but they disappear at maturity, being obscured by the oily con- tents of the cells. The cells or vesicles are round, when isolated^ but become polyhedral from the flattening of their walls against each other. They are believed by some to ori- c I. h »; ■II mr, 1*1 ^ fiG TISSUES. ginate from connective tissue corpuscles by their transforma- tion into fat cells. They are long-lived, and cxosmosis of the fat is prevented by the constant moistening of their walls, by a thin serous fluid which surrounds them, on the same principle that a moist bladder will retain fatty matter, while a dry one allows it to exude. The cell wall in fat cells can bo distinctly seen in a collapsed condition, after dissolving out the fat by means of etlier ; the nucleus Is then also readily seen by tinging with carmine. Origin and Function. — This tissue is formed partly from the fat used as food, and also by a chemical transfor- mation from the starch and sugar ])resent in the ditterent articles of diet. This process is accelerated by an imperfect su|)ply of oxygen, as is seen in the fattening of animals which are closely penned up. It is also formed in the interior of most cells of the body, when undergoing retro- grade changes, as in fatty degeneration. It fills up spaces otherwise unoccupied, gives rotundity to the body, forms a delicate pad or cushion to facilitate the action of movable ])arts, as at the base of the heart, behind the eye-ball etc., and from being a bad conductor of heat, it prevents its too rapid escape from the animal body. This is exemj^lified in those animals possessing little hair on their skin, in which there is a large quantity of adii)ose tissue beneath tl'a integument. In other instances it gives ease to the gliding movements of parts, and protects them from the ill effects of sudden changes of tem])erature, as the adipose tissue of the omentum. As fat, it supplies combustible material for the maintenance of the animal heat of the bodv. It is stored away in the body, to be used, when necessary, to maintain animal heat, and as a sourcQ of nourishment, as in the hyberuating animals, the process of absorption of fat being facilitated by the alkaline condition of the serous fluid by which the cells are surrounded. (See oils and fats). Tl parti- CARTILAGE. 67 CARTILAGE. This is a very simple form of tissun, and is found in many parts of the body. In some of the lower animals, as fishes, the skeleton is formed entirely of this tissue, as the skate, sturgeon, etc. Physical Appearance and Properties. — Its color va- ries from pearly white to light yellow, and it is possessed of a considerable degree of elasticity, flexibility and cohesive power. It yields chondrinc, when boiled. Cartilage con- sists of cells imbedded in a hyaline or inter-cellular sub- stance, or matrix. The cells ,,|^, o.., are contained in cavities or lacunjio in the intercellular substance. Some of these cavities are lined by a thin membrane, the cartilage cap- sule ; in other instances the cells appear to blend with the intercellular substance (Fig. 23). The cells are round or oblong, and vary in size from ^fj^ to ^rA,g of an inch, (55.5 to 12.5 mmm). Each cell contains a nucleus and one or more nucleoli. The nucleus varies in size from ^^'..o to j^^^ of an inch, (10 to 6.2 mmm.) and sometimes contains fat globules, as a result of some peculiar metamorphosis of the contents. Cell growth takes place by the process of multiplication by subdivision, and parent cells are frequently seen containing two or more young cells. The intercellular substance is either homogeneous, granu- lar, or fibrous. Cartilage is divided into two great classes : Temporary and Permanent ; the former constitutes the original frame work of the body, except portions of the vault of the cra- nium and bones of the face ; and is sup[)lanted by bone during development and growth ; the latter is found in Hyaline (teiniioniry) oartilago licuoming traiHfonned into l)c>ne subMtanco. Hy- aline sul)stauce witli cartilaj^e cells imbed- ded in it. r c I •it If f. ■ 1 .» I f G8 TISSUES. Fig. 24. different parts of the body and is not transformed into bone. It is also divided into three classes according to the character of the intercellular substance, viz. : Hyaline, elastic or reticular, and connective tissue or fibro-cartilage. Hyaline Cartilage. — This variety of cartilage embraces temporary, articular and costal cartilage, also the cartilages of the nose, larynx, trachea and bronchi, except the epiglottis and cornicula laryngis. In all these situations the in- tercellular substance is homogeneous or finel}' granular, but occasionally in old costal cartilage a few indistinct fibres may be seen. In temporary cartilage the intercellular sub- stance is not very abundant ; but the cells are numerous, and placed at nearly equal distances apart. They are rounded or oval, and vary in size from y^oTT to tbVo <>f an inch, (16 to 12.5 mmm.) the nuclei being finely granular. Near the seat of ossification the cells are arranged in rows, run ning towards the ossifying part, and become hardened by intersti- tial or secondary dej)osit of cal- careous salts (Fig. 24). In the cartilage of the ear in rats, mice, and other small animals, and also in the human chorda dorsalis in early foetal life, the intercellular substance is very small in quan- tity and the cells are closely packed together. This constitutes Cartilage cell8 in rows at the seat of the SO-Callcd Ccllular Cartilage, ossification. In articular cartilage which is found in joints, covering the articular surface^ of bones, the intercellular substance is more abundant than in temporary cartilage, and presento a finely granular appearance. The cells are rounded or oval, varying in size from y^^^ to ^^^ of an inch (19 to 27.8 mmm). Near the surface of the cartilage, the cells are ages, CARTILAGE. 69 numerous, and arranged in flattened groups, lying with their planes parallel to the surface. This appearance has been mistaken by some physiologists for a layer of epithelium. In the interior of the cartilage, the cells assume a linear direction pointing towards the surface. This serves to ex- explain the disposition this form of cartilage has, to split up in a direction perpendicular to the surface. In costal car- tilage, the intercellular substance is very abundant, finely mottled and sometimes indistinctly fibrous. The cells are larger than in any other cartilage of the body, being from -s\^ to -i\^ of an inch (38 to 55.5 mmm) in diameter. Some contain two or more nuclei, which are transparent, and others contain nuclei and fat globules. The cells often assume a linear arrangement, the rows being turned in different directions — probably the result of the growth of the cells by subdivision from the parent cell, and their sub- sequent separation from each other in a linear manner. Calcification of cartilajje sometimes occurs. It consists in a deposition of lime salts around the cells or cell groups, until the whole intercellular substance presents a dark granular appearance (Fig. 29.) This calcified cartilage, however, d jes not become bone. Elastic or R:.ticular Cartilage. — This is of a yellow- ish color, arranged in the form of plates or lamellae of various thickness, and enters into the formation of the external ear, epiglottis, cornicula laryngis. Eusta- chian tubes etc. These plates serve to maintain the shape of tubes or pass- ages, which require to be kept open, without the expenditure of vital force. It approaches in character to the fibro-cartilage. The intercellular substance is permeated by a clear net- work of fine elastic fibres. The cells are numerous and vary in size from T.V^ to ^1^ of an inch (19 to 27.8 ^f^^^^^^^^^T^^ mmn .) in diameter (Fig. 25). Frey!'""' "'"^ "' *''' '*"^'- Fig. 25. c c I HtT, (0 TISSUES. CoNNKCTiVE Tissue — or Fiimo-CAUTILAOE. — Film) car- tilage consists of a mixture of connective tissue and cartilage cells in various proportions. It exists in four forms, luter- articular, Connecting, Circumferential and Strnti for.it. The interarticular Jihro-cartilages ai'e flattened lamel- Ire of diflorent shapes, placed between the cartilages of the temporo-maxillary, sterno-clavicular, acromio-clavicular, wrist and knoe-joints. They are free on both surfaces ; thinner at the centre than at the circumference, and are held in position b}'^ the surrounding ligaments. 1'heir use is to increase the depth of the articular surfaces ; to moderate the effects of great pressure ; as a cushion, to deaden the intensity of shoclcs; to give ease to the gliding movements of these joints ; and to iucrease the extent of the svnovial membrane for secretion. The connecting Jibro-cartdages are placed between the bony surfaces of those joints which possess very little mo- bility ; as between the bodies of the vertebrjv, and the sym- ])hysis of the pubcs, and serve to connect them together. They are in the form of discs, com[)o&ed of concentric rings of fibrous tissue and cartilaginous laminjv placed alter- nately ; the former j)redominating towards the circumfer- ence ; the latter, towards the centre. The circmnfcrential variety comisis of a rim of fibro-car- tilage which surrounds the margin of some of the articular surfaces, and serves to deepen the cavity ; as, e.g., the glenoid and cotyloid cavities. The stratiform Jibro-cartilage lines the grooves through which the tendons of certain muscles pass ; as e.g., the bici- pital groove. Vascular SurrLY.— Cartilage is chiefly supplied by im- bition. It is covered by a layer of white tibrous tissue, contnining vessels, called the perichondrium, which corres- ponds to the periosteum of bones. From this covering the cartilage leceives its nutriment. When the cartilage is thin no vessels penetrate it ; but when it is more than ^ of an GELATINOUS AND RETICULAR TISSUES. 71 inch in thickness as in costal cartilage it contains canals for their transmission. Articular cartihige is not covered by perichondrium. It derives its nutrition by imbibition from the vessels of the synovial membrane which skirt the circumference of the cartilage, and also from those of the cancelli of the adjacent bone, which are separated from the cartilage by the articu- lar lamella. The vessels of the synovial membrane pass forward to the margin of the cartilage, and then return in loops, and those of the cancellous tissue pass to the internal surface of the articular lamella, form arches, and return to the substance of the bono. Fibro-cartilage is supplied by the vessels of the synovial membrane and j)erichondrium, with which it is invested. GELATINOUS AND RETICULAR CONNECTIVE TISSUES. ^ Gelatinous tissue constitutes the semi-solid substance which forms the vitreous humor of the eye,and the jelly-like substance which covers the umbilical cord (Whartonian jolly). It consists of a soft homogeneous intercellular sub- stance in which are imbedded a number of rounded trans- parent cells. A higher development of the gelatinous tissue is found in the so-called enamel organ of the growing tooth. The cells in this case are stellate in form. Reticular connective tissue is found in the lymph glands, and lymphoid organs, as the tonsils, thymus gland, Peyers glands, Malpighian corpuscles of the spleen, etc. It con- sists of a delicate areolar tissue in the meshes of which lie innumerable lymphoid cells (white corpuscles). It is some- times called adenoid tissue, and is believed to be a modified form of connective tissue. It is built up of stellate nucleated cells, the arms of which are united like threads, and form meshes in which the lymphoid cells are situated. The meshes are usually rounded, but may assume an elongated form. I. I' «r »-< E C r*' I «•' >ni 72 TISSUES. BONE. This constitutes the solid frame-work of the body. It forms organs of support, levers for motion, or it encloses cavities, and protects delicate organs, as the br^in, heart, lungs, &c. Physical Appearance and Properties. — It is a hard, dense, opaque substance, of a whitish color, and possesses a considerable degree of elasticity. It consists of an organic or animal, and an inorganic or earthy material, intimately blended together; the animal matter giving to the bone its elasticity and toughness ; the earthy part its hardness and density. The animal matter may be separated from the earthy, by steeping the bone in dilute nitric or muriatic acid. In this way the earthy matter is dissolved out, and the bone becomes quite pliable — so much so, that the fibula, if so treated, can be drawn into a knot. The earthy constitu- ents may be obtained by burning the bone in an open fire. By this means the animal matter is entirely consumed, and the earthy part remains as a white brittle substance. The relative proportion of these two substances varies in differ- ent persons, and in the same person at different periods of life. In the child, the animal matter forms about half the weight of the bone ; in the adult about 33^ per cent., and in old Age about 25 per cent. In certain diseases of the bones, as rachitis or " rickets " and mollities ossium, there is a deficiency of earthy matter, and in fragilitas ossium, a deficiency of animal matter. Bone, when boiled, yields gela- tine, and from the earthy matter may be obtained granules, from TTjVff to TToou of an inch, (4. to 1.7 mmm) in diameter. Chemical Constituents. — In 100 parts : — Organic matter — Areolar tissue, Blcxjd-vessels, Nerves and Fat 33- 30 rLime Phosphate 5I-04 T . Lime Carbonate 1 1. 30 Inorganic or ) Calcium Fluoride 2.60 Earthy matter. 1 Magnesium Phosphate 1. 16 I Soda and Sodium Chloride 1.20 100.00 BONE. 73 Structure of Bone. — Bone presents two varieties of osseous tissue. The one is dense, firm and compact, and always situated on the exterior of the bone, called the conx- pact tissue ; the other, loose and spongy, enclosing cells or- cancelli, and situated internally, is called the cancellous tissue. In the extremities of the long bones, the cancellous tissue is most abundant, while in the shaft the compact tis- sue predominates. In short and flat boues, the two varie- ties are more evenly distributed. The externjvl surface of. I the compact tissue (except the articular lamella^ is covered ^ by a dense fibrous membrane, the periosteum. The interior of the long bones in adult life, presents a cavity called the medullary canal. This is filled with the so called marrow, which is of a reddish or yellow color, and consists of vessels, nerves, delicate areolar tissue, fat cells, and a number of lymphoid cells. The latter are believed, by some, to be transformed into red blood corpuscles. There are also near the surface of the bone marrow, a number of myeloplaxes or giant cells (Fig. 14« e.) The cancellous tissue also contains marrow. The periosteum is abundantly supplied with blood vessels, and is intimately attached to the bone ; and if separated to any great extent, the bone perishes. It also sends prolongations, accompanied with vessels, through numerous foramina in the bone into the canals of the compact tissue for its supply. It is now settled that the medullary cavity is not lined by a membrane corres- p(mding to the periosteum (endosteum), the marrow being applied directly to the bone. If a transverse section from the shaft of a long bone be examined under the microscope, a number of apertures, sur- rounded by a series of concentric rings, may be seen. These apertures are sections of the medullary or Haversian canals (named after the discoverer, Cloptou Havers), and the rings are sections of the lamellae which surround the canals. Sur- rounding the Haversian or medullai-^ canals, in a concentric manner, may be seen a series of dark spots or centres, called lacunae. These communicate with each other, and with the c c M* c 1. fr ft*. »-.-• «< •■a 1. *.v !••' 1 i B/ «■ il % »ti, €!(•»■ %m* ■ i-ti Hi'' tn. M> t. ■> 74 TISSUES. Haversian canalM, by minute tubes, called cnnalieiili or pores. The whole constitutes a Haversian system, and is a provision made for the supply of the comi)act tissue. FItr. 26. Transverse seotion of tlie slmft o( the lunnenis x 150, Three Havorsiiin canals arc soon with eoiu'entric rings ; also tlio corjiugcles or laeunai with the canalieuli extending in all directions. The Haversian canals in the long bones run nearly parallel to each other and to the long axis of the bone ; but in the irregular and flat bones, they are irregular in their direction. They vary in size trom j,',o to io'do of an inch (125 to 12.5 mmni) and communicate freely with each other and with the outer and inner surfaces of the conijiact tissue, by means of transverse and oblique canals, (Fig. 27). They give passage to small arteries and nerves for the supply of the bone. The small arteries are derived from the nutrient artery, the vessels of the periosteum and marrow. The laminae which surround the Haver- sian canals vary in number from 8 to 15, and are called the Haversian lamellae. Besides these, some ap- Longitudinai section of bone, pear to be arranged concentrically, Bhowing the Haversian canals and , , in i their branches. around the mcduliary canal or mar- row of the shaft; these are called circumferential, and others BONE. 75 are situated between the Haversiau systems, called inter- stitial lanielhn. LA.(JUNi*l — The lacuna^ or bone cells are arranged in con- centric circles around the Haversian canals. They are small cavities of a setni-lunar shape, the concavity being turned towards the Haversian canals, and vary in size from nsVo to j„Vif of an inch, (1G.5 to 12.5 mmm). They are reservoirs for the plasma of the blood, previous to its ab- Fitf. 28. sorption Ijy the tissue, and each contains a nucleated membraneless ccll.or bone corpuscle, which is homologous with the connective tis- sue corpuscle, and which in all probability sends prolongations into the canaliculi. Canaijculi. — These aresniall tubes orpores, which issue from all parts of the circtimfer- encc of the lacuna'. They communicate with A lai-mm from tliosc fVoiu adjaccut lacuua^ and some open on c.f tiio inouso; a, tlic ircc surtacc 01 the bone. iJy this ar- tiiu lu.iie cull. rangement, the plasma ot the blood is carried into every part. They vary in size from vs^ttit to ^oAuw of an inch (I.G5 to 1.25 mmm.) in diameter. In cancellous tissue, and in the ai'ticular lamella which supports the articular cartilage, there are no Haversian canals, and the lacuna? are larger than ordinary. Devklopmknt. — Bone is not '■ij,'.29. directly formed from temporary cartilage, as was formerly sup- posed. Ossification commences in the cartilage at certain points, called jioints or centres of ossification, but the calcified cartilage (Fig 29) does not become bone. It dissolves away, and in the sys- tem of cavities thus formed the bone substance is developed from section of diaphysis of caitiiuffc ; , . ^ calciliud cartilasfu ; p, iturichoiidriutn the periosteum. r c. wr r 1. H" n: «nt m; 1 arj 1 E ',1 ■1 c 1 .1 ««♦ } ff* » fr i tirf r 76 7 ISSUES. In long bones there is usually a centi-al ]>oint for the shaft, and one for each extremity. The c(;ntral jxjint is called the diaphysis, the extremity the epiphys'us. The point of ossification of a process, as, e. g., the olecranon, is also called the epiphysis, and when finally joined to the shaft, an apojihijsis. The period at which ossification begins, varies in different bones. The earliest is the clavicle, which begins about the fouith week of foital life ; next, the lower jaw, then the ribs, vertebiJi;, femur, humerus, tibia, uj^per jaw, etc., in order of succession. n-. :m. Section of epipliysis showing the process of ossification. 1. — Cartilage colls imbedded ii* hyaline substance. 2. — Cavernous tissue, the calcified cartilage having become liquefied. 3.— Ossifying portion, (a)— Cavernous or medullary spaces shown empty, (b)— The same filled with cells, (c)- Remains- of the calcified cartilage, (d)— Medullary spaces in which lamelltB of bone tissue l^ave been foniied from the osteoblasts, (e)— Developing bone cell.. (f, g, h) — Imbedded bone cells or lacuuic. In the transformation of temporary cartilage into bone preparatory changes take place which consist in its becom- BONE. it ing .soft and vascular, the vessels growing in from tlio ]iori- chondrium. The cartilage cells multiply and form cylindri- cal piles or columns, (become ranked), sejjaratod from each other by trabecuhu of intercellular substance which is be- coming calcified ('Fig's. 24 and 30). The calcified substance soon after liquefies in places so as to form cavernous spaces or areoUu, which contain groups of cartilage cells, and basis substance. The cells next the ])eriphery of these cavernous or medullary sj)aces and which resemble a layer of epithe- lium, beconie altered in shape and are called osteoblasts. These coalesce with each other and with the inteicellular substance to form theyir.s^ lamella of bone tissue; while here and there one of the osteoblasts is pushed out of line or in- dented, and forms a lacuna or bojio cori)uscle. This process is again and again repeated by the production of cells from the basis substance until the formation is com- pleted. Each lacuna throws out arms or projections in diff- erent directions, which meet others from adjacent lacunae and in this way canaliculi or pores are formed. This endo- chondral bone which is so irregular and cavernous, is very different however from the beautiful regularity of perma- nent bone tissue. It undergoes a change. According to some the endochondral bone becomes liquified and absorbed in order to permit of the formation of medullary canals, and a new formation of bone takes place from the periosteum, into which the perichondrium has been changed. Others deny the liquefaction theory, and maintain that the change is due to interstitial growth alone ; we rather incline to the absorption theory. It is now a w^ell known fact, that living periosteum has the power of generating bone tissue, from the osteoblasts of its deepest layer. According to the absorption theory, while the liquefying process is going on in the endochondral bone, the osteoblasts of the periosteum grow downwards in cones (osteoblast cones.) These osteo- blast-cones produce the Haversian lamelUie, while the flat os teoblast layer immediately beneath the periosteum forms the general or circumferential lamelh^. This also explains r c r r art I? c ^.^■ t'l ' i (I \ it I I i 78 r/ss[/Es. the increase in thickness of the bone during growth and development. During ordinary repair, absorption from within and deposition from without are continually going on. The ossification in the vault of the cranium and bones of the face, in which there is no tem])orary cartilage, is called intra-memhranous orectosteal.in contradistinction to intra- . u * '^v ) l>J 1 f i • i i-/r e r: w »< ( ' » 1 >vc ; )i, remains of the uiiaiiiel \n:r\\\ ; c, unuinul ■■pitlieliiini on its outer (wicriilar) iiiid inner ; il, uiianiul jfcrni of tliupeniiununt tootli; u, 1, section of inferior luaxillu; y, Meclxei'H car- 89, TISSUES. gelatinous tissue, whicli is the pabulum of the columnar en- amel cells, and contains a few stellate cells. These columnar cells upon the surface of the tooth germ become calcified, and forn) the enamel rods which are completed by the super- position of cells, and their subsequent calcification. Development of the Dentine. — The dentine is devel- oped from the odontoblasts of the tooth germ, by a process of calcification. It commences as a dark area, at the base of the enamel germ. As development proceeds, the cells or odontoblasts become elongated and arranged in a linear manner vertically to the surface of the tooth ge*-m; the outer portions of the cells become calcified and form the intertubular tissue or matrix, while the central part remains unchanged, and forms the dentinal canals. This process gradrally extends inwards while the vessels, nerves, and areolar tissue recede until they come to occupy the central part, which is called the pulp cavity. About the fifth month, and prior to the calcification of the temporary teeth, a " secondary " enamel germ begins to foini on the inner side of the original one for the production of the " perman- ent " teeth. These pass through the same phases of devel- opment as those already described as the temporary set. Eruption. — When the tooth is suflficiently hard to enable it to pass througli the gum, the eruption takes place. The gum is absorbed by the pressure of the tooth against it, which is itself pressed up by the increasing size of the fang. The septa between the dental sacs, at first fibrous, soon ossify, and constitute the septa of the alveoli in which the fangs are lodged. PeHods of eruption of the temporary teeth. — The teeth of the lower jaw precede those of the uj)per. Central Incisors 7th month. Lateral " 7th to lotli " Anterior Molars 12th to I4tli " Canines 14th to 20tli " Posterior Molars i8tli to 36th " Perio MUSCLE. 83 Periods of eruption of the permanent teeth : First Molars 6i years. Middle Incisors 7 " Lateral " 8 " First Bicuspids 9 " Second •' lo " Canines ii to I2 " Second Molars 12 to 14 " Wisdom Teeth (Dentes Sapiential i/to 21 " The teeth of the lower jaw, also precede those of the upper in the permanent set. MUSCLE. Many cells of the body, and certain tissues possess the power of changing their form, from time to time, as the white corpuscles, cartilage cells, cilia, spermatozoa, connec- tive tissue, etc., but the muscles are alone those organs by which the various movements of the body are effected. They possess the property of contractility and are the active organs of locomotion. Muscular tissue is divided into two varieties. Striated and Non-striated. They may be dis- tinguished from each otlier — 1st. By their color; the striated are reddish in color, while the nonstriated are pale. 2nd. By the aid of a microscope ; the striated muscular fibres are characterized by being marked with transverse lines or striae ; other stria3 pass longitudinally, indicating the direction of the fibrilhie. The nonstriated muscular tis- sue consists of pale-colored fusiform fibre cells. 3rd. By galvanism. The striated respond to galvanism instantly, by a clonic spasm, while the nonstriated respond slowly by a tonic spasm. Muscular tissue is also divided into volun- tary and involuntary, according as it is under the control of the will, or independent of it. Striated. — This variety of muscular tissue comprises the whole of the voluntary muscles, the diaphragm, muscles of the ear, tongue, pharynx, upper part of the a^sophagus, heart, and the veins, at their entrance to the heart. When c c. UI(/' r. ». »•• *K *-.. »«f » »';> 1 (1 E, ■ .i e: .1 «*.v. I r i IT7 c. r 1' S4i TISSUES. a transverse section of a muscle, as the sartor iiis, is examined by the microscope, it appears to be formed of a number of large bundles of muscular tissue, enclosed in a coat of areo- lar tissue, which constitutes the sheath or perimysiuin ex- ternum of the muscle. Each larger bundle consists of nu- merous smaller ones, enclosed in a similar covering of con- nective tissue, called the perimysium internum. Each smaller bundle contains tlie priTnitive fasciculi or fibres, and cfch primitive fibre contains the primitive Jibrillce. In the spaces between the bundles may be seen the ves- sels and nerves for the supply of the tissue. The Primitive Fasciculi or Fibres. — Each primitive fibre contains a number of primitive fibrillae, and is sur- rounded by a sheath of transparent homogeneous membrane, the myolemma or sarcolemma. Resting upon, and sometimes beneath this membrane may be found here and there, oval nuclei surrounded by a small quantity of protoplasm. Thr primitive fibres are cylindrical or prismatic in shape, and vary in thickness from j}-j^ to ^ J „^ of an inch (125 to 50 mmm) ; their length does not exceed on an average one inch and a half. They are marked by fine, dark, wavy, or curved ^'t'- '^*- parallel lines or stride, from TuAoo to T70TJO of an inch apart(2.5to 2.12mmm), which pass trans versely around them; this is characteristic of this i|i) variety of muscular tissue. Other ]ines, less distinct, run Muscular fibre torn across; the sarcolemma Innrrif nrlinnll v inrl ion Hn, b, sinallet' liuiidles ; c, still Minallcr ; d, d, the smallest re- presenting; a sini^Ie series of sarcous elements(Shaq)ey). of an inch, (2 to 3 mmm.) When examined with a high magnifying power, a dark line, with granules above and below, is seen to cross the middle of each light particle, known as Krause's transverse lines or intermediate discs. The granu- lar appearances above and below, are called secondary discs. A white line has also been observed to cross the middle of the dark zones, known as Hensen's median disc. Late re- searches have also shown that each fibrilla is surrounded by an extremely thin membrane. This is an argument iu favor of the view, that the fibrilla is the anatomical element of muscular tissue. The striated muscle of the tongue and heart of the mammalia and man, is somewhat di fie rent from that generally met with. The fibres are not arranged in bundles, and surrounded by connective tissue, but weave or interlace among each otiier. They also anastomose with each other, so as to I'orm a narrow-meshed net work, and there is no appearance of sarcolennna. NoNSTRiATED. — This variety consists of flattened bands, c mof r i* B" »v •w •at 1 9va f IVf r. 86 TISSUES. or elongated fusiform fibre-cells, of a pale color, from — i— to to j^^ of an incli (5.5 to 7.5 mmm) broad, finely granular and containiiig a rod-shaped nucleus, which sometimes appears as a streak (Fig. 36). These fibre-cells may a.ssume differ- ent shapes ; thoy are generally fusiform, but some are club- shaped, and others of a rectangular shape, with fringed ex- Fig. 30. tremities. The length of these fibre-cells is from ^L. to —J— of an inch (500 to 2.5 mmm.) ft O 1 O O O ^ ^ ' They are held together by connective tissue, and the bands are applied to each other in such a way, as to encircle the organ into the form- ation of which they enter. This kind of tis- sue is found in all hollow organs (except the heart and veins attached), as the ducts of the salivary glands, tracliea and br« nchi, alimen- tary canal, fiom the lower part of the oesoph- agus to the internal sphincter, gall bladder and ducts, calyces and pelvis of the kidney, ureters and bladder, and in the urethra. In the female ; in the vagina, uterus, Fallopian tubes and round ligaments. In the male; in the scrotum, epididymuSjVas deferens, vesiculse seminales, prostate and cavernous bodies, in the coats of arteries, veins and lymphatics ; in the iris and ciliary muscle, and in the integu- ment called the arrectores piloruini. Mode of Development. — There is no differ- ence in the early stage of development between the striated and nonstriated varieties of muscular tissue, both being developed from cells; but whilst the striated variety goes on to complete development into fibrill8e,the nonstriated retains permanently its cellular condition. The cellular ele- ments are elongated and applied end to end,being held together by connective tissue, and in this way they encircle the organ into the formation of which the}'^ enter, or are arranged longi- tudinally or obliquely. The striated fibre is not formed as Nonstriated mus- cular fibre cells. a, Developiii)? cell from the embryo of the hoK ; b, a more advanced cell, c, to fi-, various forms of human muscular fibre. MUSCLE. 87 Fiff. 37. formerly supposed by Schwann, directly from the arrange- ment and fusion of the cells in a linear manner (except probably the fibres of the heartj, but by the arrangement and fibrillation of the protoplasm or intercellular substance under the influence of the cells. The cells appear to increase greatly in length, the nuclei increase in number, and the protoplasm and intercellular substance becoine transformed into the sarcous elements, etc. The fibre becomes trans- versely and longitudially stiiated, and increases in size by fresh additions of protoplasm upon the outside. The re- mains of the nuclei, surrounded by granular protoplasm (the muscle corpuscle) may be seen on the outside and with- in the sarcolemma, on the addition of a little acetic acid. Attachment of Tendons, — Every muscle is attached at its extremity by means of connective tissue, which consti- tutes the tendon. The extremity of each muscular fibre, whether rounded, pointed, or irregular, is covered by sarcolemma, and is re- ceived into a corresponding cavity in the tendinous bundle to which it is firmly connected, by means of a cement substance. This union is Extrcniity of imiscuiar fibru, PIT showing the uttiichineiit of the teii- so firm, that ru[)ture of the tendon don. or muscle will take place before separation at this point. It may be separated for microscopical examination, by means of a solution of potash. Chemical Constituents. — Muscular tissue consists as follows in 100 parts : Water - 76. 50. Myosine, Albuminous substances and Hemoglobine.. 18.20. Lactic acid '. i.oo. Gelatine 1.50. Creatine, Extractive, and Fatty Matter and Salts. . . . 2.80. 100.00. c. vr. V It swells out on the addition of acetic acid, and is par- tially dissolved. It is soluble in hydrochloric acid, and is 88 TISSUES. precipitated by forronyauide of iron. Muscular tissues is sometimes changed into a substance called adipocere. (See oils and fats.) Vascular Supply. — The arteries intended for the supply of the muscle pierce the sheath, and divide and subdivide, giving off small branches which pass between the bundles of which it is com])osed, until the ultimate twigs insinuate themselves between the primitive fasciculi or fibres, and terminate in the capillaries. Some of these, the longitudinal, course along the fibres, lying in the intervals between them, and others pass transversely across them. The length of the longitudinal capillaries is about Vtr of an inch (1.2 mm) the transverse vary according to the size of the fibres. The fibrillin are, therefore, supplied by imbibition through the sarcolemma. Nervous Supply. — The nerve fibres are distributed sim- ilarly to the arteries, until the filaments reach the fasciculi or fibres. Tiiey then form a scries of loop.s, which either return to the same trunk, or join an adjacent one. It is stated by some observers, that the nerve fibres pierce the sarcolemma. As they })ierce the fibre, their covering be- comes continuous with the sarcolemma, and the axis cylin- I'i;.^:*^- der or essential portion of the nerves l)ass into the interior and are dis- tributed among the fibrillre, and ter- minate either in free extremities,, loops, or neive buds (as they are called). Accord injx to other observers the nerve fibres as they approach the sarcolemma form expansions, called terminal, or motor end plates. The sheath of the nerve spreads out and blends with the sar- colemma, the white substance of Schwann terminates ab- ruptly, and the axis cylinder spreads out beneath the sar- colemma on the fciirface of the fibrillse, forming an oval ^^HQ90 Terniinatioii j_ to -J - A O O 1 o of an inch (50 to 25 mmm) in diara- plate, from eter. (Fig. 38). Properties of Muscular Tissue. — The di.stinguishing characteristic of muscular tissue is its property of contrac- tility, irritability or tonicity. Some have endeavoured to- draw a distinction between these teims ; but, after all, it is a distinction without a ditference. The term tonicity how- ever, may be understood to express that hueni'^ible and almost constant contraction by which opposing mu.scles balance each other in a state of rest — a state of passive con- traction. The primitive fibril la is the proper contractile tissue of the muscle. Still, it is a disputed point as to whether or not it possesses this property in itself, some maintaining that nerve is neces.sary to charge it with con- tractility ; others that nerve is only necessary to call it into- action, and that this ])roperty is inherent in the tissue itself. Contraction is caused by a change in the shape of the sar- cous elements; they become shorter and thicker. This change travels rapidly fi-om one end of the JihriUa to the other, and the muscle is thus very much shortened. Some vegetable structures possess an analogous property, as e. g. the mimosa or sensitive plant, and venus' fly-trap (Dionoea). If touched ever so slightly, the irritation causes a change in the shape of the cells, followed by a change in the shape or position of the v^hole leaf, in consequence of the change travelling from one cell to another. The property, there- fore, of contractility is inherent in the muscular fibrilla itself, and may be called into action by various kinds of stimuli, as by nervous influence, by pinching or pricking the tissue, by the action of an acid or an alkali, or by gal- vanism. The efiect of the application of any of these stimuli,, varies according to the kind of muscular tissue to which it is applied. If a portion of striated muscle be irritated, those fibres which are touched will contract, and those only,, the motion not being communicated to any other, and the contracted part soon becomes relaxed — the spasm is clonic. c c Mtl> r R, h »»L •w m\ mKi 1 t ■1 .4 ■ft 1 rt fnv 1 f. ■ 1 J ^'■• r.. V 90 TISSUES. If, on the other hand, a portion of nonstriated muscle be irritated, as the alimentary canal, the contraction takes place more slowly, the spasm is long continued, or tonic, and the movement is communicated to other fibre-cells, until a considerable part of the canal is affected. The muscular fibre is shortened and thickened during contrac- tion, and sometimes thrown into a zigzag shaj)o, and som(j observers, mistaking the effect for the cause, cijncluded that the zigzags occasioned the shortening. Contractility con- tinues for a short time after death This may be demon- strated, by applying to the muscular tissue any of the above- mentioned stimuli which arc known to affect it during life. The duration of this property after death, varies in different animals. In birds, only a few minutes after death ; in quadrupeds much longer ; while in reptiles it remains for many hours, owing to the nutritive changes being more sluggish in these than in warm-bloods, and the sareuus ele- ments being slowly formed and sluggish in their action, are long-lived. If irritation be continued, the contractility or irritability of the n\uscle is soon exhausted. The circulation of arterial or oxygenated blood is not only necessary for the purjjoses of nutrition, but also to the continuance of contractility. The muscles will therefore preserve their contractility after death, and the action of the heart itself will continue for a long time, if oxygenated blood be injected into the veins or if the circulation be kept up by artificial respiration. If the blood be charged with carbonic acid, or chloroform, ether, sulphocyanide of potassium, or a narcotic poison, as opium, etc., the contractility of the muscles is speedily destroyed. Every act of contraction involves the death of a certain amount of muscular tissue, and prolonged exertion causes fatigue, which is an evidence of an impaired condition. Rest is necessary to I'ecovery, and recovery is due to the nutritive process ; hence the more a muscle is used, pro- vided it receives a sufficient amount of rest and nutrition, MUSCLE. 91 tlie more vigorous and bulky does it bocomo ; as v.. g., the arm of the smitli, and the lcf(s of the rope-walker. On the other hand, disease, as paralysis, or sedentary liabits, cause thorn to become flabby and atrophied, but this may be re- medied by exercise, and the use of friction and galvanism. In some constitutions they are liable to fatty degeneration. Muscular coiitraction produces a Hound resembling the distant rumbling of carriage wheels. This is caused by the movements of the fibres U])on each other. For example, the sound caused by the contraction of the masseter and tem- poral muscles may be distinctly heard in the stillness of the night, by placing the side of the face and ear on the pillow, and clenching the teeth fiimly together. There is also an elevation of femperatitre of from 1° to 2° F. This depend-^ ])artly on the chemical changes which take ])lac'3 in tlie muscle, as a result of its action, and partly upon the friction consequent on the movements of the fibres upon each other. Muscular tissue is also said to possess a certain amount of elasticity/. This is exceedingly small, and is due in great measuie to the elasticity of the sarcolcmma and the elastic tis.sue associated with muscle. It is sh')wn by suspend- ing vertically a small weight to a |)ortion of fresh muscle ; it elongates with the weight and recovers itself when it is removed. Rigor Mortis. — This is the stiffening of the muscles which takes place after death, and is due to the coagulation of myosin. This condition is rarely absent ; but it may be very slight, and continue only a short time. Sometimes it comes on within 15 or 20 minutes after death, as in typhus fever. It commonly takes place within 7 or 8 hours after death ; but in some cases it may be deferred for 20 or 30 hours. It continues for 2-t or SC hours ; but it may ])ass off much more rapidly, or be continued for several d lys. This rigor mortis is a sort of tonic contraction of the mus- cles, and in some cases it may be very violent — as afcer 6 «- . "V, t ; > I. IMAGE EVALUATION TEST TARGET (MT-3) // 1.0 I.I 2.2 £ lifi - us IS UUu M 1.8 1.25 1.4 1,6 ■* 6" ► I v] & //, A "c^l ^» ^?> o^ ^ ,^ '4 %'V* y -(^ Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 \ ^^ % V ^ % o^ Ci? «^ '9,^ 1 92 TISSUES. death from cholera and yellow fever — and has given rise to many absurd superstitions among the uninitiated. It begins in the neck and lower jaw first, next the upper extremi- ties, and extends from above downwards until it reaches the lower limbs. It is most remarkably manifested in the nonstriated muscular tissue, as in the arteries and alimen- tary canal. In consequence of this contraction, the bowels are not unfrequently moved after death ; the arteries are found empty, and so contracted that they cannot be injected until the rigidity passes off. When the rigor mortis sub- sides, decomposition of the muscular tissue begins ; hence we may regard it as the last act of life, and in this respect it corresponds to the coagulation of the blood, when drawn from the body. The same causes that interfere with the coagulation of the blood after death, interfere, al.^o, with the rigor mortis of the muscles, as in animals hunted to death, or killed by lightning, in which both coagulation and rigor mortis are imperfect. Action of Muscles. — In the action of most muscles, and especially those of the extremities, examples of the three orders of levers are afforded. In the first order of levers the power is at one end, the weijrht at tne other, and the fulcrum between the two. In the second order, the power is at one end, the fulcrum at the other, and the weight between the two. In the tldrd order, the fulcrum is at one end, the weight at the other, and the power between the two. The first order of levers, although the most powerful, is that least used in the animal economy, as its use is less pro- ductive of extensive motion. The action of the gastrocne- mius muscle affords an e:.ample of this order, as when the foot is raised from the ground, and extended to raise the os calcis and depress the toes : here the moving power is the gastrocnemius attached to the os calcis, the weight is the anterior part of the foot, and the fulcrum is the ankle joint. The same muscle affords an example of the second order ofh bod the MUSCLE. 98 of levers, as when the foot is placed on the ground and the body raised by the action of the muscle ; here the moving power is the gastrocnemius, the fulcrum the anterior part of the foot resting on the ground, and the weight or resistance the body resting on the ankle joint. Fijf . 39. Fig. 40. Figr. 41. tr The upper three flsrures represent the three kinds of levers ; ',he first illustratingf the mode of action in two directions. The lower flgur represent t'ne foot when it takes the character of each kind of lever. F, fulcrum; P. -wer; W, weight or resistance; M, muscle, affording the power. The ankle joint also affords an example of the third order of levers, as when the foot is raised from the ground and flexed on the ankle joint ; here the moving pov er is the tibialis anticus and peroneus tertius, the fulcrum is the ankle joint, and the weight the anterior part of the foot. The biceps of the arm also affords a good example of the third order, as when a ball or weight is placed in the hand \ here the moving power is the biceps inserted into the tuber- osity of the radius, the fulcrum is the elbow joint, and the weight is in the hand In this position, power is sacrificed to extent of motion, as in raising the hand and weight these pass through the arc of a circle of considerable dimensions, while the extent of motion at the insertion of the power is extremely limited. This is still more obvious when we hold a rod in the hand, as a fishing-rod or whip, the ex- treme end of which is made to pass through a space of con siderable magnitude compared with that of the part where Uxui *- , P 'SSUES the power is app-ied. The great advantage derived from this disposition of levers in the hun^_an body, whereby motion is gained at the expense of power, is seen in the various acts of walking, running, leaping, etc. Locomotion. — In the act of walking nearly every muscle in the body is called into action, either in the movement of the limbs or in the maintenar.ee of the body in the erect position. Two main kinds of leverage are employed in walking, one kind chiefly produced by the muscles of the calf which raise the heel, and with it the weight of the body which is inished forward, and would fall prostrate, but for the other kind of leverage by which the opposite leg is pulled or planted in front of the body to support it. The advance of the opposite leg is effected })artly by swinging, but chiefly by muscular action. The muscles concerned are those of the thigh, the rectus, psoas and iliacus, which act in front; the hamstring muscles which slightly bend the knee, and those on the front of the leg, as the tibialis anticus, extensor longus digitorum, extensor longus pollicis and per- oneus tertius which raise the foot and toes, and prevent them catching on the ground. When this foot, which we will suppose to be the rigid, has reached the ground, the action of the muscles of the left leg has not ceased, but con- tinues to raise the heel and throw the body still more for- ward, until the weight is supported by the right leg, when the left in its turn swings around and is planted in front of the body. The two actions it will be seen, therefore, are taking place at the same time, and are assisting each other. At the same tin.j that the above movements are in pro- gress, the body i , being supported in the erect posture and balanced on each leg alter; itely. This is done by a slight rotation of the pelvis on the head of each femur alternately, so that the centre of gravity Cx'' the body shall fall over the foot of that side. This occasions a sliti'ht " rockinc: move- ment" which is more noticeable in females than males owing to the greater width of pelvis of the former. Tins rockicg MUSCLE. 95 movement may, however, be lessened, and made more grace- ful by a compensatory outward movement at the hip, and hence some may become more graceful in their walk than others. Running, and leaping or jumping are modifications of the act of walking. In regard to the source of muscular force, it has long been observed that in active muscular exercise, there is an increase in the urea excreted by the kidneys, and it was supposed that this increase of urea was in exact proportion to the amount of muscular exercise. The latter has been found not to be the case ; the increase in urea is only very slight, and the waste of muscle cannot be expressed by its increased excietion; neither is the substance of muscle wasted in proportion to the work it performs. There is also no evidence that nitrogenous are superior to non-nitrogenous foods as a source of muscular power ; both may afford the requisite conditions for muscular action. c v* •-■ « ' 4 1 I. 90 MEAfBRANOUS EXPANSIONS. CHAPTER IV. MEMBRANOUS EXPANSIONS. These are the serous and synovial, mucous and integu- fnent. The serous and synovial membranes, anatomically speaking, form shut sacs, with the exception of the periton- eum in the female, which communicates with the uterus through the Fallopian tubes. The mucous membrane lines cavities which communicate with the external surface, and is continuous with the integument. The integument covers the exterior of the body, and serves not only as a means of protection, but also as an organ of sensation. The mucous membrane and integument are convertible membranes. Structure. — The structure of these membranes is very nearly the same in each instance. It consists of a base- ment membrane, lined by epithelial cells on the free sur- face, and presents vessels, nerves, and lymphatics, imbed- Fijf. i-2. A^^ jjj areolar tissue which connectsitwiththe subjacent parts (Fig. 42). They there- I fore consist of three parts — \hasement membrane, with \epithelial cells or one side, Plan of a membranous expansion ; a.epithe- ., i hlnnd-iwavfils 'nt>TiWRS\T\^ Hum , b, basement membrane ; c, vessels, ^"<1 OlOOa VCSSClS, ncrveS anu nerves and lymphatics imbedded In areolar ^^^^^^^-^^^ imbedded in ar- eolar tissue, on the other. 1st. Basement Membrane. — The different varieties of basement membrane have been already described in Chap- ter II. Its function is to support the cells, and probably influence their development ; to limit osmosis of the nutri- ent fluid from the subjacent capillaries, and modify it in its passage. 2nd. Epithelium. — The layer of cells which line the free m EPITHELIUM. 97 surface of tlse membranous expansions, is called epithelium. Those which line the serous and synovial me'^ibranea and the vascular system are sometimes called endofhelium, and the striitified epithelium of the skin is called epidermis. The epithelial celh can be brought beautifully into view by staining with nitrate of silver. There are two principal varieties of epithelium, viz : Ist. Tesselated, pavement, squamous, laminated or scaly. 2nd. Columnar or cylindrical. In the serous, synovial, and mucous membranes there is generally a single layer of cells, Avith a quantity of granular matter and a layer of partially developed cells lying on the basement memb 'ane ; l)ut in the integument there are several ; the outer being flattened, scaly, and hardened by secondary deposit. The cells which line the serous, synovial and nuicous membranes, secrete a fluid which is intended to lubricate the surface, to prevent the ill effects of friction, and to give ease to the gliding movements of the parts over each other. This fluid is formed as a result of the growth, maturity, and decay of the cells. 1st. Tesselated, Pavement, Squamous, or Scaly Epi- thelium. — The cells of this variety are flattened and poly- gonal in shape, and vary in size from <,Iq to ^^ir. of an inch (50 to 10 mmm) in diameter. Each cell contains a nucleus, nucleolus, and granular matter. They are, in general, not very active, and are therefore long-lived. In health, they secrete only a limited quantity of fluid. Those which line Fig. 43. the synovial membranes, mucous membrane of the mouth, and parts of the body in which a greater sup- ply of fluid is requisite, are some- what rounded in shape and much more active. Tesselated or pave- ment epithelium lines all the serous a, epith peri epithelial cell of the mouth x 2G0 Tesselated epithelium ; a, epim- , . , . ,, eiium of the peritoneum x 400 ; b, and syuovial membranes, the mu- (fienie). cous membrane oi tlie mouth, lower part of the pharynx, oesophagus, upper part of the larynx, c ttn» If ' «■ 1 . . 98 MEM li RANG US EXPANSIONS. Kijf. 44. intercellular passages (so called), and air cells, lining mem- brane of the ventricles ot* the brain, tympanum, anterior and posterior chambers of the eye, conjunctiva and canali- culi, arteries, veins, and lymphatics, lower part of the vagina, bladder, and urinary passages, vesiculte seminales, and vas deferens. Those cells which line the bladder and urinary passages are somewhat sj)heroi(lal in shajie, and would seem to bean intermediate variety. 2nd. COLUMNAK OR CYLINDRICAL EPITHELIUM. — This variety is cylindrical in shape, as the name indicates, and placed side by side, one extiemity of the cell resting on the basement membrane, and the other forming tlie free surfac..-. They vary in size from 2.'n« to -j-gV,, of an inch (10 to 7.1 niumi.) in thick- ness, and from -g J^ to ^\-^ of an inch (42 to 28 mmm.) in length. Each cell contains a nucleus and nucleolus. In some parts, as in the gastro-intes- tinal canal, there ai)])ears to be a columnar ci.ithciin.n ; c, col- ^ouble layer of cclls / thjs depends =:;ZdS1;m;^u«n/oi on their rapid development in these "'" ""'"^' parts, the lower layer being the new cells which are rising np to take the place of the old. Therje cells not only line the free surface of the membrane, but also dip into the follicles, at the bottom of which they be- come rounded or glandular. This is owing to their greater activity in the latter situation. In some instances their free extremities are club-shaped, in order to comport with their position, as when they stand on the angles formed by the dipping of the follicles. This form of epithelium is found in the alimentary canal, commencing at the cardiac orifice of the stomach, in the ducts which communicate with it, the gall bladder, nose, nasal ducts and lachrymal sacs, frontal sinuses and antra, posterior surfac3 of the palate, upjier part of the pharynx. CILIA. m Eustachian tubes, larynx — below the superior vocal cords — tiachea and bronchi, uj)per part of the vagina, uterus, and Fallopian tubes. Placed here and there at vari- able distances among the ordinary columnar cells are peculiar oval cells known as Becher or gubld- cells (Fig. 45, a.) These are re- garded by some as the commence- ment of the absorbent system ', Coluniiiar epithelium of small intes- by OthcrS aS mere shcUs of Cpitll- tiiie; a, Uucher or jfoblet cells; b, or- ,. , ,, , . , i i (linar.v cells. elial cclls which liavc becom© emptied of their contents by manipulation, or as mucous secreting cclls. Cilia. — Both varieties of epithelial cells occasionally pre- sent a number of minute, conical-shaped filaments or prolon- gations attached to their free extremities or surfaces, termed cilia (Fig. 44, d). They are attached by their bases to the cells, their free extremities being tapered, and they vary in length from ^o'tjcj to ToVfy of an inch, (5 to 6 mmm.) From five to thirteen may be seen attached to each cell. The cilia, may be considered as prohjngations of the cell itself They are not seen in the early stage of development of the cell, but make their a])peai"ance ai it arrives at maturity. They are in continual motion ; each filament appears to bend from its root to its point and return to its original state, so as to- resemble the waving of a wheat field in a gentle breeze. This motion is independent both of the will and the life of the animal, as it is .seen to continue after death. Epithelial cells of the nose may be seen to float about in water by the agency of their cilia, several hours after they have been re- moved from the mucous surface ; and the motion of the cilia has also been observed in the body of the tortoise fif- teen days after death. Ciliary motion continues in animals- killed hjr prussic acid, narcotic or other poisons, and electri- city ; but is destroyed by chloroform, carbonic acid, mineral acids and strong alkalies. it :. ?v &' 100 MEAfliRANOUS EXPANSIONS. The object of the ciliary motion is to propel fluids over the surface, in tlie direction which the secretion is destined to take, whether external or internal, the movement being generally towards the outlets. In fishes, the external sur- face of the gills is covered with cilia, which serve to propel the water, and bring fresh portions in contact, for the pur- ])ose of aerating the l)lood. In raanj' of the lower animals, they serve not only to produce currents for respiration, but also to draw into the mouth minute particles which serve as food. The motion of the cilia is due to the vitality of the cells from which they grow, or the vital contractility of the tis- sue of the cilia themselves, and not to the presence of a kind of delicate muscular tissue, or to nervous force, as some have suggested. It has already been shown, in the preced- ing chapter, that the motion of muscular tissue is due to a change in the shape of the sarcous elements. Now, in the same way, the motion of the cilia may be produced by a change in the shape of the cells to which they belong, so that by an alternate contraction and relaxation of the cell the cilia would be made to wave as they are seen to do. The epithelial cells are developed from the protoplasm supplied by the vascular layer, beneath the basement mem- brane. Ciliated epithelium of the tesselated or' squamous variety is found in the lining membrane of the ventricles of the brain, tympanum, intercellular passages (so called), and in the air cells. Ciliated epithelium of the columnar vainety is found in the cavity of the nose (except the roof), nasal ducts, lach- rymal sacs, frontal sinuses, maxillary antra, Eustachian tubes, posterior surface of the palate, upper part of the pharynx, (extending as low down as the floor of the nares), larynx below the superior vocal cotds, and the anterior part above, trachea and bronchi, upper part of Uie vagina, in the uterus, and Fallopian tubes. SEROUS MEMBRANES. 101 SEROUS MEMBRANES. The serous membranos are the arachnoid, pleura, pericar- dium, peritoneum, tunica vaginalis, and the lining membrane of arteries, veins, and lymphatics. Each membrane, respec- tively, lines the cavity to which it belongs, being attached to the wall by means of areolar tissue. This is called the 'parietal layer. It is then reflected upon the contained organ forming the visceral layer. The free surface is lined by tesselated or squamous epithelium, sometimes called endothelium, which in health secretes a limited quantity of fluid for the purpose of moistening the surface, the process of secretion and absorption being exactly counterbalanced. The normal quantity of stious fluid in the various cavities is as follows ; in the pericardium one to two fluid drachms ; in the peritoneum one to three oimces ; in the pleural sac two to four fluid drachms. If the secretion be morbidly in- creased, or the process of absorption diminished it is retained in the cavity, and gives rise to dropsies which receive difler- ent names in different parts of the body ; in the cavity of the arachnoid, hydrocephalus ; in the pleura, hydrothorax ; in the pericardiOra, hydro-pericardium ; in the peritoneum ascites ; in the tunica vaginalis, hydrocele. The secetion is called serous fluid, and is similar to the serum of the blood. It has an alkaline reactivon, and consists of water, albumen and salts. The quantity of albumen varies in different parts, depending on the activity of the part, the degree of motion and the amount of friction to be overcome. In the serous fluid of the pleura there are 2.85 parts in a hundred ; in the peritoneum, 1.13 parts ; in the arachnoid, .6 to .8; in the subcutaneous areolar tissue, .36. The rerous membranes are looked upon by some, as large sacs or cavities, which communicate by stomata or pores, with the lymphatic vessels (Klein.) These apertures, which are about T^Vtro of ^^ i^ch (10 mmm) in diameter, may be seen between the epithelium. Milk and colored fluids have /It I ■ i J I .-I I' 102 MEMBRANOUS EXPANSIONS. been observed to pass through them into the lymphatic sys- tem. Short lateral passages of the lymphatics are also found to open into these apertures. There is also a considerable (piantity of adenoid tissue imbedded in, or forming the walls of the serous membranes. cavn the tegu hllVH SYNOVIAL MEMBRANES. The synovial membranes are ])laced between the articular surfaces of the bones. In the foetus they are prolonged over the articular cartilage ; but in the adult they cover merely the margin to the extent of a line or two, and are then rertected on the inner .lurface of the ligaments, to which they are attached by areolar tissue. In some in- stances they send fringe-lilco prolongations into the interior of the joints, as for example, the (so called) alar ligaments of the knee joint. They also form sheaths for the tendons of muscles. The free surface of the synovial membrane is smooth and moist, being lined by a layer of tesselated or squamous ej)ithelium, which secretes tho synovia, for the purpose of lubricating the joint, and preventing the ill effects of friction. If the secretion be morbidly excessive, the result would be hydrops articidi. Synovia is a transparent, viscid, oily-looking fluid, and resembles the white of an Qgg, hence its name {aw, cum, MOV, ovum.) It has an alkaline reaction, and contains water, albumen or synovine, and salts. It contains more albumen than serous fluid, more being necessary on account of the greater amount of motion in the joints. BuiiSiE. — A reflection of synovial membrane in the form of a closed sac, is found beneath some of the tendons where they glide over bony surfaces. This is called a synovial bursa. When they are situated near a joint they sometimes communicate with its synovial cavity. They line the canal or groove and are reflected around the tendon forming its sheath, at the same time excluding it from the synovial .S' VA'O VIAL MEMliRANES. 103 cavity. There is nr.other variety of bursjo situated between the integument and bony prominences, as between the in- tegument and patella, olecranon, etc. Tjjcsc ai-e called h\ir»(M mrcoscc, and are nothing more or less than an en- larged mesh in the areolar tissue, surrounded by condensed fibres, and presentirjg a partial or incomplete secreting sur- face. Synovial membranes are more readily reproduced than serous membranes. It is doubtfid whether the latter arc reproduced at all or not ; but new joints are formed and lined by synovial membrane, as is seen in old-standing dis- locations of the hip, etc. Serous membi-anes, vvlien inflamed pour out a plastic substance, which has a tendency to or- ganize and form bands ; but in inflammation of synovial membranes there is a tendency to the formation of j)us. Structure of Serous and Synovial Membranes. — They are very nearly alike. On their free surface is a layer of epithelium, of a ])olygonal shape, and more or less transparent. This rests on the basement membrane, which is also nearly transparent, and very thin. Beneath the basement membrane is a layer of areolar tissue, in which are imbedded the vessels, nerves and lynqjliatics ; this con- stitutes the chief thickness of the membrane, and gives it strength and elasticity. The areolar tissue is mo''e con- densed beneath the brisement membrane, and becomes more lax near the subjacent tissue. The vessels are arranged in a plexiform manner, running parallel with the basement membrane. In parts of the body where there is much motion, and a greater supply of bloo;l is necessary, as be- nealli the pleura and the synovial membranes, the vessels are tortuous. c * ■ * ■ V t* MUCOUS MEMBRANES. These resemble the serous and synovial, in lining cavities, but they are not shut sacs. They line the interior of the alimentary canal from the mouth to the anus, the ducts, 104 MEMBRANOUS EXPANSIONS. and interior of glands which communicate with it; the nose and the passages which open into it, the larynx, trachea, bronchi, and air cells, bladder and urinary passages, vagina, uterus and Fallopian tubes. The free surface of the mucous membrane is lined by a layer of epithelium, generally of the columnar variety ; the exceptions are the mouth, upper part of the larynx, lower part of the pharynx, oesophagus, tympanum, intercellular passages and air cells, lower part of the vagiua, bladder and urinary passages. The cells se- crete a fluid called mucus, which is intended to lubricate the surface, and protect it from the contact of air, and an}' irritating substance to which it may be exposed. Mucus is a transparent, viscid, tenacious, semi-fluid substance, insoluble in water, but may be readily dis- solved by any alkali. It is coagulated by weak mineral acids, acetic acid, and strong alcohol. A substance resemb- ling mucus may be obtained from any inflammatory exuda- tion, or even from pus, by treating it with liquor potassa and agitating it. Any irritation to the mucous surface, from wliatever cause, will increase the secretion of mucus, as for example the use of snufF, etc. It consists of about 93 to 94 parts fluid, and from 6 to 7 parts solid matter. The organic matter is termed Mucine or Mucosine. Mucus of the nose consists of ; — (Robin) Water 93. 3 Mucine 5.4 Fatty and Extractive Matter. 3 Salts '. icx).oo The salts consist of sodium and potassium chloride .6 parts ; sodium and potassium phosphates, sulphates, and carbonates, and lime phosphate .4. The part of the body from which the mucus is obtained may be determined by the form of epitheliun- present in it, the result of desquamation, It has an alkaline reaction except in the vagina where it is acid. Structure. — The mucous membrane, like the serous being largely supplied by spinal nerves, while the rest of the intestines, stomach, and oesophagus, are more directly r MUCOUS MEMBRANES. !().-> and synovial, consists essentially of three parts ; the epith- eliuvi — the basement meTnhrane — and the areolar tiisue, in which the vessels, nerves and lymphatics are imbedded, and which connects it with the subjacent parts. The latter gives the membrane its thickness, and is made up of white fibrous, and yellow elastic tissue, vessels, etc. In the raucous membrane of the erectile tissues, as in the organs of generation, some nucleated, fusiform, mu.scu- lar fibre-cells are seen imbedded in the areolar tissue. The epithelium not only covers the free surface of the mem- gf» brane, but also dips down to line the follicles, ducts, etc. It ^ ' also covers the surface of the villi and valvular conniventes. The relative amount of vessels, nerves, and lymphatics, de- H pends upon the activity of the parts; the vessels are also jii' more tortuous where a large supply of mucus is requisite «v ;. Some parts of the mucous surface are not so sensitive as others ; for example, the passage of food is not felt ir the oesophagus, stomach, and intestines until the fiwcal matter reaches the rectum, when a sensation is felt demanding its ' discharge. This depends on its nervous supply — the rectum >, i i* i under the influence of the sympathetic system. Mucous »> surfaces are not disposed to form adhesions in inflammation, owing to the presence of the epithelium and mucus. These change the character of the plastic material, and cause it to degenerate into pus ; but if the epithelium be entirely re- moved a partial organization takes place, as may be seen in the casts of the alimentary canal in dysentery, when not of a very low type. APPENDAGES OF THE MUCOUS MEMBRANE. In most parts of the body the mucous membrane is pro- vided with papillte, and follicles, or glands. In the aliuieTi- tary canal, the mucous membrane is thrown into folds called valvulae conniventes. There are also velvet-like projections called villi. These are termed appendages. I 100 ^fE^fnRANo i ^.v jcxpjns/oxs. Patill^'. — Of tlioso tlioro arc two kinds, f t )ngue, tlie organs of (he special sense o{' t(tstc, and also of touch; the former will be described with the integument. '■'- '"'• A ]iapilla is a slight ele- vation of the surface of the membrane of which it forms a part, consisting of tiie basement membrane cov- ered by one or more layers of e[)itln'lium, and contain- ing within a reticula of cap- illaries, nerves fcjrming lo()})s, lymphatics, and in s lO instances nonstriated muscular fibre- cells, the lat- A. tiUiiiionis i>ai>illu ol the luiiKl; n. edit ica tor CaUsiug it to COUtract iiiviT witli colls and olnsti>' filiros; h, tactile , , lorimsde ; c, nine fibres (Kolliker). and bcCOUie ])r()minent wllCll any irritation is applied. Some of the pai>illa» are cleft, as for exam]ile, those in the back part of tiie dorsum of the toniiue and in the hands. The papillae of the tongue may be divided into s'im])lc and ccmiHUind. The sim|)le pa})illa' are dispersed over the .surface of the tongue among the compound forms. The compound are the cu'cumvallaie, fanglform, and jillform, and are visible to the naked eye. The circumvdllatc pa])ilhv are of a large size, and vary in number from eight to ten. They are situated on the dorsum of the tongue, near its base, and consist of a row on each side, which runs obliquely backwards and inwards, to terminate in one large papilla situated in the median line, called the foramen cceciim. Ihe two lines resemble the letter V inverted. Each papilla consists of a circular flat- MUCOUS MEMBRANES. 107 toned |>n>joction of tlie mucous membrnno, from j'^ to ,'j of an inch (I to 2 mm.) in diameter, surroundid liy a narrow circular fissure, this fissure being again surrounded by a narrow circuhir elevation of tlio mucous membrane. The whole suiface of these papilho is studded with numerous smaller or secondaiy jtapillio, and investtid with epithelium, the deep layer being rounded, the superficial, scaly. I'M-. 47. The toiisiuo with its piipillif ami iiervos, (llcrscliluld). The fuvglform ])apilI;o are scattered irregularly among the filiform papilho on the dorsum of the tongue, but chiefly at the sides and a[)ex. They vary from o^ to .j^ of an inch (I to .7 nun.) in diameter, generally narrower at the base than the sunnnit, and studded with numercms smaller pa- [)ill;o, like the }> receding variety. They have a reddish color, owing to the thinness of the epithelial covering. The filiform impilUn cover the anterior two-thirds of the tongue. They are conical in shape, and vary in thickness from 6*0 to Vo of an inch (.5 to .3.5 mm.) and are about -r\, of an inch (2.5 mm.) in length. They are pale in color, owing to the density of the epithelium, and are also covered with 7 c J i uterus, uterine follicles, etc. In tially the same. They consist ol sions of the mucous membrane, or of a glove, arranged perjiendicul : which thiy open by minute apei i of a basement membrane lined b> erally columnar on the sides and covered externally by the vessels stances, as in the stomach neui subdivide into from two to foui- i pouches, and are sometimes con\ > instances they are arranged like stem, and are termed racemose as of the pharynx, trachea, etc. The mucous membrane of the > honey-combed appenrance, consi-t pits or de}n'essions, from j^-^ to mmm.) in diameter, separated In the bottom of these depressions are seen the openings of minute tubes, the gastric follicles. These are divided into two varieties, mucous follicles, or those that secrete mucus, and gastric or 'peptic follicles, or those that secrete the gastric juice. These two varieties differ only in the character of the epithelium which lines them. The mucous follicles are lined by columnar ei)itlielium on the sides and rounded in the bottom. In the pei)tic follicles, the deep ■"^'o'' :il I \l redu taini |)hat aroui circu Jto The> :l II II 1 |m: r^l 11 iiM I I I ! •' !■ I III' I - / ■ I III . I , , I '.111 ' 1 1 ' i I ' t I I I ■ ■ \ I I ■ \ n ■ - ,11 I ' ■ 1 1 I I 1 1 ' 1 1 1 1 1 .yi, .,'1 I'l I ! ! ; 1 1 1 I ( I M I I I. I : I I Ml I ' : I I I ' ' I i ' ■ M l! 'I I I U ; I ' <'■■ I'll I ; I 1 1 ' I I - I ,;/ ^jV sh.l Ih' I C.I 1.1 I \ ,i 1 \ '■ ., 1( '^l~^ 1.1 I In: I I'Cl.lllll, etc. ValvulyE Conniventes. — The valvulse conniventes arc reduplications or foldings of the mucous membrane, con- taining between them vessels, nerves, and lacteals or lym- phatics imbedded in areolar tissue. They pass transversely around the cylinder of the intestine for about | or f of its circumference, being about two inches in length, and from J to f of an inch (8 to 16 mm.) in depth at the centre. They begin at the hepatic flexure of the duodenum, and in- 110 entr.'iii diinii wluM' and < nivrii inci' tlie i! are i ' oftli. laru- the 1 hill I t« > ■■- 1 tow \ , of i A section of mucous membrane, sliowing Peycr's II'.: 1 1 \ \ . I I . 1 1 ; 1 1 j > I ' 1 1 1 1 M :_:_■ - rttioiis, or (.'Vcr.siun.s (;l'tlic mucous membrane, aud give to its surface a vel- vety appearance (Fig. 49). They are conical or fili- form in shape, and vary x\ Dccuioii oi mucous memurane, showing I'evcrs • i l\ r , . n glands, surrounded by the openings of Lieberklihns ^ lengull irom ,^g tO ^'fj Ot follicles and covered with villi. • i / -i i i \ ■» an men, (1 to A mm.) and from Ti^o of an inch in thickne.ss at the base, to y|„ of an inch (.4 to .IG nun.) near the summit. lie villi are UllO .syst D ted The (2.5 tissi byr ous In ! :/ /:/<.!. \/:S. II inn; 111 t.li(! (Inodcinnn and jojuiiuii), ' iiiiuity ill a sciuarc line ; but they 1'' ileum. Tlie total number for the |i\vardH often millions. ich villus consists of a basement mem- li a layer of columnar e})ithfcliuni, exter- in its interior a lies, nerves, and of the lacteal, lid iat ghjbules hrld togethei' Iso contains I ii liliii'-cclls. I I ;i 1 III pii .|,l||- l 1 ' ' ; 1 1 1 1 • I 1 1 ( ■ n 1 1 T > I 1 1 1 (i.'i |it cr ell ;i I'M i| |i| inn '! !lrv\<'-, liJi-, \\i .( l,c( li I III" '11,1 1 ;i1 111, 1, Ml I lii\ ■ •'■■>'- t , Am i| ' I i lr_' I . ' (KiK. 50.) ! <: ««^*;. i.nie comineiict im 111 .svsteni. >[ III' ,1 1' l;ir\ iiutuiirk ; .-, siU'Xilh iiiii-,i uUir liliru ; (/, liicteul. Duodenal OR "Brunxer's" Glands. — These are lirsd- ted to the duodenum and commencement of the jejunum. They are small, ovoid, lobulated bodies, about ^V of an inch, (2.5 mm.) in diameter, imbedded in the submucous areolar tissue, and open upon the surface of the mucous membrane by minute excretory ducts. These glands are most numer- ous near the pylorus, and diminish from above downwards. In structure, function, and in the character of their secre- fion, they rosomblc the lunercas. ■ & WW < i'>iin.l w Inn li I.,., In- hnin niir luiiilli n| t\ linr In ii liii.' I ' <'> ' n\m Ml i| iiinicd I , run ilihilu, (i( cImu'iI xciirlci liiiv Mil' Hii M|i|>!lli'H( ('\(lr(.>iv ilncl.nilil lllll. III!' iucmIu'i oI' wlin'li coiiliviii «, wliiliMli hitii'I ion cum MiHlinj' ,»|' niit'lrniotl coIIm m lvin|ili t'oi'iuiHclcM, niii'loi mikI j>rau»il»ir immHim (V\\y HM Mih'Ii lollirlo \h Hmronndod Ity n 1\ iMplwHii' vi'*'((>|, Mini n, imImuIo vm'umiImi' ih>I wuiK. (Vuin (ho 1mII(M', I'Mpillni'V vcmmcIm |»mmm iitlo ll»i« iiili>riiti innl n>(iirM in loi>|u, In {\\o l.)\r»>r p;n I ul Iho Mninll in(t«M(in*>M IIh>v ni> IVUX'"'^^I''*''*'I (oij;i>||»(M' in rinMilin of ovii.l pulclioM. (Voni Iwrnly <<» iMily in nnniUcr. cmIIimI /V'v<'I''n fuitrhrs or iilmhlitht' iiifuii ihtt.v 'ri\(«>*(' MVi' inolo nnnxMonM in lli<> Iowit piiil. oI' dx' ^.^u;^ll ml«".( inc*. i\n>l miv silnnd'tl «»n (Ii.mI pinl oj' Hip lu> lu.'.i ,li.|;in( I'liMu (111' Ml l;i.'lini.ii( ol lln' m,' .>iil .'r\ ^^•''iN I' \ I IM.I . II . ;|| .,< I.'MU.I HI ( lie I II '. in( I .1 111. , I'll. II n ' \ \ 1 I I ■ \ .'Ml. I I '. ( \ I I . I I { ' I ' I I I I ' ' 1 I I I I . I I I U' M I I I ' . 1 l'\ 1 ill' ,; 1 Hi 1 11,1 1 1, 'II ,i( [MM .(Ml. HI'. n\,i( I ri 1 1 om (iu^ M>\>.1 In |>h(li;sis thi'V \\\:\\ l>.>ciMUt' the si>m( of HiImm' o\ilnr liop^wit. wluoh soJhMis .-uhl nK'»M;it<>s, rcsnllinj^' in a (umMosvMno t\uni of vlianhuvi. INTIaU-MKNT. Tho intOi>umon( tvson\blos tlio oiIum- luonUuanou.s (Expan- sions ij> it.s ovnov.-»l stnu'tinv. anil u»iol»( Ih> iH»nsi(lor(Ml jim rtn ovortcd tnnoi^u^^ nion\br;\no. It I'ovors ;\\u\ prottH't.s (h(> Iwly ;>;':, M\-> .^r nK>(ion. aiul tnoro-os i;r;uhi;\Ily into (ho n»u- ( I ; I I CMll •.I'll mI I lllin |>'M I ',, \\\i- ifnlhrl t It ni , hin'ritl'lll III r HI. hlKllf, (Mill Mk' V" TII'I 1, IK'I V<"l, lyMl|tllM,I.M' ;, cl.r , I Itl 1 Hi l< !<' I ifl (i.it'nliii liMMiip. cmIIimI l.lir fill ill III oi fine "lull (nil, in vciuj I'll'irilKMIfM, flicro ('(ill IIk r.i, vi\ t'liiilmnin) TliiM in tiol. |H(l l»y vcM ^ hpIm, ih inticli lli'n'l<<"i' Minii ill «.ny oilier inciin- liiniin, mill nillHlHl.M nj" MIWiMlll Iliyi'lH (il ('(IN tliiiri'ii \y\ i'i'mx-mI' finli ,1 (' I Till- liiMl, Invr. ' ;Vv^0//''^iJ''■ / mIiiiico or I liu'ii' u Incli (lie Mi'\|, Mil' l<;i wini'iit iiii'liilil line ' ; I I , ( . 1 1 II I M 1 1 ; I I III I M 1 1 I p I / . . I I . , . I I r , . : . , I . I I I I . . I (In I M I I ' ' ' II I I \ ' I I ' I I II I III ' M I I I < U M I I I 'I I I I I I I I I I ', . I I I I I ' I I I I I ' I I M i In -. .■111!: I I, I :• :■;//;! an iiH'li . S III I II III ) III 'lijiiieli T, iJie Mi|'i'r(ieifi,l, ,,,',,, H Li iniiini ; Tlin e|iii|eiiniM c.uversi l,li(^ wlioki Hill race, iumI Ih not very nrii- fonn in thiclvnes;;, liein;^' v(My Miin in tli(! j^rr/m ana(!li fclie surface they become chani^ed in shape, and nitiniately fall off by a jjjfadual proeess of desipiainal-ion. In some of f/he oxanthc;- uial.'v, as scarlet I'ever, measles, etc., a {'niiiple(,e fleKipiainatioii ■it, n m 1 1 1 1 1 .in ill'' IllIrM' i|- I r -. MM'' ■ i| ill I'i'l i-^ . it' I ' h' 111' I.-. /I I , l;i \i'r. 'I'lleSi' (•el |> ai'e I liefi'j, ,lr e;i I li'( ; j if/iiir n / e. // , ;| | p | ;iri ■ v,i ■ |-\- ll 1 1 1 1 1 e)'- Mll-. in llie I'll ii |M[i|;U| r;ir'' \'\\r I 'i i] i ifi 1 , '4' lli:|lt''l' '_''i;i' I i 1; I II \' I I I 111 I III -Im - I .w :i I'l U ill. I I I l.ir. ■ ( i| ( lie , ■ , ';i |. I 111 I - Tlii' ■ li' n ai col eel cal it con re,!L^ (.<■ ;iM ()l;i, "I tile nipple, and other jtart.s of the body in pregnant women, ntievi, freckles, etc. They may assume dif- ferent shapes ; some are rounded, as those of the epidermis ; others poly- Pifem.ent cells. ^^^^1, as the epithelium lining the inner surface of the choroid coat of the eye ; while those imbedded in the substance of the choroid ^^'-esent a remark- ably stellate appearance (Fig. 52). Those which line the inner surface of the choroid contain a large quantity of pig- Micnt nrijinulcs. i'i^niictit ;_M'aiml(>s, wlicn viewed separatelx-, are traii.sj)arcnt ; but when viewed collectively have a dark color, and are seen to move about when set free from the cell, sometiincs even when contained in it. In their chemi- cal nature they resemble the cuttle-fish ink, which derives its color from the pifcment cells liniuor the ink-bajr. Pieree[>ti!)le in t' It. ls of v>'sse|s. liiT\-('-.. l\-iii]i|i;i I irs, ;i w 1 iu| i -, h i ;( I > ■■ 1 iiMi-riil;ir I i I u v- , ■, 1 1 -, ;n|i| :<<>\t\i' t;il, Hill iciMr, 1 ill ;ii i!)!,if tl^-,llt■ |'i_;-. ;, | . Tlif iih'-lii'-, mI till' arewlnr ti^>iir mv \rr\ mmmII tnwiuiU llii- ^llliae(^ Inn ••u''' laij-'T lowa.nl-. tli.' -^iil .jaei'Dl tl -lev In part-, wlict,' ■•t 1 rtlL'l M i ■, ici |nii .•,!, 1 ''1. W lill (■ ri!)i'.a|- ll -ai. j ■ i ■ , 1 ■ i , , i l l i ; i , i ■ * li« throug iie wliijle extent of the cutis, .s(;nu? of them surround the papilUu and hair-bulbs, and give rise to that 5 peculiar roughness of the surface called cutiti anserina, as is seen in the cold stage of intermittent fever. They are very abundant in the cutis of the scrotum (the dartos). Fat is found in the meshes of the deeper parts of the corium, form- ' ing a soft bed on which the skin rests, giving rotundity and symmetry to the body, and from being a bad conductor, it prevents the too rapid escape of caloric. The integument i may be tanned by any substance which will precii)itate the n»ll;i'f 'II, as nai, i(;ii u, hep lock liaik, etc., tln' tannic aci <\ I lir luon' -m -i I i \ •' | t;i pi 11:' ■, a . ( li' i .!• i il ill'' Il Mill ;ill' I lip-., Ill < i\ ;i| li;i pri I I m m||i s c;i I|im| l;ii't ilr en I' pll I'll I |''i i- Id A Tiir-.- I.d^li.- ;nv <;.'l|r| ;i i I \' I . • -'Ml . 1. ■. | .1 ! 1 ! t I , ■ III,!- , . . . r r ' 1 1 1 1 1 I I I \ . ■ I I . I ■ I i 1 I ■ 1 1 M ' 1 1 ■ > I I \ ■ I : I t 1 1 • tl I. f( eti i liaui|->, and sdlcs ut' the h'et, they are numerous, anil attain a largo size, and are so arranged as to form ridges on the surface, which are generally more or less curved and separ- ated by grooves. This appearance can be seen with the naked eye. Each ridge is produced by a single or double row of papilla3 projecting from the surface of the cutis, and covered with the epidermis. The papillne in each row are generally arranged in pairs side by side, each pair being separated from the next adjacent pair by transverse grooves which cross the ritlges at right angles. In the centre of each traiisvorse jj^i-oove iiiay Im; seen tlu' oi-ificti oj" a sweat duct. In a s(iuare incli of the palm may be seen twenty riilces, or forty rows of papilhe, and ratlier more than sixty pair in each row. The office of the papillfie is sensation or touch, and to increase the surface for cell development. They are covered and protected by the epidermis, which also fill>i in the sjjaces between them. Nails. — The nail is an extension of the epidermis, very much hardened, in order to form a protective covering for tho dorsal surface of the terminal jthalanges of the hands and feet. Each nail consists of a root, body, and extremity. The cutis i.s folded upon itself so as to form a groove, in which tile 'ut and ]u}i\y of t1i(> nail are iiiilie .,. I ; .\ ;i | i ,r '■I"!.. ■'.■■■ I .Ml' i I SI II se, s' lis lis I e I,, , I s IS i \ . ] \ II : s-l '*u-. I I I y , I I I ^ el. in I M the naked eye, for tho purpose of increasiug the cell-fdiniiug surface. The vascular and nervous supply is vary abundant in the matrix. In long illness, particularly of the mucous surfaces, the nails are marked by a transverse groove, the size of which is an index of the length and severity of the disease. It is caused by the abridgment of the nutritive process for the time being. This peculiarity is taken ad- vantage of by fortune-tellers, gipsies, etc., who, by examin- ing the nail, are able to tell the person when he was sick, and the dui-ation of tho illness, from the size of the "Toove I- 118 MEMBRANOUS EXPANSIONS. Figr. 53. and its distance from the root. The nail increases in length by the development of cells at the root, and on the under surface of the body, which push it onwards in its growth. The finger nails grow at the rate of about \ of a line per week, and the toe nails about -f, of a line per month. Hair. — Hairs are found on all , parts of the surface of the body, except the palms of the hands and soles of the feet, and vary in length, shape, and thickness. They are implanted in a saccular cavity called the hair follicle, wh'ch is formed by an involution or dip- ping of the basement membrane into the corium, carrying with it the epidermic cells, the superficial layers of which become rounded. This follicle is larger at the bottom ■jhan at the top, to correspond with the bulbous enlargement of the hair, and presents in the bottom a highly vascular papilla covered with cells, from which the hair grows. A hair Hair in its follicle, magnified .50. . '^ a, stem cut .short ; b, root ; e, bulb ; COnSlsts of a VOot Or that part im- d, hair cuticle ; e. internal, and f, ex- ,,,. />iti ?/• ternal root-sheath ; a, h, dermic coat bedded m the follicle ; a Sliaft tllO of follicle ; i, paitilla ; k, k, ducts of _ ■^ sebaceous ijlands ; 1, corium ; m, mu- part whlch prOiects frOm the SUr- cous layer of epidermis ; n, upper r i. j flattened layers of epidermis ; o, up- face ; and the extremitV, which is l)er hmit of internal root-sheath. ' ^' (lioiiiker). sometimes split. The root is the thickest pavf, and presents a bulbous enlargement. The diameter of the shaft varies from ^U to -rsVo of an inch (100 to 16.6 mmm.), and is divided into two parts — the cortical and Tnedidlavt/ portion ; the former predominates in the human subject. In structure it resembles the epidermis. On section it is seen to consli-t of cells and cement substance. In the medullary portion they are rouuded ; but toward the circumference of the cortical portion, they first becomn oval, thei ed, an i ger to t to t ext( line im mac caus man INTEGUMENT. 119 A Kcctinii (if hair then elongated or fusiform, and finally flattened and harden- ed, and the latter are so arranged as to present an imbricated appearance (Fig. 54). If the fin- ger be passed along the hair from the extremity to the root, a distinct roughness is felt, owing to this peculiar arrangement of the cells. The external surface presents fine, sinuous cross lines, and a jafjcfed boundL,ry, caused by these nvignificdatidshow- . . '' ^ . . . . iniJr tlie imbricated imbrications. If a longitudinal section be appearance. made, the cortical substance presents a fibrous appearance, caused by tlie arrangement of the elongated cells in a linear manner. A few pigment cells may be seen scattered irre- gularly among the fibres of the cortex, but they are more abundant in the medulla. The color of the hair depends on their presence. The coloring matter consists oi melamue, and is readily bleached by chlorine. It is stated that the hair has grown white iu a single night from the influence of some depressing passion, as fear, etc. It must, however, be a very rare occurrence, and can only be explained upon the supposition that some peculiar fluid is secreted at the papu- la, which percolates through the hair and destroy the coloring. The hair is increased in length by the development of cells on the papilla at the bottom of the ^olUcle, which push it upwards. The cells which are developed in the papilla are originally rounded, and those which grow on the summit continue so throughout the medulla to the extremity of the hair : while those which grow fiom the sides soon become flattened and imbricated as they pass upwards on the exte- rior of the hair. In some animals the papillae are large, and prolonged upwards in the central part of the hair above the surface of the body, and hence they bleed when cut or ex- tracted. In the disease of the hair called 'plica Polo7i{ca, the papilla} are said to be elongated, and bleed when cut close to the skin. The hair in these cases grows very fast, and becomes matted together by a glutinous secretion. Some ;. !■■( •I«(:J liii ■" ■ -* li;;. 1 t 11* • 3 lie, 11^ . 1 ' i il-. p it 120 MEMBRANEOUS EXPANSIONS. of the sebaceous glands open into the hair follicle, and pour out an oily secretion which keeps the hair smooth and glossy. Development of the Hair Follicle. — At about the sixth week of ftetal life, there is first seen a slight depres- sion or inversion of the basement membrane lined by the epidermis, forming the rudimentary follicle. It then be- comes deeper, narrower, and fiask-shaped, containing cells ; those in the centre, fusiform in shape, are arranged in a line, and form the rudimentary hair. At this time also, the papilla springs from the bottom of the follicle. The first brood of hairs are temporary, like the deciduous teeth. After birth the follicles deepen, and a new papilla io formed at the bottom of each, from which the permanent hair is developed, the old hairs being cast off. When a hair is plucked out, the follicle tills with blood, which after a little disappears, and '**the papilla is not destroyed, a new hair will spring up .uything that interferes with the vascular supply at the base of the hair, will affect its growth and cause it to fall out. The growth of the hair may be pro- moted by the application of certain stimuli, as tincture of cantharides, bay-rum, etc. ; these form the bases of hair restoratives. Sebaceous Glands. — These glands are found in most parts of the integument, except the palms of the hands and solos of the feet. They are very abundant on the scalp, face, axilla, groin, etc., and open either upon the general surface, as on the face ; or into the hair follicles, as on the scalp (Fig. 51). Each gland consists of an involution of the basement membrane, lined by the rounded or mucous layer of epithelium. Sebaceous matter is secreted from the capillaries beneath the basement membrane by these cells, which at maturity break down, and throw out their secre- tion either on the surface of the body, or into the hair follicles. In some cases the gland is lobulated or sacculated in order to increase the secreting surface. In the scalp INTEGUMENT. 121 there are two of these glands to each follicle, into which they pour their secretion, for the purpose of lubricating the hair. The excretory ducts are generally short and straight, and in some parts of the body, as the face, they become the habitat of a parasitic animal the i^teatozoon Folliculortim, These are more common about the time of puberty, and in those possessing a torpid skin. The sebaceous matter which covers the foetus is called the vernix caseosa. The development of the sebaceous gland is similar to that of the hair-follicle. At about the sixth month there is seen a knob-like depression of the basement membrane of cither the general surface or the hair follicle, as the case may be. This soon becomes deeper and narrower at the mouth, until it assumes a flask-shaped appearance, and is lined by the rounded layer of epithelium. Ceruminous and Odoriferous Glands are varieties of the sebaceous. The ceruminous secrete a waxy material which entangles particles of dust, insects, etc., and prevents their access to the delicate membrane of the tympanum. Sudoriferous Glands. — These are situated in the deep part of the corium and subcutaneous areolar tissue, being surrounded by adipose, and open by a duct upon the sur- face of the epidermis, (Fig. 51). Each gland is formed by a simple involution of the basement membrane, carrying with it the deep layer of cells, and terminating in a convo- luted tube beneath the corium. Sometimes the tube is branched, the branches being rolled up in one clump, and held together by areolar tissue. The duct, as it passes to the surface, takes a tortuous course through the corium, upon the surface of which it loses the basement membrane and is continued on through the epidermis in a spiral course, the calibre being larger, and the walls of the duct being wholly formed by the layers of cells. It opens on the surface obliquely, by a valve-like aperture, formed by the scaly epithelium. The openings are called pores, and as many as 2,800 on an average, exist on each square inch 111 1 ( o(Z of man consists both of organic and in- organic substances. The best classification is that of Dr. Prout, in which the different kinds of food are divided into four groups : 1st. The Aqueous Group. — This forms part of the food of ail animals, and enters largely into the composition of the body. 2nd. The Saccharine Group. — This group is derived chiefly from the vegetable kingdom, and comprehends sugars, starch, gums, vinegar, &/C. They consist of carbon, hydrogen and ox3'gen, the two latter in the pro[)ortion to form water. 3rd. The Oleaginous Group. — It includes oils, fats and alcohol. They resemble, in elementary composition, i\m preceding group, except that the carbon and hydrogen exist in nearly equal proj)ortions. 4th. The Witrogenous or Albuminous Gr-oup. All srh- stances belonging to this group contain nitrogen, as fibr.j, albumen, casein, gelatine, gluten, etc. They are chiefly de- rived from the animal kingdom. Gluten is the nitrogenous. ! 1 «4 :* 120 DIGESTION. Ill 'II i "■■IX principle of vegetables. They are sometimes called hiato- fjenetic aubatancea. To these may be added a Mineral or Saline Group, as sodium chloride, calcium phosphate, etc. Milk is found to contain ingredients embraced in the pre- ceding groups, and hence it is well adapted to the growth and development of the young. The aqueous group is rep- resented by the water, the saccharine by the sugar of milk (lactose), the oleaginous by the butter, the nitrogenous by the casein, and the saline group by sodium chloride, calcium phosphate, etc., which the milk contains. From the above it will be seen that the food of man is naturally subdivided into two great classes ; the non-nitrogenous embraced in the 1st, 2nd and 3rd groups, and the nitrogenous, which embraces the 4th group ; the former supplying a large amount of carbon. Lie big styles the nitrogenous substances, the plastic ele- ments of nutrition, and the non-nitrogenous, the elements ■of respiration. The latter term is objectionable, however, inasmuch as those substances are not actually required in the process of respiration. The terms nutritive for the nitrogenous, and calorifacient for the non-nitrogenous, as proposed by Dr. Thomson, are preferable, or the terms hiatogenetic and calorijic. In colder climates, a large quan- tity of the calorifacient elements are necessary to maintain the proper temperature of the body, and the natives in- stinctively feed on fats and oils ; while the natives of warmer climates feed on fruit, which contains less carbon. I'rom the construction of the teeth, and digestive appara- tus of man, a mixed diet would seem to be the most suita- ble. Both animal and vegetable food is necessary to his highest mental and physical deveh^pment. Certain diseases may arise from the want of a proper admixture of fresh vegetable diet, as scurvy. This is due to the absence of the vegetable acids in the system, as citric and malic acid, and itnay be remedied by their administration alone. If, on the other hand, the nitrogenous elements be defi- FOOD. 127 cient or absent, imperfect nutrition shows itself in the form of ulcers in certain parts of the body, as in the cornea and alimentary canal and the animals die of emaciation. Mag- endie tried the experiment by feeding dogs for some time on sugar and water alone, and ulceration of the cornea ensued. The same rosults were observed wlien the animals were fed on gum alone; and when feed on olive oil and watei*, or butter, the animals emaciated rapidly, but ulceration of" the cornea did not occur. Quantity of Food. — The absolute ([uantity of food re- quired for the sustenance of the body in health varies with the age, sex, constitution, habit, and the circumstances in which the individual may be placed. It is of considerable importance to know the average amount of food required by each individual. In the diet scale of the British navy, each seaman gets from 31 to 35^ ounces of dry nutritious food daily, 2f) ounces of which is vegetable, and the rest animal, together with sugar and cocoa. This is found to be amply sufficient for the support of strength. The soldier is allowed one pound of bread, and one pound of meat per day, with vegetables in their season, and tea, coffee, or cocoa. In the English hospitals, full diet, upon which convalescents are put, consists of half a pound of meat, twelve to fourteen ounces of bread, half a pound of potatoes, one pint of milk, and one pint of beer, or half a pint of porter. In prisons, if the prisoners are idle, they receive about 25 ounces of solid food per day, 5 or 6 ounces being meat. Some persons consume large quantities of food. The wan- dering Cossacks of Siberia devour from 8 to 20 pounds of meat daily. It has been ascertained that from 25 to 3"» ounces of solid food per day, one-fourth of which should be animal, is sufficient to maintain health. Prof Dalton esti- mates the quantity of solid food necessary for a healthy man at 38| ozs. avoirdupois per day, consisting of bread 19 ozs., meat 16 ozs., and butter or fat 3| ozs. ; and the quantity of water at 52 fluid ounces. It ^ 128 DIGESTION. lit 111 « • n It is also important todGtorminc the proper flict suitable to particular nialailicH. TIuih, in diaeaso of llio kidneys, liver or bowrls, or in rlioutnatism, gout, dy.spop.sia, or fatty ease. Beer and porter may also be found useful in various forms of indigestion ; the bitter prin- ci])le which they contain is also slightly tonic in its action. The habitual use of alcoholic liquors is highly injurious. They are poisonous in large doses, and when used in excess, produce a morbid condition of the nervo-muscular parts of the body, as is seen in delirium tremen.s, and in fatty degen- eration of the muscular tissues of the body. Intemperate persons are also more prone to epidcuiie diseases, as cholera, dysentery, fevers, etc., in consequence of the accu- mulation of effete materials in the blood, which render it more liable to "fermentation." The power of the body to endure fatigue, or to resist the extremes of heat and cold, is also diminished by the use of intoxicating liquors. Tea, when u.sed in moderation, limits the less of weight when the diet is insufficient ; prevents the loss of substance •I * 130 DICESTrON. 4 M V in the slmpo of uroa ; diiniuislics V\v amount, of prrspinition ; and lias no apprrciaMo oH'rct on rospi ration or circMiIation ; but when usod iti rxooss, \h stimulating and liigldy injurious to tijo norvous Hystom. CoFFKK is moro stinuilatin^' tlum tt-a. When UHod in modorati.' quantities it prevents waste of tlie tissues, arouses nervous ener;j;y, and invij^oratt's tho circulation ; luit in ex- cess is decidedly injurious. ToHAcro, tliouj^di not an article of diet, sliouhl ho referred to in this connection, as in excess it inti'rferes very nuich with the proper assimilation of the food. • Smoking', chew- injjf, and snutHufj;, are lji(> most harliarous customs of our race. To those unaccustomed to th(» use of tohacco, it causes nausea, vondting and purging. In habitual smokers and cheweiN, it creates thirst and increases the secretion of the saliva anil buccal mucus, which, from being nnx<;d with th(! juice, nnist bo expelled from the mouth. To some people tho fumes of tobacco are very disngreeable, and irritating to the lining mendirano of tin; lungs. The ajiplication of it tu abraded surfaces is very dangerous, and has been known to prove fatal. A substance called //>w is obtained from tobacco, which is very poisonous, almost o(|ualling in activity hydrocyanic acid. HUNOEU. — Hunger is the jxeneral want of nourishment in the system ascribi'd to tho stomach. Tho introduction of food into tho stomach alone will not allay tho sensation ; it must be partially absorbed, and enter tho circulation. Hun- ger is not occasioned by more emptiness of tho stomacli , neither can it bo duo to tho secretion of gastric juice, as some have supposed, because that fluid is not secreted, except during digestion, or when some substance is intro- duced into the stomach. It is more ])robablo that the sen- sation in tho stomach is duo to a congested condition of the capillaries, beneath tho mucous membrane, excited by the influence of the sympathetic nerves, and communicated or telegraphed to the nervous centre. If the brain is actively STARVATION. ISl «!n<,'ajj;oil, the tulnj^rnplilo iiit'ssa^o is not noticcil, nml tlnm tho scuHjition may Im! ilispcllcMl for a tiiiio. hivi.sioii of *ho ptKMinidi^'astric iiervt! anniliilates tlio HoiiHatiori of satioty, but tiot of lnmj'cr. TlHUHT. — Thirst is tho ^'cncial want of MuidH in the hvh- toni rofoncMl to tho faucos. This wMisation may ho as offi.'ct- iially allayolox luituiv. Dining the |)1'oc(\sh of \iiiuslioation, iho foo»l is mixiMl with tho saliva.. This sub- stanco is a mixtun^ of four «liM(,inct Ibiids which differ from «»ach otlicr in (l»(Mr cluMuical and physical pioptMlics, viz.: tho .secretion of th(» parotid }^land, (he submaxillary, the snblinjvunl, and tho buccal glands. The parotid gland is situated luMHVith (he ear, dost; to the teuiporoniaxillary articulation, and opens into the mouth by its ««xcr<>tory duct (^Steno's\ opposite the second mohir tooth of (,h(^ upper jaw. The submaxillary ijlaml issi(ua(ed b«>neath the lower jaw, and comnnn\ica(t>s wi(h the niou(.h through Wharton's duct, which • ens on the side of the IYmmhuu linguie. The sublingual gland is situa(.(>d beneath the (t)ugu(», near tho symphysis of the lower jaw, atul opens into th(» mouth upon an clevatcMl civst o\' mucous metnbraui* (^which may \h) felt by tl)e tip o\' the tongui*), by tifteen or (wenty opcMiings (ductus UivinianiY Stiutotuuk ok thk S.M.iVAKV (iT,ANi)S. — Th(> salivary glands consist of numerous lobes made up of smaller lobides connecteil together by anM)lar tissue, vessels, nerves, otc. Kiaeh l(>bule c«>nsists of numerous vesicular pouches, or (rei)il wliich open into a ct)mmon duct ; these vesicular })ouches are about j^l^ of an inch in diauu^ter (">() nunm.) lined by a layer of roumled or glandular epithciium, and surroumled by capillaries and nerves. The cells wliicli line tho pouches and ducts are smaller than those which secrete tho saliva. The secretion of saliva is stiujulated by tho pre.sonco of food or otlier substances in tho mouth ; oven tho aiglit or idea of food, or itlynlin or saliviii) I.34 I'i>t!issiiiiii SmI|)1u)( ynniilo ,06 ('alcium, scidiiiiii and inaf;n(!>,ium pliosphatfs. .9S Sudiimi and |)i)lassiiim idiloiidc:-. .X4 Kpilliditiin and ^land cells 1.62 I OCX). 00 It is al.s(» .said to contain a trac(3 of an)unu!n, and soinc oil globules ; it thorcl'oro becoinuH slightly turl)id on boiling, or l)y tho addition (»f nitric acid. Tlu! pi nallii gives the saliva' its vi.sciposed to be the true physiological use of saliva, viz. : to dissolve or digest the starchy portions of the food. It was very soon noticed, liowever, that in the ordinary process of digestion the starchy matters do not re- main long ej.ough in the mouth for this change to take place, but pass at once into the stomach, where ilie further conversion of starch into sugai' is retarded by the presence of the gastric juice. The most important use of the saliva is to moisten tlie food and facilitate its mastication, to lubri- cate the mass or bolus, and to assist in its pas.sage during the process of deglutition. The wateiy fluid of the parotid gland is useful in the process of mastication ; while the more viscid secretion of the other glands, and buccal mucus, serve to lubiicate the triturated mass, and facilitate its pas- sage down the oesophagus. The tonsils also secrete a viscid fluid, which serves to lubiicate the bolus of food during swallowing. During mastication, the saliva is intimately mingled with the mass, and may in this way mechanically enable the gastric juice to penetrate more readily every part, as it enters the stomach. It was observed by Spallan- zani that food enclosed in perforated tubes, and introduced ♦There are two classes of ferments, organized and unorganized. The action of the former is dependent on the life of the ferment, as for example the yeast plant whose fermentative activity depends on the life of the yeast cell ; the latter is not a living organism. DEGLUTITION. 137 into the stomachs of living animals, was more readily digested when previously mixed with saliva, than when mixed with water. The salivary glands are not very acuivc in infants until the age of six months, and they are there- fore incapable of properly digesting starchy food, corn flour, etc. DEGLUTITION. The organs of deglutition are the mouth, tongue, pharynx, and oesophagus. The mechanism of deglutition may be divided into three stages. In the first the food, when pro- perly masticated, is formed into a bolus on the tongue, and carried backwards through the anterior pillars of the fauces, by that organ, and forced into the pharynx. This is done by the pressure of the tongue against the roof of the mouth — the pressure commencing at the apex, and ending near the base. During the second stage, the hyoid bone is car- ried upwards and slightly forwards by the anterior belly of the digastiic, mylo-hyoid and genio-hyoid, the pharynx is raised by the stylo-pliaryfigeus and palato-pharyngeus to receive the bolus, the epiglottis is pressed over the aperture of the larynx, by the elevation of the pharynx and larynx towards the base of the tongue, and the bolus glides past. The baso of the tongue is now diawn slightly upwards and backwards by the posterior belly of the digastric and stylo- hyoid, the palato-glossi (or constrictors of the fauces) con- tract, and prevent the return of the bolus into the mouth, the soft palate is raised by the levator palati, the ])alato- pharyngei contract and come neaily together, the uvula tilling u}) the space between them, and in this way the food is prevented from passing into the posterior nares. In the third stage, the constrictors of the pharynx contract upon the bolus from above downwards, and force it into the oesophagus, which, by virtue of its peristaltic action, urges it onwards to the stomach. The first act is voluntary ; the second and third are involuntary. The nerve centre for 1 138 DIGESTION. n. t..: U haryngeal and ]ineuniognstric nerves, and the motor branches of the fifth, facial, hypoglossal, pneumogastric and sj)inal accessory. Vomiting. — In the mechanism of vomiting, the jirocess of deglutition is exactly reversed. This may be cau.sed by the administration of direct or indirect emetics, by mental emotion, as the sight of a disgusting object, by any unusual motion, as sailing, swinging, »Jcc., by nervous shock, as in the case of severe wounds, by derangement of the sy.stem, or the ])resence of irritating substances of any kind in the stomach, or obstruction to the ])as.sage of the food through the bowels. Its rationale may be explainetl by the theory of reflex action. The irritation or impression being applied to the periphery of the nerves, is first conveyed to the nervous centres (uiedulla oblongata), and thence a motor impulse proceeds, l)y which an impression is made upon those j)arts concerned in tlio act of vomiting, through the nerves which are distributed to Ihem. The medulla oblon- gata may be affected direcily by the presence of particular substances in the blood, or causes acting directly on the centre itself The motor nerves implanted in it are thus stimulated to action, and the abdominal muscles, diaphragm, nmscles of the larynx and pharynx, as well as the muscu- lar fibres of the stomach or (vsophagus, are thrown into contraction. First, a deep inspiration is taken ; the aperture of the glottis is closed, and the lungs being filled with air, the diaphragm is fixed. The glottis is closed by the elevation of the larynx against the base of the tongue. The pharynx is raised, the palato-pharyngei contract and close the pos- terior nares, the uvula filling the small interval between them, and thus the fluids are })revented passing through the nose. This constitutes the first act. Then the stomach contracts and is compressed against the diajihragm by the CHYMIFICA TION. 130 contraction of the abdominal muscles ; the pylorus is closed, and the contents are forcibly ejected, their passage being facilii.ited by the anti-peristaltic action of the stomach, ccsophagus and pharynx. CIIYMIFICATION. This ])rocoss takes place in the stomach, throu<^h the agency of the gastric juice. The walls of the stomach consist of three coats; an ext(!rnal peritonc^al or serous membrane; a middle muscular, consisting of longitudinal, circular and obli(iue fibres ; and a mucous coat; with ves- sels, nerves and lymphatics, all held together Vty areolar tissue. A delicate form of connective tissue is found in, or immediately beneath the mucous membrane, called reticu- lar or retiforin tissue, the meshes of which contain lymph corpuscles. There are also some noustriated muscular fibres called muHCularis mucoHW. The mucous membrane of the stomach is lined by columnar epithelium, and when examined by a lens, it presents a ])eculiar honeycombed api)earance, caused by a number of shallow depressions or alveoli of a polygonal or hexagonal form, which vary from TOO t') a Jo of an inch in diameter, separated by slight ridges. In the bottom of each alveolus may be seen the orifices of minute tubes, the gastric follicles. Tliey are arranged per[)endicularly, side by side, short, and tubular in character towards the cardiac end ; but near the pyloric extremity, they are more thickly set, convoluted, and ter- minate in dilated saccular extremities, or divide into from two to six branches, the object of which is to increase the extent of surface for secretion (Fig. -iS). The follicles con- sist of an involution of the basement membrane, lined with cells, and are divided into two varieties, which differ only in the character of the cells which line them, and the secre- tion which they produce, viz : the mucoivs follicles and peptic follicles. The former predominate towards the pylorus, and the latter towards the cardiac end. The 9 f .4 140 nraESTioiv. ♦I i-: imicroidal wWh ; abovo this it is lin(»d liy round(Ml opitholiuni, and tho upper part of tiio follicle is lined with onlinary cohunnar epitheiinni. These follicles are snpi)osed to secrete the gjistric juice. n(!sid(»s these, there are tho lenticuldv ijlauds, which resemble in structure, function and general ajipearanco, the solitary glands of tho intestine. They are situated beneath the surface of the mucous mem- brane, and are found chiefly along the lesser curvature of the stonuich. The mucous membrajie of the stomach is abundantly supplied with blood-vessels. 'I'hese break up into fine capillary plexuses, with oblong meshes, which sur- round the follicles, and are prolonge*! upwards to the ridges of nnicous membrane boimding the pits or alveoli. The nerves of tl)e stonuieh are derived from the pneumogastric and .sympathetic. In the submucous areolar ti.ssue of tho stomacli and intestines, there is a fine plexus of non- medullated nerve fibres, known as " Mei.ssner's plexus." Gastric .Tuiok. — (histric juice was obtained by Spallan- zani from the stonuichs of aninials, by causing them to swallow sponges, attached to the end of a cord, by which they were afterwards withdiawn and the fluid expressed. It has since been obtained and experimented upon, by Dr. Beaumont, of the U. S. Army, from Alexis St. Martin, a Canadian boatman, who had a permanent gastric fistula, the result o( a gun-shot wound. Schmidt has also had opportunities of examining it in a female named Catherine Kutt, who had for three years a gastric fistula under the left nuinnnary gland. It nu\y also be obtained from any of the lower animals, by nuiking an artificial opening through the abdominal walls and inserting a canula. Physical ArrKARANCE and Propkrtiks — It is a clear, colorless fluid, of an acid reaction, secreted only during digestion, or as the result of some irritation applied to the Tl GASTRIC JUICE. Ul iinicoiis coat of tl)(5 Htomaoli. Its specific jrjavity vnriow from 1001 to lOlO. It is not proiKs to decomposition, and may Ih; kept for an indefinite length of time in an ordinary glass-stoppered bottle. After stany irritation of temj)er, f«;ar, joy, fatigue, mental exertion, or any febrile distuibnnce of the system. The gastiic! juice does not act on the nmcous mend)rane of the stomach during life ; but r.fter death this menibrane is generally found dissolved and disintegrated by its action This, according to I'avy, depends upon th(! alkalinity of tin? the blood, which circulates fret.'ly during life in tho walls of the stomach, and which neutiali/es the acidity of tho gastric juice an«l destroys its digestive powers on the coats of the stomach. CHKMICAL (JOMPOSITION OF GaSTRIC JuICE: numan. Dog's. Water 994-40 97'- '7 l'oi)sinc 3-'9 '7-SO Hydrochloric acid, (free) 0.22 2.73 Sodium, potas'iium, and calcium, chlorides .... 2.07 5.87 Magnesium, calcium and iron Phosphates 12 2.73 Traces of Ammonia lcX).oo 100.00 It was formerly supposed that lactic acid was the acidify- ing agent of the gastric juice, and in all probability a small quantity is sometimes present ; but hydrochloric acid is much the more abundant and important of the two. The 1 f M A \ It \ 142 DIGESTION. c II, presence of free acid is essential to its ])hysiological proper- ties, for the gastric juice will not exert its solvent action upon the food after it has been neutralized by an alkali. The organic matter, or pepsine, is next in importance. It is precipitated from its solution in the gastric juice by alco- hol and various metallic salts ; but is not affected by potas- sium ferrocyanide. It may be coagulated by boiling. Gas- tric juice which has been boiled, or mixed with a small ■quantity of bile, loses its property of digesting substances. Function. — It dissolves the albuminoid or nitrogenous substances (proteids) of the food, and converts them into a substance called albuminoso or peptone. The licpiofying process which the lood undergoes in the stomach is thought b}' .some to be, not a sim])le solution, but a catalytic trans- formation produced in the albuminoid substances by the pepKine, which acts as a ferment (hydrolytic). The gastric juice will exert its solvent action on the food outside the body, as well as in the stomach, if kept in glass phials upon a sa!ul bath, at a temperature of 100° F. In the digestion of cooked meat, the gastric juice first dissolves the areolar tissue, and thus sets free the muscular fibres, which aie sub- sequently acted upon and dissolved. Some albuminoids, as casein of milk are first coagulated by the action of the gas- tric juice, and then acted upon similarly to the other solid principles. The albuminoid or proteid substances are acted upon so as to be changed into albuminosc or peptone. This substance differs from ordinary albumen in not being |)reci- pitated by heat, nilric or acetic acid, or potassium ferroc^'an- ide, and in being rendered di fusible, or easily absoibed. It is readily precipitated by tannic acid or hydrargyrum perchloriclg. The peptones are closely allied to the crystal- loids, which possess superior osmotic ])roperties as compared with the colloids. Some authors describe three sorts, a, b, and c, peptones; other allied substances formed during digestion are named parapeptone, metapeptone, and dyspep- tone. After entering the blood vessels, the peptones are RATE Of DIGESTION. 14S again transformed into all>innen, a change wliich is neces- sary lo prevent their passing out. The saccharine portions of food arul dextrine are at once absorbed in tlie stomach. Tlie amylaceous principles are prepared for the action of the pancreatic juice, by softening the external covering of the starch granules. Fatty ti.ssues are also partly disintegrated and the fatty matter set free, by a solution of the areolar tissue and albuminous cell walls, but tl. j fat itself undergoes no change. The gastric juice also possess ant'iHeptic pro- perties, which not only prevents the putrefaction of nitro- genous substances during digestion, but also corrects the effects of partly decomposed substances taken as food. Influence of the Neuvous System on Diuestion. — The function of digestion is arrested by strong mental emo- tion or serious bodily injuries, and the food is often rejected. The moveinents of the stomach are due to the presence of food acting as a stimulus to the periphery of the nerves, transmitted to the ganglia, and reflected to the muscular coat. Irritation of the pneumogastric nerves produces in- creased peristaltic action of the stomach, and division retards or arrests it, and temi)orarily arrests the secretion of gastric juice. Galvanization of these nerves increases the secretion of the fluid, but diminishes it when applied to the sympa- thetic. Rate of Digestion. — The time required for digestion varies in different animals. In the carnivora, fresh raw meat requires from nine to twelve hours. The average time required in the human subject varies from one to Ave and a liPvif hours, according to the nature and quantity of food taken. Dr. Beaumont's table, taken from Alexis St. Martin. Pigs' Feet i.cx) hour. Tripe i.cxj " Trout 1.30 " Venison 1.35 " Milii 2.00 hours Roast Turkey 2.30 " Roast Beef 3.00 hours. Roast Mutton 3.15 " Veal 4.00 " Salt Beef 4.15 " Roast Pork 5. 15 •* A 1 It 144 DIGESTION. • ■lit It: ft. Artificial Digestion. — An artificial digestive fluid may be made by macerating portions of the mucous membrane of a fresh stomach in water or glycerine, or by dissolving pep- sine in water and then adding hydrochloric acid (1 part in 1000.) The fluid thus formed will digest portions of food if kept at a temperature of 98 to 100° F. Such a prepara- tion is very useful in cases where deglutition is impractica- ble, and in which the body is being nourished by nutritive enemata. It is mixed with the nutritive fluid, whicli is in- jected into the bowels. 7-'cp8i'>*e is administered with benefit in some forms of dyspepsia, but should be combined with hydrochloric acid. Movements of the Stomach. — These are effected by the alternate contraction ot the longitudinal and circular flbres of its muscular coat. The muscular fibres of the orifices also keep the stomach closed during digestion. The move- ments were observed by Dr. Beaumont, in the stomach of Alexis St. Martin by introducing the stem of a thermometer. This action is more energetic near the pylorus, the bulb being grasped tightly and drawn towards this orifice. The peristaltic action of the coats of the stomach produces a kind of double current of its contents, the circumferential portions being moved towards the pylorus, while the central portions are propelled in the opposite direction, towards the cardiac orifice. The action of the stomach produces a constant movement of the food, and secures its thorough admixture with the gastric juice, which peneti'ates ever}' particle, and converts it into a greyish pulpy mass of a homogeneous a])pearance, called chyme, which then passes into the duodenum. CHYLIFICATION. This process takes place in the small intestine, but principally in the duodenum. For a description of the niucous membrane of the small intestine, see "raucous membranes." It has already been stated that only the INTESTINAL JUICE. 145 albuminoid subHtances are digested by the gastric juice. The starch, oils and fats, pass unchanged into the small intestine. Here tliey co./ie in contact with the mixed intestinal juices, and are reduced to a state fit for absorp- tion. The juices of the small intestine are the inteatiruil juice proper, or the fluid secreted by Brunner's glands and Lieberkiihn's follicles, the pancreatic juice, and the hiie. These fluids, in contradistinction to the gastric juice, have an alkaline reaction. Intestinal Juice. — This may be obtained in a tolerably j)ure state by ligating the duodenum of some of the lower animals, as the dog or rabbit, just above the opening of the choledcc duct, and establi.shing a fistulous opening into the duodenum. It is small in quantity, and consists of the se- cretion from Brunner's glands, mixed with the fluid from the follicles of Lieberkiihn, and some mucus. Physical Appearance and Properties. — It is a color- less, viscid fluid, of an alkaline reaction, closely resembling, in its physical characters, the saliva and pancreatic juice. It possesses the jiroperty of converting starch into sugar. The quantity obtained by experimenters has rarely been sufficient for a thorough investigation of its properties. Function. — It is supposed to aid in the dLq-estion of the amylaceous ])ortions of food. By its action starch is converted into dextrin, and then into sugar (glucose), in which state it is soluble, and thus admits of direct absorp- tion into the blood-vessels, or the sugar may be converted into lactic acid, and in this condition pass into the circulation. The presence of free alkali is as necessary to these changes, as free acid to the solution of the albuminoids by the gas- tric juice. Boiled starch is more readily digested by all animals than raw ; in fact, boiling is necessary to its ready digestion. Pancreatic Juice. — This substance is intended to assist in the conversion of starch into sugar, and also to digest the oily portions of the food. It may be obtained from the ■( I I ■f j tt,. t » ■ ^1 ti: 14C DIGESTION. dog by inserting a canula in the pancreatic duct (major) through a fistulous opening in the abdomen. The ])ancreas in structure, resembles the salivary glands and is present in all the vertebrate animals. In the human subject, the pan- creatic duct and choledoc duct usually open into the duo- denum at the same point. In some of the vertebrata they open ai some distance from each other, the pancreatic duct being usually below the biliary. Physical Appearance and Properties. — It is a clear, colorless, viscid fluid, of an alkaline reaction, somewhat resembling, in its physical character, the salivary fluid. It is coagulated completely by heat, not a drop of fluid being left. It is also coagulated by nitric acid, alcohol, and the metallic salts. The precipitate may be redissolved by the addition of an alkali. The average amount secreted by the human subject in the course of twenty-four hours, is about 12 to IG ozs. avoirdupois. Chemical composition of the pancreatic juice of the dog, according to Schmidt ; the following is the mean of three analyses : Mean, Extreme. Water 980.45 900.76 P.increatine 12.71 90.44 Sodium and Potassium Chlorides 3.43 7.37 Calcium, Magnesium and Sodium Phosphates... .09 .53 Soda, Lime and Magnesia, combined with Pan- creatine .32 .90 Traces of Iron 1000.00 1000.00 The most important ingredient is the organic matter, or pancreatine. It is coagulated by heat, niti-ic acid and alcohol. Tt is also precipitated by magnesium sulphate, and this distinguishes it from albumen. Function. — It acts upon the oily portions of the food and and fats, partly by splitting them up into fatty acids and glycerine, and partly by disintegrating them, and reducing them to a state of complete emulsion, the mixture being converted into a whitish, opaque, creamy fluid, which is readily absorbed. In disease of the pancreas, which is ex- SECRETION Of BILE. 147 ceetlingly rare, or occlusion of the duct, the patient invaria- bly suffers tA'trerne emaciation, and in some cases fat ap- pears iu the fiBces. The pancreas is found in carnivoious as well as herbivorous animals, thus showing that the pan- creatic secretion is chieHy intended for the digestion of fatty matters' It also assists in the conversion of starch into sugar, and in this way promotes the digestion and absorption of aniyiaceous food. It further assists in the complete digestion of albuminous and gelatinous suljstances which have escaped the action of the gastric juice. Secrktion qy Bile. — Bile is secreted by the cells of the liver from the blood of the portal vein, and may be readily obtained from its reservoir, the gall-bladdei'. It is secreted by the thepatic cells, which are situated in the interior of the lobules. When the cells become filled with bile, they break down, and the fluid is then taken up by the minute hepatic ducts which originate in the interior of the lobules. These small ducts, by frequent successive junctions, form two large ducts, each somewhat larger than a crow-quill, which emerge at the transverse fissure of the liver, one from the right and the other from the left lobe. These two ducts, together with the hepatic artery, the portal vein, nerves, and lymphatics, are enclosed in a little areolar tissue called G\is- soii'a capsule, and about an inch below their exit they unite to form the hepatic duct, which soon unites with the cystic duct from the gall-bladder, and the union of the two constitutes the ductus connnunis choledochus. This i^ about two or three inches long, and passing down behind the first portion of the duodenum, it ojiens into the second or descending portion, on its inner side, a little below the middle, in connection with the pancreatic duct. The gall- bladder is situated on the under surface of the right lobe of the liver, an carried to the riglit side of the heart, and thence to the lungs, where it is decom- posed in the production of animal heat. Puncture of the floor of the 4th ventricle, section of the cervical sympa- thetic, or inferior ganglion, or irritation of the central extremity of the 8th pair, abmjrmally increa^' ne glyco- genic function of the liver, and sugar is p.oduced ko rapidly, that the lungs cannot decompose the whole of it, and therefore it is thi'own off by the kidneys, producing what i known as diabetes mellitus. Temporary glycosuria may also be produced by the action of various substances, as the inhalation of ether or chloroform, injec- tion of curare, poisoning by carbonic oxide gas, or by injuries to the brain, and in the course of various diseases. Sugar and fat are both formed in the liver, irrespective of the kind or quality of the food. Pavy and others are of the opinion that no sugar exists in the liver during life, but only occurs after death. Function of Bile. — During fasting, the bile is stored up in the gall-bladder, but if the fast be prolonged beyond a reasonable time, tlie bile overflows into the intestine. The flow of bile into the duodenum is caused by the presence of food, or any irritating substance upon the mucous sur- u 152 DIGESTION. It, i < ■ i face of the small intestins. The bile is poured into the duodenum, never below it, a circumstance not very proba- ble if bile were solely an excrementitious substance, since it would have been quite as convenient for nature to have effected its discharge into the hepatic flexure of the colon. When the bile duct is tied, and this fluid prevented from ])assing into the duodenum, the animal becomes greatly emaciated, and ultimately dies from inanition. There can be no doubt, therefore, that the bile contributes in some way to the complete digestion and assimilation of the food. Bile cannot readily be detected in the fteces, and therefore it is supposed to be entirely changed in its passage through the bowels, or in part reabsorbed with the chyle, and thrown back into the system, to be used in the generation of heat by contact with oxygen in the lungs. Bile is both an excrementitious and digestive substance. That it is excrementitious is evidenced in the com))aratively large size of the liver and the active formation of bile in the fwtus, and the presence of meconium (biliary matter) as faeces in the intestines. The ffieces of the adult also con- tain the coloring matters, some fatty matter, and a small quantity of bilin. Through the bile is eliminated carbon, hydrogen, and other elements from the blood, which if allowed to accumulate, would render it impure. Dr. Flint regards the excretion of cholcsterine, which is changed into stercorine in the bowels, as an important function of the liver. As a digestive it assists in emulsifying the fatty matters, and by reason of its alkalinity favors their absorp- tion. The liver also performs an important ofiice in remov- ing substances which have been taken up by the portal vein during digestion, which would be injurious if allowed to enter the circulation. We may therefore conclude as fol- lows : that the liver secretes a complex fluid, the "bile," which is poured into the duodenum. Its coloring matters and some of the fatty matter and salts, are carried off" in the faeces forming the natural purgative of the body, and TESTS FOR BILE. 153 by virtue of its antiseptic properties, preventing decomposi- tion of the frecal matters. Its fat and bilin are in great part reabsorbed. It also assists in the complete digestion of those parts of the food which have escaped digestion, as starch and fatty matters. It forms sugar and fat in the circula- tion, independently of the substances in the food. It elimi- nates carbonaceous matters ; some directly, as the coloring matter, small quantities of fat and bilin ; others indirectly, as fat. sugar, and bilin, which pass to the lungs, and are converted into carbonic acid and water by the oxygen. Tests for Bile. — When nitric or nitroso-nitric acid (Gmelin's test) is added to a mixture containing bile, and shaken, a play of colors is produced, changing from green through various tints to red. This does not indicate the presence of biliary substances proper, but only the coloring matters. Pettenkofer's Test. — This is the best test for the detec- tion of bilin. A watery solution of the bile is mixed with a drop or two of a solution of cane sugar ; sulphuric acid is then added to the extent of two-thirds of the liquid, and a red, violet, and purple color are produced in succession. The reaction consists in the liberation of cholic acid from the glyco-cholic or tauro-cholic acid of the biliary salts. The sugar must be used in small quantities, for when added in excess, it is liable to be acted on and discolored by the sul- phuric acid. The solution of sugar should be about one part sugar to four parts water. Foreign matters, not of a biliary nature, such as oleine, ethereal oil, amyl-alcohol, albu- minous matters, and the salts of morphine and codeine, may produce a similar red or violet color. This may be over- come, however, by first extracting the suspected matters with alcohol, precipitating with ether, and dissolving the precipitate with water, before applying the test. The specti'U7)i of Pettenkofer's test presents characters which may distinguish it from the reactions produced by other organic substances. If some of the colored fluid ta '1 f M I It ) 154- DIGESTION, I lb: -i. ri. if *■ ,-■ r\ k. •;- ».. , I. '•, which the cane sugar and sulphuric acid have been added be placed before the slit of the spectroscope, its spectrum shows a broad, dark absorption band at E*, and extending to midway between d and E. the central part of the band being darker than the edges. When an alcoholic solution of Pettenkofer's test is examined as above, two absorption bands are seen ; one at E, identical with the one seen in the watery solution ; and the other at F, narrower and fainter than the one at E, (Fig. ho). Yv'. .'•,.'). Spectrum of Pettenkofer's test with the biliary saits in alcoholic solution. Bile if^ also dichroic, or presents two different colors when examined by transmitted light, according to the thickness or thinne.ss of the stratum under examination It is alao Jluorescent, or faintly luminous with a color of its own, especially when examined by the more refrangible rays of the solar spectrum. Summary. — The digestion of the food is not a simple operation, but consists of several different proces.ses, which occur successively in different portions of the alimentary canal. The food is first subjected to the physical opera- tion of mastication and insalivation in the mouth. It then passes into the stomach, where it meets with the gastric juice, which converts it into a pulpy mass — the chyme. Here certain soluble elements of the food, as water, wine, * The solar spectrum is crossed by vertical lines known as Frauenhofer's lines, and designated A, n, c, i), E, K, G and ii. The situation of an absorption band is indicated by reference to one or more of these letters. LARGE INTESTINE, 155 tea, saline matters, sugar, and a certain quantity of albumi- nose are absorbed by the veins and lymphatic vessels of the stomach. The food then passes into the duodenum, or small intestine, carrying with it the gastric juice, where it meets with the intestinal juices, pancreatic juice and bile. The albuminous matters which were not wholly digested in the stomach are now dissolved ; starchy matters are converted into dextrine and sugar, the oils and fats are emulsified, and the fluid is converted into chyle. This is taken up by the lacteals or blood-vessels in the process of absorption, and the coarser portions of the food, or excrementitious matters of the body, are carried off" by the large intestine. Large Intestine. — Its office is mainly confined to the separation and discharge of the freces. The mucous mem- brane of the large intestine is destitute of villi, and val- vula3 conniventes. Beneath the mucous membrane are found a few nonstriated muscular fibre cells (muscularis mucosie.) The glands are of two kinds tubular or glands of Lieberkuhn, and lenticular glands. The former are larger than those in the small intestine, and the latter closeiy resemble the glan- dula3 solitarije, and are most numerous in the csecum and vermiform appendix. The ileo-ciecal valve is situated at the junction of the ileum with the crecum, and prevents reflux of the contents of the latter. It consists of two semilunar folds of mucous membrane, each of which contains vessels, nerves and lym- phatics, together with some of the muscular fibres of the in- testine. By dividing the longitudinal muscular fibres and peritoneum at the margin of the valves, they may be made to disappear, just in the same way as. the sacculi of the large intestine can be obliterated, by a similar operation. The surface of the valve next the ileum is covered with villi, but they are entirely absent on the surface next the caecum. It is supposed by some that a certain amout of digestion takes place in the caecum. In some animals it is very large, 8 '1 f M A ! i 15G DIGESTION. 'It: « . ■'! I il I;" and would seem, without doubt, to exercise some special function in the complete solution of the food. But in man it is quite rudimentary, and has very little action upon the feces in their passage through. No material change takes place in the fseces as they pass through the intestine, ex- cepting that they become drier the longer they remain in the bowel, owing to the absorption which takes place. Nu- tritive enemata may also "be absorbed by the largo intestine. The fjcces are urged onwards to the rectum by the vermic- ular action of the bowel, where they accumulate, and are prevented from escaping by the contraction of the sphincter. The presence of the accumulated frecal matter in the rectum, causes a sensation demanding its discharge or defiecation. DEFECATION. This is the expulsion of the freces from the rectum, and it is effected by the contraction of the muscular fibres of the rectum, assisted by the contraction of the abdominal muscles and diaphragm, which diminish the size of the abdominal cavity, compress the intestines, and thus force onwards the foecal matter towards the anus. This force is at the same time quite sufficient to overcome the passive contraction oi the sphincter. If the rectum be over-distended by fsecal matter, its contractility will be diminished, and immense accumulations may take place. This is apt to occur in aged persons, and the faecal matter may lequire to be scooped out. On the other hand, when the fseces do not accumulate in sufficient quantity to distend the rectum, the act of de- fnecation may be attended with difficulty, and the straining- may cause prolapsus ani. Under such circumstances ene- mata are of great service, by distending the bowel and stimulating it to proper action. The quantity of faeces depends on the nature of the food and the state of the system. Vegetable food produces a greater amount of faeces than animal, because it contains much that is incapable of reduction in the stomach and duo- SALTS OP FAECES. 157 donum. Tlie quantity passed daily in liealtli is from four to eight ounces ; so that if we assume thirty- five ounces to be the average quantity of food per day, it may be inferred tliat about thirty ounces are appropriated for the support of the body. Analysis of Faeces — Water 73.3 Excrctine, .stercorine, salts and fatty acids Insoluljle residue of food, coloriiiy matter and other ingre- dients of bile, mucus anil epithelium 26. 7 Exckp:tine was discovered by Marcet and is associated with excretolic acid. It is a crystal lizable substance, in- soluble in water, but soluble in ether and hot alcohol, and is slightly alkaline. The crystals are in the Ibrm of four- sided prismatic needles. It fuses at lOVY. Stercorine was discovered by Prof. Flint, Jr. It has the same crystalline form as excrctine, is also soluble in ether and boiling alcohol, but fuses at a lower temperature. It is supposed to be formed from cholesterine. Salts of Faeces. — These consist chiefly of calcium and magnesium phosphates, iron, soda, lime and silica. The peculiar odor of the faeces is supposed to be caused by the secretion of the glands. Certain gases are also generated in the bowels. They consist of carbonic acid, hydrogen, carburetted hydrogen, sulphuretted hydrogen and nitrogen. They would seem to favor the passage of the fsecal matter by their distension of the bowel. In some diseases, as hys- teria, puerperal fever, inflammation of the bowels, etc., large quantities of gas are accumulated, producing iympanites or meteorisru. The natural color of the faeces is yellow, but in biliary obstruction they become clay-colored and ofi'ensive. Again, when the bile -is vitiated, or secreted in large quan- tity, they vary from green to dark brown. '1 f % It 1 f J 158 ABSORPTION, CHAPTER VI. (11 ABSORPTION. All the tissues of the body are more or less porous, and <5apable of absorbiiifj fluids brought into contact with them ; but the special absorbents are the blood-vessels, villi and lacteah, lymphatic vessels and glands, and 'prohahhj the glandula? solitarim. Blood-Vessels. — The structure and general function of the blood-vessels will be described in the chapter on cir- •culation. Villi and Lacteals. — The structure of the villi has been already described among the appendages of the mu- cous membrane, (page 111, Fig. 50.) In consequence of their number and form, they increase .greatly the secreting surface of the intestine. They hang out in the nutri- tious semi-fluid mass contained in the intestinal cavity, like the roots of a tree in its soil, and rapidly imbibe the soluble portions of the food. The lacteals commence near the apex •of each villus either by a blind extremity, or minute plexus, the precise manner is not known. In structure they resemble the capillaries, having an outer structure- less or finely fibrillated membrane ; and an inner endothelial lining. They form a network with close meshes in the sub- mucous areolar tissue, and then pass between the layers of the mesentery towards its root, anastomosing freely with each other, and traversing the mesenteric glands in their way to the right side of the aorta, opposite An intestinal villus ; (a) columnar epithelium ; (b) capillaries ; (c) nonstriated muscular fibre cells; (d) lacteal. LYMPHATIC VESSELS AND GLAI^DS. 15t) the second lumbar vertebra, where they empty them- selves, together with the lymphatics from the lower extremities into the receptaculum ehyli, or commencement of the thoracic duct. The thoracic duct, which is continued upwards.lies between the aorta and vena azygos major in the thorax ; it then passes behind the arch of the aorta, and empties itself into the upper part of the loft subclavian vein, close to the internal jugular, its orifice being guarded by two valves. The lacteals, are, however, not a si)ecial system of vessels by themselves, but may be considered as a part of the general lymphatic system. Their function is to ab- sorb the chyle. Lymphatic Vessels and Glands. — These constitute the chief system of absorbents of the body. They are found in , nearly every part of the body, except the substance of the brain and spinal cord, eye-ball, cartilage, tendons, mem- branes of the ovum, placenta, funis, hair, nails and cuticle. They commence either in a closely meshed network, or in irregular lacunar spaces among the tissues termed the lym'ph canalicular system. The latter form a connected sys- tem of very irregular branched spaces beneath serous mem- branes, as the pleura and peritoneum. Recklinghausen has shown that the serous membranes are studded with stomata which are the openings of short vertical canals which com- municate with the lymph canalicular system. The serous cavities are therefore looked upon as large lymph sinuses, or expansions of the lymph-canalicular system, (page 101.) There are two sets of lymphatics, the superjicial and deep ; the former are situated in the supei-ficial fascia, and the latter accompany the deep blood-vessels. Those of the lower extremeties empty into the receptaculum chyli, which is continued upwards through the thoracic duct, to the left subclavian vein, and those of the upper extremities, head and neck, empty by a short trunk into the subclavian vein of the right side. 'I IfiO AnsORPTION,. C V. • -" ■( »■»' -• • » Structure. — The lymphatic vessels are remarkable for the transparoncy of their walls. The larger vessels like the arteries and veins are composed of three coats. 1st, an inner ej^ithelial, (or endothelial) and elastic ; 2nd, a middle, muscular and elastic, disposed transversely ; and 3rd, an ex- ■ ternal, areolar and elastic coat. They are also provided with valves like the veins, arranged in pairs, which pievent regurgitation, and assist in the onward flow of the fluid which the vessels contain. The valves are more numerous in the lymphatics than in the veins, and the walls of the vessels are thinner and more transparent. Then^ is no di- rect communication between tho lymph-capillaries and blood-capillaries, as was formerly supi)osed. The lymphatic vessels may be readily brought into view by injecting the n with mercury. The vessels, in their course, ])ass through certain glandular bodies — the " lymphatic " or " absoi'beut " nrlauds. FiR. r>7. LYMPirATio Glands. — The lym- phatic glands, among which may bo included the mesaiicric glands, con- sistof an external layer of connect- ive tissue, and u'landular tissue within. From the innner surface of the exter- nal layer thin septa or trabecuhe are given ott', which penetrate the interior of the gland in eveiy direction, and unite with each other at various points, so that the substance of the gland isdividedinto numerous spaces .\ IvniplmtiL' ylaiui and vessels , ,. i • i - , > .t fiuoii with inemiry; 1, iifforcnt or (Uveoli, wliich communicatc With vessels ; i. efferent vessels ; (b) a i ■ i mi i i • /» lyniphatie vessel showiiijf the cach othcr. .1 lie uctworK IS hncr valves ; (e) Ivnipli eornuseles, one • ,, , , 7 ji ,1 granular anil three treated with 111 the Central Or DiednlUiry, tliaii in acetic acid showinj; the cell wall , ■• j •' mi and nucleus, also some fine Rran- the CO'i ICClL portlOn. 1 lieSC SpaCBS iiles and oil globules, (Mascagni) /.ii 1 • L^ i i i> a-j" X 4(X). are nlled with a network ot retiform or adenoid tissue (p. 71), the interstices of which are filled with lymph corj)uscles, and arc penetrated like the solitary LYMPH AND CHYLE. 161 trlands by a network of capillaries. The lymph corpuHclen chiefly occupy the central part of the alveoli, forniintj; with the retiform tissue, nodules and cords, leavirijr a space in the outer portion for the circulation of the lymph, called the bjimpJi-pat}!,. Each lymphatic vessel, as it enters the gland, divides into a number of small branches, called the vasa affereni'm which communicate with the lymph-paths ; other similar twigs form the vasa ejfercntia, which leave the gland in the opposite diiection. The lyniphatic glands an; arranged in chains, in various parts of tlie body, as in the groin parallel to Poupart's ligament, and along the posterior border of the sterno-cleido-mastoid nmscle, etc. They vary in size from a millet seed to a pea. The vessels and glands con- tain a fluid termed lymph. Lymi'H and Chyle — Lymjth is a colorless, or pale-yellow, transpaient fhiid, of a slightly alkaline reaction, and a saline taste. It contains nucleated corpuscles, resembling those found in chyle, but less numerous, which are supposed ultimately to form blood coi'puscles. It is spontanec 'isly coagulable when removed from the vessels, owing to the })resence of fibrin, which is more abundant in the large than in the small vessels. The albumen is smaller in ([uan- tity than in chyle, and there is scarcely any fatty matter. The ingredients of lymi»h are chiefly the i)roducts of the exudation from the"cai)illaries, and the waste of the tissues. It is identical in great part with the liquor sanguinis of the blood. Chyle is a whitish, opalescent fluid re- sembling milk, of an alkaline reaction, and contains numerous fat globules i'rom i„, ',,,(. to sohoo of an inch (1.25 to .8 mmm) in dia- meter, V hich constitute the molecular bane of chyle. The fat globules are soluble in 6ther. Fat KlobuloM of chyle. As the chyle passes onwards towards the ihoracic duct, it becomes more fully elaborated, the quantityof molec lies or oil t It I in:* If: 1!. I'- ■ I ■ . 1^ I! 162 ABSORPTION. globules diminish, nucleated cells ^/^o to -j^yVn of au inch, (9.6 to 8.3 mmm) in diameter, called chyle corpuscles, are formed in it, and by the development of fibrin,it acquires the property of coagulating spontaneously. The^higher it ascends in the thoracic duct, the more fully is it elaborated, the chyle corpuscles are more numerous, and advanced towards their development into red blood corpuscles, and the clot coagulates more firmly. These two fluids — lymph and chyle — are nearly similar, as will be seen from the following table which is the result of an analysis of the lymph and chyle of a donkey by Owen Rees. Molecular base and coriHiscles of chyle from the receptaculura chyli of a man. Chemical Constituents. — Lymph. Chyle. Water 96. 54 90.24 Albumen 1.20 3.52 Fibrin o. 12 0.37 Fat A trace. 3.60 Extractive 1.56 1.56 Salt 0.58 0.71 100.00 100.00 MECHANISM OF ABSORPTION. Imbibition or osmosis is a^ physico-chemical process, and occurs in inorganic as well as in dead or living organic bodies. It depends on the force of adhesion between a fluid and a porous solid, by which the fluid is drawn into the in- terstitial passages of the solid. The fluid chiefly concerned in this process is water, and the various other substances which are taken up in a state of solution, as fibrin, albumen, salts, gases, etc. The process of osmosis in the living body however, is regulated and controlled by the agency of cells, which have the power of choosing and refusing from the materials brouffht into contact or relation with them. MECHANISM OF ABSORPTION. 163 The quality of the fluid influences absorption. If water be brought in contact with the surface of the body, or taken into the stomach, it is readily absorbed, especially in the latter case, because it is brought nearer the blood-vessels ; or if a quantity of warm- water is injected into the colon, it is rapidly absorbed and excreted by the kidneys. But if the water contain a quantity of sodium chloride, or any salt in solution, it will be absorbed more slowly, while if a saturated solution be used, the fluid portion of the blood will pass out of the blood-vessels to mingle with it. When the fluid passes from without inwards the process is termed endos- mosis ; when f i om within outwards, exosmosis. The term os- mose or osmosis refers simply to the passage of a fluid in either direction, and is much more convenient. This pro- perty of endosraosis and exosmosis may be demonstrated by placing a membranous partition through a vessel of earthen- ware and placing pure water on one side, and a solution of salt and water on the other. It will be found that the water will pass more rapidly through the membrane to the side containing the salt and water, but that after a time both sides will be equally impregnated with salt. In this case the passage of the water to the salt is called " endosmosis," and the more scanty passage of salt to the water " exos- mosis.'' The instrument used for measuring the rapidity of osmosis, is called an endosmometer. A very good one may be made from a common glass funnel by tying a piece of bladder over the lower end, and fixing a glass tube, open at both ends, in an upright position within the funnel. The instrii inent is next filled with a solution of salt or sugar, and put in a vessel containing pure water. The water will then pass through the membrane at the bottom of the funnel into the solution by osmosis, and cause the fluid to ascend in the tube, which may have been previously marked, or graduated, by a common file. The height to which the fluid rises in a given time, is a measure of the rapidity of endosmosis over exosmosis. Substances are divided into two classes according 1 .4 I I if i II. I'* - a ■ ii 164 ABSORPTION. to their facility of osmosis ; those which pass through readily, and which are usually cr3'stallizable, are called c?'2/s- talloids, and those which pass with difficulty, colloids. The colloids are also distinguished from crystalloids by their in- ertness as f 3ids or bases. The cha . acter of the membrane and its affinity for the fluids influence absorption. If a piece of bladder be placed between alcohol and water, the current is from the water to the alcohol, on account of the greater affinity of the water for this membrane ; but if a membrane of India rubber be used, the current is reversed. It is necessary that the membrane should be fresh. If it be in a state of decay, or if it has been dried, it will not produce the desired effect. The position of the membrane causes a variation. In some instances, endosmosis is more rapid when the mucous sur- face is in contact with the denser solution. In other cases, it is exactly the reverse. The density or laxity, and the thickness or thinness of the membrane, also affect the result for obvious reasons. Pressure influences absorption. It promotes the trans- mission of a fluid through a membrane, and the rapidity of osmosis will depend, " cccteris imribus" on the de- gree of pressure emjiloyed. Since this promotes the flow in one direction, it also tends to retard the passage of fluids in the opposite direction ; for example, when the blood-ves- sels are distended with blood, as in plethora or inflam- mation, fluids enter with difficulty from without, while if the tension be removed by venesection, absorption takes place quite readily. Motion of the fluid in the vessels influences absorption. The motion of the fluid within the vessels promotes absorp- tion, by diminishing the pressure outwards on the walls and allowing the external pressure to predominate, and also by moving the particles onwards, to make room for those which are being absorbed. ABSORPTION BY THE LACTEALS. 165 Absorption by the Villi and Lacteals. — During the intervals of digestion, the lacteals contain a colorless trans- parent substance, similar to that which is obtained in other parts of the lymphatic system. If the food consists only of starchy and albuminous substances, very little change is noticed in the character of their contents. But if fat has been taken, the lacteals become filled with a white chyle or " molecular base," consisting of minute fat globules and a small quantity of fibrin, albumen, (or albuminose), etc. The presence of chyle in the lacteals is therefore not constant, but occurs during the process of digestion, or as soon as the fatty matters of the food have been disintegrated and emul- sified by the intestinal fluids. The absorption of fat from the intestine is not performed exclusively by the lacteals but some of it is taken up by the blood-vessels, for it has been found by Bernard in the blood of the mesenteric veins of the carnivora during digestion. It has also been found in the blood of the portal vein. Fat being a non-osmotic substance, especially when the membrane is moist, a diffi- culty has been experienced in accounting for its absorption. It has been found, however, that the presence of an alkaline fluid, as bile, mixed with emulsified fat, will facilitate the process of osmosis, and secure the complete absorption of the fatty matter. The chyle and other fluids are absorbed by the pro^ ss of osmosis, which is regulated and controlled by the agency of cells. The epithelial cells covering the free surface of the villi are the first active agents in this absorption, for during the process of digestion they are found filled with chyle. They break down, and the fluid passes through the base- ment membrane by osmosis (endosmosis) into the adenoid tissue of the villi being regulated and controlled by the lymphoid cells which are found in its meshes, and in con- tact with the lacteals. The chyle then comes in direct con- tact with the lacteals through the coats of which it again passes by osmosis, the process being determined by the cells I .4 } (I 1 1C6 ABSORPTION. «; t l» ti • r whicli lino the interior of the lacteals. The fluid then passes to the receptacuhini cliyli, and thence tlnough the thoracic duct to the left suhclavian vein. Its onward flow is facilitated by the contractile tissue, which is found in the tissue surrounding the lacteals and in the tlioracic duct, and it is prevented from regurgitating by the valves which are found in the latter vessel. AnsoiiPTioN iJY THK Blood-Vessels. — That the blood- vessels absorb, has been proved by the ex])erinionts of Magendie and Panizza. The latter observer opened the ab- domen of a hoi'se, and drew out a portion of the small in- testine, eight or nine inches in length, which ho enclosed between two ligatures. He then ligated the mesenteric vein, and made an opening behind the ligature, in order to allow the blood brought by the artery to pass out. An opening was also made in the intestine, through which was introduced some hydrocyanic acid, and almost immediately afterwards, it was detected in the blood which flowed from the ope'^ing in the vein. The above experiment was varied by simply compressing the vein, and introducing hydrocyanic acid in the intestine. In this case no effect was produced on the animal while compression was maintained, but as soon as the pressure was removed, symptoms of poist)ning by hydrocyanic acid showed themselves. The rapidity with which the blood-vessels absorb certain substances may be seen in the administration of alcoholic and other soluble sub- stances by the stomach, and also the hypodermic injection of morphine and other alkaloids. The blood-vessels not only perform an active part in the general absorption of fluids in various parts of the body, but are also specially en- gaged in the absorption of the alimentary fluids of the in- testine. The albuminous and starchy portions (and even fatty matters) of the food are absorbed by them from the mucous surface of the stomach and small intestine, in the form of albuminose and glucose. The substances taken up by the veins are thence conveyed by the portal system to the ABSORPTION BY THE LYMPHATICS. 167 liver, where some of them arc acted upon by that organ in the production of bile, sugar, fat, etc., some of which are carried back iuto the alimentary system, and otheis are thrown into the general circulation. In the process of ab- sorption, the substances pass through the basement mem- brane by osmosis, this process being regulated by the action of the cells, similar to that which takes place in the lacteals. Absorption by the Lymphatics. — That the lymphatics absorb, is perhaps best shown by the phenomena of disease ; for example, the virus of syphilis is frequently carried from the chancre on the penis, to the glands in the groin, giving rise to bubo, and the matter from the abscess is capable of imparting the disease to other individuals. The glands of the axilla become enlarged and inflamed, in consequence of a poisoned wound of the hand or arm, or in erysipelas. Ab- sorption takes place in the same way, and on the same principle, as in the lacteals and veins. In some animals, as birds and reptiles, the movement of the lymphis facilitated by the action'of certain muscular sacs, called lymph liearts. The function of the lymphatic vessels is to absorb the Ingredients of the lymph derived from the metamorphosis of the tissues, and to return it into the general circulation, in order to sub- serve some further purpose in the animal economy, or to be eliminated by the process of excretion. They also convey back the superfluous parts of the material brought by the blood-vessels for the supply of the tissues. The eflete matters are not all absorbed by these vessels, for carbonic acid seems to enter the capillaries in a direct manner through their walls, since it is found in greater quantity in venous than arterial blood. The lymphatic glands are engaged in the process of elaborating the lymph in its passage through them. The Glandulcc Solitaricc have been already described (page 111). They are regarded as the first row of mes- enteric glands situated in the walls of the intestines. 1 t 1 1 i'tl 1G8 BLOOD. CHAPTER VII. ii c ii: ri. 11 4^: 10 i 11/ r!.i'i' en, BLOOD. This fluid is prepared from the food by tlie proces of di- gestion and assimilation, and is constantly circulating through the vessels, during life. It supplies the material from which the tissues are built up and nourished ; it con- tains the substance used in the combustive process, and also contains the effete })articlcs which result from the disin- teirration of the tissues. The elements found in the blood may be divided into four classes, as follows : — 1st. The elahorative elements, as red and white corpuscles. 2nd. The histogcnetic elements, as albumen, and fat. (Fat is used to build up the adipose and nerve tissues.) 3rd. The calorific elements, as sugar (or glucose) and fats. 4th. The dejyuritic elements, as lactic, uric, hippuric, and carbonic acids, urea, creatine, volatile fat acids, odorous substances, salts, and water. Quantity. — It is very difficult to determine the exact quantity of blood in the human body ; but from various ex- periments, it has been ascertained by approximation, that the quantity of blood in a human body weighing 144 lbs. would be about 16 or 18 lbs., or as 1 to 8 or 10. PHYSICAL CHARACTER OF THE BLOOD. The blood, as it flows from the vessels, appears to be a homogenous, red fluid, of a slightly alkaline reaction, and heavier than water. The odor resembles the perspiration, or the breath of the animal. The temperature is about 100° F. The color of arterial blood is bright scarlet, and that of venous blood dark purple ; but disease of the lungs, heart or MICROSCOPICAL APPEARANCE. 16& kidney, may cause the whole mass to assume a venous hue, owing to the circulation of carbonic acid and other impu- rities in it ; or it may as-sume an arterial hue when the animal breathes pure (jxygen. It is also stated by Dr. Davy that in warm climates the blood is venous in its character. This is due to the high temperature, which reduces the ex- cretion of carbonic acid, and is a fact of very great ])ractical importance to the physician. The inhalation of chloroform or ether produces a venous condition, by interfering with the function of respiration. The specific gravity of the blood varies from 1050 to lOoO, the average being about 1055. Any substance which will modify the relation between the solids and fluids will change the speciflc gravity. For example, it may be diminished by the introduction of water into the system, whilst, on the other hand, it may be increased by the ad- ministration of drastic purgatives. In anemia, the specific gravity may be increased by good liberal diet, and iron. The specific gravity of the corpuscles (solids) is 1088, the liquor sanguinis (fluids) 1028. 3 % MICRO-5CC^ICAL APPEARANCE OF THE BLOOD. Blood, when examined by the microscope, when still in the vessels, as in the frog's foot, or bat's wing is seen to consist of a solid and a liquid portion ; the foi'uier includes the red and ivhite corpuscles, the latter, the liquor sangui- nis, or plasma. On the other hand, when the blood has been drawn from the body, and allowed to stand, it coagu- lates or separates into two portions — the oassamentum, or clot, and the serum. This coagulation depends on the pres- ence of fibrin, which coagulates spontaneously, and forms a network of fibres, in the meshes of which are included the red and white corpuscles. The clot then contracts, and squeezes out the serum. The crassamentum, or clot, therefore con- sists of the fibrin and corpu:icles ; and the serum contains c c R. m. iuru (! »» !!.■■■ IP- 170 BLOOD. the all'umen, salts and water. Blood in the living vessels, consists of SOLID. LUiUID. Fibrin \ Red and White Corpuscles. Albumen f Liquor Sanguinis, Salt.N . . ; I or Plasma. Water ) Blood out of the body consists of SOLID. LKJl'ID, i Albumen ) Clot. Sails > Serum. Water ) Blood Cokpusci-es. — The human red blood corpuscles arc circular or rounded biconcave discs, in the centre of which are seen bright or dark spots according as the microscope is within or beyond focus. These spots which have been mistaken, Fiir 1.I elephant, and sloth {Bradypua didactylus) are the only species in which the corpuscles are known to be larger than in man. In the camel tribe (camel dromedary lama) they are oval in shape, but do not possess a nucleus. In all the ovipa- rous vertebrata, as birds, reptiles, and fishes, the corpuscles are of a large size, oval in shape, and contain granular nuclei. The nuclei may be distinctly seen on the addition of acetic acid, which clears up the outer portion. The cor- puscle of the frog is from — ^ ramm) in diameter,^ Fijr. 61. Mammals. Birds. to -'- of an inch (25 to 21 1000 I a no ^ Reptiles. Fishes. Typical characters of the red-blood corpuscles in the main divisions of the Vertebrata (modified from Gulliver.) The average diameter in tlve longest axis is given in each case. Color. — In a single stratum of red corpuscles no color is observed, but when two or three are superimposed upon one another, a reddish tint becomes apparent. The color depends partly on the shape of the corpuscles, but chiefly on i«.'M WHITE CORPUSCLES. 173 the hemoglobine they contain. They also have a tendency to adhere by their concave surfaces in the form of rouleaux. (Fig. 60, c). This is peculiar to the red corpuscles, and is very much increased in inflammation. If any of the salines be added to the blood, this peculiar tendency is in a measure neutralized. White Corpuscles. — These are so named on account of their white, or colorless appearance. They have a circular outline, appear granular within, and are tolerably uniform in size, theird iameter being about jo^otr of an inch (8. mmm.) in warm-bloods, and ^^Vn (10 mmm.) in reptiles. In some of them a nucleus may be distinctly seen on the addi- tion of acetic acid ; in others the nucleus appears to be broken up, so as to give the cell a granular appearance, (Fig. GO, d). They are more highly refractive than the red under the microscope, and are generally observed in or near the margin of the field, while the red are grouped together in the central part. When examined in the circulating blood of a frog's foot, they are seen to occupy the exterior of the current, and adhere more or less to the walls of the vessels, or appear to pass from the centre to the walls and back again. The proportion of white to red corpuscles in man, is about one to -iOO or 500; but in inflammation it may be one to ten. In certain diseases as anemia, leucocy- th?emia, etc., the white corpuscles are relatively increased. In the oviparous vertebrata the proportion is higher than in man, being about one to sixteen ; while in one of the vertebrata (amphioxus) the red corpuscles are entirely absent. In ■' 8 invertebrate series, on the other hand, the corpuscles are almost invariably white, and hence the so- called white blood of this class of animals. The white corpuscles have the power of spontaneously changing their shape, and of moving in certain directions, closely resembling those of the amoeba, (Fig. 12), and hence termed amoeboid movements, (Fig. 60, e.) This is due to the contractile property of th i protoplasm. The amoeboid movements are It 174 BLOOD. c c MftJI ^■•., w • r rir. (.'•'1) arrested by the addition of water or acetic acid. The white corpuscles are reproduced by the process of fission. The blood also contains granules or molecules, -g^ig.^ of an inch, (3. inmm.) in dianietei', similar to those found in lymph and chyle, some of them fatty, and others probably al- buminous. OiiiGiN OF THE Corpuscles. — The earliest blood cor- puscles are formed from the primordial cells in the vascular tract. The embryonic heart and aorta are formed by the arrangement of masses of the primitive cells, or germinal vesicles, of the mucous or vegetative layer, in the position, form, and thickness of the developing vessels respectively. The external layer of cells is converted into the walls of the vessels, while those in the interior form the first blood corpuscles. The primordial, or primitive vesicles, are large, colorless, spherical cells, each containing a nucleus, nucleolus, granular matter, and fat globules. These cells, gradually clear up, so as to bring into view the nucleus, become reduced in size, and develope the coloring matter (hemoglobine) as they pass into the form of red corpuscles. The blood corpuscles of the human embryo thus formed are circular, disc-shaped, full colored, and, on an average, about TT^ffir of an inch (10 mmm.) in diameter. They each contain a nucleus (and in some cases two), about ^^£,'07, of an inch (5 mmm.) in diameter, and slightly granular. They are re- producv^d by the process of multiplication by subdivision, or fission. When the liver begins to be formed this multiplication of blood corpuscles in the mass of blood ceases, according to KoUiker, and a new production of colorless nucleated cells takes place in the vessels of the liver. These nucleated cells undergo a gradual change into red corpuscles, similar to those of the fir fc brood. After birth, when the lymph and chyle corpuscles are thrown into the current of blood, they are developed into red blood corpus'^les, so as to supersede tho?^" formed as DEVELOPMENT OF THE CORPUSCLES. 175 above described. This is evidenced — First by the formation of color, while the chyle and lymph are passing through the thoracic duct, due to the development of hemoglobine. Secondly, by the presence of corpuscles, which appear to be intermediate stages of development between the lymph corpuscles, and the nucleated red corpuscles in the blood of oviparous vertebrata. Thirdly, by the progressive tran"'- tion from lymph or white blood, to red blood, which may be observed in the ascending scale of animal life. Development from Chyle and Lymph Corpuscles. — Kolliker and Paget regard the red blood corpuscles as being formed irom the smaller of the lymph and chyle corpuscles by a gradual [)rogressive metamorphosis ; while Wharton Jones and Huxley maintain that they are foimed from the nuclei al(>~\e, the outer portion of the cells disappearing in the change. The weight of authority, however, appears to favor the former opinion. The change from chyle and lymph corpuscles to red blood corpuscles, takes place as follows : — The chyle and lymph corpuscle's are at first nucleated cells, the nuclei of which are generally more or less obscured by the granular matter which surrounds them, (Fig. 59.) They vary in size from ^^^^ to ^^-^ of an inch, (10 to 8.1 mmm.) in diameter. The granular matter clears up, and the nuclei disappear. They then become flattened or biconcave, contraction and consolidation of the cells take place, which reduce their size to a certain extent, and hemoglobine is developed. The white corpuscles are also developed from chyle and lymph corpuscles. Lymph corpuscles are formed in the lymphatic glands, spleen, adenoid tissue,and medullaof bone. The red and white corpuscles are regarded by some as two distinct and complete forms, neither being capable of metamorphosis into the other, and each having its own specific purpose to subserve in the ani^aal economy ; the greater number of chyle and lymph corpuscles proceeding to the formation of red corpuscles, while a few of them are ■I wm 176 BLOOD. c % I' inrue w a.: Its » it n- flM' ♦Ml developed into the white corpuscles of the blood. The argument in favor of this theory is, that the white cor- puscles have been found in the blood in a state of decay, thus showing that they were not destined to proceed to a higher development. By others they are regarded as an early or embryonic condition of the red corpuscles, or an intermediate stage of metamorphosis between the chyle and lymph corpuscles, and the red corpuscles. The latter view is supported by the following arguments : 1st, The colorless corpuscles are intermediate in shape and general appearance. 2nd. They are increased under circumstances un- favorable to normal changes, as in inflammation, or in persons of weak health, as in anemia, leucocythsemia, and in the tubercular diathesis. The red and white corpuscles are supposed by some to be developed directly from the plasma of the blood in which they float, by the ordinary process of cytogenesis. Blood corpuscles, like other cells, have their period of growth, maturity and decay, and while some are undergoing the process of disintegration, others are rising up to take their plac s. They are, no doubt, formed very rapidly, as is evidenced in their rapid formation after great hemorrha,ge, and their growth and development may be facilitated by the administration of iron, and a liberal diet. When the corpuscles are beginning to decay, they generally present at first a granular appearance ; after a little they break down, and the contents disappear. Many of them may be observed in a granular state in phthisis, albuminuria, and septic poisoning. CHEMICAL AND STRUCTURAL CHARACTERS OF THE BLOOD, Chemical Composition of the Blood. — The average proportion of the constituents of the blood in 1000 parts is as follows : — CHEMICAL COMPOSITION OF BLOOD. 177 Water 784.0 Albumen (of serum) 70.0 Fibrin 2.2 Red corpuscles (dry) . . . . . , 130.0 Fatty matters 1.4 Inorganic Salts : Sodium and Potassium Chlorides . 3.95 Sodium Phosphate, Carbonate and Sulphate . . . . . 1.30 Calcium and Magnesium Phosphates 0.25 Iron Oxide and Phosphate . . 0.5 Odoriferous and coloring matter, glucose, gases, creatine, urea, and other extractive matters . . , 6.40 1000. These proportions are subject to considerable variation, even in health, depending on diet, mode of living, etc. The proportion of the various ingredients may be determined as follows : — The blood, as it flows from the vein, is received into two vessels of equal size, the first and last portions of the whole amount into the first, and the second and third portions into the second vessel, in order that the two quantities may be nearly alike, and then weighed. The blood in the first vessel is allowed to coagulate; that in the second is whipped with a bundle of twigs, to separate the fibrin, which is then washed with water — to remove the salts, with alcohol — to remove any coloring matter, and with ether — to remove any fats. It is then weighed. The clot which has formed in the first vessel is then taken out, and after the serum has drained away, it should be weighed. From the weight of the clot subtract the weight of the fibrin obtained from the second vessel, and this will give the weight of the corpuscles. The amount of albumen may be obtained by precipitating it from the serum, filtering and weighing. In this way it may be ascertained that in 100 parts blocd, about 78 parts are fluid,^and 22 parts solid material. In the latter, there are 13 parts corpuscles, 7 parts albumen, \ part fibrin, the salts, etc., making up the balance. In ordinary analysis, the corpuscles are estimated at about 13 per cent, by weight, of the entire blood. This refers, of course, to the dry corpuscles, from which the water has been removed. But it is easilv seen, bv a M ■it It I i 178 BLOOD. c c n. !!' • s< If a:- If s II u • ». «»>■ rvr» microscopic examination, that the corpuscles, in their natural moist condition in the blood, constitute fully one-half of the entire mass ; hence the discrepancy in the analysis of different observers. Lehmann and Schmidt put the raoisi corpuscles at 512 parts in 1000, or about four times the weight as given above. Three fourths of their weight, consist of water. The red blood corpuscles are composed of a transparent homogenous substance called the stroma, in which the hemoglohine is infiltrated. The sti'oma is tough and elastic, and consists of globuline,protagon, fatty matters, cholesterine, and salts. The most important of these is the glohuline. It is a semi-liuid substance, belongs to the albuminous compounds, and is formed from albumen. It is soluble in water, but not in the liquor sanguinis or fluid plasma of the blood, and is readily acted on by acetic acid, causing the corpuscles to swell out and finally burst..- It coagulates completely at 200° F. Hemoglohine is a kind of pigment matter which is found in the red blood corpuscles, mingled with the stroma. It is more abundant than any other ingredient of the cor- pusclea. [t belongs to the albuminous compounds, being developed from albumen or fibrin, and consists of C54 H 7 N16 O21 S.o Fe.4 the latter of which is an essential ingredient. It is soluble in water, dilute alcohol and alkalies, but is insoluble in ether, strong alcohol and oils. It crys- talizes in rhombic, or hexagonal plates or prisms, form- ing the so-called blood crystals. Although a crystalloid, and soluble in water, it is not diffusible, i.e., it does not pass through the pores of an animal membrane. When heated, it is decomposed into glohuline Sind heTriatine. The distinguishing characteristic of hemoglobine is its strong affinity for ox3'gen, forming oxy-hemoglobine, which has a scarlet color ; this readily parts with its oxygen again in the presence of reducing agents, and assumes a j)urple hue. On these qualities depend its most important physiological pre th( HEMOGLOBINE. 179 properties, viz., as a carrier of oxygen. This also explains the scarlet color of arterial blood, and the purple tint of venous. It was formerly supposed that the scarlet color of the blood was produced by the oxygen rendering the cor- puscles biconcave, and the venous condition by carbonic acid which made them biconvex or rounded. Fig's. 62 and 63. a. Spectrum of oxidizeil heiuoglobiiie. t. Spectrum of cieuxidized liuiimglobine. The two varieties of hemoglobine may be readily dis- tinguished by the spectroscope. A solution of oxy-hemo- globine or diluted arterial blood, presents two absorption bands in the spectrum, between the lines D and E, one in the yellow and the other at the commencement of the green, (Fig. 62, a). The former is narrow and well defined, the latter is broader and not so well marked. The spectrum of deoxidized hemoglobine on the other hand, presents a single absorption band intermediate in position between the ^r two, (Fig. 63, b). When from any cause the red corpuscles are broken down, the hemoglobine is set free, and stains the coats of the vessels, so as to give rise to an appearance re- sembling arteritis. Rupture of the corpuscles may take place from drinking too much water, or in low forms of disease, as in typhoid fever, purpura hemorrhagica, etc. 1 I M 180 BLOOD. c c »• •f.•^ I! unit Distinction between Human and Animal Blood. — It is sometimes of the utmost importance in medical in- vestigations to distinguish between human blood and the blood of animals. In a fluid, or blood stain, when the cor- puscles have been dissolved or destroyed, the presence of blood may still be determined by the spectrum of hemoglo- bine, but the distinction between human and animal blood cannot thus be made. It is only by the use of the micros- cope that this can be determined. If the blood stain be found to contain oval nucleated corpuscles, it cannot be human blood, but that of a fowl, reptile or fish. If, on the other hand, the corpuscles are circular and without nuclei, then it will be impossible to say whether it is human blood, or the blood of some animal, as the cow, sheep, ape, dog, etc., whose corpuscles are nearly of the same size as the human. DIFt-ERENCE BETWEEN ARTERIAL AND VENOUS BLOOD. Arterial and venous blood differ from each other in general composition and color. The analysis which has already been given is of venous blood. In arterial blood the quantity of solid constituents of the corpuscles is less, but relatively they contain more hemoglobine and salts, and less fat. It also contains more oxygen and less carbonic acid. The liquor sanguinis is richer in fibrin, contains more water, and less albumen. The fatty matters of the serum are dimin- ished, and the extractive matters increased. The phosphorus which exists in the venous blood, is converted at the lungs into phosphoric acid, which then unites with the alkalies of the serum, as lime, potassa, soda, magnesia, etc., forming phosphates. Phosphorus is used in the building up of nerve and bone tissue. Blood of the Portal, Renal and Hepatic Veins. — Blood drawn from different parts of the arterial system of the same animal is nearly always the same ; but great vari- ations exist in the comjiosition of the blood in the different parts of the venous system. The portal vein contains blood GASES. 181 derived from the gastric, mesenteric and splenic veins. During digestion, the blood of the gastric and mesenteric veins is much diluted, and contains the soluble alimentary substances taken up from the stomach and small intestine, as sugar (glucose), albuminose, etc. The fibrin also found in these vessels is less perfectly elaborated than in the blood in general, and liquifies soon after ' igulation. On the other hand, the blood of the splenic vein shows a diminution of the red corpuscles, an increase of the white corpuscles, and an increase of the albumen. The fibrin is also increased, but like that of the gastric and mesenteric veins it is not fully elaborated, coagulates imperfectly, and liquifies soon afterwards. The blood of the re7ial veins is the purest in the body, having, subsequently to its purification in the lungs, been deprived of other impurities by the kidneys, such as urea, creatine, salts, etc. It contains less water, the albumen is neutral in reaction, and the fibrin is scanty and will not coagulate, (Brown Sequard.) The blood of the hepatic veins contains an increased amount of sugar and fat, which are formed during the passage of the blood through the liver. It also contains less water, albumen and salts, and more corpuscles and extractive matter, than that of the poi-tal vein. Gases, — There is a remarkable difference in the amount of gases which arterial and venous blood respectively con- tain. The former contains from 16 to 20 per cent., by volume, of oxygen, while the latter contains about 12. The quantity of carbonic acid, on the other hand, is from 30 to 35 per cent, in arterial, and from 40 to 50 per cent, in venous blood. The quantity of nitrogen varies from 1 to 2 in arterial and venous blood respectively. There are also traces of ammonia. The difference between the amount of oxygen and carbonic acid respectively in arterial and venous blood, confirms the idea that an exchange of oxygen for carbonic acid takes place in the system, and an ex- change of carbonic acid for oxygen in the lungs. The red ■1 ■ I I c c mm A. II™ »l *»\ II- Biro- »!«•■■ 182 BLOOD. corpuscles carry oxygen from the lungs to the tissues, and return carbonic acid for elimination. The serum also [tossesses the property of absorbing or dissolving carbonic acid. A certain part of the oxygen is used directly in the formation of fibrin, from albumen. The proper develop- ment of fibrin does not take place when the due aeration of the blood is interfered with, as in double pneumonia, in which case it is very much diminished. The presence of oxygen seems to I e essential to the production of fibrin, and it has been shown by experiments on rabbits, that when pure oxygen is breathed the quantity of fibrin is very much increased. Dr. Gairdner examined the blood of six healthy rabbits, and found it to consist as follows, in 1,000 parts : Fibrin 1.65 Corpuscles 82.35 Albumen 46. 30 He also examined the blood of three of these, which had been exposed to an atmosphere of pure oxygen for half an hour, and found it to contain as follows : Fibrin 2.40 • Corpuscles 69. 56 Albumen 40.23 Another of these animals was exposed to the action of an electro-magnetic current passed between the chest and spine, which produced a great acceleration of the respiratory move- ments, and the blood was found to contain 2.9 parts of fibrin in a thousand. Although the corpuscles appear to be very different in the two tables, yet their relative amount in pro- portion to the albumen is almost exactly the same in both cases. Color. — The diflference in color between arterial and venous blood, is due to the hemoglobine which the red cor- puscles contain and the change of color produced in it by the influence of oxygen. It is also partly due to the change of shape of the corpuscles. They are biconcave in arterial blood, and rounded in venous. The former is produced by the in- ■■■■ ^ INFLUEhXE OF VENESECTION. 183 fluence of oxygen ; but it may also be occasioned by con- tact with some of the salts in solution, without any direct exposure to oxygen. The blood is darkened in color by whatever tends to expand the C(M'puscles, so as to render them rounded, whilst it is brightened by whatever tends to render them biconcave. For example, arterial blood is darkened by the addition of water, which swells out the corpuscles and deprives them of some of their coloring matter. CONDITIONS WHICH INFLUENCE THE CHARACTER OF THE BLOOD. Influence of Venesection. — It has been found by ex- periment that, in bleeding, the corpuscles suffer most ; the fibrin is increased, and the water taken awav is soon re- placed by transudation from the tissues, so that the specific gravity is diminished, as will be seen from the following table, the result of the analysis of the blood of ten patients, by Becquerel and Rodier : Ist BleeJina^. 2nd Bleeding. 3rd Bleeding. Specific gravity of defihrinated blood. . 1056.0 1053.0 1049.6 Specific gravity of Serum 1028.8 1026.3 1025.6 Water 793-0 807.7 823.1 Corpuscles 129.2 116.3 99.4 Albumen 65.0 63. 7 64.6 Fibrin 3.5 3.8 3,4 Extractive and Salts 7.7 6.9 8.0 Fatty Matters 1.6 1.6 1.5 1000.0 looo.o 1000.0 From the above it will be seen that the corpuscles are notably diminished, and that.bleeding has no eflect what- ever in diminishing the amount of fibrin. Fibrin is in- creased in all inflammatory diseases, and the most copious venesection is unable to check it, but rather increases it. The following table gives the result of bleeding, in a case of rheumatism, from Christison : Water 844 Solids of Serum 93 * Corpuscles 57 Fibrin 4 3 1 c I": «,■ ■ I! *r, II *>" . crtt- • «•,•. 184 BLOOD. Influence of Starvation on the Blood. — This is somewhat similar to prolonged venesection. The following tables show the result of bleecding upon a well-fed dog ; and also the same, in a state of starvation. (Todd and Bowman) : Number of Bleedings. 1st. 2nd. 3rd. 4th. (Water 783.79 810.89 815.18 813.04 While being 1 Corpuscles 142.85 "3-54 110.58 106.95 fed. J Solids of Serum. 70.94 70.85 69.92 76.01 (Fibrin 2.42 4.72 4.34 3.99 After these bleedings, the animal was allowed to recover, and was well fed for about three weeks. He was then starved for about four days, being allowed nothing but water, and bled each day, with the following result : Number of Bleedings. Tst. 2nd. 3rd. 4th. f Water 804.40 805.44 838.30 849.84 While being 1 Corpuscles 121.08 119. 15 87.98 74.21 starved. J Solids of Serum. 72.61 71-46 68.46 71.62 (Fibrin 1. 91 3.95 5.26 5,13 In the latter case, the diminution of the corpuscles is more marked than in the former ; and it will be observed that the corpuscles had not entirely recovered from the effects of the first bleeding. It will also be observed that, in both cases, there is at first an increase in the fibrin, and after- wards a diminution — the latter being caused by the diminu- tion of the red corpuscles, and consequent non-development of the fibrin. Influence of Iron and Flesh Diet on the Blood — The quantity of blood corpuscles may be increased by the administration of iron and flesh diet. Fresh beef is the best diet for this purpose. It contains the most appropriate materials for nutrition, and is comparatively easy of diges- tion. The essence of beef, or beef tea, is still better, especially when the patient is very feeble, and the stomach unable to digest solid food. In anemia, the corpuscles have been increased from forty to sixty, and even ninety in a thousand, in a few weeks, by this mode of treatment. INFLUENCE OF AGE ON THE BLOOD. 185 Influence of Age on the Blood. — During the latter part of foetal life, the solids of the blood, especially the red and white corpuscles, are incieased, and remain high for a short time after birth. They then gradually diminish until puberty, when they are again increased, and remain so dur- ing the most vigorous period of adult life, after which they begin to decline, as old age advances. The object of these changes in the increase of solids, is to fit the blood more fully for the nourishment and growth of the body at these important periods, viz ; immediately after birth, at puberty, and during the period of ovulation in the female, and the corresponding period in the male. Influence of Sex on the Blood. — The solid elements of the blood, especially the red corpuscles, are increased in the male. In 'pregnancy, the blood has a lower sp. gr. than the average, owing to the deficiency of red corpuscles. On the other hand, the white corpuscles and fibrin are increased, the latter especially during the last three months. This may be considered a wise provision of nature to favor the formation of clots in the mouths of the open vessels after parturition and the separation of the placenta, and to prevent post-partum haemorrhage. Influence of Disease on the Blood. — It will be seen from the following table that the principal constituents of the blood may vary much, in health, in different pei-sons ; and in the same person, at diffierent times. This may be due to various causes, as the kind or quality of the food, habits, amount of exercise, etc. According to Andral, the variations may be as follows : Fibrin Corpuscles " Solids of Serum " Water etc., etc. from 2 to 3^ parts per thousand. " no to 152 " " 72 to 88 760 to 815 " " In estimating the quantity of fibrin in the blood in dis- eased conditions, it should always be borne in mind that it may contain a number of white corpuscles. These are very I .4 .1 ■^^ T IMAGE EVALUATION TEST TARGET (MT-S) // 1.0 If IK I.I 1^ Hf m IIM 1 2.0 1.8 1.25 1.4 IIIII.6 ■< 6" ► i 7 ^^/ 'c-1 Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, NY. 14580 (716) 872-4503 ^^, i^. \ m in* fi m li'j 9m fWV IM 1. l!' II' 4: 1.- > 1 £' h ill' .1 i Kir« *»■;• . >: ri;.5 !l ' »>.'i ■ 'j •ni 186 BLOOD. diflGlcult to separate, and although not very numerous in a state of health, yet in many diseases, as inflammation, anemia, leucocythsemia, etc., they are so much increased as to add materially to the amount of fibrin. There is found to be an invariable increase of fibrin in all acute inflammatory aflections of a sthenic kind. This augmenta- tion is so constant, that if more than five parts of fibrin in a thousand be found in the course of any disease, it may be positively affirmed that some local inflammation is present. The maximum proportion of fibrin in inflammation may be stated at about 13.3 (acute rheumatism), the minimum 5, and the average about 7 parts in a thousand. Even in anemia and chlorosis it rises to 6 or 7 in inflammation. In phthisis also, there is an increase, notwithstanding the deterioration of the blood. It is, no doubt, due to the local inflammation going on around the tubercles. In single pneumonia the fibrin has been found as high as 10.7; in acute rheumatism, 13.3. It is slightly increased in all the exanthemata. It is also increased in leucocythsemia. The increase in the quantity of fibrin does not depend upon the febrile condition present in inflammation, but upon the inflammation itself. For example, in continued fever it is lower than in health, but if local inflammation arise in the course of the disease, the fibrin is at once increased. In simple continued fever it has been found as low Pi 1.6. In typhoid fever it may varj' from 3.7 to 0.9, and in some cases the blood shows no disposition to coagulate, the fibrin either being entirely deficient, or very much lowered in vitality. In double pneumonia it is as low as 0.9, due to the imper- fect aeration of the blood. In scurvy it is sometimes in- creased, and sometimes diminished. In cholei*a the serum is first diminished next the albumen, and afterwards the fibrin. The vomited matters, and substances passed by the bowels are coagulable by heat and nitric acid. The fibrin is diminished in apoplexy, due probably to the arrest of nerve force. In purpura hemorrhagica it is 0.9, and ' I'i !l I I I!! INFLUENCE OF DISEASES ON THE BLOOD. 187 sometimes entirely deficient. One of the effects of a diminu- tion in the proportion of fibrin is a tendency to the occur- rence of hemorrhage from slight causes, which is difficult to arrest. The amount of red corpuscles is subject to greater varia- tion within the limits of health than the fibrin. In plethora they may be increased to 180 or 190. Plethoric persons are not on that account more liable to inflammation ; but they are very prone to congestion, especially of the brain, and apoplexy. This condition may be easily remedied by venesection. The number of corpuycles may be reduced from 180 to 144, or from 60 to 48 in one bleeding. In anemia, on the other hand, the corpuscles are diminished, in some cases as low as 27 in a thousand, but they may be rapidly increased by appropriate treatment. They have been increased in some instances from 40 to 60, and even 90, in three or four weeks. In diabetes mellitus, Bright's disease, disease of the heart, lead poisoning, tuberculosis, cancer, scurvy, leucocythaemia, etc., they are materially diminished, and often assume a granular appearance. The colorless corptuscles are said to be increased in infl'im- mation, but it is by no moans constant In the disease first pointed out by Dr. John Hughes Bennett, of Edinburgh, and termed by him leucocythsemia, they are largely increased. In this disease the specific gravity of the blood is low, and the fibrin is invariably increased. The quantity of alhv,men seems to vary very little. It is reduced in cholera, albuminuria, etc., so that the entire solids of the serum have been found in some cases as low as 52 in a thousand. The diminution in the amount of the albumen in the serum, in albuminuria, is exactly proportioned to the quantity found in the urine. The fatty matters are very much increased in some in- stances, so as to give the serum i. milky appearance, as for example in tuberculosis, Bright's disease, hepatitis, dropsy, lO ■« VI t » i 188 BLOOD. c fC'J t i,\u CF olahoration of nutrient ninturial for the tissues of tlio Ixxly, nioro ospocially in tlio in- vortobrato classes of animals. Tlicso corpuscles, which arc oat-shapt'«l in the larvai of insocts, aro found nioro numerous just before each chanfje of skin, at which time a lai'f^er supply of nouiiNlnucnt is iHMpiircd. After theso changes have taken place, they are again diminislied. Tho white corpuscles also contain a small (pumtity of iron, thus allowing that th(> characteristic color of tht5 hmI corpuschis is not due to this substance. In the V(>rtebrata, on tho other hand, the excess of colorless coipuscles is an evidence of un- healthy action; lor exam])le, they aic very nbutidant in tho blood of frogs that aro youtig, sickly, or ill-fed. In tho human subject, they are incicascd in tho disease called leu- cocythiiMuia, in anemia, and also in intlatnjiiation aceoiding to some, although, in all probability, this only occurs in sickly, scrofulous, or tuberculous patients. When the cir- culation of the blood is examined in a bat's wing, or frog's foot, under the microscope, the white corpuscles may bo ob- servctl running from the centre of the current to tho circumference, and back again, and occasionally adhering to the sides of tho vessehs. They may also be occasionally seen passing through the coat^s of the vessels by virtue of their anuTeboid movements, or iliapedesif^. In this process they throw out arms or projections which enter the pores of tho vessels and gradually force their way through. They thus pass out in large numbers in the healing process, and in in- tiammation, and are supi>osed to form the lymph. In this they arc supplemented by the proliferation of connective tissue cells in the inflamed or wounded parts. Function of Albumen. — This substance is the ))abuUim, from which the tissues of the body are formed. It is also used in the formation of the fibrin, globuline, and hemoglo- bine of the Wood itself. Albumen by itself, however, is in- capable of organization, and its conversion into the various FUNCTION OF FATS IN THE BLOOD. 197 tiH8tioa must (lopoTid on tlioir owd power of appropriation. It also assists in holding in solution in tho blood many of tho metallic salts which exist in that lluid, or which enter tho system, Tho all)uin«!n is «lerived from tho food, and when any excess is taken into the s3'stem, it undergoes a retrograde change, and is eliminated l»y the liviir and kidney. It is not excreted in health, but may be found >n the urine in certain recipilate in the form of Hakes. It may also bo bund in the voTnifa and dejecta in cholera and yellow fever. Fats, — The fatty matters taken into tho system are in^ tended in part, for tho supj)ly of tho adi|)')so and n«;rvo tissu<; ; but their chief use, liowever, is to afford material for that couibustivo |)rocess wliich is necessary for the main- tenance of animal heat. It also contributes to the formation of milk. That which is stored up in the body nmy be looked U[)on as tho suiplus. Fat is often detected in i\\Q fioce.s, and such cases indicate a diseased condition of the liver or pancreas. The other organic compounds which have been found in the blood, as sugar, lactic acid, urea, uric and hipi)uric acid.s, creatine, creatinine, fatty acids and odorous substances, but which do not properly form a ])art of it, are the result of a retrograde metamorphosis, either of the alimentary sub- stances or of the ti.ssue^ themselves, and are rajjidly elimi- nated by the lungs, kidneys, liver, .skin, etc. IVie uses of the inorganic salts are not positively known ; but such as have been investigated were '^ferred to in the chapter on the proximate principles oi the first class, Tho alkaline salts as sodium and potassium carbonates and phosphates are necessary to give the olood its alkalinity, to hold in solution the albumen, and to facilitate the passage of the blood through the capillaries, The salts are necessary also for the proper nutrition of the muscular tissue. Lime % i 198 BLOOD. c A. m ma* •ft* ■»' II BW.1 rut phosphate, lime carbonate, calcium fluoride, etc., are re- quired to build up the solid tissues, as bone, teeth, etc. The lime phosphate, in particular, may be regarded almost as a histogenetic substance, as it seems to be almost invariably present in newly-forming tissues, but more especially in the bone and teeth. Iron is an essential ingredient of the blood itself, entering into the f>rmation of the hemoglobine. Water exists in large quantities, and is liable to consider- able variation. RELATION OF THE BLOOD TO THE LIVING ORGANISM. The normal proportions of all the substances found in the blood are maintained partly by the selective power of the tissues in the process of nutrition and growth, and partly b}' means of tlie excretory apparatus, which removes the surplus materials. Each part of the body takes from the blood the peculiar substance which it requires for its nutrition, and thereby acts as an excretory organ, by removing that, which if allowed to remain in the blood/would act injuriously in the nutrition of the body generally; for example, the phos- phates and carbonates which are deposited in the bones are as effectually removed from the blood as those which are thrown off by the urinary organs. Again, the rudimentary organs, as the hair in the foetus, the mammse in the male, etc., may be looked upon as excretions serving a useful p irpose in the animal economy, by removing certain materials from the blood which might interfere with the proper nutrition of other parts of the body. Although the blood may vary slightly in its composition and properties at different periods of life, yet we find that, taken as a whole, it presents such a constancy in iti leading features, that we cannot fail to recognize in it some capacity for self-development, similar to that which the solid tissues possess. It retains its identity through life, just as a leg, an arm, or an eye. It has the power of maintaining itself from the new materials supplied to it from the food, and goes RELATION TO THE LIVING ORGANISM. 19i> through the successive phases of growth, maturity, and de- cay, similar to all vital organisms. The self-maintaining power of the blood is forcibly exhibited in the phenomena of disease, especially those of a febrile class, as the exan- themata, typhus, typhoid, etc. In all these cases the " mor- bid poison " would be eliminated by nature, if time were allowed to do so, the blood replenished, and the patient would resume his wonted health. In some instances, when a poisonour\ substance has entered the blood, the life may be saved by keeping up artificial respiration until nature has time to eliminate the poison from the system. In nearly all the toxic diseases of the zymotic class, there is a natural tendency to self-elimination of the poison, and of the pro- ducts of its action on the blood either by the agency of the excretory organs, or by the local lesions which occur in these cases, and this occurs with such regularity that we are able to predict with certainty when the changes may be ex- pected to take place. From the very nature of the action of these poisons on the blood, it is evident that no reliance whatever can be placed on the action of antidotes in check- ing their course. The object of treatment lies wholly in pro- moting the elimination of the morbid poison, in subduing local action, and supporting the vital powers of the patient during the continuance of the disease. 1 I i s 500 CIRCULATION. CHAPTER VIII. C C II. « •■V w» C •** I"'' t* in Ifit c (I «ir" ; ' CKic ea CIRCULATION. The object of the circulation of the blood is to carry to every part of the body the materials for its nutrition and growth, together with the supply of oxygen necessary for its vital actions ; and also to carry away the effete sub- stances which are formed as a result of the waste of the tissues. The organs concerned in this process are the heart, arteries, veins, and capillaries. THE HEART. The heart is the great central organ of circulation, situated in the middle mediastinum of the thorax, being placed obliquel}-^, the base upwards and to the right side, on a level v/ith the upper border of the third costal eaitilage and corresponding to the interval between the fifth and eighth dorsal vertebrse, the apex corresponding to the inter- space between the cartilages of the fifth and sixth ribs, one inch to the inner side; and two inches below the left nipple. It is a hollow, muscular organ, which, like a forcing pump, drives the blood through the vascular systen. It weighs from 9 to 10 ounces, and is about equal to the size of the closed fist of the individual, It varies in size and shape, in different classes of animals, from a simple, muscular tube, as in insects, to the complex double heart of man. In all animals, the organs of circulation are adapted and modified in structure to correspond with the organs of respiration. In the lower order of animals, as insects, the heart consists of a simple muscular tube, provided with certain valves at short distances apart. Corresponding to the situation of these valves, there are distinct constrictiont, in the tube, so THE HEART. 201 that it has the appearance of a series, or chain of hearts. As we ascend the scale, we first observe the subdivision of the heart into two cavities, the auricles and ventricles, in the acephalous mollusks. In fishes, also, the heart consists only 1 i^. 6P. Rijrht auricle and ventricle opened, to show their interior. 1, superior vena cava ; 2, inferior vena cava; 2', hepatic veins ; 3, right auricle ; 3', fossa ovalis, below which is the Eustachian valve ; 3", coronary vein ; +, +, auriculo-ventricular groove ; 4, 4, cavity of the right ventricle, the upper "figure is immediately below the seniilimar valves ; 4', large columna carnea or musculug papillaris ; 5, 6', 5", tricuspid valve ; 6, in pulmonary artery ; 7, aortic arch close to the ductus arteriosus ; 8, ascending part or sinus of the arch covered at its commencement by the auricular appendix and jnilmonary artery ; 9, the innominate and left cartoid arteries; 10, appendix of the left auricle ; 11, 11, the outside of the left ventricle, the lower figure near the apex. of two cavities, the auricle, j.ito which the blood is received from the veins, and a ventricle, which drives the blood into the main artery which supplies the gills. In reptiles, there are two auricles and one ventricle. One of the auricles c4i M 4 202 CIRCULATION. c MM *•.■^ MM in* "v. p-' It. » »l uru »»■:- cn.1 receives the blood from the lungs, the pulmonic ; and the other, the blood from the veins of the body, the systemic auricle. They both open into a single ventricle, which propels the blood throughout; the body, and also to the lungs. In birds and mammals (including the human species) the heart consists of two auricles and two ventricles, separated •by a complete septum, each auricle communicating with its corresponding ventricle, and v-Jich ventricle communicating with an arterial trunk. The course of the circulation is as ^"'s- "« follows :— The venous blood is returned from the body by the super- ior and inferior vena^ cavse, and poured in- to the right auricle ; thence it passes into the right ventricle, being prevented from returning by the clo- sure of the tricuspid valves ; from the right ventricle it passes to the lungs, through the pulmonary artery, the opening being closed behind it by the coaptation of the pulmonary semilunar valves. The blood Diagram of the circulation. ^^Ing aerated in the lungs, is returned to the left auricle through the pulmonary veins ; this constitutes the pulmonic circulation. It next passes through the auriculo-ventricular opening into the left ventricle, being prevented from returning by the closure of the mitral valves ; it is then propelled with con- PROOFS OF THE CIRCULATION. 203 siderable force into the aorta, the opening being closed behind it by the coaptation of the aortic semilunar valves, and is thence distributed to the various parts of the body, to be again returned by the veins to the right side of the heart. The latter constitutes the systemic circulation. On reference to the diagram there will also be seen a sub- ordinate stream, or offset of the general or systemic circulation which passes through the liver ; this is the liortal circulation. The variation in the course of the blood during foetal life is called foetal circulation. Proofs of the Circulation. — The circulation of the blood was discovered by Harvey in 1618. The main arguments by which he proved the circulation were as follows : — 1, The heart propel.^ in half an hour, more blood than the whole mass in the body. 2, The blood spurts iu a jetting manner from a wounded artery. 3, If true, the normal course of the circulation explains why the arteries were found empty after death. 4, If the veins were tied near the heart, it became pale and bloodless ; if the artery were tied, the heart became distended. 5, If a ligature be drawn tightly around the limb, no blood can enter and it becomes pale and cold ; if slightly relaxed, blood can enter but cannot leave the limb, hence it'swells. 6, The existence of valves in the veins, which permit the blood to flow only towards the heart. 7, The constitutional disturbance re- sulting from poisons introduced at a single point. To these may be added proofs accumulated since the time of Harvey, viz. : the effects of wounds of arteries and veins respectively ; in the former hemorrhage may be arrested by pressure above ; in the latter, by pressure below the seat of injury. The direct passage of blood corpuscles from small arteries, through the capillaries into the veins, seen by the microscope in the web of the frog's foot, the tail of the tadpole, etc. The injection of certain substances into the veins, which have been detected in the arteries a short time II •4 % 204 CIRCULATION. c MM c If' 1*9 IV-' II- Crur • •(:■,. tW iin.4 afterwards. The valves of the heart are also so arranged as to permit the blood to pass only in one direction. Muscular Structure of the Heart. — The heart con- sists of striated muscular fibres, and fibrous rings which serve for their attachment. The fibres are not arranjcred in bundles, but interlace with each other in an intricate manner, and adhere closely together, there being little or Fig. 67. Fijf. 08. kSbUs [ =u^ Fig. C". Jluscular fl'ires of the licart, sliow itg their stria), divisions and junctions none of that areolar tissue whi h exists in the external muscles, and there is no appearance of sarcolemraa. The fibres are also small n* than those of other parts of the body, and the strise are less marked. The dispo- sition of the fibres of the heart may be demonstrated by prolonged boiling, which Fiir. 68. Muscular fibres magnified, showintf r j xi. iiu i separate cells with their nuclei. hardens the tibrcs and facilitates their separation. The fibrous rings are four in number, the rigkt and left auriculo-vejitricular, the aortic and pulmonary. The former serve for the attachment of the muscular fibres of the auricles and ventricles, and also for the tricuspid and mitral valves ; the latter for the attachment of the arterial vessels, semilunar valves, and muscular fibres of the ventricles. The walls of the left ventricle are 7 lines in thickness, those of the right about 2^ lines ; the walls of the left auricle are about 1| lines in thickness, the right 1 line. The Fibres of the Auricles. — These are divided into two sets or layers, a superjicial, common to both, and a deep layer, proper to each. The superjicial fibres run in a transverse direction across the bases of the auricles, and are most distinct on the anterior surface. The deep fibres con- sist of two sets, looped and annular. The looped fibres commence at the ariculo-ventricular rings in front, pass FIBRE.; OF THE VENTRICLES. 20» upwards over the auricle, and return to the rings on the posterior part. The annular fibres surround the auricles in a circular manner, and are continuous with the circular fibres of the veins which open into them. The Fibres of the Ventricles. — These consist accord- ing to Pettigrew, of seven layers, of which three are external, the fourth central, and three internal. In the left ventricle the fibres of the first or external layer, lun almost vertically downwards, inclining somewhat fiom left to right, and are continuous at the apex with the seventh or internal layer, which pass upwards reversely from left to right ; these two, are the only layers that are inserted into the aiiriculo- ventricular and aortic rings. Those of the second layer rnn more obliquely downwards from left to right, and are con- tinuous at the apex with the sixth layer, which pass upwards with a corresponding obliquity in the reversed direction. The third layer is similar in course, but still more oblique in direction, and is continuous at the apex with the sixth layer. The fourth layer is horizontal or transverse (circular), and appears to be single. The internal laj'ers are thicker than the external, so that the fourth layer is nearer the outer, than the inner surface of the ventricular wall. The fibres of the external layer curve around at the apex in a spiral manner, and form the whorl or vortex, constitut- ing the entire thickness of the heart at this point. From the seventh layer are chiefly formed the musculi papillares and columnfe carneae. The fibres of the first four layers pass across the septum from one ventricle to the other; this is specially noticeable at the back where there are some transverse fibres — the " hinge-like " fibres of the back of the heart. The right ventricle is similarly formed, except that the external fibres are continuous with the internal, not only at the apex, but all along the anterior coronary groove. The septum is formed of fibres from both ventricles, and the left half is twice the thickness of the right. 1 ^ 206 CIRCULATION. c I ft;* llv firo \' The heart is covered externally by a layer of pericardium and lined internally by a smooth shining membrane, the endocardium, which is continuous with the lining mem- brane of the arteries and veins. Both these membranes are covered with flattened epithelium (endothelium) which gives them a smooth and glistening appearance. The valves of the heart are formed by redu{)lications of the lining mem- brane, strengthened by connective and elastic fibres, and are attached by their bases to the tendinous rings. The tri- cuspid and mitral valves which guard the right and left auriculo- ventricular openings respectively, are also attached by their ventricular surfaces and borders to the columnar carnece by slender tendinous chords, the chordce tendinece, The semilunar valves which guard the orifices of the aorta and pulmonary artery, three in number for each, are placed side by side around the orifice, so as to form three little pouches, which lie flat when the blood is passing out, but immediately bulge out to prevent any return, the corpora Arantii closing in the space between the three segments in the centre. Vessels and Nerves. — The heart is supplied by the anterior and posterior coronary arteries ; the nerves are de- rived from the superficial and deep cardiac plexuses, which are formed partly by the cranial nerves, and partly by the sympathetic. Action of the Heart. — The blood is propelled in its course by the alternate contraction and dilatation of the muscular walls of the auricles and ventricles of the heart. The two auricles contract together, and afteiwards the two ventricles ; and in each case the contraction is immediately followed by a relaxation. The contraction is called systole ; the dilatation, diastole. The auricles gradaally fill with blood flowing into them from the veins, pr.rt of which passes at once into the ventricles. When the auricles are dis- tended, they contract and force the blood into the ventricles, completing their diastole. The latter immediately contract, rsajgeaSit SOUNDS OF THE HEART. 207 and their contraction, or sys/oZe, follows so rapidly, that it ap- pears as if continuous with that of the auricles. The ven- tricles contract more slowly than the auricles, and empty themselves more completely than the latter, which always contain a small quantity of blood. The contraction of the ventricles upon the blood, closes firmly the auriculo- ventri- cular valves and forces open the semilunar, and the blood is forced into the aorta and pulmonary artery. The musculi papillarea by their contraction, and attachment through the chorda} tendinece, prevent the auriculo-ventricular valves from being everted into the auricles. The closure of the tricuspid valve is not always complete, especially if the ventricle is too full, and a small quantity of blood flows back into the right auricle. This has been called the safety valve acticm of this valve. The semilunar valves, as pre- viously mentioned, lie flat to allow the blood to pass out but immediately fill, bulge out and meet, so as to pre-' vent its return. During contraction the heart appears to become longer and narrower, although, in reality, it becomes shorter and narrower. This may be demonstrated by placing the heart of a recently killed animal, as a frog or rabbit, on the table, and transfixing the base by means of a large needle, and in- serting another at the apex, so as merely to touch it. Tf the organ is then stimulated to contraction by pricking it, the apex will be observed to recede from the needle, while the heart at the same time becomes narrower and shorter. Sounds of the Heart. — The action of the heai-t is ac- companied by sounds. These are two in number ; the first or systolic, and the second, or diastolic. They follow each other in quick succession, and are succeeded by a pause, or period of silence, after which the first sound again recurs. The duration of the first sound is double that of the second, and equal to that of the pause. Thus, if the whole period be divided into five parts, the first two would. .4 c c MM I. WIV nru rr.v lis* Jk •mi ,, litm- . 208 CIRCULATION. 1)0 occupied by the first sound, the third by> the second jsound, and the fourth and fifth by the pause, thus : 2 Parts occupied by the first sound | 1 Part occupied by the second sound > Rhythm. 2 Parts occupied by the pause ) A very short pause must also exist between the first and second sound, otherwise two distinct sounds could not be heard. This order of succession is called the rhythm of the heart, which, in a state of health, is remarkable for its regu^ larity. The first sound of the heart is a heavy, prolonged sound, synchronous with the impulse of the heart, and is most distinctly heard over the apex ; the second is a short, distinct sound, best heard over the base. These sounds somewhat resemble the sounds of the words "come " " up," whispered in rapid succession, the former representing the first sound, the latter, the second. The Jirst sound is in all probability, a compound sound, chiefly produced by the closure and vibration of the tricus- pid and mitral valves, and the collision of the blood against the walls of the ventricles. It is also partly attributed to the muscular sound produced by the contraction of the ven- tricles, and the impulse of the heart against the walls of the chest. The second sound is undoubtedly due to the closure and vibration of the aortic and pulmonary semilunar valves. They are forced back by the recoil of the blood, as one un- furls an umbrella — with an audible click as they tighten. This may be demonstrated by fastening one of the valves by means of a hook or ligature, to the side of the aortic and pulmonary arteries respectively, in some animal, as a calf, so as to allow regurgitation to take place, when it will be ob- served that a bellow's murmur takes the place of the second sound ; but as soon as the valve is allowed to resume its play, the natural sound returns. It is thought by some that both sounds of the heart are produced by the same cause, viz : the tension of the valves. Disease of the valves IMPULSE OF THE HEART. 209 gives rise to niurmurs which interfere with the distinctness of the sounds. Impulse of the Heart. — The impulse of the heart is most distinctly felt in the space between the fifth and sixth ribs, two inches below and one inch to the inner side of the left nii)))le, and is sometimes called the apex heat. The force of the imj)ulse varies in different individuals, and in the same individual at different times; it is very distinct in emaciated persony, and especially in hypertrophy of the heart. It is produced by the contraction of the spiral mus- cular fibres of the ventricles, which causes a tilting of the apex against the walls of the chest, and also by its change of shape in contraction, during which it becomes firm and globular, and impinges upon the walls of the chest. In its movement the apex describes a spiral curve from left to right, and from behind forwards. That the impulse of the lieart is not due to the tendency of the arch of the aorta to straighten itself when distended with blood, and the elastic recoil of the parts about the base of the heart, is shown by the fact that the tilting movement of the heart will take place even when the apex has been cut off. The impulse of the heart corresponds with the pulse in the arteries, con- sequently the actions of the heart may be counted by the pulse at the wrist, or in any of the arteries. The beat is not a simple shock as it seems when felt by the finger, but may be shown by the cardiograph (a modified form of the sphygmograph) to be compounded of three or four shocks the strongest of which only, is felt by the finger. Frequency and Force of the Heart's Action. — In a healthy adult, the pulsp+ions vary from seventy to seventy- five per minute. Thv. frequency of the heart's action diminishes from the commencement to the end of life, as will be seen from the following table, which represents the average number of beats in a minute : — t ■I .4 1 If I lii 4fv c MM I. 4:. 210 CIRCULATION. Fn the fn-tus 150 Al l)irlh 130 In infancy ; 1 10 In ymilli 80 Adult ai^c 75 Old ajje 65 Posture exorcises a most nMnatkable intlueiice on the fre- quency of tlio lieait's action. It is most frcMineiit in the erect posture, next to that, in the sittinj^, and least in the recmnluint position. The pulse is also most frequent in the morning, liecominnj slower towards evening, and is very much diminished iluriug the ni_L;ht. It is more frequent in those of a sanguine te>nj)ei'am(Mit, than in the i)hli!gmatic, and in females than in males. Its action is accelerated after a meal, and still more so after bodily exertion, or mental ex- citement. In health, there is a nearly uniform relation between the frecpiency of the heart's action and the n.'spira- tions, the proportion being about four of the former to one of the latter. A certain rate of movement must be maintained in the circulation, and the impediment produced by friction must be overcome l)y the muscular force of the lieart; and, since the left ventricle propels the blooil through the whole sy.s- tem, while tl^e right sends it only to tlic lungs, the walls of the former are twice as thick as the latter, and the force of the one is double the force of the other. The force of the heart's action may be estimated either by ascertaining the heiglit of the column of blood which its action will suj)port f'Haies' method), or by causing the blood to act on a colinnn of mercury (the method of Poiseuille and Volkmami.) Hales introduced a long pipe inti^ the carotid ar*^ )ry of a horse» and found that the blood rose to the height of ten feet. From this and other experiments, on the lower animals, he concluded that the human heart would sustain a column of blood seven and a half feet high, the weight of which would be about 4.1 lbs., on the square inch. Poiseuille's experiments were made with a glass tube, bent so as to form a horizontal FORCE OF THE HEART. 211 the (/^) and two porpcndletilav portions (re. c), tl>o latter Ix'iiij,' shaped like the letter IJ (Fijj. 09), namod the /inuwultfwnHi)- meter. The horizontal portion is '"'« "" adapted by a tube to the artery, and the perpeodictdar branches are partly filled with mercury, the rise and fall of which can be ineahured on scales placed behind them, and as the rise and fall are equal, the double of either will give the weight of the cohuun which t J force of the stream is able to r. aintain. The results corresponded clcsely witli Hales' estimate, being about 4] lbs. Volkmann passed a solution of sodium carbonate into the hori- zontal branch, to prevent the blood from coaffulatinjj on the sides of the vessel. From his experiments, it appears that the force of the stream is capable of supporting a column of mercury about eight inches in height, or a column of blood about nine feet. But the force which the walls of the heart must exert in order to impart such a pressure to the blood which it propels, is equal to a weight of about Hi lbs. A modification of the haemadynamometer for registering the variations of the force of the heart, or arterial tension is called a kymograph (Fig. 70). The open mercurial colmnn supports a floating rod and pen (a), in contact with a revolving paper cylinder moved at an uniform rate by clock- work. The movements of the pen, caused by the up and down movements of the column of mercury, are inscril)ed or registered on the paper cylinder. Influence of the Neuves on the Heart. — The heart's action is governed by two sets of nerves, the cxclto-motor 1 i if i c I' ««■" tnr iin.1 212 CIRCULA TION. antl inhibHorij. The ganglia and communicating nervo tibre« wliicli preside over its action, are situated in the Fijf. 70. walls of the heart. They have been carefully studied in the frog, in which there are three collections of ganglia, i wo excito- niotor — Remack's, near the infer- ior vena cava, and Bidder's, in the left auriculo- ventricular septum, and one inhibitory — Ludwig's in the interventricular septum. The heart receives its excito-motor influence through certain fibres of the sympathetic (inferior cer- vical ganglion and cardiac plex- us) from the medulla oblongata, and its inhibitory or restraining influence from certain fibres of the pneumogastric (superior car- diac). Stimulation of the sympa- thetic nerves supplying the heart, Menuriiil kvmofrraph : (n) floatiiiL' , ,, , - r\^ It f 224 CIRCULATION. c- c c I. I- ■t »<« f. KIM , <^« ^«ar<, and rccoii of the arteries, and partly also to the attractive or selective power of the tissues. Tho former has been alroatly referred to, in connection with tho heart and arterioa. With regard to the latter, it is in the capillaries that those chemical and physical changes between the blood and tho tissues take place, in which tho phenomena of nutrition essentially consist. A certain force is generated by this interchange, which promotes tho circulation of tho blood through the capillaries. It is termed the attractive or selective pow&r of tho tissues, or by Carpenter capillary power. It may be explained as follows : — As the blood charged with oxygen and nutritious substances for the sup- ply of tho tissues approaches the capillaries, a rapid imbibi- tion takes place with such energy, that it pushes before it into the veins, the blood from which tho nutritious ele- ments had been previously removed, and which also con- tains tho effete matter. This force resembles that by which tho circulation is maintained in plftQts, and in some of the lower order of animals. The capillaries are surrounded by a plexus of nerves, similar to that of the larger vessels, 'f heir contraction during anger and from fear, and their dilatation during blushing, can only be referred to the influenoe of the nerves, for in these cases the changes are so rapid that the heart has not tim<) to eit'ect them. Under one kind of nervous emotion the vessels contract, and empty themselves, and tlie coun- tena.:c° becomeo deadly pale, as in anger, fear, etc. Under another kind of nervous emotion the vessels dilate, become filled with blood, and the cheek is suffused, as in blushing. The heart's action alone is sufficient to carry on the cir- culation of the blood, but it is aided by other forces which are supplementary. The combined forces by which the blood is propelled throughout the body, are, first and chiefly, the muscular force of the heart ; second, the recoil of the elastic walls of the arteries ; third, the attractive or selective power of the tissues ; fourth, the pressure of the VELOCITY OF THE CIRCULATION. 925 muscles among which some of the veins lie ; fifth, the aetioA of the muscular tissue in the coats of the veins ; and sixth, the inspiratory movements of the chest. VELOCITY OF THE CIKCULATION. The velocity of the current of blood at any given point in the system, is inversely proportional to the sectional area at that point. The united area of the capillaries i» 400 times as great as that of the aorta, and hence the velocity of the blood in the capillaries is about f^^ of that in the aorta. Velocity in the Arteries. — The velocity of the circu- lation in the arteries, may be ascertained by an instrument similar to tliat used for measuring the force of the heart. It is greater than in any other pari of the system. Volkmann estimates the velocity with which the blood moves in the carotid artery, at about twelve inches 'per second. It diminishes during the diastole of the ventriclea and in arteries remote from the heart, as the metatarsal, in which it is 2.2 inches per second. Velocity in the Veins. — The velocity of the venous- current is to that of the arterial ^ ; two to three, or about eight inches per second, as nearly as can be ascertained. Velocity in the Capillaries. — The rate of movement of the blood in the capillaries may be determined by the microscope. It is slower than in either the arteries or veins, being on an average, about ,V of an inch per second. Velocity in the Body. — It is estimated that the ventricles and auricles are each capable of holding about three ounces of blood, and that this quantity is propelled by either ventricle at each systole, and that the whole amount of blood in the system is about eighteen pounds. This would require ninety-six pulsations for its passage through either side of the heart, and allowing seventy-two pulsations to a minute, the time occupied in transmitting % It ♦ i 226 CIRCULATION. c c I. »•• an the whole would be 1^ minutes. But it has been ascer- tained by experiments on animals, as the horse, that sub- stances in solution, such as potassium ferrocyanide, barium nitrate, etc., may be detected in the blood drawn from the carotid artery within twenty seconds after it has been introduced into the jugular vein of the opposite side. In the dog, the heart's action may be arrested in eleven or twelve seconds, by the introduction of a solution of potas- sium nitrate in the jugular vein ; in the rabbit in about four seconds, and in fowls in about six. The introduction of such poisons as hydrocyanic acid and strychnine, are equally rapid in their effects. Hence, it appears that the rapidity of the circulation is underrated in the estimate founded upon the capacity of the heart, and the number of pulsations in a minute. It has been estimated by Volk- mann, that in man the whole circuit is completed in con- siderably less than one minute. Peculiarities of the Circulation. — These are observed in the lungs, liver, brain, spleen and erectile organs. The chief peculiarity in the pulmonic circulation is, that the artery carries venous blood to the lungs, and the veins return arterial. The portal circulation is peculiar in being a kind of offset from the general circulation. The peculiarity of the circulation in the brain is, that it is provided with a uniform supply of blood. Thi^3 is secured by thf number and tortuosity of the vessels, and their large anastomoses in the formation of the circle of Willis. The occurrence of large venous trunks or indistensible sinuses within the cranium, is also peculiar. It is also stated by Dr. Kellie, that in bleeding animals to death, the brain does not become exsanguine, owing to atmospheric pressure, unless an opening be made in the cranium. But this is disputed by Dr. Burrows, who concludes, from careful experiments, that the brain may become exsanguine without any apparent aperture in the cranium, and that, in health, slight variations maj"^ occur in the quantity of blood sent to the FCETAL CIRCULATION. 227 brain. In the spleen, the most striking peculiarity is thai each of the larger branches supplies chiefly that part of the organ to which it is distributed, having no anastomosis with the adjoining branches. The erectile tissues are the penis, clitoris, erectile tissijbes of the vagina, and the nipple in both sexes. The venous plexuses of the erectile tissue become filled with blood, which swells and distends the organ, causing it to assume an erect condition. This influx of blood may be caused by local irritation, or by certain emotions of the mind communicated through the great sympathetic system. Erectile tissue consists of a plexus of veins with varicose enlargements enclosed in a fibrous envelope, with trabecular partitions. There are also some nonstriated muscular fibres, which are connected in some way with the process of erection. They may either by their contraction prevent the due return of blood from the parts, or by their relax- ation allow the plexuses'to fill with blood, and remain so until the stimulus to erection subsides, when they contract and gradually expel the excess of blood. FcETAL Circulation. — In the foetus, the course of the circulation is modified in consequence of the inaction of the lungs. The aeration of the blood is efi'ected b}' the placenta, through which also the foetus is nourished, so that the placenta serves the double purpose of a respiratory and nutritive organ, or in other words, it performs the office of the lungs and stomach in the foetus. The course of the circulation in the foetus is as follows : — The arterial blood is carried from the placenta to the foetus, along the umbilical cord, by the umbilical vein. It then entei-s the umbilicus, and passes upwards along the free margin of the longitu- dinal ligament of the liver to its under surface, where it gives oft' two or three branches to the left lobe, and others to the lobus quadratus and Spigelii. At the transverse fissure it divides into two branches ; the larger is joined by the portal vein and enters the right lobe ; the smaller 1 ■I II! 228 CIRCULATION. c MM- t\ I. I- iri MV an c f»..v & WW paseeH onwards, under the name of the ductus venosus, which joins the left hepatic vein, where the latter empties into the inferior vena cava. Hence the blood reaches the vena cava in three different ways ; most of it passes through the liver with the portal venous blood, and is returned to the vena cava by the hepatic veins ; some passes through the liver directly, to be returned also by the hepatic veins ; and the smallest quantity is carried on b}' the ductus venosus to the vena cava. In the inferior vena cava, the blood is joined by that which is being returned from the lower extremities and viscera of the abdomen ; it then enters the right auricle, and guided by the Eustachian valvo passes through the foramen ovale into the left auricle, where it is mixed with a small quantity returning from the lungs. From the left auricle it passes into the left ventricle, from the left ventricle into the aorta, to be distributed chiefly to the head and upper extremities — a small quantity passing into the descending aorta. From the head and upper extremities the blood is returned by the superior vena cava to the right auricle, where it is mixed with some from the inferior vena cava. It then passes into the right ventricle, and from the right ventricle into the pulmonary artery, but the lungs of the foetus being almost impervious, only a small quantity is distributed to them by the pul- monary arteries, and is returned to the left auricle by the pulmonary veins ; the greater part of the blood from the right ventricle passes through the ductus arteriosus into the descending aorta, where it is mixed with a small quantity of blood transmitted by the left ventricle into the aorta. It then descends along this vessel to supply the viscera of the abdomen, pelvis, and lower extremities-^ the greater portion, however, being conveyed by the umbilical arteries to the placenta. When the child is born, and respiration established, an increased amount of blood is sent to the lungs, and the placental circulation is cut off. The foramen ovale gradu* FCETAL CIRCULATION. 229 ally closes up, being completed about the tenth day. The ductus arteriosus contracts as soon as respiration is estab- lished, and is completely closed from the fourth to the tenth day. The umbilical arteries, between the umbilicus and the fundus of the bladder, become obliterated between the second and fitth days. The umbilical vein and ductus venosus also become obliterated between the second and fifth days. In some instances the foramen ovale does not close readily, and the blood continues to pass through into the left auricle after birth, giving rise to a bluish color of the surface of the body. This condition is called cyanosis or Tnorhus cceruleus, and may be remedied by keeping the child a its right side for a few days. There is also a peculiarity in the circulation of the blood in connection with the Malpighian bodies of the kidney, closely resembling the portal circulation, for which see structure of the kidney. 3 H ■A 230 RESPIRATION. CHAPTER IX. c 1. I* •I «R nnr . »«!■ : R15SPIRATI0N. As the blood circulates thiough the different parts of the body, it is deprived of a certain amount of its nutriti ele- ments and oxygen, and becomes loaded with impurities, resulting from the wear and tear of the tissues ; hence it becomes necessar^^ not only that fresh supplies of nutriment and oxygen should be continually added to the blood, but also that provision should be made for the removal of the impurities. One of the most important and abundant of the impurities is carbonic acid, the removal of which, and the introduction of fresh quantities of oxygen, constitute the chief purpose of respiration. THE LUNGS. The organs of respiration are the lungs. They are two in number, situated one in each of the lateral cavities of the chest, separated from each other by the mediastinal space. They are provided with a single air tube, the trachea, which is divided into two branches, the right and left bronchus, one for each lung. Each bronchus, on entering the hilum of the lung, divides and sub-divides dichotomously through- out the entire organ until the branches terminate in the lobular bronchial tubes. Each lung is surrounded by a serous membrane — the pleura. That portion which covers the lung is called the visceral layer, and is connected to the lung tissue by the sub-serous areolar tissue ; it is then reflected around the inner surface of the chest forming the parietal layer. These two layers are smooth, moist and covered with epithelium ; they are everywhere in contact, THE LUNGS. 231 and glide readily upon each other. It is only when filled with air or iluid that there may be said to be a cavity between thera. The respiratory apparatus consists essentially of a thin, moist membrane, with blood-vessels on one side, and air or aerating fluid on the other, through which osmosis takes place. The lungs of the newt consist of cylindrical sacs running the entire length of the body, into which the air is forced by a sort of swallowing movement, and is after- wards regurgitated to make room for a fresh supply. In the frog nnd turtle, the cavity is dividiid into smaller com- partments by thin septa, all of which communicate with the central cavity. The same principle or plan of construc- tion obtains in the higher animals, the walls of the cavity being folded and refolded in order to increase the extent of aerating surface. In fishes and most aquatic animals the respiratory organs are in the form of gilh or branchice, which are foldings of mucous membrane, containing blood-vessels. These are moved by muscles so as to bring them into contact with fresh portions of water, for the pur- pose of aeration. In certain of the lower order of animals unprovided with Inng cavities, and in the vegetable king- dom, tracheal openings, or stomata, exist for the interchange of gases. Minute Structure. — Each lung is divided into lobes, three for the right and two for the left, and each lobe is sub- divided into lobules, which are held together by areolar tis- sue. They vary in size form yhf to ^V of an inch (2 to .8 mm) in diameter. They also vary in shape ; those on the surface are large, of a pyramidal form, with their bases turned towards the surface ; those in the interior are smaller, and of various forms. Each lobule is a miniature representation of the whole organ of which it forms a part, being composed of the terminal divisions of one of the smaller bronchial tubes and corresponding air cells, blood vessels, nerves and lymphatics, all held together by areolar tissue. '4 I It ) i I 1 232 RESPIRATION. 11 c MM c I. MM 'Hi Each lobular bronchial tube, on entering the substance of the lobule, divides into from four to nine branches according to the size of the lobule, diminishing in size until they Fig. 77. reach a diameter of -^ to ^\^ of an inch, (.5 to .2 mm). They are then con- tinued onwards, their sides and extremi- ties being closely covered by numer- ous saccular dilatations — the air cells — in consequence of which the tubes lose their identity, as cylindrical tubes, and present the character of irreg- ular canals or passages — the so-called Lobule of the human intercellular passages (Fig, 77). lunsr ; a, bronchial tube rn, . ,, n i i with its divisions ; b, in- i hc air ceils are smail alveolar tercellular passagfes; c, air i • i t . « cells. recesses, which vary from yV ^ ^iir of an inch, (.3 to .V^ mm) in diameter, and are separated from each other by thin septa. They communicate with the termin- rig. 78 al bronchial tubes which thej'^ surround by large circular openings; but do not communicate with each other except through the tubes. In these small bron- chial tubes and air cells, the cartilagin- ous and muscular tissues are absent, and the mucous membrane is lined by squamous epith- elium, while the trachea and bron- chi are lined by Air cells of lungs, x 350 ; a, epithelium ; b, fibres of elastic tissue ; c, delicate lining membrane of air cells, with elastic fibres attached t it. — {KvUiker.) VESSELS AND NERVES. 233 columnar ciliated epithelium, among which are to be seen some cup or goblet cells (p. 99). Vessels and Nerves. — The pulmonary artery con- veys the venous blood to the lungs for aeration. It divides into branches .which accompany the bronchial tubes, and terminates in a dense capillary plexus beneath the mucous membrane of the terminal bron- chial tubes and air cells. Some of the capillaries also pass into the septa, between the air cells so that both sides are at once exposed to the air. The blood, puri- fied during its patisage through the capillaries, is returned by the pulmonary veins to the left auricle of the heart. The bronchial arteries supply blood for the nutrition of the lung. They arise from the thoracic aorta, and divide into several branches, some of which accompany the bronchial tubes to which they are distributed, and terminate in the deep bronchial veins ; others are distributed to the areolar tissue, and terminate partly in the superficial, and partly in the deep bronchial veins ; whilst a few ramify upon the walls of the terminal bronchial tubes and air cells, and terminate in the pulmonary veins, the blood having been purified in its passage through the capillaries. The bronchial veins, superficial and deep, unite at the root of the lung, and empty on the right side into the vena azygos major, and on the left into the superior intercostal. The lungs are also abun- dantly supplied with lymphatics. They commence in irreg- ular spaces or lacunas in the walls of the air cells, or bronchi, and in the lymph spaces of the pleura pulmonalis. Nerves. — The lungs are supplied by the anterior and posterior pulmonary plexuses of nerves formed chiefly by branches from the pneumogastric and sympathetic nerves. MECHANISM OF RESPIRATION. The movements by which fresh air is taken into the lungs, and by which it is again expelled, are those of inspiration and expiration. This is called the mechanical •3 ■ft 234 RESPIRATION. C c. IL I- »i WV •n r inr !■ «•» K act, in contradistinction to the chemical which relates to the changes which take place between the blood and the atmospheric air. Inspiration. — During inspiration the chest is enlarged in every direction, but chiefly in the vertical. The latter is effected principally^by the conti'action of the diaphragm, and its consequent descent towards the abdomen. The in- crease in the lateral and antero-posterior diameters is due to the elevation of the ribs, both in front and at the aides. The ordinary muscles of inspiration are the diaphragm, exter- nal intercostals (and the internal in front), levatores cos- tarum, serratus^magnus, and serratus posticus superior. But in extraordinary or forced inspiration, as during a ]iar- oxysm of asthma, etc., the shoulders are fixed by the patient seizing'some thing firmly, and the serratus magnus, pectoralis major and minor, trapezius, subclavian and scaleni muscles are called into action. The scaleni muscles fix the upper ribs, from which the external intercostals act, as from a fixed point, and elevate the lower ribs, by which the cavity of the chest is enlarged laterally and antero-posteriorly. This action is also promoted by the action of the other muscles previously mentioned. Expiration. — Expiration succeeds inspiration, after a brief interval, and is accomplished, in ordinary respiration, by the elastic recoil of the lungs and walls of the chest, after they have been dilated, and partly by muscular action. The ordinary muscles of expiration are the abdominal muscles, internal intercostals except in front, serratus posti- cus inferior, and triangularis sterni. The extraordinary are the quadratus lumborum, latissimus dorsi, sacrolumbalis, and those which assist in fixing the spine and pelvis. In diffi- cult breathing, almost every muscle in the body is made sub- servie to the action of respiration. The duration of in- spiration is generally less than expiration, although in some instances they are nearly or quite equal, and thero is a slight i)a ^e between the end of expiration and the com- FREQUENCY OF RESPIRATION. 285 menceraent of the next inspiration, and also between the acts. The succession of these acts constitutes the respira- tory rhythm. During inspiration and expiration a sound is heard when the ear is applied to the chest, called the respir- atory murmur. It is longer (|) and more distinct in inspir- ation, and is best heard in children, hence the terra puerile respiration. The rima glottidis is also opened at each inspiration by the action of small muscles, and is closed some- what at each expiration by the elastic recoil of the parts. The force of expiration exceeds that of inspiration by one- third. Frequency of Respiration and Ratio to the Pulse. — The number of respirations in a healthy adult vary from sixteen to twenty in a minute. The proportion of respira- tory movements to the pulsations of the heart is about one to four, and when this proportion is departed from there is reason to suspect some obstruction to the aeration of tlie blood, or some derangement of the nervous system. Any great disproportion between the number of respirations, and the number of pulsations or the amount of blood sent to the lungs to be aerated, is attended with dyspnoea. When the action of respiration is chiefly confined to the diaphragm and abdominal muscles, as in pleurisy, etc., the breathing is said to be abdominal ; but when chiefly con- fined to the muscles of the thorax, as in peritonitis, etc., it is said to be costal or thoracic. Quantity of Air Respired. — The quantity of air taken in at each inspiration varies from twenty to thirty cubic inches ; this is called breathing or tidal air. The quantity which an adult of average size (five feet eight inches), can inhale in a forced inspiration is about 230 cubic inches the excess being called complem£ntal air. After ordinary expiration, such as that which expels the breathing or tidal air, a certain quantity remains in the lungs, which may be expelled by a forcible expiration ; this is called reserve or supplemental air. A quantity still re- 13 £88 RESPIRATION. Fig. 79. c c I. IHf mains, which cannot be forced out ; this is called residual air. The respiratory capacity of the chest is called the vital capacity, and it varies according to stature, weight, and age. The vital capacity of an adult, five feet eight inches in height, is about 230 cubic inches ; and for every inch in height above this stand- ard, the capacity is increased about eight cubic inches. The influence of weight is not so marked as that of height ; but it tends to diminish the respiratory power, when beyond a cer- tain limit. The vital capacity in- creases from fifteen to thirty -five years of age, and from thirty-five to sixty- five it decreases nearly one and a half cubic inches per year. The total quantity of air which passes through the lungs in twenty- four houi-s varies from 300 to 400 cubic feet, depending on the state of the health, bodily exertion, etc. If the same air be rebreathed several times, it becomes loaded with carbonic acid and animal matter, causing head- ache, languor and depression, and if i continued, serious results will follow Spirometer for measuring sooncr or later. Experience has shown !he'ir„g"'''°'*'"*'""'*"*° that the minimum quantity of air which ought to be allowed for each person confined in prisons, hospitals, schools, etc., is about 1200 cubic feet. Provision should also be made for a constant supply of fresh air, and the removal of the impure, which is of even greater importance than the mere actual cubic space. The n. I NFL UENCE OB NER VES IN R ESP IRA TION. 237* ventilation should be such as will supply, at least from 1200 to 1500 cubic feet of fresh air for each person per hour. Influence of the Nerves in Respiration. — The^ movements of respiration are presided over by the medulla oblongata, into which may be traced the principal excitor nerves, and from which proceed the principal motor nerves. The chief excitor of the movements of respiration is the pneumogastric nerve. When this is divided on both sides in the dog, the number of respirations are diminished about one-half, and irritation of its trunk is followed by an act of inspiration. The respiratory movements are caused by tlio presence of blood, loaded with carbonic acid, in the capil- laries of the lungs, which makes an impression on the- periphery of the pneumogastric nerve. The other excitors are the nerves distributed to the general surface of the body; but especially to the face. A current of cold air, or cold water dashed on the face, is sufficient to cause a deep inspiration ; and a similar impression on the chest or body, or a slap on the buttocks, will excite inspiratory movements when they would not otherwise commence, as in the new- born infant, or in asphyxia. The first plunge into water, as in swimming, is usually accompanied by a deep inspira- tion. It is quite probable also, that the sympathetic nerves, which receive filaments from the spinal nerves and com- municate with the pneumogastric, may be excitors of this function. Tl e motor nerves concerned in the function of respiration are the phrenic, intercostals, facial and spinal accessory. The motor power of the respiratory nerves is^ exerv'jised, however, not only in the muscles of respiration, but also on those which guard the entrance to the wind- pipe. Division or injury of the medulla oblongata is followed by sudden death from arrest of respiration- After division or injury of the spinal cord in the lower part of the cervical region, inspiration is performed by the diaphragm only, and when injured above the origin of the phrenic nerve, death occurs instantly, because of the inter- 238 RESPIRATION. c c c I. I* ■t I. I m luption to all commuiiicatiou between the medulla oblongata and the diapliragrn. The respiratory njovemcntH, thougli j)artly voluntary, arc in ordinary respiration essontialiy independent of tlio will, I'or example, during sleep, coma or aniBstbesia, the respira- tory function is carried on, although the person is entirely unconscious of the movements. At the same time, it is necessary that the respiratory actions should bo ])artly under the direction of the will, since they are subservient to the production of those sounds by which individuals communicate their ideas to each other, as in speaking singing, etc. Modifications of the Rksimratory Movements. — These are coughing, sneezing, sighing, yawning, langhing, crying, sobbing and hiccup. Coughing is caused by any source of irritation in the throat, larynx, trachea or bronchial tubes. This act consists, first, in a full inspiration, the glottis is then closed and a violent expiration takes jdace, by which a sudden blast of air is forced up the air passages by the diaphragm and abdominal muscles, forcing open the glottis and carrying before it any substance that may bo present. In the act of coughing, the abdominal nniscles act as forcibly on the abdominal viscera as on the lungs, and tend to the expulsion of their contents, but the voluntary contraction of the sphincters prevents any escape at the openings. The difference between coughing and sneezing is, that in the latter the blast of air is directed more or less completely through the nose, in order to remove any irritating substance there. Sighing is simply a deep inspir " in which a larger quantity of air than usual is nip' .iter the lungs. FawmT?^/ is a still deeper inspira- .ud is accompanied by opening the mouth widely, . contraction of the muscles about the jaws. In laugh- ing, the muscles of expiration are in convulsive movement, and send out the air from the lungs in a series of jerks, the glottis being open. Crying is very nearly the same as CHANGES IN THE RESPIRED AIR. 289 laughing, altliough occasioned by a different emotion. When the emotions are mixed, an expression is produced " between a cry and a laugh." Sobbing is caused by a series of sliort convulsive contractions of the diaphragm, the glottis being closed. Hiccup is caused by a sudden convulsive contraction of the diaphragm, the glottis sud- denly closing in the midst of it; the sound is j)roduced by the impulse of the column of air against the glottis. In speaking and singing, the vocal chords are made to vibrate as the air passes over them, and produce sounds which are mouldei into words or notes by the tongue, teeth, lips, etc. Chanoes in the Respired Air. — The air consists of a mixture of 20.81 parts oxygen to 79.19 of nitrogen, in 100 I)arts by volume, carbonic acid from .03 to .00 parts in a thousand, a variable amount of aqueous vapour, and a trace of ammonia. The changes ])roduced on the atmos- pheric air by respiration are — 1st, an increase in the tem- perature equal to that of the blood ; 2nd, an increase in the quantity of carbonic acid and aqueous va])our ; 3rd, a diminution in the quantity of oxygen. The nitrogen remains nearly the same, and a small quantity of organic matter is eliminated by the lungs. The air is heated by contact with the interior of the lungs to a temperature of about 98° F. Exhalation of Carbonic Acid and Water. — The presence of an increased amount of carbonic acid in expired air, may be demonstrated by breathing through lime water, which becomes milky by the formation of insoluble calcium carbonate. It has been ascertained that there are about 4.35 parts of carbonic acid in 100 parts expired air, and subtracting the quantity in the air when inspired, leaves about 4.30 parts per cent, by volume, which is eliminated from the lungs at each ordinary expiration. This would amount to about sixteen cubic feet per day of carbonic acid, or nearly eight ounces of carbon. The elimination of i 1 it ♦ If i c c I' m IIM I.' inr , Bnr , m. . 240 RESPIRATION, •carbonic acid may be modified by a number of circum- stances. Digestion has been observed to be attended with an increased exhalation of carbonic acid, inost distinct about an hour after eating ; while fasting, on the other hand, diminishes it. Alcohol, etJier and chloroform introduced into the system, are followed by a diminution in the quan- tity of carbonic acid exhaled. Exercise increases the exha- lation of carbonic acid to about one-third more than it is during rest. During sleep, on the other hand, it is dimin- ished, owing to the quietness of the breathing ; but directl}' after 'vaking, the amount is increased. Age and sex influence the quantity of carbonic acid exhaled ; in males it ii.^.eases from eight to thirty years of age, remains stationary from thirty to forty, and then diminishes to extreme age. In females, the quantity exhaled is always less than in males of the same age; it is increased. from the •eighth year to the age of puberty, and remains stationary as long as they continue to menstruate, but when men- struation ceases, from whatever cause, the exhalation of carbonic acid again augments, after which it diminishes to extreme a je. The temperature of the external air has an important influence on the exhalation of carbonic acid. Observations made at various temperatures between 38° and 75° F. show that between these points every rise equal to 10° F. causes a diminution of about two cubic inches in the quantity of this gas exhaled per minute. Cold, on the other hand, within certain limits, increases it. Moisture of the air also favors the elimination of carbonic acid very materially. The respiratory movements influence the exha- lation of this gas. When the respirations are increased in frequency, more carbonic acid is exhaled, although the per- centage in proportion to the amount breathed is less. If the air have been previously breathed, the quantity of car- bonic acid exhaled is very much diminished. It should also be borne in mind, that the continued respiration of an AMOUNT OF OXYGEN INHALED. 241 atmosphere charged with the exhalations from the lungs and skin, is a most potent predisposing cause of disease, especially of the zymotic class. Tlie presence of an increased amount of aqueouLS va'pour in expired air, may be shown by breathing upon a looking- glass, or polished metallic surface. The amount of aqueous vapour exhaled from the lungs in twenty-four hours may be estimated, in temperate climates, at from ten to twenty ounces. A certain amount of carbonic acid and water is also eliminated by the integument. ATYimonia is an accidental constituent of expired air. The amount of organic matter given off from the lungs in twenty-four hours, is about three grains. Amount of Oxygen Inhaled. — There is always less oxygen in expired air, than in the same quantity of air before respiration. Some of the oxygen unites with the carbon in the lungs to form carbonic acid ; some is used in the chemico-vital changes which take place in the blood and tissues, and some is also used in oxidizing other sub- stances besides the carbon, as for example, sulphur and phosphorus, which are eliminated in the urine in the form of sulphuric and phosphoric acid. Its absorption depends on the strong chemical affinity of hemoglobine for it. The quantity of oxygen absorbed is about 542 grains per hour, but it varies in different persons, and in the same person at different times. It is increased by food, especially of the farinaceous kind, and is diminished during fasting. The interchange of gases in the lungs does not accord with the law of " diffusion of gases," otherwise the proportion between the oxygen consumed and the carbonic acid exhaled should never vary. Besides, the law requires that both gases should be free, and under equal pressure ; while, in reality, the gas in the blood is dissolved, under pres- sure, and is also separated by a membrane from that into which it is to be diffused. •I 242 RESPIRATION. C c IE 1. I- mv I. tta The nitrogen of the atmosphere serves only to dilute the oxygen, and moderate its action in the system. Under ordinary circumstances there is very little difference between the quantity of nitrogen inspired and exhaled. The absorp- tion of nitrogen is increased by fasting; while, under opposite circumstances, it is diminished. There is also a small quantity of nitrogen given off in the form of ammonia. Changes in the Blood in Respiration. — 1st, its color is changed ; 2nd, it absorbs oxygen ; 3rd, it exhales carbonic acid and aqueous vapour, small traces of ammonia and animal matter ; -ith, it contains more fibrin, and the temper- ature is increased from 1° to 2° F. The most obvious change is tliat of color, the darls venous blood being exchanged for the bright scarlet of arterial blood. The causes of this change have been already discussed in the chapter on blood. It is chiefly due to the absorption of oxygen, which is taken up principally by the hemoglobine of the corpus- cles and partly by the plasma, and carried to the tissues ; and to the exlmlation of carbonic acid which exists in the blood. Tlie coipuscles also assume a I ''concave shai)e, which reflects the light in such a way as to modify the color. Both oxygen and carbonic acid exist in the corpus- cles and plasma of the Ijlood, partly in a state of solution, and partly in a state of chemical combination ; but the corpuscles are the chief agents concerned in the absorption of the gases. The exhalation of carbonic acid is favored by the moist condition of the membranes of the lung, which liquefies the gas. This fact may be demonstrated by filling a bladder ■with carbonic acid, and then placing it in water ; it will soon be found to collapse and become completely emptied. Caibonic acid is being constantly generated in the blood, and is removed by exhalation from the lungs, as fast as it is produced; but if respiration is obstructed or seriously impeded, it accumulates in the blood, and may cause death EFFECTS OF ARREST OF RESPIRA TION. 243 by its poisonous effects on the nervous system. Carbonic acid is formed in three different ways in the system : 1st, in the blood, by the action of oxygen on certain elements introduced in th'3 food, as glucose and fats, giving rise to a certain amount of animal heat; 2nd, in the capillaries, by the union of oxygen with the carbon produced by the dis- integration of the tissues ; 3rd, in the lungs, by the decom- position of the alkaline carbonates. Effects of the Arrest of Respiration. — When res- |)iration is interfered with by any obstruction, or from whatever cause, the circulation of blood through the lungs is retarded, and at length arrested. This prevents tl ) exit of blood from the right ventricle, and is followed by venous congestion of the nervous centres, and all the other parts of the body. Besides, only a very small quantity of blood finds its way into the left side of the heart, and this is venous also. Hence, in death from asphyxia, the left side of the heart is nearly empty, while the lungs, right side of the heart and veins, are gorged with venous blood. The cause of the retention of blood in the lungs is due to the non-elimination of the caibonic acid ; for blood loaded with this gas does not pass freely through the capillaries. The fatal result is due, to some extent, to the weakened action of the right side of the heart, in consequence of its over-distension ; and also to the venous congestion in the medulla oblongata and nervous centres. The time which is necessary for life to be destroyed by asphyxia varies from one and one-half, to four minutes. In new-born and young animals, longer time is required than in older ones, because in the formet the respiratory changes in the tissues are much less active. Animals will recover after simple deprivation of air for four minutes, but submersion in water for \\ minutes destroys life completely. This is owing, in all probability, to the filling of the lungs with water. In drowning, very few persons recover who have been sub- merged more than three or four minutes. Cases have been ■I 2H RESPIRATION, rc^cordod in which recovery took place after the lapse of from fifteen minutes to half an hour; but in these instances it is probable that a state of synco[)e had come on at the moment of immersion. CHArTER X. C c mm r I- r. ANIMAL HEAT, LIGHT, AND ELECTRICITY. Heat. — This is closely connected with the process of respiration. The average tem])erature of the human body varies from 98° to 100° F.; birds from 100° to 111° F.; iishos and reptiles, about 51° F. In mammals and birds the temperature of the blood and internal organs is always very much above the external air, and they are therefore called " irartn-hlooded animaW In fishes and rci)tilo8, on the other hand, the temperature of their bodies (litters but little from that of the medium which they iidiabit, hence they are called " cold-hloodcd animals." In both classes, how- over, there is an internal source of heat, but it is more active in the one tlian the other. Even in vegetables a cer- tain amount of heat-producing jiovver is occasionally mani- fest, as for example, in the flowering of plants, malting of barley, etc. In disease, the temperature of the body may deviate somewhat from the natural standard, as e.g., in scar- latina, typhoid fever, etc., it rises as high as lOG" or lO?** F. In cholera, on the other hand, it often falls as low as 78° or 79" F. Continued high temperature in fever usuall}'^ indi- cates a fatal issue. The highest temperature yet observed was reported by Dr. Teale, Eng. in a case of spinal injury, in which the temperature reached 122" F. The patient recovered. In some cases of yellow fever, a remarkable rise PRODUCTION OF ANIMAL HEAT. 245 takes place very soon after death, in one iriHtanco afl liigh as 113° F., fifteen ininuteH after death. The temperature of tlie body in liealth, is ahout 1)" F. lower during sleep than while awake. It is raised by exercise, and also after eating. The temperature of the now-born child is 1" F. higher than in the adult. TnKoiiY OF THE PRODUCTION OF Animal Heat. — There have been many theories regarding this subject. Lavoisier supposed that the oxygen taken into the lungs combined with the carbon of the blood and formed carbonic acid which was at once eliminated, the f-ame amount of heat being produced as if the oxidation of a "iimilar quantity of carbon in wood or coal haaralysis ; e.g., the hand of a paralyzed arm was found to be 70"^ F., while that of the sound side had n tem- perature of 92*^ F. Again, when death is caused by a severe injury, or removal of the nervous centres, or in poisoning by woorara, etc., the temperature of the body rapidly falls, even though artificial respiration be kept uj). On the other hand, severe injuries of the nervou? system are sometimes followed by the direct opposite eff'ect This is supposed to be due to the dilatation of the arteries, in consequence of which the blood reaches the part supplied by those iterves in larger quantities; the nutrition is therefore more active. REGULA TION OF THE HE A T OP THE BOD V. 247 Certain emotions of the mind may cause a momentary in- crease of temperature, while others cause a diminution. These circumstances, however, do not prove that heat is produced by mere nervous action independent of any chem- ical change. All the functions of the organism, as nutrition, secretion, excretion, etc., are under the influence of the nerves, and when they are divided, or otherwise injured, or paralyzed, chemico-vital action is in great measure sus- pended. Regulation of the Temperature of the Body. — The temperature of the body is rendered uniform partly by loss of heat by radiation, and conduction ; but chiefly by the evaporation which is continually taking place on its sur- face and to a small extent in the air passages. The intro- duction of food and drink at a lower temperature than the body, and the removal of the excreta, also abstract a small amount of heat. Evaporation of the perspiration produces cold, on the principle that " when a fluid passes into a state of vapour heat becomes latent," and hence the loss of heat will depend upon the amount of evaporation. When the atmosphere contains much moisture the evaporation is partly suspended, and all the effects of excessive heat are made more apparent than in a dry atmosphere, in which a greater amount of evaporation takes place, and consequently a greater amount of heat is removed from the system. Per- sons have been known to remain for several minutes in a dry atmosphere, heated to 250'^F, without injury, the evap- oration being sufficient to keep the temperature of the body within certain limits. Such a degree of heat in a moist atmosphere would be certain to cause serious injury. In fevers and inflammation, the skin is hotter than in health, and is also dry ; this is owing to the arrest of the natural secretion or perspiration, in consequence of which there is little or no evaporation to produce cold. In such oases great benefit will be derived from sponging the body frequently with cold or tepid water. ■ul n ■it H if I 248 HEAT, LIGHT AND ELECTRICITY. c c c I- LIGHT The evolution of light from the living liuman body, is a phenomenon of rare occurronco. Luminous exhalations have been freijuontly observed in burial groundn, and a luminous appearance has been Homotimos notituxl in newly dissected subjects in the dark. This is due to the development of [)ho.s- phoretted hydrogen during decomposition of the tissues. A lun)inous appoaiance has been observed in old sores in the living subject, which wore in a state of ixs '>f^ an inch (2.5 to 1.2 mm) in diameter. They surround tho the small sublobular fik. so. branches of the hejiatic vein, to which each is connected at its base by a small intralobular branch. When divided longitudinally, they pre- sent a foliated margin, and on a transver.se sec- tion, they have a poly- ii'onal outline. When one of the sublobular hepatic vnns is laid open, the bases of the lobules may 1)6 seen through the thin walls of the vein on which they rest. The base of each lobule i^re- sents a polj'^gonal outline, in the centre of which may be seen the orifice of the intralobular vein. This gives them the appearance of a layer of tesselated or pavement epithelium. Structure of the Lobules. — Each lobule is a miniature representation of the wliole gland of which it forms apart. It consists of a mass of cells, a plexus of biliary ducts, an intralobular vein (which is the commencement of the hepatic vein), arteries, nerves, and lymphatics. Longitudinal section of a portal canal contaln- '"tr.(P) portal vein ; (a) hepatic artery, and (d) he- patic duct. Lobules are to be seen to the rijjht- and left.aiid also shining through the thin wall of the vein; in the centrs of each lobule is seen the intralobular vein ; a, a, portion of the ' Mial from which the vein has been removea ; b, open- ings of the interlobular veins. .4 1 .1 > J 254 SECRETING GLANDS AND THEIR SECRETIONS. c c MM I. ^ I Cnr m-. : X.U The hepatic cells form the chief ma.ss of the substance of a lobule • they lie in the interspaces of the capillary plexus, so as to fonu rows, which radiate from the centre to the cir- Fi>r. 81. h B nopatio loliuK'. Ill tlio coiitrc is st'i'ii tlio intralobular vein ; vp, ttnuination of the por- tal vein around tlio lohulc, from which a cai)ilUiry pluxus proceeds towards the centre in the lueshes of which arc seen the liopatic cells ;" b, b, biliary duuts, arising within the lobule. (Claude llcrnard.) cumference of the lobule (Fig. 81). They are generally spheroidal in sliape, but may be polygonal from mutual pressure, and vary in size, from ^j^^^ to ^o^ory of an inch Fijf. 82. (25 fo 12.5 ijuum.) in diameter. Each cell contains a distinct nucleus, sometimes two, and in the interior of the nucleus a highly- refiacting nucleolus, and some granular matter. The contents of the cell are viscid, and contain yellow particles of colouring Hepatic tells. (Frey.) matter, and some oil globules. BiLiAuv Ducts. — These commence within the lobule by a minute plexus of ducts (bile capillaries), with which the cells are in immediate contact. The ducts then form a HEPATIC VESSELS. 255 plexus between the lobules (interlobular), and the inter- lobular benches unite into vaginal branches, which lie in the portal canals. These branches finally join to form two large trunks, which leave the liver at the transverse fissure, and uniting form the hepatic duct. Portal Vein. — The portal vein, on entering the trans- verse fissure of the liver, divides into two branches, one for each lobe, which are situated in the portal canals, to- gether with the branches of the hepatic artery and duct, nerves and lymphatics. These vessels are surrounded by areolar tissue, continued inwards from the transverse fissure of the liver, called Glisson's capsule. The portal veins, in their course in those canals, give off* vaginal branches, which form a plexus. From this plexus and from the portal vein itself, small branches are given oft',which pass between the lobules and cover their external surface, called interlobular ; these then pierce the lobules, and form a capillary i)lexus within each, from which arises the intralobular vein. Hepatic Artery. — This takes precisely the same course as the portal vein and hepatic duct. It is intended chiefly for the nutrition of the liver. It gives off" in the portal canals the va.ginal branches, which supply the coats of the portal vein and hepatic ducts, and also interlobu- lar branches, which pass between the lobules ; the latter pierce the lobules, and terminate in the radicles of the intra- lobular vein. They are supposed by some to terminate in the radicles of the portal vein, but this is improbable. Hepatic Veins. — The hepatic veins commence in the in- terior of the lobules in the intralobular veins, which arise in the centre of the lobules, and leave them at their bases to join the sublobular veins. The sublobular veins unite to form larger branches, and these join again to form the large hepatic veins, which terminate in the inferior vena cava. Fv>r the secretion of the bile, and its function, see chap- ter on digestion. 1 256 SECRETING GLANDS AND THEIR SECRETIONS. c c •Mr I. h m f c iV.i THE KIDNEY AND ITS SECRETION. The kidneys are intended for the secretion of urine. They are situated in the back part of the abdotninal cavity, one in each lumbar and hypochondriac region, extending from the eleventh rib to within two inches of the crest of the ilium. The rijjht is somewhat shorter and situated a little lower than the left. They are invested by a thin, smooth, fibrous capsule, which is very easily removed from the sur- face of the gland, and weigh from four to six ounces each. Structure. — The kidney consists of two different sub- stances, an external or cortical, and an internal or medul- lary substance. The cortical substance forms about three- Fig. 83. fourths of the whole gland, is reddish in color, soft, granular, and friable in texture, and presents numerous red- dish bodies (the Malpighian bodies) in every part of it, excepting towards the free surface. It is composed of the convoluted tubuli uriniferi, blood vessels, nerves and lymphatics, held together by a small quantity of are- olar tissue. The cortical substance is from ^ to i^ an inch in thickness opposite the base of each pyramid,and is called the cortical arch. It also sends numerous prolongations inward Srf^maVkThf X-rco" towards the sinus, between the pyra- mids ; these are called the cortical columns or columns of Beriini. The Malpighian bodies are found only in the cortical substance. They are small round bodies, of a deep red color, and of the average diameter They are capsular dilatations of the Longitudinal section of the stitution of tlie organ, as made up of distinct lobules.—!. Tlie flupra-renal capsule. 2. The cor- tical portion of the kidney. 3, 3. Its medullary portion, consist- ing of cones. 4, 4. Two of the papilla; projecting iiito their cor- responding calyces. 5,5, 5. The three infundibula ; the middle 5 is situated in the mouth of a calyx. 6. The pelvis. 7. The ureter. of tJ^0 of an inch. KIDNEY AND ITS SECRETION. 257 commencing tubuli uriniferi, and are scattered irregularly in the columns of Bertini, but regularly arranged in double rows in the cortical arches. Within each body or capsule may be observed a vascular tuft or glomerulus, which consists of the ramifications of a small artery, Fig. 84. the afferent vessel, which, after piercing the capsule, divides in a radiated manner into several branches, which ultimately termi- nate in a finer set of capillaries. The blood is returned from these by a vein, the efferent vessel, which pierces the caspule near the artery and forms a venous plexus with other efferent vessels around the ad- pian of the renai circulation in 1 1 1 T /TT r.j\ mi 1 man and Mammalia, a, Terml- iaCenttubuil(Jb lg84}. ine capsules are nal branch of the artery, giving .. ,, , (>',iT I'l the afferent twig 1, to the Mal- lined by a layer oi epithelium, which pighian tuft m, from which , , . , , , , - emerges the efferent vessel, 2. 13 believed by some to be prolonged other efferent vessels, 2, are , ,/•,/. 1 1 •! 1 seen entering the plexus of ca- OVer the tuft Ot vessels ; while others plllarles, surrounding the urini- - , . . , , , . ferous tube, t. From the plexus are ot the opinion that the tuft is the returning vein, y, springs. wholly uncovered. The tuft in the frog, and other reptiles is covered by ciliated epithelium. The medullary substance, which forms about one-fourth of the gland, is pale-red in color, dense in texture, and pre- sents a striated appearance on account of the number of diverging tubuli uriniferi. It consists of conical masses the " Malpighian pyramids ", which vary in number from eight to eighteen, their bases being directed towards the circumference of the organ, and their apices towards the sinus, in which they terminate by smooth rounded extremi- ties, called the papillae of the kidney. The conical masses consist of the tubuli uriniferi, blood-vessels, nerves and lymphatics, held together by areolar tissue. The tubuli uririferi commence at the apices of the cones by small openings : as they pass towards the base they divide '.4 1 2oS SECRETING GLANDS AND THEIR SECRETIONS. C c far . »!* rtx ^'''- '^•'^- and sub-divide, and diverge un- til they reach the cortical sub stance, when they become con- voluted and anastomose freely with each other and terminate in the Malpighian capsules. There are also some convoluted tubes in the Malpighian pyramids, the loo'ped tubes of Henle, wh\ch de- scend to a certain distance in the medullary pyramid and return in loops to rejoin ohe convoluted tubes. The diameter of these A. Portion ol uriiiiferoiis lubumasf- loOpcd tubcS is ahout y-jrVlT of aU nified, B. Epithelial cells more high- . r /orv \ rni, t_ lymagiiifled mch (20 mmm). ihe number of orifices on a single papilla is about live hundred. The average diameter of the tubes is about -j^ij- of an inch (50 mmm) and they consist of a nearly homogeneous membrane lined with spheroidal ephithelium in some parts,and cubical in others. Each tube as it passes through the cortical sub- stance, from the number of loops which surround and are connected with it, presents a pyramidal appearance ; these are called the "pyramids ofFerrein," or lobules of the kid- ney. The total number of tubes is about two millions. Arteries and Nerves. — The kidney is supplied by the renal artery, which divides into four or five branches as it enters the hilum. These again sub-divide into the arie?'- iw propria} renales, which enter the kidney in the spaces between the papilkie (columns of Bertini^. They here give off' branches which supply the Malpighian pyramids, and cortical substance. Opposite the bases of these pyramids they make an abrupt bend, and give off branches (arteriolce rectoi) which supply the interior of the pyramid, descending to the apex. They are then continued on between the " lobules," or pyramids of Ferrein, under the name of inter- lobular branches, until they reach the capsule. In their SECRETION OF URINE. 250 course they supply the Malpighian bodies, giving them tufts as ah'eady described (Fig. 84). The afferent vessel after leaving \he Malpighian body, joins the capillary plexus sur- roundii.^ the tubuli uriniferi, and from this plexus arise the veins which return the blood. The circulation in the Malpighian bodies is therefore an off-set from the ordinary circulation, and in this respect resembles the portal cir- culation. The nerves of the kidney are derived from the solar plexus, the semilunar ganglia, and the lesser and smallest splanchnic nerves. Sinus of the Kidney. — This is a large cavity in the interior of the kidney which communicates with the tubuli uriniferi on the one hand, and the ureter on the other. It consists of three prolongations, the infundibula, one situated at each extremity of the organ, and one in the middle. Each infundibulum is divided into from seven to thirteen smaller portions, the calyces, each of which surrounds, like a cup^ the base of one or more of the papillae. It is lined by spheroidal epithelium. Secretion of Urine, — The secretion of urine from the blood is effected by the agency of cells. Some substances as- urea, uric acid, etc., exist ready formed in the blood, and need only to be removed ; but other substances, as the acid phosphates and the sulphates are formed by the agency of cells. It is probable, also, that the Malpighian bodies furnish chiefly the fluid portion of the urine, for it has been observed that in those animals which pass the urinary excrement in a semi-solid state, the tufts of the Malpighian bodies are very small. The secretion of urine is rapid, in com- parison with other secretions. It passes down the ureters and enters the bladder drop by drop ; this may be seen in some cases of ectopia vesica}. Some substances pass very rapidly from the stomach through the circulation, to be eliminated by the kidney ; e.g , a solution of potassium ferrocyanido passed in one minute, while some vegetable •3 f i 260 SECRETING GLANDS AND THEIR SECRETIONS. substances as rhubarb, occupied from sixteen to thirty-five minutes. The transit is slower, when the substances are taken during digestion. I. c ijli URINE. Healthy urine is a clear, limpid fluid, of a pale straw or amber color, with a peculiar odor, and saline taste. When first voided, it has an acid reaction, but after a short time it becomes alkaline from the development of ammonia ■during decomposition. In some instances the urine may become turbid on cooling, although clear and transparent at first. The specific gravity varies from 1015 to 1025, depend- ing on the time at which it is secreted, the kind of food, drink, etc. In consequence of this, the secretion has been divided into three varieties : — 1st, urina potus, or that which is secreted after the introduction of fluids into the body ; 2nd, urina cibi, or that secreted after the introduc- tion of solid food ; 3rd, urina sanguinis, or that secreted from the blood when neither food nor drink has been taken. For purposes of investigation, a portion of the urine passed during a period of twenty-four hours should be taken. In disease, as albuminuria, the specific gravity is diminished to 100-i ; while in diabetes it may be increased to 1050 or 1060. The quantity of solids in any given specimen of healthy urine may be determined approximately by doubling the last two figures of the sp. gr. ; thus 1018, (18 X 2) =36 grains of solids in 1000 grains of the urine. The whole quantity of urine secreted in twenty-four hours vai'ies, according to the amount of fluid drank, and the quantity secreted by the skin, from thirty to fifty ounces. The secretion of the skin is more active in warm weather than in cold, and consequently the quantity of urine secreted during winter is greater than in summer. Chemical Composition of the Urine. — The urine consists of water, holding in solution certain animal matters, CHEMICAL COMPOSITION OF THE URINE. 261 salts, coloring matters, etc. Its composition according to the most recent analyses is as follows, in 1000 parts. Water 950.00 Urea ii 26.20 Uric and hippuric acids, combined with sodium, potassium and ammonium 2.15 Creatine, creatinine, mucus and coloring matter i .22 Sodium and potassium chlorides 12.45 Sodium and potassium sulphates 3. 30 Sodium, potassium, calcium and magnesium phosphates ... 4.28 Sodium bi-phosphate 40 1000.00 Water. — The quantity of water varies in different seasons, and according to the drink, exercise, action of the skin, etc. In some diseases it is very much increased, as in hysteria, diabetes, etc. In other diseases, as albuminuria, diarrhoea and dysentery, it is very much diminished. In fevers, albuminuria, and in inflammation also, the quantity of water is almost invariabl}'^ diminished. Urea. — (C H4 N2 O). This constitutes more than half of the solid ma;tter of healthy urine. The quantity is in- creased by a purely animal or highly nitrogenous diet, and slightly by exercise. The increase of urea in active muscular exercise was formerly supposed to be in exact proportion to the amount of muscular exercise, but this has been found by experiment not to be the case ; the waste of muscle cannot be expressed by the increase in urea. Urea exists already formed in the blood, and is simply re- moved by the kidneys. It is formed from the decomposition of the nitrogenous elements of the food, and from the disintegration of the azotized tissues. It may be readily obtained by evaporating urine to the consistence of honey, and acting on it with four parts of alcohol ; then evaporating and crystallizing. It crystallizes in acicular crystals, which appear, under the microscope, as four-sided prisms, (Fig. 86). It is purified by filtering through animal charcoal. It may also be obtained in the form of urea nitrate (C H* N2 O H N O3 ), by evaporating urine to one-half, and then adding •3 1 i 262 SECRETING GLANDS AND THEIR SECRETIONS. c c I. MM \ an equal quantity of nitric acid, and crystallizing. Urea I'lg's sojuiii^HT. jg identical in composition witli ammonium isocyanate, (N H4 C NO=C H4 N2 0), and may be prepared artificially by the chemist, by double decompo- sition from potassium isocy- anate, and ammonium sulph- ate. Urea is colorless when pure, and destitute of smell, neutral in its reaction to test cr5ais°of urlf^ita:' """ "''• ''• paper, and soluble in water and alcohol. When urine stands for some time, the urea is decomposed, and forms ammonium carbonate. It is also decomposed, in some cases, before it leaves the bladder, as in paralysis, and some low forms of disease. An average of 500 grains (32.4 grammes) of urea are excreted from the body in twenty-four hours, when the kidney is in a healthy con- dition ; but in some diseases, as, e. g., in desquamative nephritis, Bright's disease, or congestion of the kidney from any cause, a certain portion of the urea is kept back, and circulating through the system may, by its poisonous effects on the cells, give rise to dropsies in different parts of the body, or from its deleterious effects on the nervous system, occasion uraeraic convulsions and coma. Uric or Lithic Acid (C5 H4 N4 O3 ). — This substance is rarely absent from healthy urine. It is combined with sodium and ammonium in the form cf urates. It predomi- nates in the urinary excrements of birds, serpents, and other reptiles ; while urea predominates in the mammalia, especially the herhivora. In the urine of the feline tribe, uric acid is sometimes entirely replaced by urea. Uric acid and urea are, therefore, closely allied to each other, and each alone may represent the excretion of the two. The quantity of uiic acid, like that of urea, is increased by the use of animal or highly niti'ogenized food, and decreased by HIPP URIC ACID. 263 food which is free from nitrogen. It is increased in all febrile conditions, and in gout it is deposited in and around joints, in the form of sodium urate, and constitutes the so- called "chalk-stones." Uric acid has been detected in the blood of healthy persons, and in considerable quantity in gouty patients. It is supposed to be formed in the sys- tem from the disintegration of the azotized tissues. Uric acid may be readily obtained by adding a few drops of hydrochloric acid to a portion of urine in a watch glass ; after a few hours it is found crystallized on the sides and bottom of the vessel. In larger quantities it may be obtained from the thick, white, urinaiy excrement of ser- pents or birds, which consists almost entirely of ammonium urate. This substance is dissolved in warm water, and then decomposed by nitric or hydrochloric acid. The crystals of uric acid assume very various and somewhat fantastic shapes, most frequently rhombic or diamond shaped (Fig. 87). It is insoluble in alcohol and ether. When the urates are in excess in the urine, they appear as a " brick-dust " sediment in the vessel. They may be distinguished from other deposits by their not appearing until the urine becomes cold, and by disappearing again entirely on the application of heat. HiPPURic Acid (Co Hq NO3 .) — This acid exists in small quantity in human urine, pro- bably in the form of sodium and ])otassium hippurates, but is very abundant in the urine of cows, horses and other her- bivorous animals. It is closely allied to benzoic acid (C7 He O2 ), and this substance when taken into the system, is excreted in the form of hippuric acid. Hip- puric acid is chiefly formed fi-om 8o^'S''S!a^c"S^;«^^ftS vegetable articles of food, and l^ta^ol'Zniunrur^t" ""' ^""'^ Fig's 88 ami W). 2G4' SECRETING GLANDS AND THEIR SECRETIONS. c c M» I. I- wt »a> «V t If ft £•■■ ns> • may be prepared from the urine of cows by precipitation with liydrochloric acid. It has a bitter taste, is slightly soluble in cold, but very soluble in hot water and alcohol. Greativ.e — (C4 H9 N., O2 ) occurs in very small quantity in the urine. It is a colorless crystalline body, with a pun- gent taste, soluble in water, but almost insoluble in alcohol. It may be obtained I'rom the flesh of animals. It is most abundant in the fle.sh of fowls, and in the heart of the ox. Creatinine — (O4 H7 Na O) is also found in the urine. It crystallizes in colorless crystals, has a hot, pungent taste like caustic ammonia, and is soluble in water and alcohol. It may be formed from creatine, by the action of hydrochloric acid, and is probably formed from creatine in the .system. Urochrome or Urosacine, the coloring matter of the urine, has been already described, (see proximate prin- ciples). A substance termed Indican has been found in the urine by several observers; by its decomposition indigo blue, and indigo red are produced. The urine also contains a certain amount of mucus and epithelial debris from the mucous surface of the urinary ])assages. Salts. — The salts of the urine constitute less than half of the solid ingredients. Sodium and potassium chlo»ides form a large proportion of the salines of the urine, the former being more abundant than the latter. They are derived iu part from the food, and also partly from chemical decom- position within the body. They may be readily precipitated by a solution of silver nitrate after the urine has been acidulated by nitric acid. When silver nitrate is added to healthy urine, a whitish precipitate o* silver chloride and sodium phosphate is thrown down; the latter may be dissolved by the addition of a little nitric acid. The silver chloride is readily dissolved by a little ammonia. The sulphates are more abundant in the urine, than in the THE PHOSPHA TES. 2G5 fluids and tissues of the body. They are increased by ex- ercise, and in diseases accompanied by muscular exertion, as in chorea and delirium tremens. They are also increased by the introduction of sulphur or the sulphides into the system. The sulphuric acid is formed by the oxidation of sulphur, which is derived from the decomposing albuminoid substances. The phosphates are more numerous than the sulphates. Phosphorus is derived from the decomposition of nerve sub- stance, albumen and fibrin, and like sulphur, is oxidized at the lungs, and then unites with the bases to form salts. The alkaline jihosp hates, or potassium and sodium phosphates aro those salts by which most of the phosphoric acid is elimi- nated in the urine. They are readily soluble, and never appear as a precipitate in urine. The quantity of alkalin© phosphates is increased by a diet of animal food : also by great mental exertion, and in phrenitis. They arc also in- creased by exercise, while the earthy are diminished. The earthy phosphates, or calcium and magnesium phosphates, are not very abundant in the urine. They are held in solu- tion by the sodium biphosphate, and when this is absent or neutralized they fall as a precipitate. The acid sodium phosphate, or sodium biphosi)hate gives the urine its acid reaction. It is supposed to be formed from the ordinary sodium phosphate of the blood by the action of uric acid, which unites with a part of the sodium forming sodium urate, leaving an acid sodium j^hosphate. Though freshly voided urine exhibits an acid reaction, yet- it has no free acid, but within a few hours after its discharge it undergoes the so-called acid fermentation resulting in the production of free lactic, and sometimes oxalic acid, formed from some of the organic ingredients. The latter when formed is precipitated with calcium, forming a sediment of calcium oxalate (Fig. 90). In a few days these changes- I •» 1 t i •266 SECRETING GLANDS AND THEIR SECRETIONS. c c I. f Sh.'' Fi,'H.<.oan.ini. ^^^^^^ ^^^^ ^^.^ followed by the so-callod (dhdine fermc/niation, (luring which some of the phos- phates are thrown down. This change is brought about by the decomposition of urea and its transformation into ammonium carbonate. This causes a pre- c'ii»itation of the earthy phos- phates which unite with some Kitf. ))0 Crystals of uakiiim oxulttte- , n ii , „ .^,.^«,^:,,.v. o«,1 olq Aa I'ijf. 01 crystilH of cystin. ot the ammoniuui, and aie ue- ])osited in the form of ammonio-magnesiuin phosphate (triple phosphate) Fig. 89. The urine at this time has a strongly ammoniacal odor. Cystin (Fig. 91), is occasionally found in unhealthy urine. MAMMARY GLANDS AND THEIR SECRETION. These are the organs which secrete the milk. They are large and hemispherical in the female, but are quite rudi- mentary in the male. They are situated in front of the pectoralis major, between the third and sixth ribs, and ex- tend from the sides of the sternum nearly to the axilhe. They are enlarged at puberty, increased during pregnancy and lactation, and diminished in old age. The outer surface of the mamma presents a little be^.ow the centre, a small conical eminence — the nipple — the surface of which is dark- colored, and surrounded by an areola, which has a rosy hue in the virgin, but becomes very dark-colored during preg- nancy. Its summit is perforated by numerous openings, the orifices of the lactiferous ducts. It is also provided with a number of .sebaceous glands, situated near its base and upon the surface of the areola, which secrete a peculiar fatty rubstance for the protection of the nipple during suck- ing. The nipple consists of numerous blood-vessels, nerves, lymphatics, ducts, erectile tissue, and nonstriated muscular fibre-cells, and is capable of slight erection during sexual ex- citement or irritation. MILK. 267 Structure. — The mamma consists of numerous lobes, which are made up of small lobules, connected together by areolar tissue, blood-vessels and ducts. There is also some adipose tissue between the lobules. Each lobule, which is a representation of the whole gland, consists of a cluster of rounded vesicles, which open into the smallest branches of the lactiferous ducts, and these, uniting, form larger ducts — the tubuli lactiferi. These vary in number from fifteen to twenty, and converge towards the areola, beneath which they form dilatations, ov ampulloi, which serve as reservoirs for the milk ; they then become contracted, and continue onwards to the summit of the nipple, where they open by separate orifices, which are narrower than the ducts them- selves. The entire surface of the gland is invested by fibrous tissue, from which numerous septa are derived, which ])ass between the lobes. Milk. — The secretion of milk is usually limited to the period succeeding parturition, yet this is not invariably the case. Numerous instances are on record where young women who have never borne children, and even old women, have been able to act as wet nurses. In some rare cavses, the male has been known to secrete milk in the breasts. A fluid resembling milk, may frequently be ex- pressed from the mammary glands of infants. Milk has an alkaline reaction, and the specific gravity varies from 1020 to 1030. The specific gravity alone is of no value as an indication of the richness of the milk. The average chemical composition of human milk is as follows, in 1000 1 tarts : Water 890 Butter 26 Casein andExtractive 40 Lactose 42 Fixed Salts 2 1000 When milk is examined with a microscope, a large number of minute particles may be seen, termed " milk globules," 1.5 268 SECRETING GLANDS AND THEIR SECRETIONS. c r IL |«ni tor EH.! , which vary in size from 5„'oo to xsAao of an inch (8.3 to 2 muiin) in diameter. Tliey are coated with albuminous V\k. 02. Fijf. 03. Oil ^lohitlcsof liunian milk. Oil (^lobules of cow's mill<. matter, and are sohil)le in ether and alkalies. In the colostruTn, or first milk secreted after labor, large, yellow, granulated bodies may be seen, called colostram corpuscles. Theyare supposed by some to be exudation corpuscles; others regard them as transformations of the epithelial cells of the gland, containing fatty matter. The colostrum has a pur- gative effect on the chiM, which is useful in clearing the bowels of the meconium which they contain at birth. The oleaginous matter of milk chiefly consists of the ordinary constituents of fat, together with a substance called "butyrin," to which the taste and smell of butter are due. When this substance is treated with alkalies, or suffers decomposition, the following volatile acids are produced, viz. ; butyric, caproic, caprylic, and capric (rutic.) These are called butter acids. The casein of human milk is not so readily precipitated as cow's milk. It requires a large amount of acid, and rennet does not seem to take effect upon it, unless an acid be present. The casein of asses' milk boars a closei resemblance to that of human milk, than does that of the cow. The best substitute for hinnan milk, however, is cow's milk diluted with water, and a little sugar added. Lactose or milk sugar (C12 H24 O12), may be obtained from whey by evaporation and crystallization. It strongly re- sembles glucose, into vvhich it niay be converted by the drochloric acid. The action 'P hyi of a fennent causes lactose to undergo the lactic acid fer- MILK. msi mentation; and wlien lactic acitl, or .calcium lactate is allowed to stand for some time, it is changed into Imtyric acid, or calcium butyrate, having undergone tin; " luitj-ric acid fermentation." The saline matter of the milk is nearly identical with that of the blood, with an increase in the calcium and magncsitnn phosphates. From what has been already stated, it will be observed that milk contains the four classes of ])iinciples which are i-equired for human food, viz: The aqueous, the aU)mninous, the oleafjuwus^ixud the scw)c//arme,conse(iuently it is well adapted to the nourishment of the young animal. From 20 to 40 ounc(^s of milk are secreted in 24 hours. Stimulating li(juors often used to incre se the quantity of milk, seldom act otherwise than prejudicial. Certain inedicinal agents, when administei'ed to the mother, may pass into the milk, and in this way ati'fct the child. As a rule, salines pass more readily than vegetalde substances. Medicine may be administered to the mother, instead of the child, when it is desired to act upon the latter. Eniotious of the niiud, as anger, gi'ief, fear, etc., ])ro- duce peculiar changes in the quantity and quality of the milk; for example, anger produces very irritating milk, which cap es gi'iping ii^i the child, and green stools. Grief diminishes the secretion, and frequently vitiates it. Fear also diminishes the secretion, and that which is secreted under such circumstanees is highly irritating. Violent ex- ercise, or great anxiety of mind, has also a bad effect on the secretion of milk. Cases are recorded in wliicli children have had convulsions, and died shortly after sucking milk secreted un'''3r the foregoing circumstances. 270 DUCTLESS OR VASCULAR GLANDS. CHAPTER XII. c c c. I. Ih rat I c r Ml It' Onr-, cu ciu , . '■"Jtt-'ik, ,-, DUCTLESS OR VASCULAR GLANDS. These are so named from havinf,' no excretory ducts ; they are the spleen, supra-renal capsules, thymus and thy- roid glands. They contain the same essential structures as the secreting glands, except the ducts. They are highly vascular, and are concerned in the elaboration of the blood. Their function, however, does not seem essential to life. They may become atrophied, or be removed from animals, without any serious consequences. SPLEEN. . t The spleen is situated in the left hypochondriac region, embracing the cardiac end of the stomach. It is of an oblong shape, highly vascular, very brittle, and of a bluish- red color. It measures five inches in length, three or four in breadth, and one and a half in thickness, and weighs from four to six ounces. Structure. — It is invested by two coats, an external serous and an internal fibrous elastic coat. The serous coat is derived from the peritoneum, and is intimately adherent to the fibrous coat. It covers nearly the whole organ, being reflected from it at the upper end on to the diaphragm form- ing the suspensory ligament, and at the hilum on to the great end of the stomach, forming the gastro-splenic omen- tum. Thejibrous coat consists of white fibrous and yellow elastic tissue. It covers the exterior of the organ, and sends prolongations inwards at the hilum, in the form of vagina? or sheaths, which surround the vessels. From these sheaths, and from the inner surface of the fibrous coat, numerous tra- beculse or bands pass in all directions, and these uniting STRUCTURE OF THE SPLEEN. 271 bemg bim- o the )men- ellow sends aijina3 eaths, js tra- form the areolar framework of the spleen. The presence of the elastic tissue, permits of the great enlargement of this organ which is sometimes seen. The spaces or areolae be- tween the bands are filled with a soft pulpy mass, of a dark reddish-brown color, consisting of colorless and colored ele- ments — the proper substance of the spleen, or spleen iTuXp — and some rounded bodies the Malpighian corpuscles. The colorless elements form about one-half or two-thirds of the entire pulp, especially in well-fed animals, and consist of granular plasma, free nuclei, about the size of red blood corpuscles, and a few nucleated lymphoid cells. The colored elements consist of unchanged red blood corpuscles, and blood discs in various stages of decay. Besides these, may be seen a number of granular bodies or crystals, which in chemical composition resemble the coloring matter of the blood. The Malpi(jhiaii corpuscles are rounded bodies from ,?(, to a'j of an inch (.8 to .4- mm) in diameter, of a semi-opaque whitish color, and are more distinct in early life than in '•''^-" adult age. Each con- sists of a membranous capsule,homogeneous in structure, and formed by a prolongation from the sheath of the small arteries to which it is attached. They are sur- rounded and embraced by the radicles of the arteries, and present a resemblance to the buds of the moss rose. Each showing the Mai- ^^^^^^^ contains a soft white sul)stance, consisting of granular ])lasma, nuclei, an I nucleated 13'mphoid cells similar to the colorless elements Branch of the splenic artery, pighi:iii oorpnaoles. 272 DUCTLESS OR VASCULAR GLANDS. c c c I. I- »i m\ I f c c •^';, •w' •»f ■ oa tn.1 I of the pulp. Small capillaries pass into their interior and form a minute plexus. The splenic artery is large in proportion to the size of the gland, tortuous in its course, and divides into from four to six branches, which enter the hilum. Each branch runs transversely from within outwards, and divides into smaller branches ; these ultimately terminate in tufts or pencils, which lie in contact with the pulp. The most striking peculiarity is, that each of the larger branches supplies chiefly that part of the organ to which It is dis- tributed, having no anastomosis with the adjoining branches. The cajsiZ^aries terminate either directly inthe veins, or open into csecal or lacunar spaces, from which the veins arise. The veins arise either in the ordinary way from the capillaries or by communicating intercellular spaces, or distinct csecal pouches. They are much larger and more numerous than the arteries, and by their junction form from four to six branches which emerge at the hilum, and uniting form the splenic vein, the largest branch of the portal. From this it will be seen that the blood returning from the spleen passes through the liver before it enters the general circulation. Function of the Spleen. — In consequence of the vas- cular arrangement and the large amount of elastic tissue which this organ contains, it is liable to undergo great changes in volume. Enlargement of the spleen is apt to occur from internal venous congestion, such as occurs in the cold stage of intermittent fever. When intermittent fever is long-continued, the spleen is generally very much enlarged, constituting what is commonly called " ague cake." It was formerly supposed to act as a diverticulum of the liver, relieving its vessels from undue turgescence and pre- venting congestion of the liver, stomach and bowels ; and also that it promoted the disintegration of the red blood corpuscles ; but these views cannot be accepted in the present state of our knowledge. The spleen is SUPRA-RENAL CAPSULES. 273 larger four or five hours after food is taken, and contains a larger proportion of finely granular albu- minous material, than at any other time, therefore it is supposed that this organ is the receptacle for the increased quantity of albuminous material of the food, and which can- not be admitted into the system generally, without danger, until the volume of the circulating fluid has been reduced by secretion. In support of this theory, it has been stated that animals from which the spleen has been removed, are very liable to die of apoplexy, after taking large quantities of food. It would therefore appear to be a storehouse of nutrient material, which may be drawn upon as the system requires. The increase of the fibrin in the splenic vein would show that the nutrient material is elaborated during its withdrawal. It is also supposed to form the germs of future blood corpuscles, as there is found to be a large in- crease of the colorless corpuscles in the blood of the splenic vein. SUPJIA-RENAL CAPSULES. The supra-renal capsules are situated one upon the upper extremity of each kidney, somewhat triangular in shape, the base being applied to the kidney, and the apex directed up- wards. Each gland is about one and one-half to two inches in length, rather less in width, about one-fourth of an inch in thickness, and weighs from one to two drachms. Structure. — Like the kidneys, they are divided into a cortical and medullary portion. The cortical portion, which forms the principal part of the organ, ia of a deep yel- low color, and consists of narrow, columnar masses, arranged perpendicularly to the surface, and held together by areolar tissue. These columnar masses measure about ij-j^j of an inch (35 mmm) in diameter, and consist of oval spaces or parallel tubes, containing a finely granular plasma, a mass of nucleated cells with large nuclei, and oil globules. The medullary substance consists of areolar tissue, containing a .1 c c E h m •*^v CCC: 274 DUCTLESS OR VASCULAR GLANDS. plexus of minute veins, having stellate or polygonal granu- lar cells in its meshes. It is soft and pulpy, very dark in color, hence the name atrahiliary substance, sometimes given to ib. These glands are more highly supplied with nerves than any other glands in the body. Function. — Very little is known regarding their function. They were formerly supposed to be the diverticula of the kidney. They are probably concerned in elaborating some of the materials of the blood. They are developed at an early period in foetal life, and are larger than the kidneys ; but afterwards relatively diminish. It was observed by Addison that disease of the supra-renal capsules was asso- ciated with anemia, general weakness, and a peculiar change of color in the skin, the patient resembling a mulatto. The disease is called morbus Addisonii. THYMUS GLAND. This is only a temporary organ. It reaches its largest size at the end of the second year, and then declines until puberty, when only a small part remains. It is situated partly in the anterior mediastinum, and partly in the neck, extending from the lower border of the thyroid gland to the fourth costal cartilage. It is somewhat oval in shape, of a pinkish grey color, lobulated on its surface, and consists of two lobes, [t is about two inches in length, one and a half in breadth, three or four lines in thickness, and weighs about half an ounce. Structure, — Each lobe consists of a central cavity or reservoir, around which are arranged numerous lobules, held together by delicate areolar tissue. The lobules vary in size from a pin's head to a pea, and each contains a smf».ll cavity from ^^ to -^^ of an inch (1.4 to .5 mm) in diameter, which communicates with the central cavity or reservoir of the organ. Each lobule is surrounded by smaller or second- ary lobules or acini, the cavities of which communicate with those of the primary lobules. If the capsule and areolar THYROID GLAND. 275 tissue holding the parts together be dissected off, the gland may be drawn out into a tubular cord, around which the lobules are arranged in a spiral manner. The closed cavity of the organ, and the secondary lobules or acini contain a .chyle-like fluid, consisting of nucleated corpuscles, granular nuclei and lymphoid cells. Function. — This organ would appear to be connected with the preparation of matter for the pulmonary arteries in early life. In ill-nourished children the corpuscles be- come filled with fat, which is supposed to be added to the blood. ity or held rv in THYROID GLAND. The thyroid gland is situated at the upper part of the trachea, and consists of two lobes connected by a narrow band (the isthmus), which crosses the second and third rings. Each lobe is conical in shape, about two inches in length, and three-quarters of an inch in breadth, the right being the larger. The whole gland weighs from one to tw» ounces. It is of a brownish-red color, larger in females than in males, and is increased during menstruation. It is oc- casionally very much hypertrophied, and c^^nstitutes hron- chocele or goitre. In some countries, as in Switzerland and Northern Italy, bronchocele is very prevalent in both sexes. The children of goitrous parents are dwarfish, very defective in mental and moral faculties, and are known as cyetiiis. Structure. — In structure it consists of lobules, held to- gether by areolar tissue. Each lobule consists of a number of closed vesicles, oblong or spherical in shape, each contain- ing an albuminoid plasma, consisting of granules, oil glo- bules, nuclei, and nucleated cells, the latter occupying the position of an epithelium within the vesicles. There is also some colloid substance, which is most abundant in enlarge- ment of the gland. The vesicles vary in size from ^^ to to\5w of an inch (300 to 12 mmm) in diameter. 276 THE NERVOUS SYSTEM. c c a m\- w* I' c f £:• Wttl •»7 ■ r.H. i Function. — The thyroid gland is supposed by some to act as a diverticulum of the cerebral circulation. When the brain is inactive, the thyroid gland takes on an increased action, and accommodates the blood that would otherwise go to that organ. This view is based on the fact that the arteries which supply this gland arise in close proximity to those which supply the brain. The vesicles also probably removes, and store up from the blood, certain constituents which are not required in its passive state, to be returned to it when it resumes its activity. CHAPTER XIIL THE NERVOUS SYSTEM. The nervous system consists of two portions, the cerebrospinal, and the sympathetic or ganglionic system. The former was distinguished by Bichat as the nervous system of animal life ; the latter as the nervous system, of organic life. The cerebrospinal system includes the brain and spinal cord, the nerves associated with them, and their ganglia, viz. : — The ganglia of the posterior root of the spinal nerves, the ganglion of the fifth nerve, and those of the glosso-pharyngeal and pneumogastric nerves. It includes the nervous organs in and through which are performed the several functions with which the mind is more imme- diately connected, as those relating to common sensation, volition, and the special senses, as well as those concerned in many nervous actions with which the mind has no connection. The sym^pathetic or ganglionic system consists of a double chain of ganglia connected by nervous cords, which RUDIMENTARY NERVOUS SYSTEM. 277 extend along each side of the vertebral column, from the cranium to the pelvis, and from which nerves, with ganglia upon them, proceed to the viscera in the thoracic, abdomi- nal, and pelvic cavities. This system is more closely connected with the process of organic life than the cerebro- spinal, but is less immediately connected with the mind. In the lower orders of the animal creation, the nervous system is quite rudimentary. In the ascending series of animal life, it is first found in the medusae or jelly-fishes. The ganglionic centres are situated around the free margin of the swimming bell. In these animals also, is seen the earliest appearance of muscular tissue in the animal kingdom. In its lowest and simplest form it may consist of single ganglionic centres, with sensory or afferent, and motor or efferent nerves (Fig 104;), whose function is essentially internuncial, impressions being made and responded to without any intervention of consciousness, the movements being purely exeito-motor. A simple re- petition of such ganglionic centres may exist to any extent without dissimilarity of function, or any essential departure from the mode of action just mentioned. A higher form of nervous system is that in which there is a multiplication of ganglionic centres to correspond with the diversity of func- tions, as in the higher articulata and mollusca, in which ganglionic centres are set apart for the actions of deglutition and respiration, as well as for those of motion, but their modus operandi is still the same — the actions being all excito-motor. In all but the very lowest invertebrata, the nervous system includes, in addition to the above, certain ganglionic centres which preside over the organs of sight, smell, hearing, etc. These sensorial ganglia constitute the *' brain" in these animals. The highest degree of psychical perfection, as in the class of insects, consists in the ex- clusive development of the instinctive faculty, or of simple automatic powers, by virtue of which each individual per- forms those actions to which it is prompted by impressions 278 THE NERVOUS SYSTEM. c L ^^ made upon its afferent nerves, without any self-control or self-direction, so that it may be regarded as entirely a creature of necessity. In the vertebrated series, on the other hand, the highest degree of psj'chical perfection, as shown in man, consists in the highest development of the reason t*ud the supreme domination of the will, to which all the automatic actions — except those which are essential to the organic functions — are subject, so that each individual becomes not only a thinking and reflecting, but also a self-moving and self- controlling agent, whose actions are performed with a definite purpose in view. During the early period of life, however, the mental faculties are but little in advance of those of the higher invertebrata ; for example, the infant is prompted to seize the nipple, not from any knowledge gained by experience, that by so doing it will relieve the feeling of hunger, but in consequence of the impulse arising out of impressions made upon the afferent nerves. The super-addition of more elevated endowments in the verte- brated series is coincident with the addition of a peculiar ganglionic centre, the cerebrum, to the sensori-motor appa- ratus. The superiority of the mind of man over the lower animals consists not only in the greater variety and wider range of his faculties; but also in that dominant power of the will which enables him to utilize them with the highest effect. When the thoughts and feelings of man are the mere result of the action of external impressions upon a respondent organism, he may be considered irresponsible for his actions, his character having been formed for him, and not hy him. But, whenever he can exert a volitional power of directing his thoughts and controlling his feelings, he is morally and intellectually responsible for his acts. Some persons, however, in consequence of the weakness of their will, are so much accustomed to act directly upon the prompting of any transient impulse, that they can scarcely be said to be voluntary agents ; and others allow certain CRANIOSPINAL AXIS. 279 dominant ideas or habitual feelings to gain such a mastery over them as to usurp for the time the power of the will. The fundamental part of the cerebro-spinal system is the craniospinal axis, which consists of the spinal cord, medulla oblongata, and the sensory ganglia, the latter con- sisting of those ganglia lying along the base of the skull in man, and in which the nerves of the special senses have their origin, viz., the corpora striata and quadrigemina, the thalami optici, etc. This cranio-spinal axis, which re- presents the whole nervous system of the invertebrata (except the rudimentary sympathetic they posses.s), exists without any super-addition in the lowest known vertebrated animal, as in the case of the little fish called the amphioxus. This condition may even be found in the human species, as in the case of acephalous infants, in which neither the cerebrum nor cerebellum is present ; such have existed for several days, breathing, sucking, crying, and performing various other actions. In man, however, and in all the higher vertebrata, large ganglia, which form the principal mass of the encephalon, are found superimposed upon and embracing the sensory ganglia. These are the cerebrum and cerehdlwm ; the former is the seat of the will, and presides over, controls, and regulates all the actions and movements of the body, except the organic functions and excito-niotor actions ; the latter is concerned in the regulation and co-ordination of the actions of the spinal cord. The action of the cerebro- spinal system may be elucidated by the following diagram — Caipenter. -i-The Will Intellectual operations + . Emotions. + - Ideas. + Sensations — I Centre of Bensori-uiutor reflexion. 1.. i- Cerebrum. Centre of emotional and ideo-tnotor re- flexion. -+■ Sensory jjanglia- Impressions +- Spinal Cord Motor Impulse. Centre of excito-niotor reflexion. ^, S.T. s.aJ IMAGE EVALUATION TEST TARGET (MT-3) A {/. % <; .

If these ideas are associated with feelings of pain o • pleasure, they give rise to emotions ; and either as simple or emotional ideas, they become the subject of intellectual operations whose final issue culminates in an act of the luill, which may be e.-erted in producing or checking a muscular movement, or in controlling or directing the current of thought. If this ordinary upward course be interrupted, or if the action be excito-motor, the impressions 'villexert their power in the transverse direction, and a reflex action will be the result; for example, if the interruption be produced by division or injury of the spinal co/d, below the sensory ganglia, reflex movements being produced without sensation will be purely excito-motor. So, again, if the connection between the sensory ganglia and the cerebrum be severed, or if the function of the cerebrum be in abeyance, they n)ay react on the motor apparatus by the reflex power of the sensory ganglia themselves ; such actions, being dependent on the promptings of sensation, are sensori-motor. The alferent and efferent nerves, and their connection with the spinal cord, constitute an excito-motor nerve arc, and the spinal cord consists of a longitudinal series of excito- motor arcs, since an impression may be made through the afterent nerve which produces action of the muscles supplied by the efl'erent nerve, the whole being consumed without leav- ing behind any impression on the nervous centre. The nerve arc may be connected to a ganglion by means of a band or STRUCTURE OF THE NERVOUS SYSTEM. 281 commissure, tlirough which a por^on of the nervous in- fluence passes to be stored up. This is called a registering ganglion, as, for example, the corpus striatum, thalamus opticus, etc., and these, in their turn, are connected to the cerebrum, this connection constituting what is called the influential arc. The registering ganglia are regarded as the sensorium, and correspond with the sensory ganglia. Their function appears to be to receive and retain impres- sions of ideas, events or occurrences, the time, place, and order in which they occurred, and other circumstances which are usually ascribed to the faculty of memory. Structure of the Nervous System. — The organs of the nervous system are composed essentially of two dirlerent elements, nerve fl^hres and nerve cells. The former, on account of their color, are often called the white or medullary substance ; the latter, the gray or cineritious substance. Nerve Fibres. — There are two different kinds of nerve fibres, the niedullated and the non-medullated. They are intermingled in most nerves, the former being more numerous in the cerebro-spinal .system ; the latter pre- dominating in the sj^mpathetic. The medullated nerve fibres consist of tubules of simple homogeneous membrane, the neurilemma, similar to the sar- colemma of striated muscular tissue, within which is con- tained the proper nerve substance, consisting of two differ- ent materials. The central part consists of a greyish ma- terial called the axis cylinder ; the outer portion which surrounds the axis cylinder is usually opaque, and dimly granular, and is called the white substance of Schwann. It is the predominance of this substance which gives the cerebro-spinal nerves their white appearance. The axis cylinder consists of a Krge number of primitive fibrillae, and is the conductor of nerve force. It is the es.sential element of the nerve tube, and may be compared to the " core " of the submarine cable ; the white substance of Schwann to 282 THE NERVOUS SYSTEM. c c •a* c. I. «v i uninterrupted course from its origin at a nervous centre, to its destination, whether this be the i)eriphery of the body, in another nervous centre, or the same from which it issued. They anastomose or communicate with each other iu their course, sometimes joining at acute angles with others proceeding in the same direction ; but they never coalesce, or unite with the substance of any other fibre ; for although they cross and mingle with each other, yet each separate nerve fibre re- tains its identity throughout. The nerves, iu certain parts of their course, form plexuses in which the3' anastomose with each other, as in +,he cervical, brachial, lumbar, and sacral plexuses. In the formation of a plexus, the component nerves divide, then unite, and again sub-divide, and in this way the fasciculi become intricately interlaced. The object of such interchange of fibres is to give each nerve a wider connection with the spinal cord, so that the [)arts su[)plied may have 286 THE NERVOUS SYSTEM, c c MM L I- m. «). I B tS'l B tS'l «1 »«. rsi tiii.i . wider relations witli the nervous centres, and also that groups of muscles may be associated for combined action. OiiKHN AND Termination of Nerves. — The point of connection of a nerve with the brain, spinal cord, or r^anglion is called, for convenience of description, its origin, root or central termination ; the point of distribution its 'peri- pheral termination , or peripherij. With reference to their origin, some of them originate in nerve corpuscles, or their prolongations, others probably form simple loops. As the nerve fibre approaches the nerve cor- puscle or its prolongation, the white substance of Schwann gradually disappeais, the tubular membrane or sheath blends with the nerve corpuscle, and the axis cylinder becomes con- tinuous with the contents of the cell. More^fil>res have been counted leavingthan entering a ganglion, from which it may be inferred that some of them arise from the corpuscles. It has not yet been determined whether this relation of nerve fibres to nerve cor})usoles is common to all kinds of nerve fibres. Some are of oi)inion that sensitive fibres alone are ])i'ought into this intimate relation with nerve corpuscles. 1 1 does not appear, however, to belong exclusively to either the cerebro-spinal or S3nn])athctic nerves. The peripheral termination is also exceedingly difficult to determine, but examples of /li'e different modes have been observed. 1st. In loops or plexuses. In this mode of termination, each fibre, after issuing from a branch in a terminal plexus, runs over or through the substance of the tissue ; it then turns back and joins the same, or avi adjaceni branch, and pursues its way back to the nervous centre. This mode has been found in mucous and serous membranes, in the anterior epithelium of the cornea and in muscular ti.ssue. 2nd. In terminal bulbs, csdled tactile corpuscles of Meisii- ner and Wagner, (Fig. 100 A) ; end-bulbs of Krause, (Fig. 100 B) ; and Pacinian bodies, or corpuscles of Vater (Fig. 10 1.) Tlio tactile corpuscles are oval shaped bodies, formed -2T5PK-— TERMINATION OF NERVES. 287 •of delicate connective tissue, ju'ound winch the nerve passes in a spiral manner. They are found in the ]mp- illa' of tln^ skin, especially in the palms of the hands and the soles of the feet. Thcnr length is about ^i,, and their thickness ^i,, of an inch (100 to 50 mmm). The end-hulh.9 of Krause resemble the tac- tile corpuscles in api)earanco, but are .-jmaller and more a. cutmeonsiapmaof tllollillul;ra,)t•orti- , . , cal layer williceils and L'liiHtictlliros; (fc) tactile Simple in structure. Ihey corptiacle ; (c, , tcniiination of the nerve ; 9. o ^ O vvSrthe\me*^'\s%pef^^ ^^® peiUclc, and after traversing the A Pacinian cor apex ; :i, 3, sub 288 THE NERVOUS SYSTEM. c c t I. an tlU:l. Fig. 102. several layers of membrane, it terminates in the centra? cavity in a bulbous enlargement, or a bifurcation (Fig. 101/ The function of these bodies is not known; they are pro- bably reservoirs for nerve force. 3rd. In motorial md-plates, as described by Rouget and others. This is the mode of termination in striated muscular tissue. As the nerve fibre approaches the muscular fibre it expands, the sheath blends with the sarcolemma, the white substance of Schwann terminates abruptly, and the axis cylinder spreads out beneath the sarcolemma on the sur- face of the fibrilho, forming an oval plate from -sU to Toio of an inch (50 to 25 mmm) in diameter (Fig's 38 and 102) 4th. Some nerves appear to termi- nate in cells, or nerve corpuscles, aw those of the eye, interal car and other parts. 5th. In free ends as from the fine plexuses in non-striated muscular tissue, and in the cornea. Some nerve fibres appear tohaveno peripheral termination. It has been Termination of a nerve fibre sllOWn by Gcrbcr that nCrVC fibres bv anii)ti)rial eiul-plate in anuis- • 11 r 1 i 1 • • ciiiar fibre (Longet.) occasioually tomi loops by their junc- tion with a neighboring fibre in the same fasciculus, and return to the nervous centre without having any peripheral termination. He considers *''^'- ^"•'• these to be sentient nerves, for the suppl}^ of the nerve itself, the nervi nervorum, upon which the sensibility of the nerve depends. This is some- v^hat similar to those nerve fibres met with at the posterior part of the optic commissure, where a set of fibres pass from The optic commissure, one optic tract across the commissure to the tract on the FUNCTION OF NERVE FIISKES. 28J> opposite side, without having any connection with the optic nerves — the inter-cerebral fibres; other i appear to have no central connection with the cerebro-spinal centre, as those forming the anterior fibres of the 0])tic commissure — the inter-retinal fibres. These commence in the retina on one side, pass along the optic nerve, and across the commissure to the retina of the opposite side. Medullated nerve-fibres lose the white substance of Schwann, before their final distribution, and bear a close le- semblance to the non-modullated fibres. The sympathetic nerves consist of medullated and non- medullated fibres, intermingled in various proportions in different nerves, and are enclosed in a sheath of areolar tissue. The mode of distribution of these nerves is essen- tially the same as that of the cerebro-spinal. The most striking peculiarity is the frequent formation of ganglia in the coui'se of the trunk and their branches. They are chiefly distributed to the head and trunk, being very limited in their connection with the extremities. Function of NerveFibres. — The functions of nerve fibres and neive centres are determined by comparing their a7ia- tomy in man with that of the lower animals; by experiments on recently-killed or living animals, and by clinical obser- vation. The office of the nerves is to convey or conduct nervous impressions. The function is of a two-fold kind — -first, they serve to convey to the nervous centres the impressions made upon their peripheral extremities, or on parts of their course ; and, secondly, they serve to transmit impressions from the brain, and other nervous centres, to the parts to which they are distributed. These impressions are of two kinds, viz., those that excite muscular contraction, and those which influence the processes of secretion, growth, ttc. Those ner\ ts that convey impressions from the periphery to the centre, are called sensitive, centripetal or afferent nerves, or nerves of sensation; and those which transmit im- iOO THE NERVOUS SYSTEM. c c L I vet' •t5 ■ Fi(f 104. pulses to the muscles, are called inoto7\ centnfugal or effer- ent nerves, or uervea of luotion. This peculiarity cannot be account* (1 for from any special variety of structure which the nerves possess, or the tis- sues to which they are distri- buted. The two kinds of nerves lie side by side in the same sheath. Those which surface havc no peripheral termination 1. Diaffraiu of reflex action ; (ei)itliuliuiii) ; 2, iniisole ; A, iiorve of NcriKa- ii i ' j i l _ tion; B. ocntrki ncrvc.\eii; c, ne.veof are Called mfercentrctl, as motion : A, U, C, form the )ic»TC ncr wliich ,. i ii i i i /? xi presides over reflex action. thOSC at the baCK part 01 tllO optic commissure. The nervous force (vis nervosa) by which secretion, nutrition, etc., are influenced, seems to be conveyed aUmg both sensitive and motor nerves. Nerve fibres require to be stimulated, in order to manifest their peculiar endowments, since they do not pos- sess tlie power of generating force in themselves, or of ori- ginating impulses to action. The property of conducting impressions is called excitability ; but this is never mani- fested until some stimulus is applied. The stimuli by which the action of nerves is ordinarily provoked, are of two kinds, mental and phymcal ; the former relates to the will, the latter to the influence of external objects, and chemical, mechanical and electric actions or irritations. These stimuli when ^applied to parts endowed with senia- tion, or to .'sensitive nerves, produce sensations, and when applied to the nerves of muscles produce contractions. Nerves, though divided, when irritated or stimulated have, by virtue of their excitability, the power of exciting con- tractions in the muscles to which they are distributed ; but when the ct)ntinuity of the nervous matter is broken, or the fibre bruised, or seriously injured, the property of propa- gating nervous force is destroyed. Nervous action is also excited by temperature ; for example, any very hot substance applied to the body produces muscular contraction, and a sensation of pain is transmitted to the nervous centre ; the LA IVS OF ACT/ON IN NERVE FIBRES. 291 ;on- but or the application of a very cold substance has a somewhat similar effect. Chemical stimuli excite the action of both sensitive and motor nerves, when their effect is not so strong as to destroy the structure of the nerve to which they are applied. A similar manifestation of nervous power is produced by electricity. Nerve force travels along the fibres with im- mense rapidity ; its velocity has beon ascertained by Helra- holtz and others at 111 feet per second in motor, and 140 in sensory nerves. Lav,^s of Action in Neuvk Fiuuks. — All nerve fibres are mere conductors of impressions. An impression made on any fibre is transmitted along it without interruption, and without being imparted to any of the fibres lying near it. This is probably due to the fact, that the contents of each fibre arc isolated from those of adjacent fibres, by the membrane or sheath in which it is enclosed. It is also sup- posed that the white substance of Schwann acts as an in- sulatoi". No nerve fibre can convey more than one kind of impression ; for example, the motor nerve conveys only motor impulse ; the sensitive nerve transmits only sensation when propagated to the brain, and the nerves of special sense, as the optic and auditory, convey only sensations of light and sound. Nerves of sensation are able to convey impressions only from the parts to which they are distri- buted, towards the nervous centre with which they com- municate ; for example, whon a sensitive nerve is divided, and irritation is applied to that portion still connected with the nervous centre, sensation is perceived, or a reflex action ensues ; but w^hen the distal portion is irritated no effect is produced. When the trunk of a nerve is irritated, the sen- sation is felt in all the parts which receive branches from it ; for example, if the ulnar nerve be compressed behind the internal condyle of the humerus, a peculiar tingling sensa- tion is felt in the little finger, and in the ulnar half of the ring finger. Even when part of a limb has been amputated, any pressure or irritation to the remaining portions of the 292 THE NERVOUS SYSTEM. c c I. Ml- urn •nr ' Hv ■ nerves which ramified in it, gives rise to sensations whicli the mind refers to the lost part, as well as to the stump, and tiuglings and pains are complained of in the lost finger, toe, hand or foot, as the case may He. Again, when the relative position of the peripheral extremities of sensitive nerves is changed artificially, as in the restoration of the nose from the integument of the. forehead, the sensation produced when the new nose thus formed, while connected by its isthmus, is touched, is referred to the forehead. This j)eculiarity may be exemplified by the following experiment : — Cross the middle fingar of the hand behind the index finger so that the extremity is on the radial side of the latter, then roll the two fingers over a pea or marble, and a sensation will be produced which leads the mind to suppose the existence of two distinct bodies. This is owing to the impression being made at the same time on the sides o:^ the fingers most re- moved from each other in the natura .position. Generally, however, the mind discerns the exact part of a nerve fibre that is irritated, and even when, as is the case in the retina, two or more impressions are made at the same instant on dift'erent parts of the same fibre, the mind can discriminate and perceive each, and compare the one with the other. Several of the laws of action in motor nerves are similar to the foregoing. For example, motor influence is trans- mitted only in the direction of the fibi.'s going to the muscles, and ir]-itation of a motor nerve excites contraction in all the muscles supplied by the branches given off" below the point of irritation ; but those supplied by branches given off' above this point are never directly affected. Again, since motor nerves are isolated as completely as sensitive, the irritation of a part of the fibres of a motor nerve does not affect the motor power of the whole trunk, but only that of the portion to which the stimulus is applied. Development of Nerve Tissue. — Keive fibres appear to be formed in the same manner as muscles. The primitive cells are imbedded in protoplasm or intercellular substance DEVELOPMENT OF NERVE TISSUE. 29:1 [ear live bee which is arranged in the shape and form of the developinir nerve fibre. The cells elongate, the nuclei increase in number, and the protoplasm and cell contents become trans- formed into the different parts of the nerve fibre — viz, the sheath, white substance of Schwann, and axis cylinder or " band of Remak." In the nerve centres the cells remain in their primitive state, the only change being that they in- crease in size, and dcvelope in their interior some pigmentary granules. In the process of regeneration, after incision or injury,, the extremities of the nerves are united at first by fibrous tissue, which after a time is replaced by nerve tissue, if the cut extremities are not too far removeil. Perfect restoration of the action of the nerve, however, does not generally take place, owing probably to the want of exact coaptation between the cerebral and peripheral i)ortions of the same fasciculi ; for example, the cerebral portion of a motor fila- ment may unite with the peripheral portion of a sensitive one, and the action of each will be partially neutralized. Vascular Supply. — The blood-vessels supplying a nerve terminate in a minute capillary plexus, disposed similarlj'' to those of muscles, running parallel to the nerve fibres. Thoy are connected together by short transverse branches, forming narrow oblong meshes. Function of the Nervous Centrb:s. — The nervous cen- tres embrace all those parts of the nervous system which contain nerve corpuscles, as the brain, spinal cord, and the ganglia of the cerebro-spinal and sympathetic system. Their function is that of variously disposing and transferring the impressions received through their several sensitive nerves. Nerve fibres, as already stated, are simply conductors of nervovs influence. Nervous centres are not only conduc- tors, but also communicators and reflectors of nervous im- pressions. The brain conducts, communicates, rejiects, and perceives or takes cognizance of impressions. 294 THE NERVOUS SYSTEM. c c a L h m ft* m I f »«■ ■ ffS. till . Conduction. — When an impression is produced on the periphery of a nerve, as, e. g., in the mucous membrane of the intestines by the presence of a portion of food, it is conducted to the adjacent ganglia of the sympathetic, from which a motor impulse returns to the intestines and pro- duces a movement of the muscular coat. If, however, any irritant substance, as a drastic cathartic, be mixed with the food, a stronger impression is produced, and this is con- ducted through the nearest ganglia to others more remote, and from all these, motor impulses proceed which excite a more forcible and widely extended action of the small in- testine ; or the impression may be conducted through the ganglia of the spinal cord, from which motor impulses may proceed to the abdominal and other muscles, producing cramp. Besides, the same morbid impression may be con- ducted through the spinal cord to the cerebrum, where the mind can perceive and take cognizance of it. Communication. — Impressions made on the nervous cen- tres may be cortimunicated from the fibres that brought them to others, and in this communication they may be either transferred or diffused. The transference of im- pressions may be seen in disease of the hip joint. The im- pression made by the disease on the nerves of the hip is conveyed to the spinal cord ; it is thence transferred to the central termination of the nerve fibres of the knee joint ; through these the impression is conducted to the brain, and the mind, referring the sensation to the part from which it is accustomed, through these nerves, to receive impressions, feels as if the pain were in the knee. In the same way, when the sun's rays fall strongly on the retina, a tickling may be felt in the nose, causing sneezing ; or irritation in any part of the respiratory organs gives rise to a sensation of tickling in the glottis, and produces coughing. Wiien an impression received at a nervous centre is transferred to many other fibres in the same centre, it is said to be dif- fused, the sensation extending far beyond the part from REFLEX ACTION. 295 ■ay, ing in ion len to lif- lorn whicli the primary impression proceeded, as is seen in tooth- ache, in which the adjoining teeth and surrounding parts are similarly aftected. The pain caused by the presence of a calculus in the ureter or bladder, is diffused far and wide. Reflection or Reflex Action. — The reflection of im- pressions exhibits an important function common to all ner- vous centres, and is the source of all reflex moA eraents. The preceding examples are all instances of reflecMon, or reflex action, for the manifestation of which three conditions are necessary. First, sensitive nerve flbres, to convey an im- pression. Secondly, a nervous centre, to which the im- })ression may be conveyed, and in which it may be reflected. Thirdly, motor nerve flbres, upon which this impression may be conducted to the contracting tissue (Fig. 104). If any of these conditions be absent, a proper reflex action cannot take place. They are all involuntary, and in health they have a distinct purpose L subserve in the animal economy, as in the movements of the intestines, the respiratory organs, con- traction of the pupils, closure of the glottis, etc. ; but in disease many of them are irregular and purposeless, as in chorea, convulsions, etc. Reflex actions may be divided into primary, and secondary or acquired. As instances of the former, may be mentioned sucking in infants, contraction of the pupil, etc. ; and of the latter, walking, reading, and writing. Nerve Force (vis nervosa). — The special endowment by which nerves act and manifest their vitality is a peculiar one inherent in the structure and constitution of the nervous substance. It manife,sts itself in its effects on the muscles, in sensation, secretion, excretion, nutrition, etc. Nervous force, though not identical, presents many points of resem- blance to Voltaic electricity. For the production of the latter, the ordinary requisites are two dissimilar metals, as zinc and platinum or copper, and an interposed' compound fluid, as dilute sulphuric acid. When these metals are placed in contact with each other, chemical action com- T 296 THE NERVOUS SYSTEM. c c L CSV mences, a current sets in a definite direction, and a state of 'polarity or electrical tension is produced. The produc- tion of nervous force, or nervous polarity, may have as anal- ogues two kinds of nervous matter, cells and fibres, and the presence of a fluid. From the structure and peculiarity of the nervous centres, there is much to justify the opinion that each nerve vesicle, and fibre connected with it, together with the blood-vessels and fluid surrounding them, is a distinct apparatus for the "development of nervous polarity. The whole nervous sys- tem is therefore in a constant state of nervous polarity, and is prepared at any moment to receive, conduct, or communi- cate impressions, or convey motor impulses. A slight me- chanical or chemical stimulus to a nerve, is capable of pro- ducing in it a state of polarity, and rendering it capable of conducting impressions or motor impulse ; e. g., pain is ex- cited by touching a sensitive nc^ve, and contractions may be produced by irritating the motor nerve of an amputated limb. THE SPINAL CORD. The spinal cord is n cylindrical column of nerve substance, connected above wii i the brain, through the medulla ob- longata, and terminati lielow — opposite the first or second lumbar vertebra — in a slender filament of grey substance, {\\Q filunn terminale, which lies among the leash of nerves forming the cauda equina. It presents two enlargements, one in the cervical region, extending from the third cervical to the first dorsal vertebra, and the other in the lumbar, op- posite the last dorsal or first lumbar. The spinal cord con- sists of two symmetrical halves, united in the middle line by a commissure. They are separated in front and behind by a vertical fissure, the posterior fissure being deeper, but narrower than the anterior. On each side of the anterior fissure, a linear series of foramina may be seen, from which emerge the anterior roots of the spinal nerves ; this is the STRUCTURE OF THE CORD. 297 irce, ob- 2ond mce, •ves mts, deal op- Icoa- Jline bind I but trior lich the BO-called anterior lateral Jiaaare of the cord. On each side, near the posterior part of tlie cord, and corresponding with the posterior roots of the spinal nerves, may be seen a deli- cate fissure, the posterior lateral fissure. On each side, n,nd near the posterior fissure, is a sli^-ht longitudinal furrow — the posterior rtiedio-lateral fissttre. These fissures divide each half of the cord into four columns, anterior, lateral, posterior and posterior median columns. The anterior col- umn is situated between the anterior median and the ante- rior lateral fissures. It is continuous with the anterior pyr- amid of the medulla oblongata, in which decussation of the anterior columns takes place. The lateral column is situ- ated between the anterior laterals nd posterior lateral fissures, and is continuous above with the lateral tract of the medulla. The posterior column is situated between the posterior lateral and the posterior medio-lateral fissures, and is con- tinuous with the restiform body of the medulla. The 2)ost- erior median column is a narrow segment situated between the posterior medio-lateral and the posterior median fissures, and is continuous above with the posterior pyramid of the medulla oblongata. Structure of the Cord. — The cord consists of fibrous and vesicular, or white and grey nervous substance ; the former is more extensive, and situated externally ; the latter occupies the centre, and consists of two crescentic masses, connected together by a transverse band, the gray commis- sure. In the centre of this commissure, and extending the whole length or the cord, is a minute canal lined by colum- nar ciliated epithelium, which communicates above with the fourth ventricle. Both in front of and behind the gray commissure is a transverse band of white substance, the anterior and posterior white commissures; these connect the white substance of each lateral half of the cord, and form the floor of the anterior and posterior median fissures respectively. Each crescentic mass of gray matter presents an anterior and a posterior horn ; the former is short and 298 THE NERVOUS SYSTEM 4-; ".V r Mr> thick, and does not quite reach the anterior lateral fissure ; the latter is long and slender, and extends to the posterior lateral fissure. The anterior roots of the spinal nerves are connected with the anterior horn, and the posterior roots with the posterior horn. The white substance of the cord A, the anterior median fissure; B, jiostorior median fissure ; C, anterior lateral depression, over which the anterior nerve-roots are seen to spread ; D, posterior lateral ffroovc, into which the posterior roots are seen to sink ; JO, anterior roots passinff the (janfflion ; k, the anterior root divided ; F, the i)osterior roots, the fihres of which pass into the ganglion; G, the united or com- pound nerve, and its division into anterior and posterior branches. consists of transverse, oblique, and longitudinal nerve fibres, blood-vessels and areolar tissue ; and the gray substance consists of smaller nerve fibres, nerve cells, blood-vessels, and delicate areolar tissue (neuroglia). There are a number of large multipolar nerve cells in the anterior and posterior cornu, and also midway between the two cornu, near the external surface of gray matter. Spinal Nerves. — The spinal nerves consist of thirty-one pairs, issuing from the sides of the whole length of the cord. Each nerve arises by two roots, an anterior or motor, and a posterior or sensitive. The posterior root is larger than the anterior root, (except the first), and has a ganglion developed on it (Fig. 105). Immediately beyond this gan- glion the two roots coalesce, and the trunk thus formed passes through the intervertebral foramen, after which it again divides into two branches, an anterior, which supplies the anterior surface of the body and the extremitie.s, and a posterior, which supplies the posterior part of the body, each branch containing fibres from both roots. The ante- rior roots arise from the antero-lateral columns, and are also FUNCTION OF THE SPINAL CORD. 299 rty-one of the jmotor, larger Inoflion Is gan- lormed licli it [pplies and a [body, I ante- also connected with the anterior horn of the gray substance, and the multipolar cells found connected with it ; and the post- erior roots arise from the posterior part of the lateral col- umn and the posterior horns of the gray substance ; the former consist exclusively of motor fibres, and the latter exclusively of sensitive fibres. Function of the Spinal Cord. — The spinal cord trans- mits impr ssions from the periphery to the brain, and also enables the latter to bring into action the motor nerves. Division of, or injury to the spinal cord, causes an interrup- tion of voluntary motion and sensation in those parts sup- plied by nerves below the part affected, while the functions of the parts above remain unimpaired. But though»the in- fluence of the brain in receiving sensation, and exciting vol- untary motion is cut otF or interrupted, the portions of the cord below the affected part still possess excito-motor action, and hence the cord may be regarded as a nervous centre ; for example, in cases of paralysis, muscular action may be excited by tickling the palms of the hands, or soles of the feet with a feather. It has been shown, by experiment, that irritation to the anterior columns of the cord is fol- lowed by convulsive movements of all the parts supplied with motor nerves below the irritated part, but no signs of pain are manifested ; while irritation of the posterior col- umns appears to cause excruciating pain, without producing any muscular movement besides such as may be produced by the will or reflection. Again, when the spinal cord is completely severed, irritation of the posterior columns of the severed part produces no effect ; but irritation of the anterior columns is followed by violent movements. On the other hand, irritation of the posterior columns of the portion of the cord connected with the brain causes acute pain and reflex movements ; while irritation of the anterior columns of the same produces no effect. Again, when both anterior columns alone are divided, the power of voluntary motion is lost in parts below, the sensibility remaining per- 17 300 THE NERVOUS SYSTEM. c c I. V m. •» I. "v & IW ■ ffij till . feet ; and when both posterior columns are divided, sensation is lost in the parts below, the power of motion remaining unimi)aired. From this it would appear that the anterior columns are motor, and the posterior sensitive ; nevertheless, the result of injuries, and disease of different parts of the cord, arc not always in accordance with, but in some in- stances directly contrary to it ; for example, cases have been seen in which comi)lete loss of motion occurred without any impairment of sensation, as the result of lesion of the pos- terior columns of the cord, the anterior being wliolly intact. Injuries to the posterior columns are invariably attended with hyperoisthesia (Brown-Sequard). The spinal cord has a crossed action for both motion and sensation ; for example, in cerebral apoplexy the paralysis and loss of sensation are always on the side opposite to that on which the lesion has taken place. The decussation of the fibres of motion occurs between the anterior pyramids of the medulla oblongata and the opposite lateral columns of the cord and may be seen with the naked eye, (Fig. 105). The discovery of the crossed action for sensation is due to Brown Sequard. His experiments show that a decussation •of sensitive impressions takes place between the posterior columns throughout the whole extent of the cord. The sensitive impressions reaching the cord, ascend for a short distance, and ultimately pass across to the opposite side of the spinal cord to reach the brain, so that if the posterior column of one side be impaired, sensation is lost on the op- posite side of the body. The spinal cord,'as a nerve centre, or aggregate of many nervous centres, has the power of conducting and commu- nicating or transferring impressions received, and of ex- Jiibiting rejiex action. The two former have been already referred to in a general way. Impressions are conducted through the gray matter of the cord, there being in all pro- bability, separate parts for conducting motor and sensory impressions. The spinal cord does not posess any power of isation mining .nterior theless, of the me in- ^e been )ut any ,he pos- r intact, ttended ion and aralysis 3 to that lation of yramids iumns of ig. 105). due to ssation (osterior The short side of losterior the op- many XommU' of ex- ilready Wucted ill pro- ^ensory )wer of FUNCTION OF THE SPINAL CORD. 801 autorruUic or independent action, like the higher nerve centres. The reflex function oi the spinal cord is essentially similar to that of all the other nervous centres, and may or may not be under the control of the will. In health the will can, in a great degree, control and prevent the development of reflex actions in the extremities. If ou^ of the leffs be paralyzed, as in hemiplegia from disease of the brain, and a stimulus be applied to the sole of the foot in the paralyzed limb, reflex actions are readily produced ; but on applying the same stimulus to the sound limb, no such movements occur, the patient being able to resist the ten- dency to action which it produces. In cases of paraplegia from disease of the spinal cord, even where the loss of motion and sensation is complete, patients are sometimes tormented with involuntary movements of the lower extremities at night, which not only prevent sleep, but also occasion pain and distress. It is no doubt caused by irritation at the seat of the lesion. The reflex action of the spinal cord is essentially involun- tary ; for example, the respiratory movements are performed while the mind is occupied, or during sleep or anaesthesia ; yet, the mind can by a voluntary act direct and strengthen them, and adapt them to the several acts of _j)eech, effort, etc. Some reflex actions may be controlled, or entirely pre- vented by the will, which thus exercises an inhibitory action over them ; for example, when the sole of the foot is tickled we can by an act of the will control the reflex action which it occasions. When the limb is pinched or pricked, it is in- voluntarily withdrawn from the instrumentof injury,and the e3'e is involuntarily closed when a blow on the face is threat- ened; but both these reflex actions may be controlled by an effbrtof the will. Many reflex actions are entirely involuntary as for example, the contraction of the pupil, the movements of the intestines (except defecation), the action of the uterus in parturition, etc. 302 THE NERVOUS SYSTEM. c t n I. I' »• «\ «1 II- ini ' •»> KKX The spinal cord, with its encephalic prolongation, may be said to supply, by its reflex power, the conditions requisite for the maintenance of the various muscular movements which are essential to the continuance of the organic pro- cesses ; and, as Marshall Hall has pointed out, it especially governs the various orifices of ingress and egress. Thus, the act of deglutition is entirely dependent on the spinal axis (medulla),and the nerves proceeding from it. The action of the cardiac and pyloric orifices of the stomach is wholly regulated without the consent of the will. The movements of the intestines are influenced by the spinal cord through the sympathetic system. The sphincter ani and sphincter vesicae are under its influence, although partly subject to the control of the will. The reflex action of the spinal cord is also exhibited in the ex])ulsion of the generative products as the semen, in defecation, micturition, and in par- turition in its second stage. The phenomena of spinal reflex action in man are more marked in disease than in health ; e. g„ in tetanus a slight touch on the skin, or a breath of air, is sufficient to throw the whole body into convulsions ; a similar state is induced by the introduction of strychnine or opium in frogs. In these instances, the spinal cord is in a state of polar excite- ment, and is kept so b}' the constant irritation propagated to it by the wounded part, on the one hand, or the poison- ous substance circulating in the blood, on the other, there being no inflammatory or congested condition either of the cord or its membranes. The spinal cord is constantly in activity ; in all periods and phases of life, the movements which are essential to its continued maintenance are kept up without sensible effort. " The spinal system never sleeps ; " it is the brain alone which is torpid during sleep,and whose functions are affected by this torpidity. It has, however, its periods of momen- tary rest, similar to other organs of the body, as the heart, lungs, etc., which appear to be constantly in action. ENCEPHALON. 303 more jriods I to its iifort. lalone lected imen- leart, Ki''. 10(1 ENCEPHALON. The encephalon is situated in the cranial cavity, and consists of the medulla oblongata, 'pons Varolii, cerebellum and cerebrum. Medulla Oblongata. — The medulla oblongata is the cephalic prolongation of the spinal cord, and connects it with the brain. It is larger than the spinal cord, and is divided into segments, which are continuous with the columns of the spinal cord below. It is separated into two lateral halves by fissures, which cor- respond with the anterior and posterior fissures of the cord ; and each lateral half is again subdivided by minor grooves into four columns, the anterior pyramid, lateral tract and olivary body, resti- forvibody a.nd posterior pyra- mid. These are continuous with the anterior, lateral, posterior, and posterior me- dian columns of the spinal cord respectively. Structure. — ThQanterior pyramid is c omposed entirely *; ' ^ Aiitoriui- view of thu iiieilulla •.lilon.;ata of white fibres derived from 'i'"' I'O"** Viuoiii. \. infuiuiibuiuin ; •>., tuber fiiiureum ; 3, corpora albicaiitia ; 4, cerebral the anterior column of the r<=rtuncle ; 5, pons varolii ; e, origin of the middle peduncle of the cerebellum ; 7, cord of its own side, and from nntcriormiramUho/themedulla oblongata; 8, decussation of the anterior pyramids; the lateral C lumns of the ^' 'I'^^^'J/ bodies ,• lO, rcsti/orm bodies ; 11, arci/orm fibres; 12, upper extremity of the opposite half of the OOrd, and ^P"',*1 «=°'''1 -.l^, liga-uentum denticulatum ; '^ '■ '14, dura mater of the cord ; Ifi, optic tracts ; is continued upwards into 1«. "Ptic conimlssure or chiasni ; 17. motor r .V .. ociili ; IS, ])athetic ; If), fifth nerve ; 20, ab- the eerebrnm and PPrpbplbim dni-'ons ; 21, facial; 22, auditory ; (2:5, nerve tue V^eieuiumdUU CCieueiiUm. ^f Wrlsberg); 24, glosso-pharyngeal ; 25, Thp PPrpbpllnr fil-»rp« i->n>a« pneumogastric; 2(i, 2C, spinal accessory ; 27, ±lie Leieueildl noreS pass hypoglossal ; 28, 21), cervical nerves. (Sappcy). beneath the olivary body, join the restiform body and sot THE NERVOUS SYSTEM. c c c L !• •I m, I • IV' n«'. («. spread out in tho corobelluin;somo of the cerebral fibres in- close the olivary body and enter the pons as the olivary fas- ciculus, but the niasH of the fibres enter the pons Varolii in their pansage upwards to the cerebrum. The decussation between the anterior pyramids n»ay bo distinctly seen with the naked eye. Tiie lateral tract is continuous with the lateral column of the cord. Its fibres pass in three different directions ; the external join the restiform body, and pass to the cerebellum^ the internal pass forwards, pushing aside the fibres of the anterior column, and form part of the o[)posite anterior pyramid, and the middle fibres ascend to the cerebrum, forming thii fasciculi teretes in the floor of the fourth ven- tricle. The olivary body presents on a transverse section, a whitish substance externally, and a grayish-colored body in the interior — the corpus deniatum — which presents a zig- zag outline, and contains some white substance in the in- terior, which communicates with that on the external sur- face by means of an aperture in its posterior part. The restiform body is continuous below with the posterior column of the cord, and receives some fibres from the lateral and anterior columns ; superiorly, it divides into two fasci- culi ; the external one enters the cerebellum ; the internal one joins the posterior pyramid, and blends with the fasci- culi teretes as it passes up to the cerebrum. The i>osterior 'pyramids are continuous with the posterior median columns of the cord. Opposite the apex of the floor of the fourth ventricle, they present an enlargement {i^ro- cess clavatus), and diverging, form the lateral boundaries of the calamus scriptorium. They then join the external fas- ciculus of the restiform bodies, and pass with them up to the cerebrum. In the lower part of the medulla the gray matter is ar- ranged as in the cord ; but in the upper part it becomes more abundant,, and is disposed apparently with less regularity. FUNCTION OF THE MEDULLA OBLONGATA. 8C5 jsof fas- to ar- Imes less Function of the Medulla Ohlongata. — The general function of the medulla oblongata is similar to that of the spinal cord. It may be regarded as a conductor of impres- sions, in which respect it has a wider extent of function than any other part of the nervous system, since all impressions between the brain and spinal cord ])ass through it. In con- sequence of the decussation of the anterior pyramids, motor impressions proceeding from the bra? i \ pass across to the op- posite side of the spinal cord ; for example, in injury to one side of the head, producing paralysis, the loss of motion is always on the side opposite to that on which the injury was received. Besides the function of conduction, the medulla oblongata, acting as a nervous centre, presides over the functions of respiration, deglutition, etc. The brain of the lower animals may be wholly removed above, ano yet life maj' continue, and the respiratory function be carried on. The same is the case when the spinal cord below the phrenic nerve is removed ; and even when both the brain and spinal cord are removed, the function of respiration may be con- tinued ; but whenever the medulla is wounded the function is instantly arrested, and the animal dies as if asphyxiated. The medulla oblongata may continue to discharge its func- tions as a nervous centre after the power of conduction has ceased to act ; thus, in coma from apoplexy or compression, and in antesthesia from ether or chloroform, patients con- tinue to breathe, although they are wholly insensible. The reflex action of the medulla is peculiar from having a very wide range of connection. The principal centripetal nerves engaged in respiration are the pneumogastrics; but that these are not the only ones may be shown by their division when respiration becomes slower, but is not arrested. The wide range of connection which belongs to the medulla is further shown by the fact that impressions on the surface of the body may induce respiratory movements, as e.g., dashing 306 THE NERVOUS SYSTEM. L Us // cold water on the face or body is instantly followed by a deep inspiration. From the medulla arise the movements required in the act of deglutition. This may be shown by the persistence of the power of deglutition after the removal of the cere- brum and cerebellum, and by its complete arrest when the medulla is injured. The reflex power of the medulla in de- glutition is much simpler and more restricted than in re- spiration. It is also the centre for the movements required in speech anc* *Tiastication ; for the special senses of hearing and taste ; for regulating the action of the heart (p. 212) ; the action of the iris and ciliary muscle ; and the secretion of the saliva. It is likewise the chief vaso-motor centre from which fibres pass down the cord, accompanying the spinal and sympathetic nerves, and are distributed to the blood- vessels (p. 219.) The gray matter in the floor of the fourth ventricle when irritated produces glycosuria, and is there- fore called the diabetic centre (p. 151.) This is probably tlie result merely of stimulating the vaso-motor centre. Pons Varolii. — The pons Varolii, meso-cephalon or tuber annulare, is the bond of union between the cerebrum, cerebellum, and medulla oblongata. In structure it consists of longitudinal and transverse fibres, intermixed with gray matter. The longitudinal fibres are continued up through tlie pons from the anterior pyramids, olivary bodies, lateral and posterior columns of the cord. The transverse fibres connect the two hemispheres of the cerebellum, forming the transverse commissure, and are divided into a superficial and deep layer ; the former passes across the surface of the pons, and the latter, situated deeply, decussates with the longi- tudinal fibres. Function of the Pons —It acts as a conductor and also as a nerve centre. As a conductor it is the channel through v/hich impressions are conveyed from the spinal cord to the .cerebrum and cerebellum, and also between the two hemi- jspheres of the cerebellum. It is the nervous centre for stasis ed by a d in the rsistence Aie cere- hen the la in de- ll in re- required hearing 12) ; the )n of the ;re from e spinal 3 blood- e fourth s there- )robably tre. alon or ebrum, consists th gray irough lateral fibres ing the ial and e pons, longi- d also irough to the hemi- stasis THE CEREBELLUM. 307 find progressiori, and may also be regarded as the connecting link between the different portions of the encephalon, for when the cerebrum and cerebellum are removed in one of the lower animals, it may still have sensation of painful im- pressions and power of motion, (Vulpian.) It is a ner- vous centre for higher and more definite reflex actions than the medulla or any part of the spinal cord — reflex actions of an emotional and instinctive character. In hemiplegia from disease of the corpus striatum, there is paralysis on the opposite side of the body, and paralysis of the face on the same side as that of the body (cognate). This shows that the cranial nerves have a crossed action as well as the spinal nerves. Unilateral disease of the pons Varolii is liable to involve the facial nerve, before decussa- tion has taken place, and the ]»aralysis of the face will then be on the opposite side to that of the body (alternate). Hence in lesions of the brain above or in front of the j)ons, there is cognate paralysis, and in lesions of the pons, iilternate paralysis. Cerebellum. — The cerebellum consists of two lateral herkiispheres connected together by a trar sverse commissure or band, the vermiform process. It is situated in the pos- terior fossa of the cranium, beneath the ])osterior lobes of the cerebrum, from which it is separated by the tentorium oerebelli. It is oblong in shape, measuring from three and a half to four inches transversely ; from two to two and a half from before backwards, and two inches in thickness, and weighs from five to six ounces. Each hemisphere is divided into several lobes, of diffei'ent sizes, and its surface is marked by numerous curved furrows or sulci, which vary in depth in difierent parts. Its surface is covered by the pia mater. Structure. — It consists of gray and white matter ; the former, darker than that of the cerebrum, occupies the sur- face ; the latter the interior. When divided vertically it is •seen to consist of a central stem of white matter, which con- .M08 THE NERVOUS SYSTEM. t c I. I- ■1; •». f Si;;. tnr tains in its interior a frrayisli mass— tlio corpus «lontatuni. Tho central stoni of white matter sends fortli laminae towards the surface, whicli are surrounded by tlie j?ray matter so thai has been given. A vertical "•^ '"' section of the ^M-ay matter or cortical substance [)>osents the following apjx^ar- ance. Externally is a thick layer of fine connective tissue in which is seen a luntiber of splierical corpuscles like those of the granular layer of the retina; n(>xt is a single layer of branched nerve cells (cells of Varkivjc) i\w branches of which |)ass u|)wards into the external i:^ layer and blend with the corpuscles, U and some single branches downwards. ■(i5>5. Heneath this is tho so-called granular Si^ layer which cousists of a dense layer of rounded cprjniscles, resembling tho voriI7rtr^i^r!7,-^s luiclear layer of the retina ; and lastly a k'^^ISus";.;'":;- 'r;:;uh!]o I l'»y«i- of "^>-ve fibres with a tew scattered pl-iXlM C.'r'or;,;;';';; coVpuscles ; this layer partly belongs to .ibm.witba v.n. ..ut,o,v.i ^|^,, ^^,,,5^^ substanco. The cerebellum is connected with the rest of the en- cephalon by processes or ]>rolongations, called peduncles. These are three in number, tlie superior, middle and iii- fevior. The superior 2)ed uncles connect the cerebellum with the cerebrum. They pass ujnvards beneath the testes to the crura cerebri and optic thalami.each peduncle forming part of the lateral boundar}' of the fourth ventricle. Beneath the corpora quadrigemina the innermost fibres of each pe- duncle decussate with each other, some fibres from one side of the cerebellum conununicating with the opposite side of the cerebrum. The middle peduncles, the largest of the three, connect together the two hemispheres of the cere- bellum, and form the transverse fibres of the pons Varolii. FUNCTION OF THE CEREBELLUM. 300 lirming iiieath 3h pc- side ide of >f the ccre- arolii. Tho inferior 'pednnden (crura C(ircbelli) comiocfc the core- b(ilhirn with tho nioduUa ohlon^^ata. Tlioy pass clown wards to tho l)ack part of the inodulla, and form part of the resti- form hodios. FuNOTFON 01'" TiiK (Ikkkhkllum. — Tho corcbcllum is in- sonsihle to irritation, and may ho cut away withotit causinij pain ; but if any of the crura bo toucliod, pain is instantly felt. Its removal is not attended with ai»y loss or disorder of sensibility ; tho animal can soo, hoar, smell, etc., as before its removal ; but ho has lost tho power of springing, flying, walking, standing, etc., and his actions are like those of a drunken man. The action of its two lialv(!S must always bo balanced, for if oruvhalf of the cerelxiJlum be removed, or one of its crura dividocl, the animal exhibits a tendency to r. ;ver upon its longitudinal axis, and from the side in- jutv;vi. From the above circumstances it would appear, that the function of tho cerebellum is to regulate uTid co-ordinate the muscular Tnovcmtnts of the body. The influence of each half of the cerebellum is directed to muscles on the opposite side of the body. It is also the organ through which tho mind acquires a knowledge of the state and posi- tion of the muscles, and exerts a will upon them — the organ of muscular sense. The ceiobellum is supposed by some to be the organ of sexual instinct, or of amativeness. The facts adduced in favor of it are — 1st, cases in which atrophy of tho testes and loss of sexual passion have resulted from injuries to the cerebellum ; 2nd, disease of the cerebellum has been attended with almost constant erection of the penis, and frequent seminal emissions ; 3rd, that it has seemed possible to esti- mate the degree of sexual passion in different animals by the conjparative size of the cerebellum. In reference to the first class of facts, the loss of sexual passion may have been the consequence of atrophy of the testes, and hence these facts have little bearing on the question, unless it can be shown that the loss of sexual passion followed the injury of SIO THE NERVOUS SYSTEM. c c I. tin f U itv< the cerebellum, before the testes began to diminish. Disease of the cerebellum proves nothing, because the same thing more generally occurs in diseaoe of the medulla and spinal cord. On the other hand, cases are recorded in which the whole of the cerebellum has been disorganized, or completely absent, without loss of the sexual passion. Besides, among animals there is no proportion between the size of the cere- bellum and the development of the sexual passion, and cas- tration in early life is not followed by any diminution of this organ. The cerebellum of the cock is no larger than that of the hen, although the sexual passion is many times greater. The cerebellum in frogs and toads is only a small bar of nerve substance, yet the sexual instinct is very strong. The Cerebrum. — The cerebrum occupies the upper part of the cranial cavity, resting upon the anterior and middle fossae of the base of the skull, and is separated posteriorly from the cerebellum by the tentorium cerebelli. It is ovoid- al in shape, and is divided into two lateral hemispheres, which are connected together by a broad transverse com- missure of white matter — the corpus callosum. The aver- age weight of the brain is about fifty ounces in the male, and forty-five in the female. The weight of the brain in- creases rapidly up to the seventh year, more slowly up to twenty, and still more slowly up to the fortieth year. When it reaches the maximum, it remains stationary for a few years, and then declines as age advances about one ounce for each subsequent decennial period. As a rule, the size of the brain bears a general relation to the intellectual capa- city of the individual. The brain of Cuvier weighed rather more than sixty-four ounces ; Dr. Abercrombie sixty-three; RulofF, a celebrated linguist, executed for murder in 1879, fifty-nine ; James Fisk, Jr., fifty-eight ; Spurzheim fifty-five; Daniel Webster, fifty-three; Agassiz, fifty-three ; Dupuy- tren, forty-nine (Cruveilhier). The brain of the Hon. D'Arcy McGee, the celebrated Canadian statesman, weighed fifty- THE CEREBRUM. 311 Disease me thing id spinal -^hich the mpletely 3, among the cere- and cas- lution of o larger is many is only a t is very )per part d middle isteriorly is ovoid- ispheres, se com- he aver- male, rain iu- up to When a few |e ounce size of d capa- rather -three; 1879, '■-five; Hipuy- 'Arcy fifty- nine ounces. Cromwell's brain was said to have weighed eighty-two ounces, and Byron's seventy-nine ; but these figures are not generally accepted by physiologists. On the other hand, the brain of an idiot seldom weighs more than twenty-three ounces. Wagner, however, mentions a case of an idiot whose brain weighed fifty-four ounces, and Dr. Tuke reports a case in which the brain of a congenital epi- leptic idiot weighed sixty ounces, but these are exceptional. In only two animals is the brain larger than in man, viz., the elephant and the whale. The 'mere comparative size of the brain, or quantity, how- ever, does not always give an accurate measure of the am- ount of mental power, for not unfrequently men possessing large and well-formed heads are seen, whose mental capa- bilities are not greater than those of others whose crania have the same general proportion, but are much smaller. Large brains, with deficient activity, are commonly found in per- sons of a lymphatic temperament ; whilst small brains, and great activity, characterize the sanguine and nervous tem- peraments. The quality of the nerve tissue in regard to fineness of nerve fibres, and cells, the degree of vascularity, and the number and extent of the convolutions, bear an important relation to the intellectual capacity of the indi- vidual. Structure. — The cerebrum consists of two kinds of nerve tissue, the gray and the white ; the former is situated externally, the latter internally. The surface of the cere- brum presents a number of convolutions or foldings, separ- ated from one another by depressions or sulci of various depths. The outer surface of each convolution is composed of gray matter, which is sometimes called the cortical sub- stance, and the interior consists of white matter. The con- volutions are admirably adapted to increase the extent of surface or amount of gray matter, without occupying much additional space. The gray matter of the convolutions, when closely examined, however, appears to consist of from 312 THE NERVOUS SYSTEM. c c ^ aw •-ti-*.. iour to six layers of gray and white tissue placed alternately, iVotn two to three layers of p;ray substance, and an equal number of white ; the latter occuj)ying the surface. A vertical section of these layers presents the api)earance represented in the accompanying figure: 1st, horizon- tal transverse and ol)lique nerve fibres ; 2nd, a layer of fibres with a few nerve cells ; 3rd, a layer with numerous cells of different shapes ; 4th, a layer consisting of pyramidal cells, with their bases down- wards, characteristic of the cerebrum; they receive two processes at their inferior extremity, and give off one upwards, and are interspersed among radiating nerve fi- bres; 5th, a narrow layer with irregular cells like those of the cerebellum ; 6th, a broad layer with irregular and fusiform cells. The sulci are generally about an inch in depth ; but they vary in different brains, and in different parts of the same brain, being usually deepest on the outer surface of the hemispheres. The convolu- tions of the brain are the centre of intel- lectual action, and their number and ex- tent and the depth of the sulci, bear a close relation to the intellectual power of the individual. The}' are entirely absent in some of the lower orders of mammalia, and increase in number and extent as we ascend the scale. The largest and most constant convolutions of the human brain are the convolutions of the corpus cal- losum, supra-orbital convolutions, and the convolutions of the longitudinal fissure. Each hemisphere is divided into five lobes : the frontal, (F), 'parietal (P), teraporo -sphenoidal (T), occipital (O), and central lobe, or island of Reil, which are separated from Vertical section of the cortical substance of the cerebrum ; i)ni, jiia mater ; c, capillaries ; nc, nerve cells in the neuroglia ; pc, pyrami- dal cells (SehoflelU;. STRUCTURE OF THE CEREBRUM. 313 M-natcly, n equal :cui)ying 3f these resented horizon ■ ) fibres ; w nerve 3 cells of listing of ;s down- ura ; they inferior irds, and nerve fi- ir regular n ; 6th, a fusiform ibout an different the same ihe outer couvolu- of intel- and ex- :i, bear a dividual, lorders of e ascend lutions of •pus cal- utions of frontal, (O), and Ited from I'ach other by the following fissures : the fissure of Sylviua, i'^), fissure of Rolando (central fissure) (c), and parieto-occi- V, frontal loue ; F, parietal lobe ; I), occipital lobe; T, temporo-spheiioiilal lobe ; S, fis- sure of Sylvius ; S', horizontal, S", ascendiiifr ramus of the same ; c, sulcus centralis (fis- sure of Rolando) ; f 1, superior, f2, inferior ; f3, praicentral fissure ; ip, interparietal fissure ; po, parieto-occipital fissure ; tl, first ; t2, second temporo-sphenoidal fissures (Eclier). pital fissure (po). (Fig. 108.) The lobes are again sub- divided into lobules. The frontal lobe is bounded behind by fissure of Rolando, and below by the fissure of Sylvius ; the parietal lobe, in front by the fissure of Rolando, and be- hind by the parieto-occipital fissure, which in man appears as a notch in the inner margin of the hemisphere ; the tem- poro-sphenoidal lobe is situated beneath the horizontal branch of the fissure of Sylvius ; the occipital lobe is situated be- liind the parieto-occipital fissure ; and the central lobe, or island of Reil, is situated upon the under surface of the 314 THE NERVOUS SYSTEM. c c c I. ^ ■\ ■HI. I 6 IBT' anterior part of the cerebrum at the bifurcation of the fis- sure of Sylvius. The under surface of the frontal lobe occupies the anterior fossa of the base of the cranium, the parietal and temporo-sphenoidal the middle fossa, and the occipital the posterior fossa. They were formerly named anterior, middle, and posterior lobes respectively. The figures in the accompanyinjy diagram of the human brain are made to correspond with the areas of the brain of the monkey as determined by the experiments of Ferrier, and the effects of stimulating the various areas refers to the brain of the monkey. 1 (On the superior parietal lobule). Movement of the opposite hind foot as in walking. 2, 3, 4, (The fissure of Rolando). Complex movements of the opposite leg and arm, and of the trunk, as in swimming. a, 6, c, d, (Postero-parietal convolution). Combined move- ments of the fingers and wrist of the opposite hand, closure of the fist, and prehensile movements, 5, (Superior frontal convolution). Extension forward of .the opposite arm. 6; (Upper part of the antero-parietal convolution). Sup- ination and flexion of the opposite forearm. 7, (Median portion of the same convolution). Elevation of the opposite angle of the mouth — zygomatic action. 8, (Lower down on the same convolution). Elevation of the ala nasi and upper lip, and depression of lower, on the opposite side. 9, 10, (Inferior extremity of the same convolution, Broca's convolution). Opening of the mouth with (9) protrusion and (10) retraction of the tongue. Region of aphasia. Bi- lateral action. 11, (Between (10) and postero-parietal convolution). Ac- tion of jilatysma. 12, (Posterior portions of superior and middle frontal con- volutions). Elevation of eyelids, the pupils dilate, and the head turns toward the opposite side. gf STRUCTURE OF THE CEREBRUM. 315 i-d of Sup- sroca s irusion Bi- Ac- il con- id the 13, 13', (Supra-marginal lobule and angular gyrus). The eyes turn to the opposite side with an upward (13) or down- ward (13') deviation. The pupils generally contracted, {Centre of vision.) 14, (Superior temporo-spheuoidal convolution). Pricking of the opposite ear, the head turns to the oppo dte side, and the puj)ils are dilated. {Centre of heav'iny.) Fenier places the centres of ta.ste and smell at the ex- tremity of the temporo-sphenoidal lobe, and that of touch in the gyrus uneinatus and hippocampus major. The points of dilierencc lietvveen the brain of man and the aj)eH, and tliose of all other animals, consist in the rudi- mentary character of the olfactoiy lobes, the well-duhned fissure of Sylvius, the larger size of the po>terior lobe com- pletely covering the cerebellum, and the [)resence of poster- ior cornua in the lateral ventricles. The distinguishing features between the brain of man, and the ape, consist of the larger size of the brain, the greater number and comphixity of the convolutions, and the blunted quadran- gular contour of the frontal lobes in man ; and the greater prominence of the temporo-sphenoidal lobe, the distinctness of the parieto-occipital fissure, and the upward oblique di- rection of the fissure of Sylvius in the ape. The white matter of the cerebrum consi'.ts of three kinds of tibres ; diverging or peduncular, transverse and longitudinal commissural fibres. The diverging or 'peduncular fibres connect the cerebrum with the me- dulla oblongata and spinal cord, and constitute the crura cerebri. Each crus consists of two bundles, super- ficial and deep, separated by a dark gray mass in the interior — the locus niger. The superficial fibres are con- tinued u]) wards from the anterioT- pyramids to the cere- brum. The deep fibres are continued upwards from the lateral and posterior columns of the medulla and the olivary bodies. As the peduncles of the cerebrum enter the hemi- spheres, they diverge from one another to enclose the inter- i8 ^ 31G THE NERVOUS SYSTEM. c «). an I y "11:1 , peduncular 8j)ace, and the fibres of each pass through two large masses of gray matter, the ganglia of the brain, called the thalami optici and coipora striata, which project from the upper and inner side of each peduncle. Above these masses is situated the great transverse commissure — the corpus callosum — which connects the hemispheres together. The space bounded by the ])oduncles and ganglia on the sides, and the corpus callosum above, forms the general ven- tricular cavity. The upper part of the cavity is divided into two lateral ventricles by the .septum lucidura, and the lower part constitutes the third ventricle, which communi- cates above with the lateral ventricles, and behind with the fourth ventricle, through the itn^ a tertio ad quartavi ventri- culum. The Jifth ventricle is situated in the space between the two layers of the septum lucidum. The transverse fibres connect together the two hemispheres, forming the corpus callosum, and the anterior and posterior commissures. The longitudinal fibres connect together difierent parts of the same hemisphere. They form the fornix, ttenia semicircularis, peduncles of the pineal gland, stria? longi- tudinales, gyrus fomicatus, and the fasciculus uncinatus. Vascular Supply. — The blood-vessels of the brain are numerous and capacious, it being supplied by four large ar- teries, the two internal carotids and the two vertebral arteries. These vessels, in their passage, pursue a winding course to reach the brain, the object of which is to increase the extent of the surface over which the blood passes, and thus add to the amount of impediment produced by fric- tion, in order that the supply may be more equable and uniform. These curvatures in the vessels also tend to moderate the force with which the blood may be sent to the brain under certain circumstances, as during great excite- ment, violent exercise, and the like. These vessels also anastomose freely with each other after entering the crani- al cavity. This takes place not only between the smaller branches, but also between the primary trunks ; the former FUNCTION OF THE CEREBRUM. 317 ugh two n, called ect from ve these ire — the together. , on the oral ven- 1 divided and the ammuni- with the 71 ventri- between 7'se fibres le corpus es. 3nt parts X, tsenia IB longi- ncinatus. rain are large ar- ertebral winding increase ises, and by fric- able and tend to nt to the ,t excite- :s also e crani- smaller former is seen all over the surface of the encephalon ; the latter constitutes the well-known circle of Willis. This is form- ed in front by the anterior communicating and anterior cerebral arteries ; on each side, by the trunk of the internal carotid and the jwsterior communicating ; and behind by the posterior cerebral and point of the basilar. These ves- sels divide and subdivide upon the suiface of the brain, until they terminate in very small arteiios, which aie con- nected together by some areolar tissue, constituting the pia mater, from which very small vessels are given off" that l)ierce the brain substance. No large vessels pierce the cerebral substance, except at the perforated spaces ; but prolongations of the pia matter, carrying with them the blood vessels, pass into the interior of the brain at the tran- verse fissure, to form the velum interpositum and choroid plexuses which arc situated in the ventricles. Function of the Cerebrum. — From its anatomical re- lation, the brain does not appear to be one of the essen- tial or fundamental poitions of the nervous system, but is a superadded organ, receiving all its impulses to action from the parts below, and acting upon the body at large through them. But its great size, its position at the summit of the cerebro-spinal system, and the vesicular substance of its convolutions affording a termination to the fibres in connec- tion with it, mark it out as the highest in its functional re- lations, and as the organ through which all the processes of thought, reason, and intelligence are carried on. It is the organ of intellectual action, emotion, ideo-motor action and volition, the seat of which is the gray matter of the convo- lutions. There is a very close correspondence between the relative development of the cerebrum, in the several tribes of verte- brata, and the degree of intelligence they respectively pos- sess. In the lower animals it is difficult to say what part of their actions may be regarded as instinctive and what as intelligent. Intelligent actions are exhibited : 1st, in the 318 THE NERVOUS SYSTEM. c c t L ^ ■I •A IM I f til t M variety of means used to accomplish tlic same enfl.s by dif- ferent individuals, and by the same individual at diffbient times ; 2nd, in the improvemen!; in the mode of accomplish- ing the object, which results from experience; .'hd, in the adaptation of means to altered circumstances. The difi'ei*- ence between the intelligence of lower aninmls and pure in- stinct, is well seen in comparing birds with insects. Their instinctive propensities are nearly similar ; but in the ad- aptation (jf their operations to peculiar circumstances, birds display a ceitain degree of intelligence. Certain tribes of birds, especially the parrot and its allies, are capable of be- ing taught to perform tricks and to pronounce words, in which they exhil)itsim[)le actsof reasoning, similar to those of a child when first learning to talk. Some of the domes- tic animals, as tlie dog and the hoise, manifest a consider- able degree of intelligence. There is no evidence, however, that any of the lower animals have the power of directing their mental operations in obedience to the will. With reference to the sensibility of cerebral matter, it has been ascertained by experiment that no sensation of pain is produced by irritation of the vesicular or fibrous substance. In fracture of the skull, accompanied by pro- trusion of the cerebral matter, it may be excised without exciting either sensation or convulsive motion. When one of the hemispheres is removed from an animal, it is follow- ed V)y temporary weakness of the limbs on the opposite side of the body, and a loss of sight in the opposite eye, but the pupil remains active. When both hemispheres are remov- ed from a j)igeon, the animal remains motionless and, ap- pears to be in a sleepy state, from which it cannot be fully aroused, but consciousness still remain-:!, the persistence of which proves that the cerebrum is not its exclusive seat. In the frog removal of the cerebrum is attended with simi- lar results. The animal remains motionless unless when disturbed. It sits up naturally and breathes quietly ; but when pricked it jumps away, or thrown into the water it FUNCTION OF THE CEREBRUM. 319 by aii- Hff'eront iinj)lish- , in tho e difi'or- |)ure in- Their tliu atl- es, binls tribes of e of be- rords, ill to those 3 domes- lonsider- lowever, lirecting jr, it has tion of fibrous by pro- witbout len one foUow- Isito bide but the lemov- irid, ap- e fully ence of |ve seat. h simi- when y; but ater it swiuis. In this state a reptile or bird may survive many weeks if its physieal wants bo supplied. The influence of disease on the cerebrum is somewhat anomalous. In some instances extensive disease has occurred in one hemisphere, without any obvious injury to the mental powers, or inter- ruption of the influence of the mind on tho body ; Vjut mor- bid phenomena are invariably i)rcsent when both hemispheres are att'ected. On the other hand a .sudden lesion, although of a trifling character, may occasion very severe symptoms; for example, a slight eft'usion of blood in or around the substance of the corpus striatum is followed by paralysis and loss of sensation in the opposite side of the body. Although there are two hemispheres, and each ap- ])ears capable of discharging in a general way the functions of both, yet the mind combines the impressions derived from both, and the ideas or impiessions become single. The theory is steadily gaining ground that each faculty of the mind has a special portion of the brain appropriated to it, just as other com})ound organs or sj'Stems in the body, in wliich each has its special function. This is supported by the difference in the mental functions in different indi- viduals, and at different periods of life ; also by the phe- nomena of some forms of " ^ sanity. In the latter it is not often that all the faculties are disordered ; some are increas- ed while others are diminished. The phenomena of dreams, in which some of the faculties appear to be awake, while others are at rest, also support this view to some extent. In cases of hemiplegia, in which the posterior part of the third frontal convolution of the left side is diseased, it is frequently associated with ajyha/iia or loss of power of ex- pressing ideas in language. It has therefore been inferred that this portion of the brain is the centre for language, or rather that its healthy condition is essential to the faculty of speech. The empirical method by which Gall first fixed upon certain parts of the brain as the seat of cer- tain faculties, is exposed to the serious fallacy that a part 320 THE NERVOUS SYSTEM. c c c L am I >** I on the surface of the brain may appear largely developed in consequence of the large size of some subjacent or neigh- boring part, — for example, a thick neck and large occipital region may indicate a large pons and medulla more fre- quently than a large cerebellum. Again, with respect to the cranium itself, large prominences just above the eye- brows may indicate large frontal sinuses rather tiian a large development of " certain organs " on the anterior lobes of the cerebrum. Gall divided the whole cerebrum into twenty-seven dift'eront organs to represent different facul- ties, and Spurzheim divided it into thirty-five. In some diseases, as for example, in typoid fever, the mind is more or lessobtunded,and unable tocombine the impressions receiv- ed through both hemispheres, and the patient fancies him- self as two individuals. He also sometimes holds converse with the alter ego he fancies is lying alongside of him and constitutes a part of himself, or requests some attention to be given to the person beside him, when in reality the at- tentions are required for himself. The capacity for performing mental acts is known as the intellect, or reasoning power ; and the capacities for those various forms of intellectual activity which pertain to the mind are called the intellectual faculties. These are per- ception, imagination, memory and judgment. When impressions are made upon some part of the body that is supplied with afferent nerves, they are transmitted through them to the sensorium, and occasion affections of the con- sciousness, which are called sensations' Every impression which affects the consciousness produces some change in the nervous centre, by which that impression is perpetuated in such a manner as to permit of its being again called up before the mind at any future time. The nature of the change by which sensory impressions are thus registered is not understood, and probably never will be. The acuteness with which particular sensations are felt, depends on the degree of attention they receive from the mind ; for FUNCTION OF THE CEREBRUM. 321 ?veloped >r neigh- occipital iiore fre- specfc to the eye- ri a large lobes of urn into nt facul- In some is more IS receiv- ;ies him- converse him and ention to y the at- m as the or those to the are 'per- When that is through ;he con- press ion tange in aetuated ailed up of the stei'ed is cuteness on the ad ; for example, ordinary impressions are not felt during sleep, or when the mind is engaged in some deep subject of study. On the other hand, impressions which are in themselves very slight may produce painful sensations, when the mind is directed strongly towards them. They are also much modified by the influence of habit. Sensations not attended to bec(jme blunted by frequent repetition ; whilst sensations attended to become much more readily cognizable by the mind. Every student knows that the efliuvia of the dissecting room becomes tolerable, after the nose has become habituated to it. In some instances, sensations may be produced by in- ternal causes ; these are called subjective sensations, in contradistinction to objective, which are caused by a real material object. The most common cause of these sub- jective sensations is congestion or inflammation ; e. g., con- gestion in the nerves of common sensation gives rise to pain or uneasiness ; in the retina or optic nerve, it produces " flashes of light ; " and in the auditory nerve it occasions "a noise in the ears." Again, subjective sensations may be produced by sensations originating in objective impres- sions on other parts, as e. g., a calculus in the bladder gives rise to pain in the glans penis ; disease of the hip occasions pain in the knee. The mental recognition of the cause of sensation is called perception. For the production of a sensation a conscious state of the mind is all that is required ; but for the exercise of the perceptive power, the mind must be directed towards the sensation, and hence, when the mind is inactive, or engaged in study, the sensation may not be perceived or remembered. The perception of sensation gives rise to ideas; some of these partake of the nature of feeling ; others relate to knowledge. An idea is a mental rej)resenta- tion of an object which has been perceived by the mind— ^ something grasped by the mind, and held up before it is an intelligible object of contemplation. Ideas may be com- 322 THE NERVOUS SYSTEM. c t Mm •V m. t c ft* Ifc' II ei %i I' '•"(> inr. Hi.. (» raunicated and rendered intelligible to other minds by means of visible signs, or by spoken language, in w^'^h certain combinations of sounds are used to express ideas ; and the nearer the signs or sounds employed are to the natural expressions of the ideas which the}'^ represent, the more readily are they comprehended. When ideas are associated with feelings of pain or pleasure, they give rise to emotions. These, unlike ideas, cannot be communicated or expressed in language to others; they are unutterable. Those emotional states of the mind which determine a great part of the conduct of individuals, are the result of the attachment of the feelings of pleasure and pain, and of other forms of emotional sensibility to certain classes of ideas. Thus, grief is the painful con- templation of loss, misfortune, or evils of any kind. Jo^/ is the pleasurable feeling which accompanies success, good fortune, or good jnospects, etc. Fear is a painful emotion excited by an expectation of future evil. Hope is the pleasurable exnectation of future enjoyment. Benevolence is the pleasurable contemplation of doing good to others. Malevolence is a positive pleasure in the contemplation of the misfortunes of others, and so on. The emotions are partly under the control of the will, and partly independent of it. The determining power of the ivill acts both upon the body and the mind ; but the only sensible effect which the strongest effort of volition can produce on the bodily frame is that of contraction of the voluntary muscles. The im- mediate oiieration of the will is not upon the muscles, but upon the biuin, in which it excites nerve force, which is transmitted along the nerves, and stimulates the muscular tissue to contraction. With reference to the action of the will upon the mind, it may be said that it possesses the power of recalling ideas which are present in the mind, ex- cluding some and bringing others more prominently before it. This is effected by the power of voluntary attention. CORPORA QUADRIGEMINA. 323 nds by 1 ideas ; to the ent, the pain or e ideas, ) others; lie mind viducils, pleasure )ility to ful ecn- Joy is 5S, good emotion is the evolence others, itiou of ons are wndent Don the ich the y^ frame he im- es, but lieh is uscular of the es the nd, ex- before ention, which is the chief means through which the sequence of our thoughts is directed by tiie will. When the will is most strongly exerted, it causes the consciousness to be so com- pletely engaged by one train of ideas that the mind is, for the time, incapable of receiving any other idea or impression, the individual being as insensible as if he were in a pro- found sleep. This power of concentration of the mind on the subject of study, is of very great importance and ad- vantage in the acquirement of knowledge and the pursuit of truth, and one which is capable of cultivation to a consider- able extent by habitual exercise. Sometimes the cerebral processes are carried on unconsciously, as for example, when one has tried in vain to remember some particular date, oc- . urrence or name, and has given it up, and hours or days afterwards, it suddenly and unexpectedly flashes across the mind. This is called unconscious cerebration. The crura cerebri are the principal conductors of impres- sions to and from the cerebrum. When one of them is divided, the animal moves round and round on a vertical axis from the injured to the sound side ; this is caused by a partial paralysis on the side opposite the injury. In each crus cerebri is found a small mass of gray substance, the locus niger, from which arises the third cranial nerves, so that this may be looked upon as the nervous centre for the chief movements of the eyeballs. The corpora quadrigemina, including the corpora genicu- lata are the representatives of the optic lobes in birds, reptiles and fishes, and may be considered as centres of the sense of sight, since their removal or diseased condition is accompanied with blindness. Injury or disease on one side is followed by blindness of the opposite eye, and a slight rotatory motion, as after the division of the crus cerebri ; the pupil is also dilated. They are not only the centres from which the optic nerves arise in part, but also the organs through which the mind perceives the sensation of light The centres for co-ordination of the movements of the eye- 324. THE NERVOUS SYSTEM. c t m I I balls, and contraction of the pupil, lie in the nates or anterior tubercles of the corpora quadrigemina. The thalami optici are also concerned to a certain extent in the function of vision, for part of the fibres of the optic tracts may be traced to their surfaces. In persons born blind, the optic thalami, and also the corpora quadrigemina, are found extremely small. Destruction of one of them pro- duces effects similar to those of division of the crus cerebri ; the animal remains standing, and turns continually round. The corpora striata were supposed by Magendie to be the centres of motor power for ^ac/ayanZ moverat.o, and that foTivarcl movement was excited by the cerebellum, these two powers being exactly counterbalanced, and hence divi- sion of the corpora striata caused an irresistible tendency to run forwards. This, however, has not been confirmed by other exjierimenters. Longet and others assert that animals remain stupid and immovable after division of the corpora striata, and it is only when irritated by pinching or pricking that they exhibit any disposition to move. Lesion of both thecorpora striata and optic thalami on one side of the human brain, is attended with loss of sensation and voluntary power on the opposite side of the body and face. The corpora striata are regarded by some as motor, and the optic thalami as sensory ganglia, but this division of functions has not yet been clearly proved. The corpus callosu7)i connects together the two hemi- spheres of the cerebrum. It is entirely absent in birds, reptiles and fishes. Its division is followed by severe general injury. It probably enables the two sides of the brain to act in harmony in the performance of its highest functions. The Mind and its Relation to the Body. — With lefer- ence to the relation of mind and matter, and the nature and source of mental phenomena, there are two theories, that of the materialist and the spirit italist. The material- ist supposes that all the operations of the mind are but sen MIND IN RELATION TO THE BODY. 325 hemi- birds, severe of the " expre.sions of material changes in the brain ;" that thus man is but a thinking machine, his whole conduct being determined by his original constitution, his character being formed for him and not hy him, his actions being simply the result of the reaction of his cerebrum upon the impres- sions which called it into play. According to this doctrine, the highest elevation of man's 'psychical nature is to be at- tained by proper attention to those circumstances which promote his physical development. The arguments in sup- port of this theory are : — 1st, the dependence of the normal activity of the mind upon the healthy nutrition of the brain, and its proper supply of pure blood ; 2nd, the pecul- iar effects of lesions of the brain upon the intellectual oper- ations, as is seen in loss of speech, memory, etc., after severe injury to the head; 3rd, the production of mental imbecility as a result of disease in the parents, or defective nutrition in the offspring during childhood ; and — 4th, the complete perversion of the mind and moral feelings which is pro- duced by intoxicating agents. Now, though this doctrine recognizes some great facts regarding the dependence of mental operations upon the organization and functional activity of the nervous system, yet there is beyond and above all this a self-determining power which can rise above the promptings of external suggestions, and which can suit external circumstances to its own requirements, in- stead of being completely subjugated by them. The spiritualist regards the mind in the light of a separ- ate immaterial existence connected with the body, but not in any way dependent upon it, except as deriving its know- ledge of external things through its agenc}', and as making use of it to execute its determination so far as these relate to material objects. According to this theory, the operations of the mind, having no relation to those of the body, are never affected by its irregularities or defects of functional activity ; and the mind, thus independent of the body, is endowed with a complete power of self-goveiiinient, and is 326 THE NERVOUS SYSTEM. c ^ •V an I f t F ott. responsible for all its actions. But nothing can be more plain than that the introduction of intoxicating agents into the system really perverts the action of the mind, and oc- casions many strange results at variance with its normal action. So that, however true it may be that there is some- thing in our mental constitution beyond and above any agency which can be attributed to matter, the operations of the mind are in a great degree determined by the material conditions with which they are so intimately associated. The whole system of education recognizes the importance of external influences in the formation of the character ; and it is the duty of every teacher to foster the develop- ment and promote the right exercise of that power by which each individual becomes the director of his own conduct. Hence it will be seen th.it any attempt to bring mind and matter into the same category is attended with ditticulty, since no relation of identity can exist between them. But although no relation of identity or analogy subsists between mind and matter, a very close relation may be shown to exist between iniind and fores, or between mind-force and nerve-force. In the phenomena of voluntary movements the will operates upon the nervous matter, and developes nerve-force, the transmission of which along the nerve trunks is the determining cau.se of muscular contraction. Hero is evidence of the excitement of nerve-force by mental agency. The converse of this is equally true, viz., that mental activity may be excited by nerve-force. This is the case in every act in which the mind is excited through the instrumentality of the sensorium ; the impression is first conveyed to the sensorium (or sensory ganglia), in which it produces a certain active condition of the nervous matter, which is the immediate antecedent of all consciousness — whether of emotions or ideas. And since the will can de- velope nerve- force, and as nerve-force can develope mental activity, there must be a correlation between the two forces, not less intimate than that which exists between nerve-force INFLUENCE OF MIND ON THE BODY. 327 and electricity. The nervous matter of the cerebrum is the material substratum through which the metamorphosis of nerve-force iuto mind-force, and mind-force into nerve-force is effected, and like all other changes, every act of the mind involves the disintegration of the nervous substance which ministers to it. The influence of the mind over the body is a most re- markable phenomenon, and one well worthy of attention. Many of its effects are quite familiar ; for example, fear or great anxiety of mind produces a desire for frequent mictu- rition, and not unfrequently the bowels are moved also. The announcement to the patient of the arrival of the ac- couclieur, suspends for a time the labor jiains The sight, or even the thought of very unj)alatable medicine, produces nausea, and sometimes vomiting. Under the influence of the mind, opium pills have been known to produce cathar- sis, when the patient su|)posed that he had taken a cathar- tic. In this way also, persons have been much benefited, and in some instances entirely cured, by the simplest reme- dies. Much of the success of the homoiopathist is no doubt due to this fact. In all modes of treatment, therefore, it is absolutely necessary to have the entire confidence of the patient. It has also been observed, that when the mind is directed to any tumor or growth of the body, its increase is greatly accelerated. In consequence of the waste of nerve tissue during its activity, it is necessary that a periodical suspension should take place in order to permit of nutritive regeneration; this is called sleep. In deep sleep there is a state of complete unconsciousness, and the body may remain for a considera- ble time motionless ; but the individual is capable of being- aroused by external impressions. In this it differs from coma, which is generally the result of some pressure upon the brain, in which the patient is incapable of being aroused. The tendency to fall asleep is favored by a succession of dull, monotonous sounds, as a dull, prosy speech or sermon ; 328 THE NERVOUS SYSTEM. c c t L ■u I f t f •«>': "Ml. or by aound.s accompanied by gentle movi'inonts, as is seen in putting infants asleep. Anotiier method is to close the eyes and lix the attention upon some object, or refteat a certain word until the mind becomes completely lost or unconscious. The average amount of sleep required by a healthy adult is about eight hours in twenty-four ; children require more. On some occasions the sleep is more or less distur])ed by dreams. These generally refer to something that has en- gaged the attention previously ; but in some instances they would appear to indicate things that are to happen ; at all events, there is in many instances a singular coincidence between dreams and occin-rences which follow them. An uneasy or anxious state of mind is unfavorable to sleep. It is said that criminals under sentence of death sleep badly while they have hopes of a reprieve, but as soon as they are assured that their death is inevitable, they usually sleep more soundly. Derangement of the digestive organs, or a disturbed state of mind, in some instances, gives rise to a dreaming state called somnambnlisni. In this state the individual acts as if he were awake, and as if all the phenomena presented to him were real. He answers questions rationally and with readiness ; he walks with precision and avoids obstacles ; yet, not unfrequcntly, accidents happen which show that he has not full command of his senses. A state remarkably analogous to somnambulism may be induced in some persons, which has been called mesmerism. The production of this state requires the apparent influence of another individual, who looks directly in the face of the pei'son experimented upon, and makes certain movements before him called 2^(-^sses ; or the person is required to gaze steadfastly upon a piece of metal or other substance held in J hand, until a state of unconsciousness is induced. Re- markable statements have been made, implying that in these cases the faculties are very much exalted, and the peri,.n acquires powers of a superhuman kind. Such state- CRANIAL NERVES. 329 ments, however, are made by those interested in such seances, or by those who are ignorant of the deception re- sorted to in order to obtain notoi'iety. ited to with iiacles ; lat he I ay be wrlsTii. iuence of the enients jO gaze held in Re- hat in nd the state- CRANIAL NERVES. The cranial nerves include those nerves which arise from some part of the cerebro-spiiial contrc and are transmitted through foramina at the base of the brain. There are in reality tw(;lve pairs of cranial nerves, but they are ar- ranged in nine pairs in the following order from before back- wards : — 1st Olfactory 2nd Optic Motor Oculi Pathetic 3rd 4th 5th 6th ^,, f Facial or portio dura ( Auditory or portio mollis C Glosso-pharyngeal 8th < Pnoumofifastric Trifacial or trigemini i. Spinal accessory, Abducens 9th Hypoglossal. The nerves of the 7th and 8th pairs are so combined in their distribution, that it is almost impossible to separate them in either their anatomy or physiology. The cranial nerves may be subdivided into four groups, according to the peculiar function of each, viz., 1st, nerves of special sense, as the olfactory, optic, auditory, the lingual branch of the trifacial, and part of the glosso-pharyngeal ; 2nd, nerves oj common sensation, as the greater portion of the fifth, and part of the glosso-pharyngeal ; 3rd, nerves of motion, as the motor oculi, pathetic, part of the trifacial, abducens, facial, and hypoglossal; and 4!th, mixed nerves, as the pneumogastric and spinal accessory. The olfactory nerve arises from the cerebrum by three roots, and presents a bulbous enlargement which rests upon the cribriform plate of the ethmoid bone, from which delicate filaments are given off which supply the nose. It is the nerve of the special sense of smell. In structure it differs :{:{() THE NERVOUS SYSTEM. from tlio other iiervoH, in boiii^ soft and grayisli in color, and tlcstituto of tlie whito substance of Schwann. Kljf. 1 10, I I £ s; •*» Ol. Kxtonial wall of tlio 110*0. a, 01fttotor.v nerve ; h, olfiictory bulb upon the eribriionn pliile of thoi'lliinoid ; Iil'Iow i.s.sut^ji lliu Uiatiibutioii of the branches uiHiii the iiji|)i>r and tlin niiihlle tiirbiiia od bone» ; c, fifth !n:vve \»;»h Ous- veriun u>ini;lioii ; o, its palatine bnincheb. Tlie ('/>//<; nerve is distributed to tl.e eye, in which it ex- pands to form the internal layer of the retina, and is tlie nt^'ve of the special sense of sight. Division of the optic nerve produces total blindness and dilatation of the pupil, but does not destroy ordinary sensibility or paralyze mus- cular action. The auditory no've (vortio mollis) is the s])ecial nerve of the sense of hearing. It convevs to the brain the sensation of sound, and is incapable of transuiitting any other, being entirel}' destitute of ordinary sensibility. Tlie filarnents Sive distributed to the cochlea, semicircular canals and vestibule. The motor-ocidl is a nerve of motion, and is distributed to all the muscles of the eyeball, except the superior ob- lique and external rectus. It also supplies motor filaments to the circular fibres of the iris. In paralysis of this nerve, the up})er eyelid falls down over the eye, so that it appears half closed {ptosis), the pupil is dilated and insens- TRIFACIAL NERVE. 331 ible to light, tho movements of the oyisball arc nearly sus- pended, and the eye is directed outwards, <)vvin«( to tho action of the external rectus. OwiuLjto the irre<;ularity of the axes of the eyes, double sight is often experienced. The stimulus of light on the retina produces contraction of the circular tibres of the iris, and partial closure of the ])upil. This is a reflex action, the stimulus being conveyed by tho optic nerve to the brain, and thence reflected through the third nerve to tho iris; consequently tho iris ceases to act when cither the optic or third nerve is divided or destroyed^ or the nervous centre injured or compressed. The rad'uUivg fibres of tho iris are supplied by filaments from the fifth cranial nerve and the ophthalmic or ciliary ganglion. The jtaUietic nerve, the smallest of the cranial nerves, is also a nerve of motion distributed to the suj)orior obli(jue muscle. When the nerve is irritated the muscle acts spas- n\odically, and its division causes paralysis and a loss of rotatory motion of the eyeball on its axis, and sometimes double vision The abdacens supplies the external rectus with motor power. Irritation of this nerve produces convulsion of the muscle, and the eye is turned outwards. Division or injury is followed by convergent strabismus. The trifacial nerve closely resembles the spinal nerves. It arises by two roots an anterior, smaller or motor, and a posterior or sensory, wliich has a ganglion (the Gasserian ganglion) developed on it. The functions of this nerve are various ; it is the great sensitive nerve of the head and face ; the motor nerve of the muscles of mastication (except the buccinator), and its lingual branch is one of the nerves of the special sense of taste. This nerve, within the cran- ium, is divided into three branches — the ophthalmic, which passes through the sphenoidal fissure, the superior max- illa'i'y, which passes through the foramen rotundum, and the inferior maxillary, which passes through the forainen ovale. The first and second divisions are purely sensory ; 19 332 THE NERVOUS SYSTEM. c t L I- •»i •V IM I r >>> Mr. (d the third division contains filaments of special sense, sensa- tion and motion. It is the most intensely sensitive nerve in the body, and irritation of its sensory filaments is followed by intense pain. Any irritation to this nerve, or any of its branches, as e. (j., a carious tooth, may give rise to neuralgia of the corresponding side of the face, and in many instances one-half of the tongue is found covered with a white fur, while the other half is perfectly clean. Division of the fifth nerve produces loss of sensibility and motion in the parts supplied by it, and is followed by inflammation of the corresponding eye ; the cornea becomes opaque, and a low destructive inflammation of the conjunctiva, sclerotic, and interior of the eye occurs, which usually goes on to complete and permanent destruction, and sloughing of the organ ; the senses of smell, hearing, and taste, are at the same time im- paired or lost. Injury to the fifth nerve, or some of its branches, is sometimes followed by total blindness in the corresponding eye. These phenomena may be due to the trophic influence of the nerve on these organs, and the defective nutrition which follows its injury. Paralysis of the third nerve may also follow neuralgia of the fifth nerve. The facial newe (fortio dura) supplies all the muscles of the face, the platysma, buccinator, the muscles of the ex- ternal ear, digastric and stylo-hyoid, the palate, stapedius and laxator tympani muscles. It also supplies the parotid gland, and through the chorda tympani it gives branches to the submaxillary gland, lingualis, and other muscles of the tongue. It is a nerve of motion, and not of sensation, and therefore its division, which was formerly resorted to in "ases of tic douloureux, is incapable of relieving neuralgic r »ut is followed by paralysis of the muscles which it les. Division or paralysis of the facial nerve pre- onts the eye from being closed, and its continued exposure to the air, and particles of dust, is apt to produce inflam- mation. The sense of hearing, taste, and smell may also be impaired. In facial paralysis there is an absence of GLOSSO-PHA R YNGEAL NER VE. 333 €xi)re8sion on the affocted side, the angle of the mouth is lower, and the eye has an unmeaning stare. In drinking, the fluids flow out at the corner of the mouth, and the food lodges between the clieek and gums. Wlieu the tongue is paralyzed, it is drawn to the sound side when protruded, in consequence of tiie paralysis of the muscles on the aflected side. The glosso -pharyngeal 7ierve is distributed to the tongue and pharynx, being the nerve of sensation to the mucous membrane of the pharynx, the fauces and tonsil ; of motion to the pha'yngeal muscles, and a special nerve of taste to the posterior part of the tongue. It also supplies filaments to the fenestra ovalis and rotunda, the Eustachian tube, car- otid plexus, and spheno-palatine ganglion. The tongue is supplied by two special nerves — the lingual branch of the fifth, and the glosso-pharyngeal ; the former supplies the anterior and lateral parts of the superior surface, and the latter the posterior and lateral parts. This may be proved by division of either of these nerves, when the sense of taste is lost in the part supplied by the injured nerve. The hypoglossal nerve is a nerve of motion. It is dis- tributed to the muscles which belong to the hyoid bone and tongue, and is concerned in articulation. Irritation of this nerve produces contraction in the muscles supplied by it, and is sometimes attended with pain, the sensibility having been borrowed from the nerves with which it communi- cates. Its division or injury is followed by paralysis. The pneumogastric nerve is one of ihe most remarkable and important in the body. It supplies the pharnyx, epi- glottis, glottis, larynx, trachea, oesophagus, heart, lungs, liver, stomach and spleen. It possesses motor, sensitive and sympathetic or ganglionic nerve fibres, and is therefore regarded as a triple-mixed nerve. The pharyngeal branch is the motor nerve of the muscles of the pharynx ; the superior laryngeal is chiefly sensory, and supplies the mucous mem- brane of the larynx ; the inferior or recurrent laryngeal jll 334 THE NERVOUS SYSTEM. c c I m I r k larr SCI is for the most part motor, and supplies tlie muscles; the oesoj^hageal branches supply its muscular tissue ; the cardi- ac branches constitute a channel through which the influ- ence of the central organs and the emotions of the mind are transmitted to the heart ; the pulmonary branches form a channel through which the impressions on thelungsaro convey- ed to the medulla oblongata; the motor filaments of the pneu- mogastiic nerve supply the motor influence by which the function of deglutition is performed. In the functions of the larynx, the sensitive filaments suppl}'^ that acute sensi- bility by which the glottis is guarded against the ingress of foreign bodies or irrespirable gases. These are instances of " reflex action." The cardiac branches of the pneumogastric have an in- /tivcvO?'?/ or restraining influence upon the heart (p. 212). When divided the heart's action is increased ; while on tlio other hand when stimulated, as by a galvanic cuirent, the heart's action is diminished, or if a strong current be used, it is arrested altogether in diastole. Division of the pneumogastric nerve or its inferior laryn- geal branches produces loss of voice, by paralyzing the riiuscles of the larynx which act upon the vocal chords, Di visioL of the pneumogastric nerves is also followed by a diminution of the frequency of the respiratory movements. In young animals it is often quickly fatal, owing to the closure of the glottis, which is due to the yielding nature of the cartilages; but in older animals death ensues more slowly, owing to the rigidity of the cartilages wdiich surround the glottis. Death takes ])lace in from one to six days after the operation, and is caused by the engorgement of the lungs. They are commonly very much congested, nearly solid, and the bronchial tubes are filled with a frothy, bloody fluid, and mucus. This is due in part to the slowness of the respira- tory movements, the imperfect aeration of the blood, and the accumulation of carbonic acid in the air cells, and also in part to the paralysis of the blood-vessels themselves. ungs. J, and d.and spira- d, and d also elves. PNEUMOGASTRIC NERVE. 335 Since respiration is still carried on after the division of the pneumogastric nerves, it is evident that though they are the chief agents by which the respiratory stimulus is conveyed to the medulla oblongata, they are not the only ones. The secretion of gastric juice is temporarily suspended after division of the pneumogastric nerve, and the digestive function is more or less disturbed in various wavs, but the sensations of hunger and thirst still remain. In many in- stances the food taken by the animal never reaches the stomach owing to the paralysis of the cesophagus, but is re- gurgitated in a few moments afterwards — this action being excited by the influence of the sympathetic nerves. The muscular coat of the stomach is also paralyzed by section of this nerve. Division of the pneumogastric nerve also interferes with the proper function of the liver, and irritation of the cen- tral extremity of the divided nerve is followed by the rapid development of sugar in this organ, probably \sy causing paralysis of the hepatic vaso-motor nerves. The sjnnal accessory nerve arises ])artly from the medul- la oblongata, and jiartly from the spinal cord. It is essen- tially a motor nerve; but it also contains sensitive fibres, and is connected with the ganglion of the pneumogastric. From these circumstances it may be regarded as a mixed nerve. It supplies the sterno-mastoid and trapezius mus- cles, and it is also connected with the vocal movements of the glottis. If the spinal accessory nerve be divided on both sides, or its branch of communication with the pneu- mogastric nerve, the voice is instantly lost, the animal be- ing incapable of uttering a single sound. Division of the pneumogastrics or their inferior laryngeal branches, para- lyzes both the movements of respiration and phonation, while section of the spinal accessory paralyzes the move- ments of phonation alone, or those muscles which nar- row the glottis and ai)proximate the vocal chords, the movements of respiration, which open the glottis and sepa- 336 THE NERVOUS SYSTEM. c t IIB L »» M I rate the vocal chords remaining intact. It may be stated as a general law, that when any part of the body receives nervous lilaments from two different sources, it is for the purpose of enabling it to perform two different functions. This is exemplified in the muscles of the larynx. These muscles are concerned in the respiratory movements, the nervous stimulus for which is conveyed by the facial, hypo- glossal, and pneumogastric nerves; but they are also con- cerned in the formation of the voice, the nervous influence for which is conveyed by the spinal accessory. SYMPATHETIC NERVOUS SYSTEM. The sympathetic system (or nervous system of organic life), is so named because it was formerly supposed to be the system through which distant organs manifested sym- pathy with each other in morbid action. It consists of a series of ganglia connected together by intervening cords, extending on each side of the spinal column, from the base of the skull to the coccyx ; some of the ganglia may also be traced into the cranium. These two gangliated cords lie parallel to one another as far as the coccyx, where they communicate through a single ganglion — ganglion mipar. It is also stated that they communicate at their cephalic extremity through a small ganglion, situated on the anter- ior communicating artery — the ganglion of Ribes. They are arranged as follows : — In the cephalic region there are four ganglia on each side (and the ganglion of Ribes); in the cervical region, three; in the dorsal region, twelve ; in the lumbar region, four ; in the sacral region, five ; and in the coccygeal region, one — the ganglion impar. Each ganglion may be regarded as a distinct centre from and to which, branches pass in various directions, as follows — 1st, communicating branches between the ganglia ; 2nd, communicating branches to the cerebral or spinal nerves ; 3rd, primary branches of distribution to the arteries in the vicinity of the ganglia, to the viscera, or to other ganglia in THE SYMPATHETIC SYSTEM. 337 iu the the thorax, abdomen, and pelvis. The latter consist of two kinds of nerves, the syr)i2iathetic and spinal, and have a remarkable tendency to form intricate plexuses which sur- round bhe blood-vessels, being conducted by them to the viscera. Many of these primary branches, however, pass to a series of ganglia in the thorax and abdomen, the chief of which are the cardiac and semilunar ganglia. Fibres of the sympathetic are distributed to the nonstriated muscular tissue of the intestines and other hollow organs, and to the blood-vessels (vaso-motor nerves) ; to the heart — excito-motor ; and to the various glands. Centripe- tal fibres also pass to the vaso-motor centre in the medulla oblongata. The difference between the cerebro-spinal and sympathetic nerves has been already stated (p. 282). Both kinds of nerves are distributed to ail parts of the body. The ganglia of the sympathetic system are regarded by some writers as reservoirs of nervous force, which they equalize and correctly balance, by storing up all transient excesses, and furnishing all transient deficiencies. In struc- ture they are essentially similar, containing nerve fibres entering and emerging, nerve cells, or ganglion corpuscles, and other corpuscles that appear free (Fig. 08). Comi)lex as the whole sympathetic system appears, however, each of its parts exhibits a wonderful simplicity; for each ganglion with its afi'erent and efferent nerves forms a simple nervous system, and might serve for the illustration of all the ner- vous actions with which the mind is unconnected. Function of the Sympathetic System. — The sympa- thetic nervous system is endowed with sensibility and the power of exciting motion exactly similar to the cerebro- spinal system ; but in the exercise of these functions it is less active. When irritation is applied to a sensitive nerve in one of the extremities, the evidence of pain or motion is acute and instantaneous ; while, on the other hand, irrita- tion of the sympathetic nerve is felt distinctly enough, but is only responded to after somewhat prolonged application. S38 THE NERVOUS SYSTEM. mK^--W C t t tn I I* I c c ^\ m This comports very much with what is known of those organs, supplied chiefly by the sym})athetic system, e. g., the movements of the stomach and intestines are not felt under ordinary circumstances; but any excessive or pro- longed irritation maj' cause them to be exceedingly painful. The general processes which the sympathetic system ap- pears to influence are those of involuntary motion, secretion, and nutrition. The ganglia have the power of conducting, transferring and reflect Ing impressions made on them simi- lar to the cerebro-spinal system, and the sympathetic nerves are conductors of impressions. Parts chiefly suppli- ed with sympathetic nerves are usually capable of only involuntary movements, as, e.g., the heart, stomach and in- testines, and these parts may still continue to move for a short time after the death of the animal. Thus, in the mammalia the heart continues to beat for one or two minutes after it is taken from the body ; in reptiles and amphibia for several houis ; and the peristaltic action of the bowels is continued for a prolonged period. Division of the sympathetic nerve produces immediately a vascular congestion in the parts supplied by it. This was first pointed out by Bernard ; he divided the sym- pathetic nerve of a rabbit in the middle of the neck, and found that congestion of the corresponding side of the head immediately followed, which was most distinctly marked in the ears ; and the venous blood returning from the part had a ruddy hue. The pupil is also contracted and the eye partially closed, ov/ing to the increased sensibility of the retina from vascular congestion of the parts. The conges- tion appears to be caused by the dilatation of the vessels and consequent increased rapidity of the circulation, for when any irritation is a])plied to the divided end of the nerve, the vessels contract and the congestion disappears. The vessels therefore appear to be under the influence of the sympathetic nerves, which accompany them in all their varied distributions and minute ramifications. They are nges- ssels for the Dears, e of their are THE SYMPATHETIC SYSTEM. 339 distributed to the muscular coat of the vessels, the function of which is to regulate the supply of blood to the various organs. The congestion of the vessels caused by division of the sympathetic nerve is also accompanied by an eleva- tion of temjieratiire in the affected part ; this increase of heat has been found as high as 8° to 9°F., and like the vascular congestion, to which it is due, may last a consider- able length of time. The sympathetic system has also some connection with the special senses, especially with the sense of sight. The ophthalmic ganglion gives off' small branches t(i the iris, and receives a communicating motor branch from the third nerve. The contraction of the pupil under the influence of light, and its dilatation in the dark, are affected through this ganglion. With reference to the influence of the sympathetic nerve in the processes of secretion and nutrition, little is known except that it is in great measure connected with the supply of blood to the parts. It serves as a medium of reflex action between the sensitive and motor portions of the digestive, excretory and generative organs, and it also takes part in reflex actions which may be referred to the cerebro-spinal system ; foi- example, the contact of food in the intestine excites, through the medium of the sympa- thetic nerves, a peristaltic movement in the muscular coat. The irritation produced by undigested food in the ali- mentary canal may give rise to diarrhoea, or it may produce, through the medium of the sympathetic and cerebro-spinal systems, epileptic convulsions, especially in children. a4() THE SPECIAL SENSES, C\[\VT¥Al XIV. C t •i« •t M I r Hi or. TllK SI'KCIAL SKNSES. The spocial senses avajive in number, i^iiieU,^ I eri<)r, middle and nferior turbinated bones, beneath which lire the meatuses ; q, frontal sinuses ; s, narrow part of thepliarynx; t, tonsil ; u, anterior |)illar of the fauces; v, ixi.sterior pillar; y, tlio epi- glottis ; z, orifice of the Eustachian tulx!. which it may contain, in their passage through them, so as to bring them into more immediate contact with the mucous surface, by means of which their peculiar characters are more fully impressed on the olfactory nerves. 1^\\q frontal sinuses are supposed to assist in the extension of the sense of smell ; but since they do not receive filaments from the olfactory nerves, and are largely developed in some animals, 342 THE SPECIAL SENSES. c t I. Ih K L iWi' OH as the grey-hound, in which the sense of smell is by no means acute, it is highly improbable. The sense of smell varies much in different individuals, and, like all the senses, may be improved by frequent practice. It may become blunted by long-continued exposure to one kind of smell, as, for example, the effluvia of the dis- secting room. Various odors also affect it differently, as musk, asafoetida ; and some produce nausea and even fainting. The irritation produced by the contact of substances which act mechanically or chemically on the mucous mem- brane, as ammonia, nitrous acid, etc., must not be confounded with the sense of smelling. These impressions are conveyed to the sensorium by the fifth nerve, which is the nerve of sensation. The sense of smell may be impaired or destroyed by a dry state of the mucous membi'ane ; by the obstruction of the air passages, as in the case of polypi ; by chronic in- flanmiation, as catarrh, oziena, and by the frequent use of finuff, which tends to blunt its acuteness and cover the sur- face with its particles. Besides the olfactory and fifth nerve, there are some fila- ments from the spheno-palatine ganglion distributed to the nose. The function of these is not very well known ; but from the connection with the fiftli nerve and the sympathy between the sense of smell and taste, they are probably nerves of associate function. All animals have not the same facility for perceiving odors. Carnivorous animals have the faculty of detecting readily, animal odors, and tracking other animals by the scent. Herbivorous animals, on the other hand, possess the power of detecting readily the odor of vegetable matters. The sense of smell in man is not so acute as in most animals, but it is more uniform and extended. The extreme delicacy of the sense of smell is shown by the fact, that ao.wTjV.ooo of a grain of musk may be distinctly smelt. Some odors are pleasant, and some are oH'onsive, but the cause of the difference is not known ; many SENSE OF SIGHT. 34a odors also which are agreeable to one individual, are ofien- sive to another. Certain sensations also frequently produce a smell, for example, electricity produces a smell like phos- phorus, and the negative pole of the battery applied to the nose a smell of ammonia , while the positive pole produces an acid odor. In disease or derangement of the olfactory nerve, subjective sensations of smell frequently occur. SIGHT. The eye is the organ of the special sense of sight, and is situated in the cavity of the orbit. It is ^pherical in form, having the segment of a smaller and more prominent sphere engrafted on its anterior surface. It measures about an inch in the antero-posterior diameter, and a little less trans- versely. It consists of three coats : an outer, consisting of the sclerotic and cornea ; a middle, consisting of the choroid coat, ciliary processes, and iris ; and an internal, the retina ; and three refracting media, — the aqueous humor, the vitreous humor, and the crystalline lens and capsule. The sclerotic is a dense fibrous membrane, thicker behind than in front, which covers the ])osterior five-sixths of the eye. It is continuous in front with the cornea, and behind with the sheath of the optic nerve, which is derived from the dura mater. Behind, it is pierced, a little to its nasal side, by the optic nerve, around which are openings for the passage of the ciliary vessels and nerves. The cornea projects forwards, somewhat resembling a watch-glass, and covers the anterior sixth of the globe. It is concavo-convex, the degree of curvature varying in dif- ferent individuals, and in the same individual at different periods of life, being generally more prominent in youth than in advanced age. This diffTerencein the curvature in- fluences considerably the refractive power of the eye, and is partlj'' the cause of long and short-sightedness. The cornea in health, is perfectly transparent, contains no bloodvessels, and consists of five layers; — the cornea proper, 11 'i 344 THE SPECIAL SENSES. c r «1 iBr* 'V.I, Vertical tiecition of the eye ball. 1, sclerotic; 2, choroid; 3, retina; 4, crystalline lens; 5, hyaloid membrane; 6, cornea ; 7, iris ; 8, vitreous body. elastic lamirife, consist of a central fibrous structure ; in front of this, the anterior elastic lamina, covuied by the conjunctiva; behind, the posterior elastic la- mina, covered by the lining mem- brane of the an- terior chamber of the eyeball. The conjunctival epithe- lium consists of sev- I'lal layers of cells, the superficial ones being flattened and scaly,and the deeper ones columnar or cylindrical. The an- terior and posterioi" laminfe, consist of a thin, transparent homo- genous membrane, and have a tendency to curl upon themselves, with the attached surface inwards, when separated from the cornea proper. The cornea pro- per coLsists of finely fibrillated bundles of transpa- rent connective tissue, in the spaces of which the branched cornea corpuscles lie. The branched cornea cor- puscles are capable of passing from one space to another by their amoeboid movement. When this tissue is injured in any way, it presents an opaque milky appearance. The posterior elastic lamina and the single layer of epithelium which covers it, is known as Descemet's membrane. The nerves that supply the cornea are derive'^1 from the ciliary nerves. The choroid is a thin, highly vascular membrane, of a dark color, which covers the posterior five-sixths of the globe, and is situated between the sclerotic and retina. It is pierced behind by the optic nerve, and terminates in front at the ciliary ligament, where it bends inwards and forms ff SENSE OF SIGHT. 34.5 upon when the ciliary processes. It is com])osecl of three layers, the emternal, which consists of the larger branches of the ciliary arteries, but chiefly tlie veins and some star-shaped pigment cells; the middle, which consists of a fine capillary plexus (tunica Ruyschiaui) ; and the internal or pigmentary \a.yer, which is made up of a single layer of hexagonal cells, loaded with pigment granules, so arranged as to resemble tesselated epithelium. The principal use of the choroid coat is to ab- sorb the rays of light which pass through the retina, and prevent them from being thrown back to dazale the images formed on the retina. In perfect Albinoes the cells contain no pigment, and they can s-^e best in moderate light, or twi- light. The ciliary processes are formed by the folding inwards of the middle and internal layers of the choroid around the margin of the lens, behind the iris. They vary in number from sixty to eighty, and are about one-tenth of an inch in length. They are similar in structure to the correaponding layers of the choroid. The iris (tpii, a rainbow) is a thin, circular-shaped con- tractile curtain which regulates the quantity of light trans- mitted to the retina. It is suspended in the aqueous humor behind the cornea, and in front of the lens, and presents, at the nasal side of its centre, a circular opening, the pupil, for the transmission of light. It separates the cavity for the aqueous humor into two parts, the anterior and posterior chambers. It consists of a fibrous stroma, Tnuscular fibres, and pigment cells. The muscular tissue is involuntary and consists of circular fibres which surround the pupil, and radiating fibres which converge from the circumference of the iris to the margin of the pupil ; the former contract the pupil, the latter dilate it. The circular fibres are sup- plied by the third cranial nerve, and the radiating fibres by the fifth and sympathetic (p. 331). The fibrous tissue forms a delicate net-work in which the pigment cells, vessels and nerves are contained. The pigment cells are found in the 346 THE SPECIAL SEASES. stroma, and also as a distinct layer on the anterior and posterior .surfaccH, and j^ive rise to the different coh)r of the iris in dirtbront individuals. On blic posterior surface of the iris there are several layers of round cells filled with pig- ment granules. These are called the uvea, from their resem- blance in color to a ripe grape. The iris is connected to the choroid and to the external coat of the eyeball at tlie junc- tion of the sclerotic and cornea, by means of a circular band of white fibi-ous tissue, the ciliary li(jsed of three principal layers, together with blood-vessels and delicate areolar tissue ; the external or columnar ; the v.kldle or grantdar ; and the internal or nsrvods layer; each of these is again subdivided into sub- layers, as shown in Fig. 114. The external or columnar layer is exceedingly tiiin, and consists of solid columnar rod-like bodie.., with cones filled with fluid interspersed at regular intervals (a, b). These are se))arated from tlie granular layer by a transparent homo- geneous membrane, the niembraiKi Umltans externa, '''he middle or granular layer is transparent, finely fibrillated and comprises one-third of the thickness of the letina. It consists of two layers of rounded nuclear i)articles (c, e) separated by an inter-granular layer (d). The external granular layei* is the thicker, and its particles are glohidar, 20 348 I HE SPECIAL SENSES. c c t I h I*.. and coMJioct(Ml witli tlic rods jind coiios by fihres passing throni^li l,li(» mcniln'jina li mi tans. 'V\w intoi'nal ^lannlar layor ' '"^ '"* is tli(^ tliinM(M', and its pnrticlos arc flat- tened, looking lil<(! pieces o[' money seon edir( colls arc, liowovef, hipohir sendin{^ oiu) process ontwarils tliidnj^h the inter-grannlar layer, and another in- waids through the molecular layer, to r(>ach tlio expansion of the oi)tic ncrvo. The Internal or nervous layer is thin, semi-tianspai'ent and consists essentially ol' the expansion of the terminal fibres of the optic nerve, and nerve cells, it also ))resents three layers ; the nwleeular or linely granular layer, resembling the mol(>cular matter found in the gray substance* of the brain and spinal cortl ; tho layer of ganglion cells or nlhilar Vertioai siHtioii .'f iii« hwer, whicli consists of multipolar hiiniiin ivtiiiik. a, Uods; 1'. ,, ^ , • i • i ••Olios. ivtiiiK upon till! cells, some oi the processes of which pass niomliranii liiiiitims I'Xtoniii; .-, cxtoiiiai uiaiuiiar la.Mi-; (»ut\vard t(^ the uiolccular layer and d, inli'iyi-.innliir hixiT ; i", _ ^ '' intorna) miuiuiar liiMi; t. others inwards to the fibrous layer; ■loU'Uilav lav or ; jr. la\Of of _ . ', «:aii-iion >oiis ; ii.iM>aii>ioii .^,,,1 ^hc fibroLis layer or expansion of ( lie of the optu- noi-M- libios : i, -^ •' ' mcmbranalimitttiis interna. optlC ncrVC. The ncrVC fibres of tluS l.iyer consist only ol' the axis cylinder, and some of them become contiiuu)ns with the })rolongations of the ganglictn cells. Tho inner surface of tho retina is lined by a trans- parent homogeneous membrane, which separates it tfom the vitreous body, the mend)ra)Hi liwifans interna. Blood- vessels are only found in the internal layer, and extending to the internal granular stratum of the middle layer. In tho external or rod-and-cone layer of birds, the cones predomi- nate, while in man tho rods are more numerous. In noctur- nal animals, tis the owl, bat, mole, etc., the cones are entirely absent. In the fovea centralis, where vision is most acute> SENSE OF SIGl^T. 349 all tlio layiM'H of tlio retina am tliiiincr except the rods and cones which are increased, from vvhicli it wonld apjx-ar that these are more especially concerned in tlie fnrkction of vision. The ((([iieoufi humor occupies the anteiior part of the giohe, and coniph^tely fills the anterior and posterior cham- bers of the eye. It is a clear, thin fluid, havin*^ an alkaline reaction, which is due to the presence of chloride of sodium. In the adult, the anterior and posterior chambers communi- cate through the pupil ; hut in the foetus, before the seventh month, the pupil is closed by the meml)rana pupillaris. The persistence of this membrane sometimes occasions congeni- tal blindness. The viireouN liamor occupies the posterior fbur-til"ths of the globe. It is perfectly trai'.sparent, of the consistence of jelly, aiul consists of numerous layers of sim|)le membiano with the intervening spaces filled with fluid. It is sur- rounded by the hyaloid membrane, and is hollowed out in front for the reception of the crystalline lens. It refracts tho rays of light, and fills the globe of tiie eye so as to keep the retina at a [)i'o|)er distance from tin; lens. The vitreous humor contains some salts and a litth; albumen. In the foetus, a minute artery passes through the centre to the pos- terior part of the capsule of the lens, the arteria centralis retliicv ; but it di,sa[)pears in the adult. The crystalline ^c/t.s, enclosed in its capsule, is situated in front of the vitreous humor and behind the pupil. The aip- Hule is a transparent brittle membiane, highly elastic, and is dis})o.si!d to curl inwards upon itself when ruptured. It surrounds the lens, to which it is connected by a layer of nucleated cells, and is held in position by the HaHpensori/ ligament, which connects it to the anterior margin of the retina. The suspense .y ligament consists of two layers blended together; the outer, a milky, granular layer, cornea in contact with the inner surface of the ciliary processes ; the inner, is an elastic transparent membrane. This liga- ^p 350 THE SPECIAL SENSES. c t Ml t L h •J in i mcnt forms part of the boundary of the posterior cliainber of tlie eye ; its posterior surface is separated from .e hya- loid membrane by a triangular interval — the canal of Petit. This canal is about one-tenth of an inch wide, bounded in front by the suspensory ligament, behind by the hj^aloid membrane, and the base is foi'ined by the capsule of the lens. The lens itself is a transparent double convex body, being more convex behind than in front. It measures about four lines transversely and three lines from before back- wards. It appears to consist of concentric laminae, like the coats of an onion, the central ones forming a hardeneo nu- cleus. It also ap))eai\s to consist of three triangular seg- ments ; this is readily demonstrated by boiling, or immersing it in alcohol. The lamina? consist of minute parallel fibres, hexagonal in shape, the edges being dentated and fitting into each other, and are about saoo of an inch (5 mnmi.), in diameter. The refi'acting media of the eye are the cornea, aqueous humor, crystalline lens,and the vitreous humor. There are two forms of the lens in the human eye, viz., the concavo-convex or 7}ieniscus, as the cornea ; and the double convex, as the crystalline lens. The essential parts of the eye, appear to be : 1st, a dark coat to absorb the rays of light — the choroid ; 2nd, a nervous expansion to re- ceive and transmit to the brain the impression of light — the retina ; 3rd, a concavo-convex lens to collect the rays of light from the object and direct them inwards, and a double convex lens to collect the rayt. of light and bring them to a focus, so as to form a correct image on the retina — the cornea and the lens ; 4tn, a contractile cui'tain with a central opening, to regulate the quantity of light enter- ing the eye — the iris. The eye is thus a simple o])tical in- strument, endowed with vitality, and acting as required without assistance. It is abundantly supplied with blood-vessels. In addition to the conjunctival vessels, there PHENOMENA OP VISION. 351 cli amber -d hya- of Petit inded in hj-aloid e of the f^x body, es about •e back- like the !ned nu- lar .seer- mersing parallel ted and an inch eye are vitreous ye, viz., a-nd the a,l parts iorb the n to re- light— he rays s, and a I bring 3 retina in with ^ enter- ical in- 3quircd i with 3, there are the vessels of the sclerotic, choroid, iris and retina. The latter are derived from the short, long, and anterior ciliary arteries, and the arteria centralis retinae. Phenomena of Vision. — In order fully to understand the physiology of vision, it will be necessary to refer briefly to some of the laws which regulate the transmission of light. 1st, — Light travels in parallel rays through a medium of uniform density. 2nd, — When the rays meet with a medium of increased density, they become refracted, or changed in direction, to- wards a line which falls perpendicularly to the surface of the body which they enter. 3rd, — When the rays of light meet with a medium of diminished density, they are refracted from the perpendicu- lar line. 4th, — When the rays of light fall upon a convex lens, they are collected ; and if this be a double convex body, they come to a point or focus at a certain distance, de- pending on the degree of convexity of the lens ; the greater the convexity the shorter the distance and, vice versa. The image formed by thj refraction of the rays of light in coming to a point or focus will be an inverted one. 5th, — If the convexity of the lens be too great, the focus will be formed in front of the mirror or reflecting body. If too slight, the focus will be formed beyond it. Vision is accomplished by the formation of an image of the object looked upon, on the internal surface of the retina. The impression made upon this produces a sensation, which is conveyed to the sensorium by the optic nerve, and the mind takes cognizance of it. The image is formed in the following manner : — The rays of light are reflected from the object (A. B.), and im- pinge on the outer convex surface of the cornea (c. c), through which they pass, becoming refracted towards the perpendicuk,r. Those which fall on the circumference of 352 THE SPECIAL SENSES. the corn(;a impinge upon the iris, and are reflected, show- ing the color of this structure; those which pass nearer its Fi'T. 115. c Ik t L h m ■v I IB) F lar> •»» . «n centre, converge and enter the pupil. They now penetrate the crystalline lens (e. e.), by means of v/hich they are still further converged, their convergence ^^jijig completed by their passage through the vitreous humor, and are brought to a focus on the inner surface of the retina (a. and b.). If the retina be not at f., but at g. or h., certain luminous spots, e and o, or c and f, will be seen ; for at n the rays have not yet met, and at G thej'' have crossed and are again diverging. Since rays of light come from all points of the object, and are refracted in their passage, they must cross each other, and thus the image of the object on the retina (f), will be inverted, but this is corrected by the sensorium. The angle of crossing is called the visual angle. Accommodation of the Eye to Vision. — It is quite evi- dent that some arrangement of the refractive parts of the eye is necessary to adapt it to the vision of near and distant objects. The precise manner in which this accommodation is effected is a disputed point ; some maintain that it is due to an alteration in the position of the lens ; while others regard it as being due both to an alteration in the position and shape of the lens. The eye, in its normal state, is accommodated for distant vision, under the guidance of the recti muscles ; this may be called its passive condition. The ACCOMMODATION OF THE EYE TO VISION. 353 ;•!, sbow- U'arcr its Denetrate ' are still ileted by brought lb.). If luminous the rays are again its of the ust cross lie retina nsorium. luite evi- ts of the \ distant nodation it is due e others position state, is CO of the on. The active accommodation of the eye for the vision of near ob- jects is caused by the advance of the crystalline lens towards the cornea, and also by the increased convexity of its ante- rior surface. It is advanced towards the cornea chiefly by » ^ . action of the ciliary muscle, and partly by the compres- sion exercised upon the posterior three-fourths of the eye- ball by the recti muscles. It may therefore be inferred that the recti muscles adapt and adjust the eye for ordinary vision ; while the ciliary muscle may be regarded as the Ane adjuster, which regulates the eye for the vision of near or very small objects. The rays of light which pass through the margin of a lens are more refracted than those which pass through the centre, and owing to this unequal refraction the rays do not all meet at the same point. This defect is called spherical aberration. The formation of distinct and correct images on the retina is favoured by the action of the pupil, which prevents the rays of light from passing through any part of the lens but its centre, and thus preventing any tendency to spherical aberration. In optical insti uments, as the micro- scope, telescope, etc., spherical aberration is prevented by the use of a diaphragm with a circular aperture, which shuts out all the marginal rays. Distinctness of vision is further secured by the black coating of pigment on the inner surface of the choroid, which absorbs any rays of light which may be reflected within the eye, and prevents them from being thrown back again upon the retina, so as to produce dazzling of the image there formed. When a ray of light passes through an ordinary lens it is partly decomposed into its elementary colors, and a colored margin appears around the image owing to the unequal re- fraction of the elementary colors. This is called chromatic aberration, and is corrected in optical instruments by the combination of two or more lenses, differing in shape and density. The combination usually consists of two lenses of unequal refraction, a convex lens made of crown glass and 354 THE SPECIAL SENSES. c c. t L I r and a concave one of flint glass, but the number may be varied to suit the circu instances. Such combinations of lenses are called achromatic. The unequal refractive powers of the different media of the eye prevent chromatic aber- ration. If a ray of white light be passsed through a prism the different colors are refracted in different degrees, and a colored band appears, called the spectrum, arranged as fol- lows : violet, indigo, blue, green, yelloiu, orange and red. The violet rays are most refrangible ; the red the least ; hence the image of a small white object appears as if sur- rounded with a yellowish or bluish fringe, because it cannot be accurately focused on the retina, This is called irra- diation. For this reason a white figure on a black ground appears larger than a black one of the same size on a white ground. The inverted image of any bright object, as the windows of the room may be distinctly seen in the eye of any albino animal, as a white rabbit ; or if an opening be made at the superior surface of the eye so that the retina can be seen through the vitreous humor, a reversed image of any bright object may be seen on the posterior wall of the eye. Impressions once produced on the retina remain for a short iime afterwards; their duration depending on the intensity of the impression they have left. A moment- ary impression of moderate intensity continues about one- eighth of a second. This is the reason why the act of wink- ing does not interfere with the continuous vision of surround- ing objects. The spectra which remain on the retina after viewing colored objects are always of the opposite or com- plemental color ; e. g, the spectrum of a red object is green, that of violet, yellow, etc. This is because the retina be- comes fatigued by the color looked at ; but remains sensitive to the other rays. There is in front of the eye a certain space within which objects are perceived, and beyond which nothing can be distinctly seen ; this is called the circle or Jleld of vision THE BLIND SPOT. 355 and varies in extent in different circumstances. For ex- ample, if the eye is intently fixed upon one word in the middle of the page, this word and those that immediately surround it, which are in the circle of vision, are distinctly visible, while those at the circumference are imperceptible while the eye remains fixed. It is largest when the view is not confined to any near object. The distinctness with which an object may be seen, appears to depend largely upon the number of rods and cones covered by the retinal image, hence, the nearer an object is to the vision of the eye, the more distinctly are its details seen. The images of two points require to be at least T7^ot) of an inch (2 mmm) apart, in order to be distinguished separately. That portion of the retina which corresponds to the entrance of the optic nerve is insensible to light, and is called the blind spot. It we close the left eye, and direct the right steadily upon the circular spot here shown, while • + the page is about six inches from the eye, both marks are visible. If the distance be gradually increased, the cross disappears from view, and if the book be still further re- moved, it comes in sight again. The eye, in the uneducated state, cannot comprehend the properties of the objects seen, as color, form, etc., or the distance of the object; this is acquired by experience. Simultaneous Action of the two Eyes. — Although an imageof the object is formed oneach retina, yet tlie impression of the object conveyed to the mind is single. This is, no doubt owing to the fact that the image is formed on identical points of both retinae, giving rise to but one sensation, and the perception of a single image — the result of a mental act. This unity of action may be favoured by the continuation of the optic filaments across the anterior part of the chiasma of the optic nerve, but is not dependent on it ; for, if the visual axis of one eye be altered, objects are seen double. 35G THE SPECIAL SENSES. c 11 K r This may be demonstrated by pressing the eyeball on one side with the finger in order to rotate it upon its axis, while the eyes are fixed upon some object, as a book or lamp ; two images of the object are seen as in diplopia from strabismus. This is owing to the formation of images of the objects on different parts of the two retinae. The power 'of combining tlie two images is subservient to the faculty of obtaining a j)roper conception of bodies raised in relief. When a solid object as a cube is viewed, a different perspective of it is seen by each eye, and more of the surface of the body is seen than if viewed with one eye ; in other words a stereo- scopic effect is produced. Defects of Vision. — The normal, or emmeto^opic eye brings parallel rays of light exactly to a focus on the retina (Fig. IIG, i) and all objects except near ones (within 20 feet), are seen without any effort of accommodation. In looking at near objects the eye is accommodated by the action of the ciliary muscle, and the rays which would otherwise meet behind the retina are correctly focused upon it, (Fig. 116, 2, dotted lines). The defects of vision are myopia, hyperme- tropia, presbyopia and astigmatism. Myopia is due to an abnormal elongation of the eye ball, and too great a degree of convexity of the lens. The rays of light are brought to a focus in front of the retina, and the images are indistinct and blurred (Fig. IIG, 4). The eye is naturally accommodated for a near point, and objects near the eye are exactly focused, while those beyond the .%r point cannot be distinctly seen. This defect is remedied by wear- ing concave glasses. On the other hand, when the eye is short, and the lens flat, parallel rays are focused behind the retina; the eye is naturally accommodated for distant objects (Fig. 11 G, 3). This is called hyperm^etropia, and may be remedied by wearing convex glasses which converge the rays of light Presbyopia is an ervor of refraction, and must not be con- founded with hypermetropia. It is the gradual loss of the power of accommodation which occurs with advanced age, DEFECTS OF VISION. 357 1 on one ^; is, while »np; two abismus. bjects on )nibinin£r :aining a n a solid of it is body is a stereo- >pic eye le retina 20 feet), looking iction of ise meet . 116, 2, i/perme- ye ball, ! rays of md the e eye is ts near ir point Y wear- issliort, retina; :s (Fig. nedied f light )e con- of the d age, and is likevvi.se remedied by the use of convex glasses. As- ti(/ mat 187)1, first discovered by Airy, is due to a greater cur- vature of the eye in one ])lane than in another, so that vertical and horizontal lines crossing: each other cannot be l-'i^'. lUi. focused at the same point, and the images are blurred and indistinct. It may be remedied by using glasses curved only in one direction — cylindrical glasses. Daltonism, or color blindness, is also a defect of frequent cocurrence ; many persons are wholly unable to distinguish between red, green and yellow. This would appear to arise from some defect in those elements of the retina which re- ceive the impressions of these colors. ^m 358 IT///-: S/'EC/A/. SENSES. HEARING. The ear is the orgun of hearing, and is composed of three l)ortions, the external, middle and internal oar. The external ear consists of an expanded portion, the pinna, the meatus auditoriua txternus, and auditory canal. Its use is to collect the vibrations of the air, and conduct them to the membrana tympani, or drum, which separates the external from the middle ear. The canal contains some fine hairs at its outer part, and also a number of sebaceous glands throughout its whole extent, which secrete a waxy- substance termed cerumen. Fijf. 117. O, Pinna ; b, external auditory passage ; c, membrana tympani (section) ; d, insertion of membrana tympani in bony canal ; e, insertion of malleus in membrana tympani ;/, base of stapes, inserted in the fenestra ovalis ; g, incus, joining stapes and malleus, and complet- ing the chain of ossicles ; h, cavity of the tympanum ; (', Eustachian opening of tym- panum ; j, opening of Eustachian tube in the pharynx ; k, posterior part of pharynx; I, semicircular canals ; tii, n, cochlea ; u, trunk of auditory nerve. The middle ear or tj/m'panum is situated in the petrous portion of the temporal bone, between the membrana tym- pani externally, and the internal ear or labyrinth in- ternally. It is filled with air, and communicates with the .s7;a;s/-; r/ hearing. So) of three ion, the y canal. conduct eparates ns some baceous a waxy isertion of i;/, base of 1 complet- jf of tym- larynx; I, )etrous a tym- th in- th the l)liarynx thi-on^jli tho Eustacliiaii tiibt', wliich opens at tho back part of t Ik; iniorior meal.ns, (Fin; iHj. Tt als(* com- municates postei'iorly with ;iir cuvitios in iln- mastoid process of the temporal bone, the; 'laasfoid celh. It is crossed by a chain of movable bones, which receive the impressions from the memlirana t3'mpaiii, and serve to FL'. 1 18. Interior of til osseous lain liiitii. V. \u.'5tiliulo, iA ni->r.or niovfrin f\f lamiiiii! spirulis ; .v.s, sulcus -| inili.s ; .'/x, H;an},'lioinpir!klo tne Upptl maigin OI seatoa on «(!, tUo nu.vus ouohloaiis, itidiuitcit l.y tho flio 01/7/11.U o.iQi.//7i"u '^''^"'' """• '""• 'a""'"' spiralis* <)s^ea ; /, uniuibruiia tiie .•> t«/(/0 ct/.5 Hffll K/Vm tectoriaof Corti ; b, ineinlirana liasilaris ; Cn, or;,'un of i. . i 1 ,1 Corti : /;(i), li!,'iiiJiurituni spirale: 1, inturiial i'(k1 of stretches across another Corti; 2, external .0.1 of CorU. Section tlirouj^li one of tlie( oilsof tlic cochlea ht, seala tynipani ; »v, scala vcstiliuli ; cc, s.iala media or canalis coclileaj ; u, nicnil)ranc of Hcissuer, witli itti sinirle layer of nucleated flattened cells ; lis, liinhu.s Corti, Fur- 7nem- forms membrane which covers over the organ of the memhrana tectoria, or membrane of Corti. ther inwards is another thin membrane, the brane of lieissner, which stretches across and the scala media, or canalis Goohlea}. The organ of Corti is situated upon the membrana liasilaris. It consists of the rods of Corti, arranged in a series of arches formed by the internal and external rods roofing over the zona arcu- ata (Fig. 119. i, 2.). They incline inwards towaids each other, and each ends in a swelling termed the head, the con- vexity of one fitting into the concavit}-- of the other like an articulation. It has been estimated that there are about 3000 of these pairs of rods or pillars from the base to the apex of the cochlea. On both sides of these rods are cylin- drical epithelial cells, some of which are provided with cilia (cells of Corti.) Within the osseous labyrinth is contained the membran-- ■mp 362 IHE SPECIAL SENSES. c L mi I OILS labyrinth, upon wliicli is distributed the tiliinicuts of the auditory nerve. Tlie nieinbrauous labyrinth is lilled with a transparent lluid, called cndolynipli ; while between it and tlie osseous covering is a lluid called peril i/viph, so that tlie sonorous vibrations which reach the auditoiy neive in these parts arc conducted through lluid, to a membrane con- taining fluid. In the vestibular })ortion of" the mend)ranous hibyrinl.h arc two cavities; the upper and larger is named he uti'iciiliifiyiind the lower the saccnlus. They are situ- ated respectively in the fovea hon'ielliptica and the foveti hemiKphevlcd and contain small masses of calcareous matter, the oioliths (Fig. ll.S). The utricle connnunicates with the membranous semiciicular canals and the saccule with the canalis cochlear The iMr.rnANiSM of ITk.vuino. — The ((KdUori/ nerve as it enters tlio ear divides into two branches, one to the vestibule and the amjmlhe of the semicircular canals, and the other to the cochlea. The branches of the cochlear nerve enter through openings at the base of the modiolus, and pass ijito canals between the ))lates of the lamina spiralis, in which they form a plexus containing ganglion cells (Fig. 110, //n), and terminate in the oi-gan of Corti. The external (>ar favors the proi>agation of sound by collecting the r.onorous undulations, and conducting them to the meml)rana tym- pani, and also by the resonance of the column of aii' con- tained in the auditory canal. The elevations and depressions of the pinna servo a useful pui])o,se, for sonorous umlulations from whatever direction they come, must fall perpcndiculaily upon the tangent of some one of them. Sonorous vibra- tions are conducted to the ear by three different media, the air, the osfficlefi of the car, and the Jiuid of the labyrinth. The propagation of the sounds to the fluid, is made more perfect by reason of the ossicles being fixed in the middle of a tense vibrating membrane, with air on both sides, as the tympanum. Sounds are collected by the external ear and are transmitted to the membrana tympani. They THE MECHANISM OF HEARING. 363 are here modified by the tense or lax state of this mem- brane, produced by the action of the laxator and tensor tympani muscles. The modified vibrations from the mem- brana tympani are thence conducted along the chain of bones to the fluid of the labyrinth, and through it trans- mitted to the auditory nerve, which receives the impressions.' and conveys them to the sensorium. From various experi- ments which have been performed, it appears that tension of the membrana tympani is unfavorable generally to the propagation of sounds, especially those of a low pitch. This may be shown by making a continuous eflfort of expir- ation or of inspiration, while the mouth and nostrils are closed by the hand. The eftbrt of expiration causes the air to be forced into the tympanum through the Eustachian tube, the membrana tympani is made to bulge out and become tensp,, and the hearing is indistinct. The effort of inspiration exhausts the air from the cavity of the tym- panum, and the pressure from without causes the membrana tympani to bulge inwards and become tense, and is fol- lowed by temporary deafness. The action of the chain of bones, as conductors, is en- hanced by the presence of air in the cavity of the tympa- num. It serves to isolate the bones so as to propagate the vibrations with concentrated intensity, and prevent the dispersion of sound. The air is supplied through the Eusta- chian tube, which communicates with the pharynx just be- hind the posterior .ares. When persons are listening very intently, the mouth is usually partly open, in order to allow a free current of air to pass through the Eustachian tube. The semicircular canals collect the sonorous undulations from the bones of the cranium and conduct them to the ampullae and utriculus, where the auditory nerve is distributed. The cochlea is intended for the spreading out of the nerve fibres over a wide extent of surface, and for the perception of sounds by the solid parts and the walls of the labyrinth. The membranous labyrinth of the vest 'le and semicircu- 21 864 THE SPECIAL SENSES. c c E h In M I lar canals is suspended free in the perilymph and receives the sounds through the medium of that fluid, while on the other hand the lamina spiralis upon which the cochlear nerve is expanded is continuous with the solid walls of the cochlea from which it receives impressions directly. The function of the rods of Corti is probably to receive impres- sions of various notes and tones, and communicate them to the brain through the filaments with which the rods are connected. The intensity of a sound is due to the length of the vibrations, the 'pitch to the number in a second, and the quality to the number of secondary notes. The power of determining the direction and distance of sounds is ac- quired by experience. Any irritation or excitement of the auditory nerve, as congestion, cerebral disease, etc., may give rise to ringing or buzzing sounds in the ears. These are called subjective sounds, because they are produced by internal causes. The sense of hearing varies much in different individuals, and in the same individual at different times ; some will discern the most delicate sounds without the least difficulty, whilst others are wholly incapable of receiving similar im- pressions. Hearing may be impaired by a preternaturally dry state of the membrana tympani, or the partial closure of the external meatus by collections of wax, particles of dust, etc. In some of the lower animals, the sense of hear- ing is very acute. SENSE OF TASTE. The principal organs of the sense of taste, are the tongue and fauces. The conditions necessary are the presence of special nerves to convey the impressions received, and the excitation of these nerves by sapid matters in a state of solution. The nerves are the lingual branch of the fifth, and the glosso-pharyngeal (p. 333). The tongue is a muscular organ, covered with mucous membrane andpresentsnuraerous papillae. These have been already described (p. 107). The muscles are divided into intrinsic, or those that form the receives e on the cochlear Us of the ;ly. The e impres- } them to rods are length of , and the power of Is is ac- oerve, as ) ringing ruhjective 5es. ividuals, Dine will lifficulty, Qilar ira- laturally 1 closure :'ticles of of hear- e tongue isence of and the state of ifth, and nuscular uraerous 7). The orm the SENSE OF TASTE. 365 greater part of the substance of the tongue, as the lingual es -^ and extrinsic or those which attach it to surrounding parts, as the hyo-glossus, genio-hyoglossus, stylo-glossus, etc. The epitiieliura of the tongue is of the squamous variety. Fig. 120. The tongue with its papilla; and nerves. 1, Hypogii)ssal nerve. 2, Lingual branch of the trifacial. 3, Lingual branch of the glosso-pharyngeal nerve. 4, Chorda tynipani. «, Sub-maxillary ganglion. 11, Anastomoses of the lingual with the hyi)oglossal uerve. 12, Facial nerve.' 13 Mucous membrane detached and thrown upwards ; thi circumvallate papilla) aie seen behind. (Hirschfeld.) and covers every part of the surface, but is thinner in some parts than others, as on the fungiform papillre. Peculiar structures,knowii as taste huds or taste goblets,ha.ve been dis- covered in the circumvallate papillje and on the posterior surface of the epiglottis. They are oval in shape,and con- sist of narrow fnsif orm gustatory cells surrounded by a layer of broader fusiform or encasing cells (Fig. 121). A depress- ion exists in the epithelium over the goblet, and the gusta- tory cells present hair like processes which resemble cilia. These bodies are found side by side in considerable nura- bers,and are believed to be gustatory in function, but as yet no nerves have been traced into them. The fauces, uvula, tonsils, and upper part of the pharynx, all of which are supplied with branches of the glosso- 366 THE SPECIAL SENSES. \ t v.. pliaryngeal nervc,are endowed with the sense of taste. In most persons the sense of taste is most acute in the tip and edges of the tongue; while in the middle of the dorsum it is feeble. The tongue also possesses an accurate sense of touch, and Fig. 121. is capable of receiving im- pressions of heat or cold, pain, mechanical pressure, and the form of surfaces. Its common sensibility may be impaired or lo-^t, and the sense of taste still continue. The nerve fibres for these two sensations, although found in the same papilla3, distinct, just as the nerves and the nerves of common sensation in the nose are dis- tinct. The senses of smell and taste are closely associated, for if the former be impaired or lost as in disease, the latter is rendered less acute. Taste appears to be governed to some extent by the same principles as that of sight ; viz. that those tastes which are opposite or comple- mentary, render each other more distinct, as sweet and bitter acid and alkaline, etc. The sense of taste is very delicate though not to be compared with the sense of smell. It may be rendered less distinct in regard to any substance by constant contact with it, in the same way as the eye becomes fatigued with the constant perception of a single color Subjective sensations of taste frequently occur in diseased conditions of the nerves of taste, or their associate nerves. Taste goblet; a, depression in the epitlioliuiu ai'C over the goblet ; b, nuclei of encasini!; cells; . c, two nuclei of the gustatorj' cells. oliactory SENSE OF TOUCH. The sense of touch has a wider range than the other senses, and varies greatly in the different parts of the body. It is greatest at the extremities of the fingers, lips and SENSE OF TOUCH. 367 taste. In le tip and rsum it is ouch, and iviug im- or cold, pressure, rfaces. Its yi^ may be and tlie continue. for these although e papillae, as the and the are dis- closely in disease, irs to be as that of comple- and bitter i delicate 3mell. It stance by e becomes gle color L diseased nerves. the other the body. lips and tongue, and least in the integument of the trunk, arms and thighs (p. 124). There are no special nerves of the sense of touch ; they are simply the nerves of common sensation supplied to all parts of the body, and hence it is that all parts are endowed with this sense. Touch is simply an ex- altation of common sensation. Some are of the opinion, that common sensation and tactile sensation are communi- cated to the sensorium through different sets of nerves. Those parts of the body in which the sense of touch is most acute are abundantly provided with papilUe, which increase the extent of surface for nerve distribution. These papilUe vary in size from t'io to ^i^ of an inch (.25 to .1 mm). The nerves distributed to them are destitute of the white sub- stance of Schwann, and ap- fi?. 122. pear to terminate in oval- shaped bodies, formed of connective tissue named tactile corpuscles (Fig. 122, a). In some of the pa- pillae, as those of the lips, tongue, palate and integu- ment of the glans penis, the nerves terminate in small round bodies, ttJo of an inch (42 mmm,) in diam- eter, the end bulbs of ^ ^^^^,.^^ cor,.u.sdo ; KraUSe(Fig. 122,B). In the Kra«se (see pa^jo 2sT). palms of the hands, points of the fingers and soles of the feet, the papillae are arranged in rows, and form ridges and furrows which may be seen with the naked eye (p. 116). The sense of touch is peculiar from being widely distributed; even the eyelashes, hair (near the root), nails and teeth ex- hibit this sense in a manner peculiar to themselves. The integument is endowed not only with the sense of touch, per se,but also with the ^Qn^Qoipressvire^temperatiive audpam ; the latter being a highly exalted sensation of the three former. 368 THE SPECIAL SENSES. c I I Hi Hi Some parts of the body are sensitive to tickling as the axilla) a,nd soles of the feet, but are comparatively blunt in regard to the special sense of touch. The sense of touch enables the mind to become acquainted with the condition of bodies, whether hot or cold, rough or smooth, hard or soft, wet or dry, and their size, form, etc. The organs by which touch is chiefly exercised, are the hands, and especially the points of the fingers, which are abundantly provided with papillae for that purpose. The variation in sensibility in different parts may be determined by the aid of a pair oi' compasses. Thus the two ]:)oints of a pair of compasses may be separately distinguished by the point of the finger when only about one-third to one-half a line apart, while they require to be twenty to thirty lines apart, to be separately felt on the integument of the spine, arm, thigh, sacral or gluteal region. The two points are f ^It separately on the tip of the tongue when i^ of an inch apart, on the middle of the dorsum of the tongue, \ of an inch, on the lip \ of an inch, and on the tip of the nose, when \ of an inch apart. The CBsthesio7nete7% an instrument for determining the relative sensibility of the arms or legs in paralysis, is constructed on this principle. The sense of touch may he very much increased by constant practice, as is seen in the case of the blind, who acquire a remarkable facility for reading raised letters, by the aid of the fingers. The sense of pressure is produced by weight or tension, and is intensified according to the increase of the weight or tension. In lifting a body we judge of its weight partly by the pressure on the hands, and partly by the amount of muscular force used in raising it. The latter is called the Tnuscular sense (p. 309). These two faculties give us the power of discerning the relative weight of bodies. We have also the power of estimating beforehand, and regulating the amount of muscular force required in lifting heavy bodies. If we attempt to lift an object which we have conceived to be heavier than it really is, we are liable to be SENSE OF TEMPERATURE. 369 the axillae in regard cquainted . , rough or form, etc. I, are the which are ose. The etermined ) points of led by the one-half a lirty lines the spine, ats are f 3lt f an inch ue, \ of an f the nose, nstrument ms or legs 16 sense of practice, as -emarkable le fingers, or tension, the weight ight partly amount of 5 called the jive us the odies. We I regulating 'ting heavy h we have liable to be overturned by the muscular effort unnecessarily put forth to overcome the supposed resistance. The sense of temperature is distinct from that of touchy and may remain unimpaired when the latter is for the time in abeyance, as when a nerve is pressed upon or partly in- jured. The sensations of temperature, however, are very deceptive, and cannot be relied upon; as e.g. in the cold stage of disease, the patient feels excessively cold, while the ther- mometer shows that the temperature is over 100"F. Again, if one hand be put in cold water, and the other in water at a temperature of 110°F., and both are then immersed in water at 80°F., it will feel warm to the hand previously in the cold water, and cold* to the other. In examining patients in cases of fever or inflammation, in regard to the heat of the skin, no reliance can be placed on the sensation of heat communicated to the hand, and therefore the ther- mometer should always be used. Some parts of the body will bear a higher degree of temperature than others, e.g., the hand will resist a temperature which would be intoler- able to the body. Only ordinary temperatures can be dis- criminated, viz., from 50° to 120°F. ; very high or very low temperatures produce a burning sensation. Subjective sen- sations of touch, arising from some internal causes, are of frequent occurrence, as heat, cold, rigor, neuralgic pains, itching, formication, etc. 370 THE VOICE. CHAPTER XV. VOICE. \ C t ^ Hi if The Larynx is the organ of voice, and is situated at the upper part of the air passage, between the trachea and base of the tongue, at the upper and anterior part of the neck. It is narrow and cylindrical below, but is wide and triangular at the upper part. It is composed of cartilages, which are held together by ligaments, and acted upon by numerous muscles. It is lined by mucous membrane, covered with columnar ciliated epithelium below the super- ior vocal cords and the upper part in front; the rest of its extent is covered with squamous epithelium. The upper part of the larynx presents a triangular-shaped orifice, wider in front than behind — the glottis. This opening is guarded by the epiglottis, which is situated in front, between the open- ing and the root of the tongue. The epiglottis closes the orifice during the passage of food or fluids, and prevents their passage into the larynx. Within the cavity of the larynx, on each lateral wall, may be seen two elevated bands, the superior and inferior vocal cords, separated by an elliptical depression — the ventricle of the larynx (Fig. Ill /,) p. 341. Of the two vocal cords, the inferior consists of a band of yellow elastic tissue, covered by mucous mem- brane, and is called the true vocal cord; while the superior, which is formed entirely by a folding of the mucous mem- brane, is called the false vocal cord, because it is not con- cerned in the production of the voice. It is in the larynx that the sounds are originally produced; but they may be modified during and after their production by the tongue, palate, ^ GLOTTIS AND VOCAL CORDS. 371 Fig. 123. teeth, lips, etc., constituting, in man, the faculty of speech. The interval between the true vocal cords in the median line is called the rvnxa glottidis, or chink of the glottis, the narrow- ing or widening of which, and the tension or laxity of the cords, produce those variations of sound which are characteristic of the human voice. The narrower the opening and the tenser the cords, cceteris paribus, the higher the pitch of the note. The tension of „, 1 1 • PI Olottm seen ivith the lar>in(/nncope the vocal cords and the size of the dnnwj the emix«i„n o/ hiijh-pUched sounds.— I, 2, base of the toll^me ; 3, aperture, are regulated by mus- *. epi^'iottis ; .5, «, pharynx ; 7, ary- ^ o ^ teiioiU cartilages ; 8, o))eniii>f between CleS which are situated in the t"?**^ ^tt-^e vocal conls ; O, aryteno-epl- (f lottidean folds ; 10, cartilage of Siin- larvnX. It has been IJrOVed ^o""'.; ^l- cnnelfonn cartilage; 12, •' A superior vocal cords; 13, inferior by observation on the living vocai cord8.-{Le Bon.) subject, as well as by experiments on the larynx of the dead body, that the sound of the voice is caused by the vibration produced by the currents of expired air passing over the margins of the true vocal cords. For example, if a free opening be made in the trachea, the sound of the voice eeafes, but returns as soon as the opening is closed. Again, distinct vocal sounds may be produced in the dead subject by forcing a current of air through the larynx, and this will occur even when all the structures above the vocal cords are removed. The essential parts of the larynx are the thyroid carti- lage, the cricoid cartilage, the two arytenoid cartilages and the true vocal chords. The latter are attached behind to the front portion of the base of the arytenoid cartilages, and in front to the depression between the two alse of the thyroid cartilage, so that all movements of the arytenoid cartilages produce an effect on the vocal cords. Movements of the cricoid cartilage also produce an effect on the vocal cords indirectly, since the arytenoid cartilages rest upon its poste- 372 THE VOICE. an til rior part. Those muscles which act upon the arytenoid car- tilages either directly or indirectly, nine in number, are calle'l the intrinsic muscles of the larynx, viz. : two crico- thyroid muscles, two thyro-arytenoid, two posterior crico- arytenoid, two lateral crico-arytenoid, and one arytenoid muscle. The crico-thyroid, produce tension and elongation of the vocal cords by drawing downwards and forwards the thyroid cartilage over the cricoid. The thyro-arytenoid draw the arytenoid cartilages forwards towards the thyroid and relax the vocal cords. The posterior crico-arytenoid rotate the base of the arytenoid cartilages outwards and backwards, separate the vocal cords and open the glottis. The lateral crico-arytenoid rotate the arytenoid cartilages inwards and close the glottis. The arytenoid mus- cle approximates the arytenoid cartilages and closes the glottis, especially at its postei'ior pjst. The nerves which govern these actions are the branches of the pneumogastric and spinal accessory (p. 333). The combined action of the muscles places the vocal cords in the various positions necessary for breathing and the production of sounds, as in singing, speaking, etc. In ordinary tranquil breathing the opening of the glottis is wide and triangular, and becomes a little narrower at each expiration. In the production of sound it is narrowed,and the tension of the vocal cords increased. In the production of higher notes the vocal cords are more closely approxi- mated and rendered more tense (Fig. 123). In the space between the arytenoid cartilages at the posterior part of the glottis, no regular vocal sound is produced, nothing more than a mere rustling or gurgling sound. The tone of the voice is somewhat lowered by the action of the epiglottis when it partially covers the cavity of the larj'^ux. The ven- tricles of the larynx are for the purpose of affording free space for the vibrations of the vocal cords. The modes of sequence of the notes of the voice are three in number ; 1st. The monotonous, as in ordinary speaking, I COMPASS OF THE VOICE. 373 vocal with occasional intonation for the sake of accent ; 2nd, the transitional, from high to low notes and vice versa with- out intervals ; such as in crying in man, and the howling of animals, and 3rd, the musical, in which each note has a determinate number of vibrations. The compass of the voice varies in different individuals from one to three octaves, and some singers may even ex- ceed three octaves. Before pubert}', the pitch of the male and female voice is nearly the same, the male voice being a little louder ; but at this period the larynx of the male undergoes certain changes, during which the voice is said to " crack," and the pitch falls about one octave. This change does not take place in eunuchs, and they retain the puerile character of the voice. The different pitch of the male and female voice depends on the different length of the vocal cords in the two sexes, viz. : as three to two respectively^ The lowest note of the female voice is an octave higher than the lowest note of the male voice, and the compass of the two is about four octaves. There arc two kinds of male voice, the bass and tenor, and also two kinds of female voice, the contralto and soprano, all differing from each other in tone. The bass voice reaches lower than the tenor, and its strength lies in the low notes; while the soprano reaches the highest in the scale. The essential dis- tinction between the different voices, however, consists in the tone which distinguishes them when they are singing the same note. Most persons have the power of modulating their voices through a double series of notes of different characters, viz. ; the chest notes or the notes of the natural voice, and the falsetto notes. The former are produced by the ordinary vibrations of the vocal cords and are much stronger ; the latter, in all probability, by the vibration of only the inner border of the vocal cords, and are of a fiute- like cha^'acter. The voice is principally used in man in the formation of speech. The tone of the speech depends much upon the ^ %. .^V', w IMAGE EVALUATION TEST TA.^GET (MT-3) ^. *<"'' ^ /&, ^^^ 1.0 I.I |50 *' 1.8 !.25 1.4 1.6 ^ 6" »■ i! ;? VQ ^nx. All out vocal el sounds rough the pt conso- /ided into •uption to Y the lips, isified ac- tive rise as J, V, s, y as r. modifica- o imitate ished by es of the 1 almost expired ne of the •u of the bhat part cireum- Derforra- n of the It con- uscles of ain raus- ne stam- ofchers do so at every attempt to speak. It is much increased by any mental excitement, surprise, etc. Females seldom stam- mer, although more subject to nervous disorders generally than males. The cure of stammering is best effected by training the muscles in the production of the sounds most easily formed, and thence proceeding to the most difficult ; to avoid all causes of excitement to the patient, and prevent him from thinking about his condition as much as possible Some have recommended the use of pebbles in the mouth, or small pieces of ivory ; but it is very doubtful whether or not these can be of any great service. CHAPTER XVI. REPRODUCTION. The process of reproduction comprises the several provi- sions made for the multiplication o- individuals and the propagation of the species. There are three modes by which the multiplication of individuals takes place in the lower orders of organized beings, while in the higher forms it is restricted to one of these types. The first and simplest mode consists in the division of the being into two, each of these again subdividing into two others/and so on. This is multiplication by subdivision ; or fissiparous multiplication (Fig. 124). It is seen in the lowest plants, as in the cells of fungi and lichens, and also in carti- ageand other cells of the human body. The amoeba also furnishes a good example of this mode of reproduction. It throws out a large process in a certain direction, becomes contracted at or near the middle, and divides into two or more parts, each containing a portion of the original nucleus. Some organizations, as the polyp, when divided artificially 1 mm 376 REPRODUCTION. c \ •n In into segments, have the power of developing into a perfect form from each segment. The second mode takes place by a process of gemmation, or budding from the parent stalk. These buds, which con- sist of a mass of cells, are at first entirely nourished by the parent stalk, but gradually become less dependent, and at Fipr. 124. Fife'. 125. A coll uiiilergoing the process of inultiiilica- tioii by sulHlivisioii ; a, original cell ; b, coll be- coming oval ; c, undergoing hour-glass ^lontrac- tion ; d, division of the cell into two. Amoeba ; in the centre is seen the nui 'ens and surrounding it a number of vacuoles and granules last detach themselves and maintain a separate existence. This is termed multiplication by gemmation or geTumipar- ous multiplication. The hydra affords a good example of this variety. The first change which is observed is a slight ele- vation on the surface, which assumes a globular form ; a cavity is then formed in the interior, which communicates with the parent. After a time this channel of commnnica- tion closes, ^the newly-formed polyp drops off, and a new creature is formed. The joints of the common tape-worm multiply in this manner. This process is also common among the Bryozoj,, and leads to the formation of colonies. The third Tnode is called true generation, and consists in the union of the contents of two different cells, the sperm cell and the germ cell, from which is produced a new being differing from both. The simplest form of this process is seen in the Algae in conjugation. At first the opposite cells of two filaments form a process on the sides next each other ; these at length meet and fuse, and the contents of the two cells become mixed and form a new body termed a spore or sporangium, from which the new plant is formed. > a perfect imviation, s^hich con- ed by the it, and at ST. 125. in the centre mil 'eiia and ; it a number md granules existence. emmipar- spleof this slight ele- form ; a municates mmnnica- nd a new ape-worm common colonies, onsists in he sperm lew being process is osite cells ch other ; ■ the two d a spore id. ACTION OF THE MALE. 377 In the higher plants and animals distinct organs are set apart for the formation of the sperm cells and germ cells ; the former are produced by the male organs of generation, the latter by the female. Through the action of the con- tents of the sperm cell the ovum becomes impregnated, and an embryo is formed from which the adult animal is gradu- ally developed. In some instances, however, as in the class of insects, several distinct changes or metamorphoaes are passed through before the animal is fully developed, as the larva, chrysalis, and perfect animal. In other instances the embryo, instead of being developed into the perfect animal, only attains a sort of larval condition, and there may be several series of these imperfect or larval forms, each larva producing other larvse, until at last they give rise to perfect forms, which propagate only by the production of ova. This is called by Prof Owen "r.ietageaens. Action of the Male. — The male furnishes the sperma- tic fluid or sperm, which is secreted by the testes. This fluid contains the sperm cells in Fi^'. 126. which are developed the sperma- tozoa; also an albuminous substance^ various salts and an animal substance resembling fibrin termed sperma- tine. The sperm cells are large spherical vesicles, in which are con- tained from two to nine smaller cells or nuclei, in each of which is found , rT\^ L ii. Human spermatozoa magnified a spermatozoon, ihe spermatozoa .V)0 diameters ; b, sperm cell con- , , I'll 1 /» ii taining the spermatozoon coiled are the isential elements 01 the spe"- up within it ; c, ceii elongated by ,. n ' 1 1 If 1 ,1 tn^ partial uncoiling of the sper- matic fluid, and are set tree by the matozoon. breaking down of the sperm cells (Fig, 126 ,a). They are transparent filamentous bodies, about *"® of an inch (42 mmm.) in length, and from s-^s to Tir^Tny of an inch (5 to 25 mmm.) in thickness, being thicker at the anterior ex- tremity or head than the posterior or tail. Their move- ment is accomplished by the constant vibration of the tail ; 378 REPRODUCTION. \ ft, k they are said to move at the rate of one inch in seven and one-half minutes. Their movem'^nts may be sus- pended, and their power of impregnation destroyed by profuse leucorrhceal discharges or acrid secretions of the vagina, and by the action of solutions which act chemically upon them, as solution of silver nitrate, zinc sulphate, zinc chloride, etc. In the female organs of generation the move- ments continue longer than in any other situation. In the act of coition the seminal fluid is deposited in the vagina, and the spermatozoa make their way into the uierus and meet the ovum at or soon after its discharge from the ovary. One or more are supposed to pierce the vitelline membrane and pass into the interior of the ovum or germ cell, and unite with it, after which they disappear. It is also supposed by some that they enter through a small opening or micrapyle, and by others that they perforate the vitelline membrane. The fecundation of the egg may take place eititer in the uterus, Fallopian tube, or ovary, in each of which situations spermatozoa have been found after coition. The high degree of nervous excitement which att 3nds the act of coition, is followed by a corresponding amount of depression, and the too frequent repetition of it is very injurious to the general health. This is still more the case with that solitary vice, which it is to be feared is practised by too many youths. Nothing is more certain to reduce the powers both of body and mind, than excesses iu this respect. Action of the Fjiimale. — The essential parts of the female organs of generation, and counterpart of the testes, are the ovaries, in which the ova are developed. Each ovary is about an inch and a half long, three-fourths of an inch wide, and half an inch in thickness, and is attached to the uterus by the ligament of the ovary, and to the Fallo- pian tube by one of the fimbriae, the rest of the surface being covered with columnar epithelium, beneath which is the proper covering of the organ — the tunica albuginea — ACTION OB THE FEMALE. 379 in seven ' be sus- royed by »ns of the hemically hate, zinc the move- n. ed in the the uierus I from the ? viteUine m or germ , It is also L a small ■ perforate ; egg may r ovary, in bund after snt which esponding ition of it still more feared is certain to xcesses in 'ts of the Ithe testes, ed. Each rths of an Ittached to Ithe Fallo- rface being |ich is the mginea — which is a dense, firm membrane, enclosing the parenchyma, or stroma. The stroma consists of two parts, an external or cortical portion, whitish in color, and an internal medullary or vascular zone, reddish in color, and consisting of vessels elastic fibres and connective tissue among which are a number of non-striated muscular fibres. The external por- tion consists of a network of connective tissue in which th« Graafian vesicles are ff-vnied. There are also a large num- ber of nuclei in the interstices. The Graafian vesicles or ovisacs, exist in very large numbers from the earliest periods of life, and in all stages of development. They vary in size from a pin's head to a pea, and contain the ova. Each Graafian vesicle consists of an ex- ternal vascular, and an i^iternal serous coat, named the ovicapsule. The internal coat is lined internal]}^ by a layer of nucleated cells, called the menibrana granulosa, and within this is situated the ovu7n. Fig. 127. The cells of the membrana granu- Graaflaii vesicle: 1, stroma; 2, l)crit(meuin ; 'A and 4, coats of the Graatian vesicle ; 5, membrana {rranulosa ; 0, fluid of the Graa- fian vesicle ; 7, discus proligerus ; 8, ovum. Fig. 128. losa are accumulated in large num- bers around the ovum, forming a granular zone, the cumulus, discus proligerus, retinacula or chalaza. The cavity of the Graafian vesicle is filled with an albuminous fluid in which granules float. The ovum is a small spherical body, about fjr-jj of an inch (.2 min) in diameter. It con- sists externally of a transparent envelope, the zona j)ellucida or vitelline membrane, and within this is the yolk or vitellus. Imbedded in the substance of the yolk is a small vesi- Ctdar body, the germinal vesicle, and within 8potT2?gernfinai"v"s- the germinal vesicle is the germinal spot. p'^efiucida •* 5,' 'aiscub The latter is about ^o^oo of ^^ ii^ch (8mmm.) ?Int|r™uies or cells, in diameter. The vitelline membrane is a colorless transparent membrane, which appears as a bright 22 380 REPRODUCTION. fet I ring with a dark border externally and internally, and is about ^Aff of an inch (10 mmm.) in thickness. The yolk consists of granular protoplasm, the smaller granules resembling pigment, and the larger, more numerous at the periphery, fat globules. The germinal vesicle contaim a watery fluid in which are found a few granules. At the approach of the menstrual period, one (or probably more) of the Graafian vesicles enlarges, ai)proaches the sur- face of the ovary, and when mature, forms a small projec- tion on the surface. It finally bursts, the ovum escapes, and is caught by the fimbriated extremity of the Fallopian tube, and by it conducted to the uterus. Corpus Luteum. — When the Graafian vesicle has ma- tured, and is about to burst and expel the ovum, it becomes highly vascular and opaque, and its coats are thickened by £>, glutinous looking substance. As the ovum escapes, it leaves behind it the external vascular and the internal serous coats of the Graafian vesicle, the cavity of which is immediatel}'' filled with a bloody fluid which soon coagulates, and the cicatrix presents a yellowish appearance ; hence it has been called the corpus luteum (Fig. 129). After a short timo the Fiff^^. coagulum contracts, and the mem- branes become convoluted and hyper- trophied, so that when the corpus luteum is divided transversely, about three weeks after its formation, it is seen to consist of a central firm coa- gulum surrounded by a convoluted Corpus luteum, natural size, ii p ij* r ii i eight days after conception: a. Wall 01 a reddish ycllOW COlor. Corpora lutea are divided into true and false ; the former are found only when conception has taken place ; the latter are met with in the unimpregnated state. They are both produced in the same way, and for the first three weeks there is no dis- tinction between them ; but the true corpus luteum becomes external coat of tlie ovary ; 6, stroma of the ovary; c, convo- luted wall of the Graafian folli cle ; d, clot of blood. ACTION OF THE OVIDUCTS. 381 mlly, and less. The r granules •us at the jontaim a r probably 2s the sur- all projec- m escapes, ) Fallopian ie has ma- it becomes kened by &, 3S, it leaves erous coats rimediately >s, and the t has been t time the the mem- and hyper- the coipus rsely, about lation, it is il firm coa- convoluted olor. d into true, found only '0 met with )roduced in e is no dis- jm becomes Fig. 130. larger and remains longer than the false, in consequence of the increased vascularity of the parts after impregnation. At the end of the third week they each measure about one-half or three- fourths of an inch in diameter. After this the false corpus luteum begins to diminish, and entirely disappears in the course of about two months, corpus luteum. natural Mze at while the true increases in size, nt^nll^r^he^^VryTrZlo: until about the fourth or fifth dofrdecoiorized';;o?;^ month, and then gradually declines °JJ* Z*"^" "i^*' " t le corpus lute- until after parturition, when it rapidly disappears. Action of the Oviducts. — In the human subject the oviducts commence by a wide fringed expansion — the fimbriated extremity of the Fallopian tubes. The ovum, in passing through the Fallopian tube to the uterus, absorbs a certain quantity of fluid, increases in size, and if impreg- nated soon presents a number of minute villi on its surface which give it a shaggy appearance. This is called the chorion. In fowls, as the ovum leaves the ovary it enters the ovi- duct, and in passing the first portion, which is about two inches in length, it ab-sorbs fluid and becomes more flexible and yielding. In the second portion, which is about nine inches in length, the mucous membrane is thick and glan- dular. In the upper part, it secretes a vi.scid fluid which surrounds the yolk and forms a gelatinous deposit around the vitelline membrane, and from the rotation given to the egg by the oviduct the two ends become twisted in o])po.site directions from the poles of the egg and form the chalazoe. The membrane which connects the chalazse, is called the cha- lazif erous membrane. In the rest of this portion, an albumin- ous secretion is poured out to form the albumen or white of the egg. In the third division, which is about three inches in length, a material is poured out which conden.ses and forms three fibrous membranes, an internal, middle and 382 REPRODUCTION. c c »!■> Ik: B ■^v. external. The egg then passes into the fourth division, whicii is about two inchcH long. This pours out a secretion containing calcareous matter, which is deposited in the meshes of the external membrane of the egg, forming the shell. After the expulsion of the eg^, evaporation of some of the watery in^nedients takes ])lace through the pores of the shell, its j)lacc being filled with air. The air cavity is situated between the internal and middle membranes, at the , large end of the egg. The vitellus is the essential part of the egg, the white simply contributing to the nourishmert of the chick until it leaves the shell, and the membranes and shell affording the protective coverings. Development of the Ovum. — After the ovum is im- pregnated a remarkable change takes })lacc, which is known as the spontaneous division or segmev 'atior of the vitellus. A furrow first shows itself sur/ounding the vitellus in a vertical direction, which gradually becomes deeper until it Fig's, 131-4. has divided into two portions. Each of these portions is again subdivided into two, and the four segments thus pro- duced are divided into sixteen, and sixteen into sixty-four, and so on, until the whole mass has assumed a mulberry ap- pearance, and is finally converted into " vitelline spheres " or " true animal cells," which adhering together, form the bladodermic membrane. These cells are also sometimes called the primordial or primitive cells, or germinal vesicles. The albuminous matter liquefies, and gradually passes by osmosis through the vitelline membrane into the interior of the egg. The blastodermic membrane then divides into two layers, the external blastodermic serous or ■ division, secretion ed in the ming the a of some e pores of cavity is les, at the ial part of irishmen t lembranes m is im- 1 is known le vitellus. jllus in a ir until it lortions is thus pro- dxty-four, [berry op- spheres " form the sometimes germinal gradually ! into the ane then , serous or DEVELOPMENT OF THE OVUM. 383 ani/mal layer, and the internal hlastodei'mic, mucous or vegetative layer, both of which are composed of cells. The former produces the spinal column and organs of animal life ; the latter the alimentary canal and organs of vegetative life. Up to this stage, the process is the same in all animals, birds, fishes, reptiles and mammalia. The simplest form of development is seen in the egg of the frog. The egg, when discharged from the body and fecundated, is deposited in the water, surrounded by a layer of albuminous matter, and is freely exposed to the light and heat of the sun. The first sign of organization is the thicken- ing and condensation of the external blastodermic mem- brane in one part, foi ming an elongated oval spot with opaque edges. This is called the emhryonic spot. Enclosed Fi','. i;wi. The lm])rcj,'iiated ovum showing the enihr.vonic spot, aieapullucida and primitive trace. Oommenclnvr formation of the embryo; a, external l)lasloder- raic layer ; b, vitellus ; c, embryo. within this is a narrow transparent space, the area pellucida, in the centre of which is a longitudinal line, the primitive trace. On each side of the primitive trace in the area pellucida, the blastodermic membrane rises up in two plates, called the dorsal plates, which at last meet and enclose a foramen, the spinal canal, in which nervous matter is de- posited to form the spinal cord, being enlarged anter'orly to accommodate the brain. At the same time the external blastodermic membrane grows outwards and downwards, to form the abdominal walls which embrace the internal blasto- dermic membrane and the fluid in its cavity. Beneath 384 REPRODUCTION. \ In I \ \ •J' Diagram of a scution of tlie embryo Hliowinjf the formation of the npine ; a, cpibloHt : h, hypoblast ; c, iiie.sol)la»t ; d, miirKin of tlie lamina ih)rMaIis; e, medullary i^roove ; (, chorda dorxalis or notocliord ; Xi prhnilive or protovertebra. the spinal canal is formed a cartilaginous cord, which is called the chorda doi'salis, from which the vertebrce are subsequently developed. As the whole mass grows rapidly, the head becomes thick and voluminous, while the tail begins to project baokwardfl, and the embryo assumes an elongated form. The internal blastodermic layer forms the alimentary canal, the mouth and anus being developed by atro])hy and perforation of l,he external layer of the blasto- dermic membrane at these points respectively. The young tadpole then ruptures the vitelline membrane and escapes, after which the extremities are developed by a process of budding or sprouting, and when fully formed, the tail atro- phies and disappears. The animal at first breathes by gills ; but these are subsequently replaced by the lungs. In the development of the chick which has been studied very carefully by various observers, the blastodermic mem-, brane, or hlastoderm divides into three layers, the two lay- ers already referred to in the frog, and an " intermediate layer " or mesoilast. These three layers are designated by .some, the epihlast, mesoblast or middle layer, and the hypo- blast. The epiblast forms the epidermis and appendages, cere- bro-spinal nerve centres, sensorial epithelium of the nt se,eye, ear etc., and the epithelium of the mouth and sali varj' glands. From the mesoblast is formed the tissues of the body, con- nective, muscular and nervous tissues, vascular and genito- urinary systems, and digestive canal except its epithelium ; and from the hypoblast is developed the epithelium of the alimentary canal and the ducts that open into it, and also the parenchyma of the glands, as the liver and pancreas. In the egg of the fowl, a whitish circular spot is seen, about ^ of an inch (5 mm) in diameter, immediately beneath the vitelline membrane, the cicatricula, in the centre of which DEVELOPMENT OF THE OVUM. 385 which is ebrre are 8 rapidly, hick and the tail inkwardfl, mraes an B internal orrns the le mouth eloped by lie blasto- "he young :1 escapes, process of tail atro- s by gills ; •n studied mic mem-. two lay- ermediate ;ynated by the hy-po- ages,cere- ; ncse.eye, r}'^ glands, jody, con- tid genito- lithelium ; im of the and also creas. In n, about \ neath the of which is the germinal vesicle. When the egg is fecundated, seg- mentation begins in the cieatriculain the manner already de- scribed, until the blastoderm comes to occupy the place of the cicatricula. It then separates into the three layers above mentioned, in which certain prominences and foldings take place which mark out the commencing development of the difterent parts of the embryo, as the " headfold," " tailfold," etc., (Fig. 138.) On each side of the primitive trace (Fig. 135), the epiblast rises up to form the dorsal plates (laminae dorsales), which soon meet and close in the spinal or medul- lary groove, and form a canal for the reception of the spinal cord and brain (Fig. 137, d). Beneath this canal in the me-soblast is formed the c/iorc/a cZorsa^is or notochord, which ultimately becomes the spinal column ; on each side of the chorda dorsalis, a longitudinal thickening of the mesoblast takes plact from which is formed the primitive vertebrae (protovertebrie). These structures form the bases out of which the spinal column and muscles are afterwards d • veloped. On the outer side of the primitive, or protover- tebrse, the mesoblast splits into two laminae, one joins the epiblast (fcomatopleure) and forms the parietes of the trimk, and the other joins the hypoblast (splanchnopleure) and forms the alimentary canal and other parts. The general cavity of the body is formed by downward foldings of the blastoderm, somewhat resembling the formation of the nervous canal (Fig. 138). These downward foldings are called the visceral plates. In the frog these plates close in the whole of the vitellus. In the chick, fish, etc., the internal blastodermic membrane is divided into two parts by a constriction, one of which forma the intestinal canal, while the other, remainingoutside, forms the umbilical vesicle, which is surrounded by a portion of the external blastodermic membrane, and is gradually atro- phied as development proceeds. In the human embryo the umbilical vesicle becomes more completely separated, and forms a cord by its constriction, 386 REPRODUCTION. c c [ I* L I to at the distal extremity of which is situated the vesicle, which contains a clear transparent fluid (Fig. 139, g). The umbilical vesicle may continue until the end of the third month, after which it gradually disappears in the advancing develojiment of the adjacent parts (Fig, 141). Formation of the amnion and Allantois. — These are two accessory organs which belong to the higher order of animals, and their development has been carefully studied in the chick. The amnion is formed from the external layer of the blastodermic membrane, and the allantois from the internal ; the former encloses a cavity or sac containing fluid in which the foetus floats ; the latter is a vascular structure destined to bring the blood of the embryo to the Fiff. i;!8 Fis- i;^i>- Diajjfriun of tlio formation of the aiunioii and allantois :— rt, vitelline membrane covered with the villi of the chorion ; h, folds of the amnion suircuuling the emliryo ; e, point of meetinf; of amniotic folds ; tn load by the olfactory groove into the cavity of the mouth. After the formation of the palatine arches, this cavity is divided into two parts ; the lower forms the mouth ; the upper, divided by a septum, the nose. The olfactory nerve is derived from a prolongation of the anterior cerebral vesicle. Fl(f. 146. Area vasculosa of an embryo, ventral surfauu. 1, Terminal sinus. 2, Omjihalci-mesen- teric vein. 3, Its posterior branch. 4, Heart in the form of an S. .">, Primitive aorta, or posterior vertebral arteries. C, Omphalo-inesenteric arteries. — Binchvff. Development of the Extremities. — The upper and lower limbs are formed as buds from the anterior and pos- terior part of the embryo, by a projection of the somato- pleure covered by the epiblast. The division of the extremity of these buds into fingers and|toes, which have a webbed appearance, takes place at an early period, and soon after, a constriction or groove marks the situation of the wrist-joint. As growth proceeds another groove shows itself, at the elbows be mouth, cavity is louth ; the ory iiervo ■ cerebral nipluild-niesen- nitive aorta, or ippor and • and pos- e somato- extremity a webbed on after, a vrist-joint. the elbows DE VELOPMENT OF THE VA SCULA R S YS TEM. 397 and knees. In all animals, the anterior extremities precede the formation of the posterior. Development of the Vascular System. — The vascular system assumes three different forms during different periods of life, viz., the vitelline, placental, and complete. The vitel- line circulation commences at a very early period in the chick, and consists of a number of vessels which ramify over the surface external to the embryo, and form a plexus, the " area vasculosa." The vessels are formed from the cells of the mesoblast, which become elongated, or branched, unite with each other and become liollowed out to form the capil- lary walls (p. 222). The blood corpuscles are formed from the nuclei of these cells. The function of this structure is to absorb the nutrient material from the vitellus. About this time the heart begins to make its appearance. This organ and the larger blood-vessels are formod on the same plan. Masses of embryonic cells of the splanchnopleurc are arranged in the position, form and size of the develoi)iiig structures; the external layers of cells are converted into the walls of the organs and the internal form the first blood corpuscles (p. 174<). The heart may now be seen as a minute red pulsating point, even before the muscular fibres have been formed ; this is the " punctum saliens" of Harvey. The heart is at first tubular in form, and receives posteriorly the two omphalo-mesenteric veins, and opens anteriorly into the primitive aorta, which divides into two vessels^ ''''''' ^*^- the vertebral arteries. These form a series of arches, and give off the two omphalo-mesenteric arteries to the area vasculosa. It then becomes curved or bent upon itself like the letter S or a horse shoe, and partly divided by constrictions into three cavities. The one corresponding with jayonncubation the arterial end, is t^^e bulbus arteriosus ; the .rt'he'luricieTs,' one at the venous end, the auricle ; and the one the bulbus'artt- inthe middle is the ventdcle, which becomes ~-2'''«"«i'- more rapidly developed uhan the others. In some animals-'. Heart of the 398 REPRODUCTION. r ! I as tho Amphibia, this form remains, no other division by se|)ta takinj^ place ; but in tho liij^her animals ami man, both auricle and ventricle are subdivided by septa, and the bul- bus arteriosus disappeais in the ventricles. In man and the higher animals in which tho vitellus is small, the vitelline form of circulation f^oon disappears, and is replaced by the pldcoital or allantoic circulation. Tho two omphalo-mesenteric arteries become blended into one artery, and the correspondin<^ veins into one vein. They are called omphalo-mesenteric arteries because they supply in part the " omphalos" or umbilicid vesicle, and j)artly the mesentery and intestine. After a time the umbilical vesi- cle and its vessels diminish, the mesenteric vesselj increase, and the allantois grows out from the posterior part of the intestinal cavity, carrying with it tho allantoic or placental vessels. There are two uinhilical arteries and at first two corresponding veins, but after a tim-^ one of the veins dis- appears, and the whole of the blood is returned from the placenta by one vein. The complete circulation takes the place of the placental circulation, which is abruptly terminated by the separation of the placenta at birth. This transition is more abrupt than the preceding ; but has been duly provided for by the gradual development of the necessary organs. The blood vessels first commence to form, as previously stated, in the area vasculosa external to the body of the embr^'o. The first aortic arch is formed by the division of the primitive aorta into two branches, which arch backwards, and, after descending, unite into one vessel in front of the vertebral column (Fig. 148). Other pairs of arches are formed in succession behind the first, to the number of five. These are not all to be seen at the same time, for as some develope, others disap])ear. In fishes they all persist thiough life and form the distribution as seen in the gills. In man and the higher animals, the anterior ones disappear and the posterior ones become transformed into the carotids (5 ), visi(Ui by iiinn, both (1 the biil- vitulhis is pears, and ion. The 1 Into one Tliey are su])i)ly in )artly the lical vesi- j increase, art of the • placental , first two veins dis- from the phicental leparation re abrupt "or by the ireviously \y of the ion of the ick wards, nt of the rches are er of five. as some t through In man pear and tids (5 ), ) DE VELOPMENT OF THE VASCUI.A A' S VSTKAf. 300 subclavian (4 ), arch of the aorta, pulmonary artery, ductus arteriosus, and descending aorta (Fig. 148). The veinn that first ajjpear are, as alniady stated, the omphalo-niesenteric which soon unite to form one. Next is formed the two umbilical veins, which return the blood from the ])lacenta, the left enlarging, while the right disaj>pears. When the liver begins to be formed branches pass into that organ* and give origin to the hepatic vein.s. This organ receives blood from two sources, the portal, and the und)ilical veins. The systemic veins are formed froa pmr trunk veins, two above, and two below, which unite into a canal (sinus of Fi;.'. US. V\]i 141». Aiirtic arcliesiflvopuirsurosliowTi, thcui)|)erone!iilisai)pe(ir, the throe lower remain, and reiiresent tlio carotids (.'■>), the sulxilaviaii (4)iiiid arch of tlie aorta (3). 1, Triinlis which spriiii,' from the ventricles ; 2, descending aorta, the left (2) is finally obliterated; the ductus arteriosus is seen at the junction of the arch with the deaceiidin^f portion (0). I)ia;;rum of the develop- ment of the veins : c, c, cardinal veins ; j, j, j'lK"- lar veins ; h, hc|iatic veins; dc, ducts of Ouvier ; sv, sinus venosus. Cuvier) on each side, and open into the rudimentary auricle. (Fig. 149). The two above are called the anterior cardinal, or jugular veins, and the two below are called the posterior or inferior cardinal veins. When the umbilical vein is formed, it at first communicates with the sinus of Cuvier, but after the inferior vena cava is developed, it empties info the latter. The auricle now receives blood from the inferior vena cava, and the sinuses of Cuvier which now become the right and left supei;ior vena cava respectively. The left vena cava finally disappears and its ,.., f 400 REPRODUCTION. In I I JO, orifice is converted into the coronary sinus ; the right, forms the superior vena cava. An anastomosing branch between the anterior jugular veins becomes the left innominate, and the termination of the right jugular the right innominate vein. The inferior cardinal veins return the blood from the Wolffian bodies, vertebral column, and parietes of the trunk. The inferior vena cava is formed about the fifth week, and finally receives the blood from the inferior cardinal, and the crural veins. The upper part of the cardinal veins remains, the riglit c^e as the vena azygos major, and the left as the vena azygos minor and superior intercostal. The middle portion disappears, and the lower becomes the hypogastric. Devflopment of the Alimentary Canal and Glands. — The alimentary canal is formed at a very early stage. It is at first closed at each end, by the blastodermic layers, and communicates with the umbilical vesicle. It consists of three parts ; the anterior, which forms the pharynx and oesophagus ; the middle which forms the stomach, intestines, and upper third of the rectum ; and the posterior which forms the middle third of tlie rectum. The lower end of the rectutn and buccal cavity are formed by a depression in the middle and external layers of the blastoderm, and do not communicate with the common cavity till a later date, hence the occasional occurrence of imperforate anus and im- perforate a3sophagus. The middle portion of the intestine, is at first a wide groove, which becomes converted into a straight tube, and is gradually separated from the umbilical vesicle. It now becomes divided into the different parts, as the stomach, small intestine, and large intestine, and is sus- pended in the abdomen by the mesentery which attaches it to the spine. The principal glais Js are the limr, pancreas, spleen and salivary gla'tids. The liver is developed from two promi- nences of the blastoderm in the form of hollow cones, which involve the omphalo- mesenteric vein, from which they re- DEVELOPMENT OF RESPIRATORY ORGANS. 401 ■ight, forms ch between ninate, and innominate od from the f the trunk. week, and lal, and the ns remains, left as the Che middle lypogastric. ID Glands. f stage. It rnic layers, It consists larynx and , intestines, irior which r end of the 3sion in the and do not later date, iius and ini- le intestine, rted into a le umbilical snt parts, as and is sus- attaches it spleen and two promi- ones, which sh they re- ceive branches. These prominences are developed into the right and left lobes. This organ is of large size in propor- tion CO the body, and secretes a substance which is poured into the intestine, termed the meconium. The gall bladder is developed as a pouch from the hepat'o duct. The salivary glands are developed from the epiblast lining the luuath, in the form of simple canals with bud-like processes, sur- rounded with protoplasm and communicating with the mouth. The canal becomes more ramified as development proceeds. The pancreas is developed from the hypoblast lining the intestine, in a similar way, and the spleen is developed from the mesoblast, proceeding from a segment of the peritoneum. Development of the Respiratory Organs. — The lungs first appear as small tubercles in front of the oesoph- agus. They are formed from the hyyoblast of the alluieu- tary canal. They at first open into the (esoj)hagus, buE, soon a separate tube is formed at Fig. 150. their point of junction ; this is the trachea. The primary tubercles thus formed next send off secondary branches into the surrounding meso- blast, and these again tertiary ones a, u.aeveioimieutof thciung,*, 1 . , ,1 . n n if, tertiary bran'ihes and air on which the air cells are lonned. cLiis. The diaphragm appears early, in the form of a fine mem- brane separating the lungs from the Wolfiian bodies, stomach and liver. ' Development of the Urino-sexual Organs. — These organs are formed from the mesoblast. The Wolffian body or primitive kidney may be seen as early as the third week. It has a glandular structure, in many respects * similar to the kidney, is provided with an excretory duct, and secretes a fluid containing urea which is con- veyed to the bladder It pUaiiie its highest development, about the sixth week ; it then diminishes, to be replaced by i 402 REPRODUCTION. c t [ •ft I n*' i; the kidney, il)y ppdad sanears the end of the third month The duct of the WolfHan body is formed in the mesoblast behind the pleuro-j ericoDeal cavity. The duct is first hollowed out, and then the tubes of the Wolffian body begin to form as branches of the duct which terminate in Malpighian bodies. Next a thickening occurs between the Wolffian body and the mesentery, termed the Wolffian ridge or "geim epithelium" from which the testis or the ovary is developed, as the case may be. A groove is now formed internal to the Wolffian duct, called the duct of Muller. These ducts, together with the ureter, when formed, open into the urogenital sinus, or termination of the intestinal cavity. The Wolffian ducts re- main in the male, and form the A, ki.iney ; h, ureter ; c. Bladder ; cpididymus, vas deferens and u. urachus ; k, constriction which pipp„l{,fnrv f\nok nn Pflph cjidp becomes the urethra; v. Wolffian ejaCUiaiOiy UUCL OH eacil 'slue. body ; o. Wolffian duct, with its opeiiinjf below, o'; n, duct of Mitller, united below, from the two sides. into a single tube, j', whiih iircsmts a single oi)ening. .i, between the openings of tlie Wolffian ed mases, in which are formed the calicos. It has therefore a lobulated appearance which continues for some time. The supra-renal capsules are developed from the same mass as the kidney, [and are at first much larger. A small portion of the Wolffian body lemains in the female term- ed the parovariuvi, while the re- DEVELOPMENT OF UTERUS AND VAGINA. 403 ird month mesoblast ct is first the tubes begin to the duct ^alpighian ling occurs idy and the ! Wolffian lum" from e ovary is nay be. A internal to d the duct s, together m formed, al sinus, or intestinal ducts re- form the jrens and each side. Wolffian male term- lile the re- uct which forms the mesoblast and leads ed from a )rmed the ice which jsules are Iney, [and The bladder is next developed from the urachus ; this is a hollow tube wliich connects the posterior part of the intes- tines with the allantois. As the abdomen closes at the umbilicus, the part of the urachus outside the body forms part of the cord, while the portion included in the abdomen becomes dilated and fusiform at the lower part, and forms the bladder ; the upper part becomes obliterated and forms a fibrous cord which extends from the summit of the bladder to the umbilicus. Sometimes, though very rarely, this part remains pervious and permits of the escape of urine at the umbilicus. The testes or ovaries which are formed on the inner side of the Wolffian bodies, soon begin to descend, the former to the scrotum and the latter to the pelvis. This was formerly supposed to be caused by the action of a muscular organ, the gubernaculum testis, but this is not now g. nerally supposed to be the case. The means by which it is effected are not known. The testicle in its descent pushes before it a pouch of peritoneum, be- hind which it lies, which ultimately forms the tunica vagi- nalis or serous covering of the testicle. The uterus. Fallopian tubes, and vagina are developed from the ducts of Mliller, already described. The union of the two ducts below form the vagina, cervix, and lower portion of the uterus, while the upper portions form the upper part of the uterus and Fallopian tubes. This explains the occurrence of an occasional bicornute condition of the uterus. The external organs of generation are, at an early stage, the same in both sexes. The urino-genital opening, or sinus, is formed at the same time as the anal cavity, by a reflection of the epi blast inwards. There is first seen a tubercle in front of the sinus, the genital tubercle, which is soon surrounded by two folds of integument, the genital folds. The tubercle is surmounted by a glans, and is grooved upon the under surface (Fig. 151), yet no distinction of sex can be made out. As development proceeds, the urino- genital sinus in the female remains and communicates with 2.i 404. REPRODUCTION. the vagina; the genital tubercle retractn and forms the clitoris, and the foldings of integument are converted into the nymphae and labia majora. In the male, the genital tubercle elongates, the glans is developed, and the margins of the sinus meet on the under surface to enclose the ure- thra. The large cutaneous folds form the scrotum, which receives the testicles about the eighth month. When the urethra fails to close, hyposfoLclias results, and an appear- ance of hermaphroditism is present, which is increased by the retention of the testicles in the abdomen. I f ?*■■■ forms the '^erted into he genital le margins 3 the ure- um, which When the m appear- jreased by APPENDIX. METRIC SYSTEM OF WEIGHTS AND MEASURES. Equivalents. Metre Decimetre -zqi Centimetre '."*.'.".'.,.*."" ^q Millimetre (mm) '.'.*.'.'..'."!.*...'...' Micromillimetre (mmm) or 391 or 2i or I 039 or tjV 000039 or ^^j-jj3 inches. Gramme ,- Decigramme * '"' j ^^ Centigramme 1^4 Milligramme ...,......" ore or 15^ or i^ or i or ^ II II 11 II grams. II II II THE METRIC SYSTEM IN MEDICINE. Old Style. MioT gr.i equals /si or ,5i , ........"." 4 /si or |i „ '"^2 The decimal line instead of points makes errors impossible. A teaspoon contains 4 gins. ; a tablespoon 20 gms. Jletric. 06 gms. ti AVERAGE SIZES OF VARIOUS HISTOLOGICAL ELEMENTS. Fractions of an inch. Air Cells ^o to ^i,. _ , - " 10 -" 3 7 Blood Corpuscles, Red, ^^..^ Metric. to •• n White 3j)'oo Canaliculi of Bone TTri^Tnr Capillaries, 7^-Vir Cartilage Cells, ^i^ to ^^,^ „ to Chyle Corpuscles, -j^Vo ^^^^^ Tl^oo iO J-^Tf 6 to Cones of Retina, T^ion End-bulbs of Krause, ^^ .12 mm 71 mmm 8 mmm 1.4 mmm 8 mmm 12 mmm 8 mmm mmm 2 mmm 41 mmm c c i h K M I ti K m \ By. 406 APIENDIX, Epithelium, Columnar, j^,,^ to . ,, lo to 7.1 mmm II Squamous si, i to .x^'ao 50 to ic mmm Fat Cells, j^o to „},<, 83 toji mmm Granules, y^l^-^ to _. J ^u 2.5 to i mmm Haversian Canals, .^,',0 to j^'o,, 120 to 12 mmm Lacunae (bone), xfl'oo ^4 mmm Lirabus Luteus, ^^ i mm Malpighian Bodies, (kidney), yA„ .2 mm II II (spleen), ^^ .4 mm Muscle, Striated, ^^^ to ^J^ 125 to 50 mmm •t Nonstriated, ^^7 to j^^75^ 8.510 5.5 mmm Nerve Cells, 5^-,,- to y^Vt ^3 ^° 2,5 mmm II Fibres, (medullated) ^^j^tj to Y2-J-„-vr .... 12 to 2 mmm II II (non-medullated) ^^j^ to -B-^fVir-- 6 to 4 mmm Ovum, Ta( .2mm Pacinian Bodies, ^'o to iV 2.5 to 1.7 mmm Papillae of Skin, 3^^ to ^7^ 25to .1 mm II of Tongue, tV to Vo 2 to .3mmm Tactile Corpuscles, ^io .imm Tubuli Uriniferi, sin 50. mmm Villi, Vo to ijio 5 to .imm AVERAGE SPECIFIC GRAVITY OF VARIOUS FLUIDS. (Water = 1000). Bile 1020 Blood 1055 Cerebro-Spinal Fluid 1006 Chyle 1024 G^tric Juice 1005 Intestinal Juice loii Lymph 1020 Lungs when fully distended with air, 126; when deprived of air, 1056 ; ordinary postmortem condition, 345 to 746. Milk 1025 Pancreatic Juice 1012 Saliva 1005 Serum 1026 Sweat J004 Urine 1020 AVERAGE QUANTITY OF VARIOUS FLUIDS SECRETED IN TWKNTY-FOUR HOURS. Ota. I 12 I .2 •4 5° S-5 3 2.5 D 2 3 4 .2 3 1.7 .1 3 -3 .1 50- ) .1 IDS. mmm mmm mmm mmm mmm mmm mm mm mm mmm mmm mmm mmm mmm mm mmm mm mmm mm mmm mm 1025 1012 1005 1026 J 004 1020 deprived of LE'J'ED 30 25 40 gnis'. 930 780 1250 APPENDIX. REACTION OF THE VARIOUS FLUIDS. 407 All the fluids of the body have an alkaline reaction, except the following, which are acid : Gastric Juice. Sweat. Urine. Mucus of the Vagina. CLASSIFICATION OF THE ANIMAL KINGDOM. ( Gegenhauer.) INVERTEBRATA. i Rhizopoda ; amoebae, foraminifera. -: Gregarinre. I Infusoria ; vorticella, paramaecium. f Spongine ; sponges. \ Acalephae ; hydra, coral, sea-anemone, polyps, medusiB, beroe. f leeches, earth worm, round worm, thread \ worm, tape worm, guinea worm, bryozoa. star-fish, sea-urchins, sea-cucumber. / Branchiata ; crab, lobster, barnacle. ( Tracheata; scorpion, spider, beetle, cock- roach, bee, ant, butterfly. f Ecardines ; lingula. ( Tcsticardines ; terebratula. I Placophora ; chiton, cryptochiton. I Conchifera ; oyster, cockle, whelk, snail,clio, argonaut, cuttlefish, nautilus. J Copelata ; oikopleura. \ Acopa ; salpa, pyrosoma. ' VERTEBRATA. Acrania : Leptocardii ; amphioxus. r • f i Cyclostomata ; myxinoidea, petromyzontes. l^ramota : | Onathostomata. i Pisces. (a) Anamnia : \ Amphibia ; frog, newt, triton, sal- ( amander. /'Reptilia ; lizard, snake, crocodile. ) chameleon, tortoise. Aves. Protozoa : Coelenterata : Vermes : Echinoderma Arthropoda : Brachiopoda : Mollusca : Tunicata : (b) Amniota : \ Mammalia. ADDENDUM. r Mr' Spuuiiiieit of blood showing: marked leucocytha3)iiia. Tlie proportion of wliite to rod cwrpiuelex is as one to seven. if wliite to rod INDEX. Abdiicena Absorption Mechanism of by villi and lactoals by blood ves.sols by lymphatics Acini of Ijiver Adipocero Adipose tissue Appearance and properties of Function of .lEsthesionietcr Air, chany:es in respired (Quantity respired Breatbin4 04 115 213 214 215 214 210 217 210 225 374 243 342 !457 330 395 277 281 B Bacterium 35 Basement membranes 58 Paoi. Basement membranes. Function of . . . . 59 Bernard on the function of the liver. . . 150 Bile 147 Appearance anil properties of 148 Chemical composition of 148 Bile salts or bilin 149 Function of 151 Tests for 153 Bilirubine 44, 149 Blliverdine 46. 140 IJhistodennic niem)>rane 382 Uleedin]^'', effects of, on blood 183 Blood, Elements of I(i8 Quantity of 168 Physical character of 108 Jlicroscopical a|)i)car.ince of 169 lied corpuscles of 170 White corpuscles of 173 Oriyin of Corpu-ides of 174 Development i)f Corpuscles of 175 Chemical composition of . . . 177 Ilenioyloliine 178 Distinction between human and animal blood 100 Difference between arterial and venous 180 Portal, renal, and hepatic venous blood 180 Oases of 181 Causes of Color of 182 Influence of venesection on 183 " Starv.atiiiu on 184 " Iron and flesli diet.. .. 184 " Ajje and se.x 185 " Disease on 185 Blood Poisons 188 Coagulaticin and vital |)roperties of. 188 Time required ior coajfulation 189 Theories of coajfulation 190 Cupped and P. iffed condition of. .. 191 Coa!,'ulat'on ot promoted 192 retarded 191 Function of fibrin of 194 " red corpuscles of 195 " white corpuscles of. . . 196 " albumen of 190 " fats of i97 salts of 197 Relation of, to livin;,' organism. . .. 198 Globuline of 178 Increase of fibrin of 185 Circulation of blood 200 Changes of in respiration 242 Bone 72 Appearance and properties of 72 Chemical constituents of 72 Structure of 73 Haversian canals of 73 Lacuna; and canaliculi of 75 Articular lamella of 75 Development of . , 75 III 410 INDEX. c to i h I "-. m 8 I Haur. Bono, (Irowth of 78 Briiiii 310 Avuragc weijfht of 310 Htructuro of 311 Vasculiir Huppiv of 310 VentrirluH of 31(1 Function ol, Ac :tl7 Uuntru for laiiKuaij;e 310 " vision 315 " heurint; 315 Bronchoiiule or noitro 275 Bro\vn-8d(|uar(i on Hpinal uord 3U1 Brunnur's i^lanilH Ill BurHU! 102 Butter acids 208 C Caiiuliuuti Canal o( I'etit Capillurio.M, Structure of Circulation in Influence of nerves upon Velocity of Circulation in Carbonic acid, Inhalation of How affected Ih)W favored Cardinal veins Cardioff rapli Cartilnjfe Appearance and jiroperties of Tenijiorary and I'ernianeut Hyaline Reticiilur Fibro-cartilajfc Vascular snpjtly of Cartilagine or Chondrinc Casein 40, Oriifin and function of Cauda Kquina Cause of Orjfanization . . . : : . . Cells Ueflnition of a Cell Variation in shape and size •Structure Cell nuclei Cell contents Color Development and j,'rowth ol, Permanent ctiantfc of shape Tcniixirary chanH;e of sliape Function of Cells JIaiiifostation of cell life Cells of Purkinje Cement substance 03, Cerebellum Structure of Peduncles of (crura) Cerebral vesicles Cercbrine Cerebro-spinal nerves 27(1, Cerebrum Averajfe wci(fht of Structure of Convolntiiins of Sulci of Lobes of Fissures of Areas of (Fcrrier) Ventricles of Vascular supply of Function of . . ." I 'rura cerebri HM 222 223 224 225 231) 240 242 300 200 t)7 07 07 (18 CO 70 70 42 208 41 200 55 47 47 47 48 40 50 50 ri3 53 54 50 57 308 113 307 307 30S 393 4(i 285 310 310 311 311 312 312 313 314 310 310 317 323 I'AOB. Cerebration, unconsclouil 323 Cerundnous Rlands 121 Cervical fissures 804 Cerumen of ear H58 Chalaza 370, 381 Chalazifcrous membrane 381 (Jholesterinc 33, 140 Chorda Dorsalisor Notoehord 384 Chorion, formation of 388 Choroid 344 Chromatic aberration SIfi Chyle, Molecular base of 101 Comiwsition of 102 ChvliHcation 144 Chymillcation 1!J0 Ci>'atricula 384 Ciliarv Ligament 340 Ciliary Muscle 346 Ciliarv Processes 345 Cilia 00 (irowth and motion of 54, 00 Ciliated e)iithelium 100 Circulation 200 Course of, in the adult 202 Proofs of 203 Peculiarities of . . . 226 Velocity of 225 Vitelline circulation 307 Fcetal 227 Cleft i)alatc 304 (Joaffulable Ivmidj 58, 106 Cochlea .". 360 Coflfee 130 Collagen 43 Coloring matters 43 Colloids and Crystalloids 104 Colostrum 208 Coldblooded animals 244 Connnunication of lu'rvous impressions 204 Conduction of nervous impressions — 204 Conjugation 376 Connective tissue 00 Corium or oitis vera llf> Cor> ea, structure of 343 Con)ora am vlacea '-4, 284 Corpora striata 324 Corpora quadrigemina 323 Corpus lutcum 380 Corpus calliisuni 324 Corptisclcs of the Blood 170 Origin of 174 Develojinicnt of 175 Coughing 238 Craiuo-spinal axis 279 Cranial nerves 329 Creatine and creatinine -204 t!retinism 275 (.'rying 238 Crystalline lens and capt '" 349 Cumulus 379 Cyanosis 229 Cytoblastcnia 50 Cytogencsis 51 Laws of 51 Modes of 52 Conditions necessary to 53 D Daltonism 357 Decidna Vera 389 Reflexa 300 Serotina 390 INDKX. 411 I'AOB. 328 121 81)4 8f)8 ...371», 381 381 33, 140 384 388 344 aifi 1(11 102 144 130 384 346 346 345 00 ....54, 119 100 200 202 203 22« 225 397 227 394 ... 68, 196 360 mo 43 43 104 268 244 prcssidiis 204 s»ioiiM. . . . 294 376 00 115 343 24, 284 324 323 380 324 170 174 175 238 270 320 204 275 238 349 379 229 50 51 51 52 53 357 .S80 .390 300 I'AQII. Deou8)iatioii of Medulla Dcfocatiun Dcgliitltioti, MuclmniHin of Deiitinu l)uvelo|iiiioiit of Devclopinont of collo of tho embryo " Hpiiiu, craiiiiiin and nervous Hystoin " fuce " eye, uiir, noso " extruniitius " vaacular Nystem " intestinal cnnul und glands. . " lunifs iirino-sexual organs nerve centr > Diabetic Digestion Kate of Influciiuo of nerves on ... . Artificial Movements of stomach in. Digestive fluid Discus Proliiferus Dorsal |)lates Dreams Drink • Ductless glands Diapliysis E Ear, Structure of IJones of Ectopia Vesicas Elastic tissue . . * Elasticine : Electricity ; Currents of .* Phenomena of. in man " " animals Electrotonus Elementary forms of tissue Elen.ents of respiration Embryo, development of Embryonic spot Emotions Enamel Develojnnent of Encephalon End-bulbs of Krause 116, Endosmosis and exosmosis Epiblast Epidermis Epiglottis Epithelium Tessolated Columnar Ciliated Erectile tissue Excito-motor nerve action 212, 219, Excretine Expiration Muscles of. 304 160 137 79 82 51 302 303 394 395 390 397 400 401 401 300 125 143 143 14^ 144 144 379 383 328 128 270 76 358 359 259 62 43 248 248 249 251 250 46 120 392 383 322 80 81 303 Eye. Structure of Accommodation to vi.slon. Simultaneous action of . . . Essential parts of Blind spot 280 103 384 113 370 96 97 98 100 227 277 157 234 234 343 843 352 365 350 355 I'AUK. Facial nervo, Paralysis oi 333 Paeultlus, Intellectual 320 En.'ees, Analysis of 167 Fats and oils 20 PliVNlcal appearance of 30 Function of 82, 00 Fenestra ovalls and rotunda 300 Formonts 34, 136 Fil)rous tissue 60 Fibrocartilugo 70 Fibrino..... 38 Physical a])pearance of 30 Coa^'uiatlon of 39 Function of 40, 1114 As elTete material 40, 1 95 Filunj termlnale 296 Fission, or Fissiparous multiplica- tion 62, 376 Fine adjuster of tho eye 353 FcL'tal circulation 227 Changes in, after birth 220 Follicles 108 Food 126 Cla-sslflcation of 126 Illatogenetic substances of 120 (Quantity of 127 (Quality of 128 Force, nervous 20.'V, 326 Fovea centralis 347 Frontal sinuses 341 P Facial nerve 332 Division of, for tic doloureux 332 Galvanic pile 249 Ganglion Inipar 330 Ganglion of Hibes 330 Ganglia of the Nervous System 270 of the Svmpathetic 337 Structure of 284 Gases 22, 181 Gastric juice.. .. 140 Physical appearance of 140 Chemical composition of 140 Function of 142 Gelatine 14, 43 Gelatinous tissue 71 Gemniiparous multiplication 52, 376 (Jeuenitlon, True 376 Genital tubercle and fold 403 Germ Cell 379 Germinal Vesicle 379 Spot 279 Membranes 59 Matter 47 Globullne 41, 178 Glottis 370 Gli>ss<)i)haryngoal Nerve 333 Glycogen 25 Glycogenic function of I/iver l.'iO (J(il)let or Hccher culls 99 Graiudcs ( u- .Molecules 57 (iraafian Vesicles 379 Growth of Bone 78 Nails 118 Hair. 119 H Hiomadynamometer 211 Hair. .."... 118 follicle 120 Hare-lip 394 Haversian system 74 Canals 74 412 INDEX. c c ^ n I S r I « Paur. Heart 200 Htmeluronf 204 VoMKols uml Norvos of 206 Actidii of 206 Soiiiuls of 207 Khythni of 2(18 Ciumus of soiukIm of 208 V/onlH roprcsoiitiiiK nouiuIh of 208 Iii\|)Uliie of 2011 Freciiiency aiul force of outluii 201) I'lfluence of nerves on 211 K\('ito-inotoruiiiliiiliil)itory nerves 211 Heariiitf ' 358 Mei^haniMni of M(J2 Sense of, impaired 'Mii Heat 244 Theory of |>ro(iuutioi> of 245 IiiHuuncu of nerves. ... 246 Loss of, by evaporation 247 Latent 247 Development of, in muscle 1)1 Hematine 178 Hemofflolilne 43, 178 Hepatic cells 254 Hiccup 231) Hippiiriu acid 2(13 Ilistojfeiietic substances of food 120 Klemcnts of blood 108 Humor, aipioous 340 Vitreous 340 Huntfor 130 Ilypernictropia 350 Hypoblast 384 Hypoglossal nerve 333 Hypospadias 404 I Ideas 321 Ideo-niolor action 270, 317 Inanition 1,'il Ima^'e formed on the retina 351 Imi>ulse of the heart 200 Impressions 280, 320 Kegistration of 281, 320 Inhibitory nerve action. . .212, 210, 301, 334 In.salivation 134 In8)>iration 234 Muscles of 234 Instinct and intelligence 318 Intellect ;>20 Intellectual faculties 320 Integument 112 Kiiithelium of 113 Color of 114 Coriumof 115 Appendages of ll(i Papilla; of 110 Function of 122 Intestine (large) 155 Intestinal juice 145 Appearance and i)roperties of 145 Function of 145 Intestine, villi of.. 110, 158 Inter-cellular passages in lungs 232 Involution of the uterus fA, 392 Iris, structure of . 345 Irradiation 364 K Katelectrotonus 250 Keratine 43 Kidney 250 I PAok. I Kidney, Structure of 260 I Malpighian bodie§ of 2)i7 Tubull urinifcri 267 Pyramids of 268 Papillie of 257 Vessels and nerveH of 268 Sinus of 269 Function of 260 Kymograph 211 Labyrinth 360 Vestibular portion of 361 Lacteals : 168 Absorption l)y 105 Lactose, or sugar' of milk 20, 208 Lacunio of bone 76 Larynx, organ of voice 370 Structure of 370 Vocal cords of 371 Ventricles of 370 Muscles of 374 Laughing 238 Laws of cytogenesis 51 of Nerve action 201 regulating transmission of light... 351 of nervous distribution 303 Lccithine 45 Lenticular glands 140, 155 Lenses 350 Leucine 46 Levers 92 LicberkUhn's follicles 109 Light , 248 Ligaments 60 Limbcus luteus 347 Lime phosphate . . . .^. 19 Carbonate 19 Li(|uor Amnii 387 Liver 252 Structure of 253 Hepatic cells of 254 Function oi 147 Vessels of 264 Locomotion 04 Lungs 230 Structure of 231 Air cells of 232 Vessels and nerves of 233 Action of 233 Exhalation of Carbonic Acid by .. . 239 Inhalation of Oxygen by 241 Luteine 45 Lyni|)h, composition of 160, 102 Lymphatic vessels 159 Structure of 160 Absorption by 167 Lymphatic glands 100 M Magnesium i)hosphate and eari)onate. . 22 Malpigbian bodies, Kidney 256 Bodies, Spleen 271 Pyramids 257 Manmiary CMands 266 Structure of 267 Milk 267 Chemical composition of milk 267 Colostrum of 268 Effect of medicinal agents on 269 " emotions on 209 Margarine 20 INDEX. 413 Paoii. .... 250 .... 'A7 ... 267 .... 2r)8 .. .. 2r.7 .... 2fi8 .... 'iCM .... '2fiU .... 211 ... ;jriO .... :»6i .... l.'iS .... Ktf. .29, 2(W .... 76 .... :<70 .... ;t70 .... «71 .... -MO .... 374 .... 238 .... .-il .... 2i)l t... 361 .... 303 .... 45 140, 165 .... 350 .... 40 .... 92 .... 100 .... 248 .... «0 .... 347 .... 19 .... 19 .... 387 .... 262 .... 253 .... 254 .... 147 .... 264 .... 94 .... 230 .... 231 .... 232 .... 2.'« .... 233 V... 239 '... 241 .... 45 160, 102 . ..159 .... KiO .... 107 .... 100 22 256 271 257 266 267 267 fmilk 267 268 Its on 269 269 29 I'AOK. .MarHliuiI Hall on Mpiiiikl cord .MiiNtinttloii .MllHL'IU!* of .MiitiTtiul inviiibraiiuH .MikturiuliHt doc'trino .Muconiuiii 152, .Mudiillu oldonxuta .Structure of Kuiicticin of DuCUHHUtloM of .Mcdullutud nurvu fibroM MulxHiior'M pluxua .Vluliiuinu .Moiul)riiii()UH uxpaiiMton!* Structure of .McinbnineN (Mhu|iU') .Meinbraiie-t ul the fcutus .Meiul)ruiiii liiiloii .VIetanior|ilioHis in iininiulM Metajfenesia .Mind-force .Mind, ami Its relation to tlio body .... Morbus Cieruleus '. Micrococci Micropyle ' .Mind, Influonce over the body .Morbus Addisonii .Motion, cause of .14, Ciliary 54, Motorial end-plates 88, .Motor oculi .Mucous McniliraneH Structure of Appenda|,'es of Mucus Chemical ci mstitucnts of Mucine or .Mucosinc 42, Mulberry .Mass Multiplication by subdivision .J2, b.\' i^enunation .">2, .Muscle Striated Primitive fibres of " Kibrilhe of Non-striated Mode of development Attachment of, to tendons Chemical composition of Vascular iind nervous supply Properties of Sound in contraction of Heat in contraction of Elasticity of Rigor mortis of Action of .Muscular sense. 301), .Musculine or myosine Muscularis mucosie Myolemma .Myojua N Nails 117 Nervous system 276 Of lower animals '277 Cranio-spinal axis of 279 D.ajiriuu i>f action of 279 802 132 138 58 324 268 30.S 803 806 804 281 140 44 96 9(1 68 391 379 868 160 328 884 80(1 377 377 826 324 229 35 378 327 274 89 1«) 288 330 103 106 105 104 104 104 382 376 376 83 83 84 84 85 8(1 87 87 88 89 91 91 91 91 92 368 42 139 84 350 pAna. NurvouH system. Nerve ■re 280, 21.0 Htructure of 2S1 NervellbruH 281 Nerve colls 2«;< (ian^lia of 284 (Jliendital uom|>uHltion of 284 IMstribution of nerve Hbres 285 Plexuses of 285 < )ri){in and tonniiiatlon of 286 Function of nerve llbn:s 280 " of nerve centrox 298 AtTerent and efferent nerves 289 Kxcitability ot nerves 290 Laws of action of nerves 291 development of nerve tissue 292 Ite^fcncratioii of 293 Vascular supplv of 298 ilcHex action of -MM), 296 Automatic action of 277 Koree (vis nervosa) 296 Nervous polarity ,. ... 296 Nervi nervorum 288 Nerve arc 280 Centres, function of '03 (Jonduetion 294 Connnunicaiion 294 Nourilennna 281 Neurotflia 288 Nitro>{cuous substances 16 " erystalli/able 46 Non-medullated nerve llbres 281 Notes, of voice, chest 373 Falsetto 37.'l Nucleus 49 Nucleolus .'>0 O Odoriferous glands 121 Oils and fats 29 Oleine 29 Olfactory nerves 329 Optic nerves ">30 Chiasma of 288 Optic thalamus 324 t»ptlc vesicle 396 Ora scrrata 347 Org.inic substances 15 Putrefaction of 36 O.sniosis 163 ( >steoblasts 77 Ovaries .•J78 Ovicapsule 379 Oviducts, action of ."{80 Ovum 379 Development of 382 Sejrinentiitiou of 3.S2 Oxygen 22 Amount inhaled by lungs 241 P Pacinian corymseles 287 Pancreatic juice 145 Appearance and proiierties of 146 Chemical composition of 14(1 Function of 146 Panerc;itine .. 42, 146 Panniculus adiposus (i5 Papiliie ....106. 116 Paralysis, alternate .SO? (Jognate 307 Parovarium 402 Partiiritiou 3'./'2 c c I L r 414 INDEX. I'athetio iieivu Paveiiieiit opitholiuin Pcpsiiie 41, Peptic follicles 108, Peptone ;!7, Perception I'ersinrution ("lu'iuical constituents of Function of ... r. Payer's glands . . . .'. Pliarynffeal arches Phrenoloffy, absurdity of Pit,'nient cells " Placenta, formation of Plastic elements of nutrition 12(5, Pneuuiojfastric nerve . Function of Division of '2M7, Inhibitory action of 21'2, .Stinudation of 212, Pons Varolii Structure and function of Poiassiuui clilorido Prehension Presbyopia Pressure, sense of Primitive trace Primitive or primordial cells Primary forms of tissue Primary memhranes Protein compounds Protoplasm 47, Protovertehriu Proximate pniicii)les Definition of Mode of extraction ("lassitication of First class of .Second class of Third class of Ptosis Pulse Head-wave of Venous Pinictuni saliens Putrefaction ot nitrojrenous matters. .. Pvramids of Ferrein I'ytaline 42, I'AdB. .. «3] t)7 142 139 142 321 122 122 123 111 394 :{19 114 391) 24.'i 333 :i33 334 3,34 334 3(Ht 30(t 18 132 350 308 383 382 40 59 34 50 385 14 14 14 15 10 22 33 330 217 217 220 307 35 2.58 135 K Ued blood corpuscles 170 Function of 195 Size of, in different animals 171 Color of 172 Reflex action 295 UeKisterinjr (jan^'lia 281 llcproduction 375 Three modes of 375 Action of male in 377 Action of female in 378 Respiration 230 .Mechanism of 233 [''relenic artery 272 Spore or sponinjfiuni 376 Stammttrin^' 374 Starvation 131 Starcli 23 Physical appearance of 23 Conversion of into sugar 25 Function of 25 Test for 25 Stearins 29 SteatozUon folliculoruui 121 Stereorine 157 Stoniacl) 108 Mucous membrane of 108, 139 Follicles of 108, 139 Movements of 144 Sudoriferous glands 121 Sugars 26 Function of 26 Tests for 27 Supra-renal ca))sules 273 Structure of 273 Function of 274 Disease of 274 Suspensory li^rament of lens 314 Symj)atbc"tie system 270, 330 Nerves of 286, 289, 336 Function of 337 Division of 338 Synovial membranes 102 Structure of 103 Synovia 102 I'AOK. Tactile corjjusclcs 116, Taste, sense of Taste goblets Tea Teeth 79, Structure of .... Development of Kruption of Temperature of the body in disease of animals how produced Regulation of Influence of nerves Sense of Tendons Attachment of Tesselated epithelium Tests— '1 rommers' Fehling's liquor test Fermenlatitm Toniliu Moore's Iodine test OniclinV bile test Pettenkofcr's Thalanii optici Thirst Thymus gland Structure of Function of Thyroid gland Structure of 286 304 365 129 132 79 80 82 244 244 244 245 247 246 369 60 87 97 27 27 28 28 28 25 153 153 324 131 274 274 275 275 Thyroid gland. Function of Tissues Attractive or selective power of.. . . Tissue cement Tobacco Tongue 133, Papllhu of Touch, sense of Transference of nervous impressions... Trifacial nervi' Division of Irritation of Trochlear or pathetic nerve True generation Tuber annulare Tubes of Ilenle Tynii)anum Air in Tymi)anitea IT Umbilicus, anmiotic Umbilical vesicle Cord Unconscious cerebration Urachus Urine Secretion of Specific gravity of Chemical composition of Urea Uric or litliic acid •. Hippuric acid Creatine Creatinine Salts of I'rosaciiie or urochronie 45, Acid fermentation of Alkaline fermentation of Uterus, preparation for ovum Involution of 82, Muscular fibre cells of 32, 276 60 224 6:5 130 3(i5 106 Valvuhe Conniveiites.. Vasomotor nerves .. .. centre Vasa VHsonim Vasa deferentia Veins Structure of Valves of Circulation In Velocity of circulation In Ventricles of the larynx 341, Ventrilo(iuism Vernix Caseosa Vestibule Vice, solitary Villi (if intestine 110, Struiture of Absorpt ion by of chorion . .'. Vis ii tergc > Vis nervosa Visceral plates , Vislim, ))iienomena of Circle or field of Anule of Defects of Vital elements of the blood Vital capacity of the chest 294 331 3:52 332 331 376 30(> 258 3r.H •MVi 157 3s7 385 391 323 403 200 259 260 261 261 202 263 264 264 264 204 265 2(itJ 389 3i>2 392 109 219 306 214 402 219 219 220 220 225 370 374 121 360 378 168 111 165 388 220 296 385 361 354 352 188 2:6 *9 416 INDEX. Taoe. Vitelline membrane H79 Vitelline spheres 382 Vitreous humor 349 A'ocal cords 370 Voice 370 Tones of voice 372 Compass of Si 3 Modifications 374 Voluntary attention 322 Vomitiuff , mechanism of 138 Vowels and Consonants 374 VV Warm-blooded animals 244 Water 16 Function of 16 Whartonian Jelly 71, 302 White fibrous tissue GO Appearance and properties of til Paok. White fibrous tissue, Development of . . 63 White blood corpuscles 173 Amueboid movements of 58, 173 Function of 196 White substance of Schwann ""l Will, power of >.^ 278, 322 Willis, circle of 217, 317 Wolrtian bodies 401 Y Yawning 238 Yolk 279 Yellow elastic tissue 62 A|)pearance and properties of 62 Development of 63 Z Zona pelludida 379 mma Page. nientof.. 63 173 58, 173 196 -l ,....278, 322 217, 317 401 238 279 62 iS of 62 63 ... 379 OJLT JLXjO G-TJE OF LINDSAY & BLAKISTON'S PUBLICATIONS. MEDICAL, DENTAL, CHEMICAL, PHARMACEUTICAL, AND SCIENTIFIC BOOKS. .laving for many years given their whole attention to the publication and sale of Medical Books, and keeping on hand as large an assortment as any other house, they arc always prepared to fill orders promptly, whether for single books by mail, or in larger quantities by express, at the lowest prices. Being Special Agents in the United States for Messrs. J. & A. 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Eighth Edition, Revised and Enlarged. Price ;^4.oo This new and thoroughly revised edition of Professor Riddle's work has incorporated in it all the improvements as adopted by the New United States Pharmacopceiajust issued. It is designed to present the leauing facts and prineijjles usually comprised under this head as set forth by the standard authorities, and to nil a vacuum which seems to exist in the want of an elementary work on the subject. The larger works usually recommended as tc.Kt-books in our Medical schools are too voluminous for convenient use. 'ibis will be found to contain, in a condensed form, all that is most valuable, and will supply students with a reliable guide to the course of lectures on Materia Medica as delivered at the various Medical schools in the United States. balfourTgTw.), m. d., Physlcrn to the Royal Infirmary, Edinburgh | Lecturer on Clinical Medicine, &c. CLINICAL LECTURES ON DISEASES OF THE HEART AND AORTA. With Illustrations. Octavo. Price . . . $4.00 BYFORD (v^), A.M., M.D., Professor of Obstetrics and Diseases of Women and Children in the Chicago Medical College, &c. PRACTICE OF MEDICINE AND SURGERY. Applied to the Diseases and Accidents incident to Women. Second Edition, Revised and Enlarged. Octavo. Price SAME AUTHOR. ON THE CHRONIC INFLAMMATION AND DISPLACEMENT OF THE UNIMPREGNATED UTERUS. A New, Enlarged, and Thoroughly Revised Edition, with Numerous Illustrations. 8vo. ^2.50 Dr. Byford writes the exact present state of medical knowledge on the subjects presented; and does this so clearly, so concisely, so truthfully, and so completely, that liis book on the uterus will always meet the approval of the profession, and be everywhere regarded as a popular standard work. — Buffalo Medical and Surgical Journal. c c I h' i I r f 10 BLACK (d. camprkll), M. D., L. R. C. S. Edinburgh, Member of the General Council of the University of Glasgo*' , Lc, Lc, THE FUNCTIONAL DISEASES OK THE RENAL. URINARY, and Reproductive Organs, with a General View of Urinary Pathology. Prite $2.00 The stylo <»f th« author is clonr, ensy, niid ftprrcnhh*, . . . his work is a valuable contri- bution to medical .scionce, an their children to become useful men and women. It is full of fresh thoughts and graceful illustrations. CLARKE (w.fairue), M.D., Assistant Surgeon to Charing Cross Hospital. CLARKE'S TREATISE ON DISEASES OF THE TONGUE. With Lithographic and Wood-cut Illustrations. Octavo.' Price ;J!4.5o It contains The Anatomy and Physiology of the Tongue, Importance of its Minute Exam- ination, Its Congenital Defects, Atrophy, Hypertro]>hy, Parasitic Diseases, Inflammation, Byphilis and its effects, Various Tumors to which it is subject, Accidents, Injuries, &c., &c. COOPER (s.). A DICTIONARY OF PRACTICAL SURGERY AND ENCY- CLOPEDIA OF SURGICAL SCIENCE. New Edition, brought down to the present time. By Samuel A. Lane, F.R.C.S., assisted by other eminent Surgeons. In two vols., of over 1000 pages each. ^12.00 c c I S 2 f I 4;. 12 CLAY (cHARLES), M D. Fellow of the London Obstetrical Society, kc, THE COMPLETE HAND-BOOK OF OBSTETRIC SURGERY, or, Short Rules of Practice in Every Emergency, from the Simplest to the most Formidable Operations in the Practice of Surgery. First American from the Third London Edition. With numerous Illustra- tions. In one volume. ;^2.oo CHAMBERS (thomas k.), M. D., LECTURES, CHIEFLY CLINICAL. Illustrative of a Restorative System of Medicine. CORMACK (sir john i^^^K. B., F. R. S. E., M. D. Edinburgh and Paris, Fellow Royal College of Physicians, Physician to the Hertford British Hospital, Paris, &c. CLINICAL STUDIES, Illustrated by Cases observed in Hospital and Private Practice. With Illustrative Plates. 2 Volumes. Octavo. $5.00 . KX COBBOLD (t. spencer), M.D., F.R.S. WORMS: a Series of Lectures delivered at the Middlesex Hospital on Practical Helminthology. Post Octavo ^i-75 . to* CLEAVELAND (c. h.), M.D., Member of the American Medical Association, &.c, A PRONOUNCING MEDICAL LP:XICON. Containing the Cor- rect Pronunciation and Definition of Terms used in Medicine and the Collateral Sciences. Improved Edition, Cloth, $1.00; Tucks, ^1.25 This work is not only a Lexicon of all the words in common use in Medicine, but it is also a Pronouncing Dictionary, a feature of great value to Medical Students. To the Dis- penser it will prove an excellent aid, and also to the Pharmaceutical Student. It has received strong commendation both from the Medical Press and from the profession. COLES (oakley), D.D.S. Dental Surgeon to the Hospital for Diseases of the Throat, &c. A MANU/iL OF DENTAL MECHANICS. Containing much information of a Practical Nature for Practitioners and Students. INCLUDING The Preparation of the Mouth for AfLificial Teeth, on Taking Impressions, Various Modes of Applying Heat in the Lal)ori,tory, Casting in Plaster of Paris and Metal, Precious Metals used in Dentistry, Making Gold Plates, Various Forms of Porcelain used in Mechanical Dentistry, Pivot Teet'.i, Choosing and Adjusting Mineral Teeth, the Vulcanite Base, the Celluloid Base, Treatment of Deformities of the Mouth, lleeei])ts for Making Gold Plate and Solder, etc., etc. With 140 Illustrations. Price $2.00 SAME AUTHOR. ON DEFORMITIES OF THE MOUTH, CONGENITAL AND ACQUIRED, with their Mechanical Treatment. Second Edition, Re- vised and Enlarged. With Illustrations. Price, . . . DOMVILLE (EDWARD ;.), M. D. A MANUAL FOR HOSPITAL NURSES and Others engaged in Attending the Sick. i2mo. Price . . . . . ;^i.oo : SURGERY, the Simplest to Surgery. First nerous Illustra- ;^2.oo ■ a Restorative E., M. D. ish Hospital, Paris, &,c. n Hospital and Octavo. ;^5-oo s. lesex Hospital • $1-75 aining the Cor- ledicine and the ; Tucks, ^1.25 Medicine, but it is lents. To tiie Dis- iit. It has received itaining much Students. ipressions, Various Paris and Metal, (inns of Porcelain Mineral Teeth, the lie Mouth, lleceijjts . $2.00 NITAL AND nd Edition, Re- 18 CLARK (f. le gros), F. R. S., Senior Surgeon to St. Thomas's Hospital. • OUTLINES OF SURGERY AND SURGICAL PATHOLOGY, including the Diagnosis and Treatment of Obscure and Urgent Cases, and the Surgical Anatomy of some Important Structures and Regions, Assisted by W. W. Wagstaffe, F. R. C. S., Resident Assistant-Surgeon of, and Joint Lecturer on Anatomy at, St. Thomas's Hospital. Second Edition, Revised and Enlarged. Price .... ^2.00 COTTLE (E. wyndham), M. A., F. R. C. S., &c. THE HAIR IN HEALTH AND DISEASE. Partly from Notes by the late George Navler, F. R. C. S., Surgeon to the Hospital for Diseases of the Skin, &c. i8mo. Cloth. Price . . $0.75 CURLING (t. b.), F.R.S., Consulting Surgeon to the London Hospital, Lc, A PRACTICAL TREATISE ON THE DISEASES OF THE TESTIS AND OF 't^hE SPERMATIC CORD AND SCROTUM. Fourth Revised and Enlarged Edition. Octavo. Price. . $$-50 BY SAME AUTHOR. OBSERVATIONS ON DISEASES O^/ THE RECTUM. With Illustrations. Fourth Edition, Revised and Enlarged. Octavo. Cloth. Price $2.75 CAZEAUX (p.). M. D., Adjunct Professor of the Faculty of Medicine, Paris, etc. A THEORETICAL AND PRACTICAL TREATISE ON MIDWIFERY, including the Diseases of Pregnancy and Parturition. Translated from the Seventh French Edition, Revised, Greatly Enlarged, and Improved, by S. Tarnier, Clinical Chief of the Lying-in Hospital, Paris, etc., with numerous Lithographic and other Illustrations. Price, in Cloth, ^6.00; in Leather ........ ;^7-oo M. Cazeaux's Great Work on Obstetrics has become classical in its character, and almost an Encyclopifidia in Its fulness. Written expressly for the use of students of medicine, its teachin.i^s are plain and explicit, presenting a condensed summary of the leading principles established by the musters of the obstetric art, and such clear, practical directions for the management of the pregnant^ ])arturient, ami pueriieral states, as have been sanctioned by the motit authoritative practitiouers, and confirmed by the author's own experieuce. ers engaged in . $1.00 DOBELL (HORACE), M.D., Senior Physician to tdo Hospital. WINTER COUGH (CATARRH, BRONCHITIS, EMPHYSEMA, ASTHMA). Lectures Delivered at the Royal Hospital for Diseases of the Chest. The Third Enlarged Edition, with Colored Plates. Octavo. Price $350 BY SAME AUTHOR. ON LOSS OF WEIGHT, BLOOD-SPITTING, AND LUNG DISEASE. Witii a Colored Frontispiece of the Lung, a Tabular Map, &c., &c. Octavo. Cloth. Price . . . . • $3-^5 c I 14 DIXON (jAMEs), F.R.C.S. ■ Surgeon to the Royal London Ophthalmic Hospital, &c. A GUIDE TO THE PRACTICAL STUDY OF DISEASES OF THE EYE, with an Outline of their Merlical and Operative Treatment, with Test Types and Ilhistrations. Third Edition, thoroughly Revised, and a great portion Rewritten. Price ;^2.oo Mr. Dixon's hook is essentially a practical one, written by an observant author, who brings to his special subject a souud knowledge of general Medicine and Surgery. — Dublin Quarterly. DILLNBERGER (dr. emil). A HANDY-BOOtC OF THE TREATMENT OF WOMEN AND CHILDREN'S DISEASES, according to the Vienna Medic-1 School. Part I. The Diseases of Women. Part II. The Diseases of Children. Translated from the Second German Edition, by P. Nicol, M. D. Price . . . . . . . . . . . ^1.50 Many practitioners will be glad to possess this little manual, which gives a large mass of practical liints on the treatment of disea.ses which probably make up the larger lialf of every-day practice. The translation is well made, and explanations of reference to German medicinal preparations are given with proper fulness. — Tlie Practitioner. DUNGLISON (RICHARD j.), M. D. THE PRACTITIONER'S REFERENCE BOOK. Containing Therapeutic and Practical Hints, Dietetic Rules and Precepts, and other General Information Useful to the Physician, Pharmacist, and Student. Octavo. Cloth. Price . . . . • $3-So r h ft;. DUCHENNE (dr. g. b.). LOCALIZED ELECTRIZATION AND ITS APPLICATION TO PATHOLOGY AND THERAPEUTICS. Translated by Her- bert TiBBiTS, M.D. With Ninety-two Illustrations. Price . $3.00 Duchenne's great work is not only a well-nigh exhaustive treatise on the medical uses of Electricity, but it is also an elaborate exposition of the dilferent diseases in which Electric- ity has proved to be of value as a therapeutic and diagnostic agent. Part 11., illustrated by chromo-lUhographs and numerous wood-cuts, is preparing. DURKEE (siLAs), M.D., Fellow of the Massachusetts Medical Society, tiz, GONORRHCEA AND SYPHILIS. The Sixth Edition, Revised and Enlarged, with Portraits and Eight Colored Illustrations. Octavo. Price . . • . . . . . . . • $3-50 Dr. Durkee's work impresses the reader in favor of the author bv its general tone, the thorough honesty everywhere evinced, the skill with whicli tiu' book is arranged, the man- ner in wliidi the facts arc cited, the clever way in which the author's experience is brought in, the lucidity of the reasoning, and the care with which the therapeutics of venereal com- plaints arc treated. — Lancet. DRUITT (ROBERT), F.R.C.S. THE SURGEON'S VADE-MECUM. A Manual of Modern Sur- gery. The Eleventh Revised and Enlarged Edition, with 369 Illus- trations. Price . . . . . . . . . $5.00 EASES OF ve Treatment, ighly Revised, . ^2.00 ithor, who brings )ublin Quarterly. )MEN AND eclic"! School. s of Children. NicoL, M. D. vcs a large mass le larger lialf of ereuce to Geruiau Containing Precepts, and liarmacist, and . $3-50 PLICATION ated by Her- rice . $3-oo medical uses of which Electric- s preparing. tion, Revised ions. Octavo. . ^3-50 general tone, the rranged, the man- ■rienee is brought of venereal com- Modern Sur- nth 369 lilus- . $5.00 15 DALBY (w. B.), F. R. C. S., Aural Surgeon to St. George's Hospital. LECTURES ON THE DISEASES AND INJURIES OF THE EAR. Delivered at St. George's Hospital. With Illustrations. Price $150 "We cordially recoinmcml this admirable volume by Jlr. Dalby as a trustworthy guide in the treatment of the aH'eetions of the ear. The book is moderate in |)riee, beautii'iiUy illus- trated by wood cuts, and got up in the best style. — Glusyow Medical Journal. DAY (wiLLi.\M henry), M. D., Physician to the Samaritan Hospital for Women and Children, &c. HEADACHES. THEIR NATURE. CAUSES, AND MENT. Second Edition. i2mo. Cloth. Price TREAT- $2.00 DUNGLISON (robley), M. D., Late Professor of Institutes of Medicine, &c., in the Jefferson Medical College. A HISTORY OF MEDICINE, from the Earliest Ages to the Com- mencement of the Nineteenth Century. Edited by his son, Richard J. DuNGLisoN, M. D $2.50 ELLIS (EDWARD), M. D., Physician to the Victoria Hospital for Sick Children, &c. A PRACTICAL MANUAL OF THE DISEASES OF CHIL- DREN, with a Formulary. Third Enlarged Edition, Revised and Improved. One volume. . . . . . . . g2.oo The AUTUOR, in issuing this new eflitiou of his book, says: "I have very carefully revised each chapter, adding several new sections, and making considerable additions where the Bubiects seemed to reouire fuller treatment, without, however, sacrificing conciseness or unduly increasing the bulk of the volume." FOTHERGILL (j. milner), M. D., Assistant Physician to City of London Hospital for Diseases of the Chest, die ' THE HEART, ITS DISEASES AND THEIR TREATMENT, including the Gouty Heart. Second Edition, Entirely Rewritten and Enlarged, with Two Full-Page Lithographic Plates and Forty other Illustrations. Octavo. Price ...... " Dr. Fothergill's remarks on rest, on proi)er blood nutrition in Heart Disease, in the treatment of Sequela; of it, and on the action of special meilieines, all indicate that in stiuly- ing the pathology of Heart Disease, he has earnestly kept in view the best means of mitigat- ing suti'eriug and of prolonging life." — Lancet. FOX (CORNELIUS B.), M. D. SANITARY EXAMINATIONS of Water, Air, and Food. 94 En- gravings. 8vo. Price ....... ^4.00 FOX (tilbury), M. D., F. R. C. P. Physician to the Department for Skin Diseases in University College Hospital. ATLAS OF SKIN DISEASES. Consistin<,r of a Series of Colored Illustrations, in Monthly Parts, together with Descriptive Text and Notes upon Treatment ; each Part containing Four Plates, reproduced by Chromo-Lithography from the work of Willan & Bateman, or taken from Original Sources. iSIow Complete in 18 Parts. Price, per Part, $2.00 ; or in one large Folio volume, bound in cloth. Price . . $30.00 16 c c I f I FENNER (c. s.), M. D., &c. VISION: ITS OPTICAL DEFECTS, and the Adaptation of Spec- tacles; embracing Physical Optics, Physiological Optics, Errors of Re- fraction and Defects of Accommodation, or Oi)tical Defects of the Eye. With 74 Illustrations. Selections from the Test Types of Jaeger and Snellen, etc. Octavo. Price $3-So FOSTER (BALTHAZAR), M. D., Professor of Medicine in Queen's College. LECTURES AND ESSAYS ON CLINICAL MEDICINE. Re- vised and Enlarged by the Author. With Engravings. Octavo. Price . . ^ $3.00 FRANKLAND (e.), M. D., F. R. S., &c. HOW TO TEACH CHEMISTRY, being the substance of Six Lectures to Science Teachers. Reported, with the Author's sanction, by G. George Chaloner, F. C. S., &c. With Illustrations . 1^1.25 FENWICK (SAMUEL), M.D., F.R.C.P. THE MORBID STATES OF THE STOMACH AND DUO- DENUM, AND THEIR RELATIONS TO THE DISEASES OF OTHER ORGANS. With Ten Plates $4.25 FLINT (AUSTIN) ,^M.D., Professor of the Principles and Practice of Medicine, &c., Bellevue Hospital College, New Yorki CLINICAL REPORTS ON CONTINUED FEVER. Based on an Analysis of One Hundred and Sixty-four Cases, with Remarks on the Management of Continued Fever; the Identity of Typhus and Typhoid Fever j Diagnosis, &c., &c. Octavo. Price . . ^2.00 GANT (FREDERICK J.), F. R. C. S., Assisted by Drs, Morrell, Mackenzie, Barnes, Erasmus Wilson, and other Specialists. THE SCIENCE AND PRACTICE OF SURGERY. Second Edition. 1700 Pages. 1000 Illustrations. 2 Vols. Price, cloth, $11.00; sheep $13.00 DISEASES OF THE BLADDER, PROSTATE GLAND, AND URETHRA, including a Practical View of Urinary Diseases, Deposits, and Calculi. Fourth Edition, Revised and Enlarged. With New Il- lustrations. Now Ready. Price $3- 50 -»o»- GODLEE (r. J.), M.D.. Assistant-Surgeon University Ce'.lego Hospitalt AN ATLAS OF HUMAN ANATOMY. Illustrating the Anatomy of the Human Body, in a Series of Dissections. Accompanied by References and an Explanatory Text. To be completed in Twelve or Thirteen Bi-monthly Parts, Folio Size, each Part containing Four large Colored Plates, or Eight Figures. Seven Parts Now Ready. Price per Part $2.50 17 ition of Spec- Errors of Re- els of the Eye. of Jaeger and • $3-50 CINE. Re- igs. Octavo. . ^3.00 :c. tance of Six hor's sanction, IS . $1.25 AND DUO- )1SEASES OF $4-25 ige. New York. ^. Based on :h Remarks on f Typhus and . ;^2.oo pecialistSi RY. Second cloth, $11.00; $13.00 AND, AND uses, Deposits, With New II- • $3-5° the Anatomy companied by in Twelve or ing Four large iy. Price per . $2.50 GROSS (SAMUEL D.), M. D., Professor of Surgery In the Jefferson Medical College, Philadelphia, etc. AMERICAN MEDICAL BIOGRAPHY OF THE NINETEENTH CENTURY. With a Portrait of Benjamin Rush, M.D. Octavo. $3.50 GREENHOW (e. headlam), M. D., Fellow of the Royal College of Physicians, etc. ON CHRONIC BRONCHITIS, Especially as Connected with Gout, Emphysema, and Diseases of the Heart. Price . . . $1.50 BY SAME AUTHOR. ADDISON'S DISEASE. Being the Cronian Lectures for 1875. Delivered before the Royal College of Physicians. Revised, and Illus- trated by numerous Cases and 5 full-page Colored Engravings. One volume, octavo. Price . . . . . . • . $3-°° HARLEY (GEORGE), M. D., F. R. C. P., _ Physician to University College Hospital. THE URINE AND ITS DERANGEMENTS: With the Applica- tion of Physiological Chemistry to the Diagnosis and Treatment of Constitutional as well as Local Diseases. New Revised and Enlarged Edition preparing. With Engravings. We have here a valuable addition to the librrry of the praetisiiiff physician; not only for the information wliieh it contains, but also for the siij^gestive way in which many of the subjects are treated, as well as for the fact that it contains the ideas of one who thoroughly believes in the future capabilities of Therapeutics based on Physiological tacts, and iu the important service to be rendered by Chemistry to Physiological investigation. American Journal of the Medical Science. HEATH (CHRISTOPHER), F. R. C. S., Surgeon to University College Hospital and Holme Professor of Clinical Surgery in University CoHege. OPERATIVE SURGERY. Elegantly Illustrated by 20 Large Col- ored Plates, Imperial Quarto Size, each Plate containing several Fig- ures, drawn from Nature by M. Leveille, of Paris, and Colored by hand under his direction. Complete in Five Quarterly Parts. Price, per Part, ;j{2.5o; or in one volume, handsomely bound in cloth. Price $14.00 HEWITT (graily), M. D., Physician to the British Lying-in Hospital, and Lecturer on Diseases of Women and Children, &c. THE DIAGNOSIS, PATHOLOGY, AND TREATMENT OF DISEASES OF WO .EN, including the Diagnosis of Pregnancy. Founded on a Course of Lectures delivered at St. Mary's Hospital Medical School. The Third Edition, Revised and Enlarged, with new Illustrations. Octavo. Price in Cloth . . . ;^4.oo " Leather . . . 5.00 This new edition of Dr. Hewitt's book has been so much modified, that it may be considered Bubstantially a new book ; very nnich of the matter has been entirely rewritten, and the whole work ha-s been rearranged in such a manner as to present a most decided improvement over previous editions. Dr. Hewitt is the leading clinical teacher on Diseases of Women in liOndon, and the eharaeteristic attention jiaidto Diagnosis by liiin has given his work great |io|)ularity there. It may unquestional)ly be considered the most valuable guide to correct Diagnosis to be fouud in the English language. n 18 c I It L c i I HILLIER (THOMAS), M.D., Physician to the Hospital for Sick Chiidren, &c, A CLINICAL TREATISE ON THE DISEASES OF CHILDREN. Octavo. Price ......... $2.00 Wc havo said enough to indicate and illustrate tho excellence of Dr. Ilillicr's volume. It is eminently the kind of book needed by all medical men who wish to cultivate clinical accuracy and sound practice. — London jMitcct. HOLDEN (luther), F.R.C.S. HUMAN OSTEOLOGY, comprising a Description of the Bones with Delineations of the Attachments of the Muscles, &c. With numerous Illustrations. Fifth Edition, carefully Revised. Price, 1^5.50 HOLDEN'S MANUAL OF DISSECTIONS OF THE HUMAN BODY. Fourth London Edition. With Illustrations. Price • LANDMARKS. MEDICAL AND SURGICAL. Second Edition, Revised and Enlarged. Price . . . . . . $1.00 HARRIS (ciiAPiN A.), M. D., D. D. S. Late President of and Professor of the Principles and Practice of Dental Surgery in tlie Baltimore Collegfe, &c. THE PRINCIPLES AND PRACTICE OF DENTAtRY. Tenth Revised Edition. . In great part rewritten, rearranged, and with many new and important Illustrations. Including — i. Dental Anatomy and Physiology. 2. Dental Pathology and Therapeutics. 3. Dental Sur- gery. 4. Dental Mechanics. Edited by P. H. Austen, M.D., Pro- fessor of Dental Science and Mechanism in the Baltimore College of Dental Surgery. With nearly 400 Illustrations, including many new ones made especially for this edition. Royal octavo. Price, in cloth, ^^6.50; in leather . 1^7.50 This new edition of Dr. Harris's work lias been thoroughly revised in all its parts — more 60 than any previous edition. Soyreut have been the advances in many branelies of dentistry, that it wasi found necessary to rewrite the articles or subjects, and this has been done in tiie most efficient manner by Professor Austen, for many years an associate and friend of Dr. Harris, assisted by Proijisor Gorgas and Thomas tS. Latimer, M.D. The publishers feel assured that it will now be found the most complete text-book for the student and guide for the practitioner iu the English language. SAME AUTHOR. A DICTIONARY OF MEDICAL TERMINOLOGY, DENTAL SURCiERY, AND THE COLLATERAL SCIENCES. Fourth Edition, Carefully Revised and Enlarged, by Ferdinand J. S. Gorgas, M. D., D.D.S., Professor of Dental Surgery in the Baltimore College, &.c., &c. Royal octavo. Price, in cloth, ^6.50; in leather . . 57-5o The many advances in Dental Science rendered it necessary that this edition should be thoroughly revised, which has been done in the nuxt satisfactory manner li ''rofessor Gorgas, Dr. Harris's successor in the BaUin4()re Dental College, lie having added m ;trly three tiiou- sand new words, besides making many additions ami corrections. The doses of the more prominent medicinal agents have also been added, and in every way the book has been greatly improved, and its value euhauced as a work of reference. HABERSHON (s. o.), M. D., F. R. C. R, Senior Physician, Guy's Hospital. ON DISEASES OF THE ABDOMEN, STOMACH, and Other Parts of the Aliinentary Canal. Third Edition. 8vo. Price. S5.00 CHILDREN. ;g2.oo iUier's volume. It cultivate cliuical of the Bones les, &c. With l1. Price, $5.50 HE HUMAN Price • 2Cond Edition, altimore Collee;ei ic. TRY. Tenth and with many il Anatomy and 3. Dental Sur- EN, M.D., Pro- lore College of :ling many new Price, in cloth, all its parts — more ancliesofiU'iitistry, lis bwn tlone in tlie and friend of Dr. The publishers feel ident aud guide for Y, DENTAL Fourth Edition, GoRGAS, M. D., ollege, &:c., &c. $7-5° edition should be Professor Gorgas, luarly three thou- doses of tiie more >ok. has been greatly I P. ;H, and Other Price. 55- 00 19 HArDWICH and DAWSON. HARDWICH'S MANUAL OF PHOTOGRAPHIC CHEMISTRY. With Engravings. Eigluh Edition. E "ticnl. The reader feels that he is in the hands of a teacher who lias a right to speak wi. authority, and who, if he may bo said to be positive, is so from the fulness of knowledge and experience, and who, while'well jic- quiiinted with the writings and labors of other authorities on the matters he treats of, haa himself practically worked out what he teaches. — Loudon Medical Tivies and Gazette, LEBER & ROTTENSTEIN (drs.). DENTAL CARIES AND ITS CAUSES. An Investigation into the Influence of Fungi in the destruction of the Teeth, translated by Thomas H. Chandler, D.M.D., Professor of Mechanical Dentistry in the Dental School of Harvard University. With Illustrations. Octavo. Price . . .51.25 This work is now considered the best and most elaborate work on Dental Caries. It is everywhere quoted and relied upon as authority by the profession, who have Been it in the original, and by authors writing on the subject. LEGG (j. wickham), M. D. Member of the Royal College of PhysiclanS) &c. A GUIDE TO THE EXAMINATION OF THE URINE. For the Practitioner and Student. Fourth Edition. i6mo. Cloth. Price, ^0.75 Dr. Legg's little manual has met with remarkable success; the speedy exhaustion of two editions has enabled the author to make certain emendations which add greatly to ita value. It caa confidently be commended to the student as a safe and reliable guide. LEARED (ARTHUR), M.D., F.R.C.P. IMPERFECT DIGESTION: ITS CAUSES AND TREATMENT. The Sixth Edition, Revised and Enlarged $1-50 KOLLMEYER (a. h.), A. M., M. D. Professor of Materia Medica and Therapeutics, Montreal College, CHEMIA COARTATA ; or. The Key to Modern Chemistry. With Numerous Tables, Tests, &c., &c. Price, .... $2.25 LIVEING (EDWARD). M. D. ON MEGRIM. SICK-HEADACHE, AND SOME ALLIED DISORDERS. With Colored Plate. Octavo . . . $5-25 c c I t i I 22 LEWIN (dr. george). Professor at the Fr.-Wllh. Unlversltyi and Surgeon-ln-Chlef of the Syphilitic Wards and Skin Diseases of the Charity Hospltali Berlin. THE TREATMENT OF SYPHILIS by Subcutaneous Sublimate Injections. With a Lithographic IMate illustrating the Mode and Proper Place of administering the Injections, and of the Syringe used for the purpose. Translated by Carl Prqcgler, M.D., late Surgeon in the ' Prussian Service, and E. H. Gale, M.D., late Surgeon in the United . States Army. Price $^-5^ MASON (FRANCIS), F. R. C. S., Surgeon and Lecturer on Anatomy at St. Thomas' Hospital, Slc, THE SURGERY OF THE FACE. With loo Illustrations, En- graved on Wood, of Various Operations Performed. Octavo. Cloth. Price, $2.25 LIZARS (JOHN), M. D. Late Professor of Surgery in the Royal College of Surgeons, Edinburgh. THE USE AND ABUSE OF TOBACCO. From the Eighth Edinburgh Edition. i2mo. Price, in flexible cloth, . $o.c;o Tills little work contains a History of the introtluetiou of Tobacco, its penerul characteris- tics; practical observations nj)on its cficcts on tlie system; tlie opinion of celebratctl profes- sional men in regard to it, together with cases illustrating its deleterious iuilueuee, «te., &c. MACNAMARA (c). Surgeon to the Ophthalmic Hospital, and Professor of Ophthalmic Medicine in the Medical College, Calcutta. MANUAL OF THE DISEASES OF THE EYE. The Third Edition, carefully Revised; with Additions, and numerous Colored Plates, Diagrams of the Eye, many Illustrations on Wood, Snellen's Test Types, &c., &c. Price ^4.00 MARSH (SYLVESTER). SECTION-CUTTING. A Practical Guide to the Preparation and Mounting of Sections for the Microscope — special prominence being given to the subject of Animal Sections. With Illustrations. Cloth. Price, $0.60 MACKENZIE (morell), M. D., Physician to the Hospital for Diseases of the Throat, Jic. GROWTHS IN THE LARYNX. Their History, Causes, Symp- toms, &c. With Reports and Analysis of One Hundred Cases. With Colored and other Illustrations. Price $2.00 OTHER WORKS BY THE SAME AUTHOR. THE LARYNGOSCOPE IN THROAT DIS^-.ASES. With an Appendix on Rhinoscopy. Third Edition, Enlarged. With New Il- lustrations. Price ........ THE DISEASES OF THE THROAT AND NOSE. Including The Pharynx, The Larynx, Trachea, CEsophagus, Nose, Neck, &c. With numerous Illustrations. Preparing. DIPHTHERIA. 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For the use of Students. Price, 52.00 MENDENHALL (george), M.D., Professor of Obstetrics In the Medical Collogo of Ohio, &.c. MEDICAL STUDENT'S VADE MECUM. A Compendium of Anatomy, Physiology, Chemistry, the Practice of Medicine, Surgery, ObstetricK, Diseases of tlie Skin, Materia Medica, Pharmacy, Poisons, &c., &c. Eleventh Edition, Revised and Enlarged, with 224 Illustra- tions. In cloth 52.00 MAXSON (EDWIN R.), M.D., Formerly Lecturer on the Practice of Medicine in the Geneva Medical College, Sic, THE PRACTICE OF MEDICINE 53- 00 No. 7. The Brain and Nerves. No. M. Tile Orj^an.-i of the Senses and Organs of tlie Voice. Plate 1. Nn. 0. The Organs of the Senses. Plate 2. No. 10. Tli(! iiieroseopie Structure of tlie Textures. Plate 1. No. 11. Tlie Microscopic Structure of the Textures. Plate 2. MARSHALL (joiin), F.R.S., Professor of Surgery, University Colleee, London. PHYSIOLOGICAL DIAGRAMS. Life-size, and Beautifully Col- ored. 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Author of " Climatology and the Use of Mineral Waters," THE HEALTH RESORTS OV EUROPE AND AFRICA for the Treatment of Chronic Diseases. .\ Hand Book the result of the Author's own Observations during several years of Health-Travel in many Lands, containing, also, the substance of the Author's former Work on Climatology and THt: Use of Mineral Waters. Oc iivo. Price ........... ^2.50 24 c I I f f c I MAUNDER (c. f.), F. R. C. S. Suri^eon to the London Hospital i formerly Demonstrator of Anatomy at Guy's Hoipltal. OPKRATIVK SUR(,il<:RY. Second Kdition, with One Hundred and Sixty-four Engravings on Wood. Price . . . J52.25 BY SAME AUTHOR. SURGICRY OF THE ARTERH':S, includincr Aneurisms, Wounds, HicniorrliagL's, Twenty-seven Cases of Ligatures, Antiseptic, etc. With 18 IMustrations, Price ........ $1.50 ■ 01 MAYNE (r. c), M. D., and MAYNE (j.), M. D. MEDICAL VOCABULARY: An Explanation of all Names, Synonyms, Terms, and Phrases us"(l in Medicine and the Relative Branches of Medical Science. 4th Edition. 450 pages. Price, $3.00 MAYS (THOMAS j.), M. D. ON THE THERAPEUTIC FORCES. An Effort to Consider the Action of Medicines in the Light of the Doctrine of Conservation of Force. i2mo. Cloth. Price . . . . . . $1.25 MARTIN (JOHN 11.). Author of Microscopic Objects, &c. A MANUAL OF MICROSCOPIC MOUNTING. With Notes on the Collection and Examination of Objects, and upwards of One Hun- dred and Fifty Illustrations. Second Edition, Enlarged. Price, $2.75 MEADOWS (ALFRED), M.D. Physician to the Hospital for Women, and to tho General Lying-in Hospital) &.c, MANUAL OF MIDWIFERY. A New Text-Book. Including the Signs and Symptoms of Pregnancy, Obstetric Operations, Diseases of tlic Puerperal State, &c., &c. Second Ameriian from the Third Lon- don Edition. Revised and ICnlargcd. With 145 Illustrations. $3.00 This book is espeeiiilly vulimble to the Student as containing in a condensed fornj a large amount of valuable iiitornintion on the subject wiiieh it treats. It is also clear and niethfidl- cal in its arrangement, and llierelbre useful as a work of retereuce for the practitioner. The Illustrations are numerous and well executed. MILLER ( JAMES), F.R.C.S. Professor of Surgery University of Edinburgh. ALCOHOL, ITS PLACE AND POWER. From the Nineteenth Glasgow Edition. 121110. Cloth flexible. Price . . . $0.50 LIZARS (JOHN), M.D. THE USE AND ABUSE OF TOBACCO. Pric^ ).5o MILLER AND LIZARS. ALCOHOL: Its Place and Power. By James Miller, I^R.S.E., late Professor of Surgerv in the University of Edinburgh, &c. — THE USE AND ABUSE OFTOBACCO. By John Lizars, late Professor to the Royal College of Surgeons, &c. The Two Essays in One Volume. i2ino. . . . . . . . . . . ^i.oo loipltal. : Hundred ;i52.25 s, Wounds, ;, etc. With . D. ill Names, the Relative Priee, $3.00 !onsider the iservation of . $1-25 th Notes on of One Hun- Price, $2.75 ncluding the , Diseases of e Third Lon- tions. ^3.00 «il form a large ir iiiid inotliDtli- uctitioiicr. The Nineteenth . $0.50 . i^O-SO .R.S.E., late —THE USE rofessor to the One Volume. . J^I.OO 26 MARSDEN (aikxander), M. D. A NEW AND SUCCESSFUL MODI-: OF TRI':ATING CERTAIN FORMS OK CANCER. Second Edition, Colored Plates. . ^3.00 MACDONALl) (j. d.), M. D. Deputy Inspector-Gonnral of Hospitalsi Assistant Professor of Hygiene, Army Medical School, Sie, A GUIDl-: TO THE MICROSCOPICAL EX/VMlNATiON OF> I)RINKIN(; WA TER. With 'IVcnty Full-page Lilhogra^jJiic Plates, References, Tables, etc., etc. Octavo. Price . . . $2.75 NORRIS (geougew.), M. D., Late Surgeon to the Pcnnsylv&nla Hospital, Slc, CONTRIBUTIONS TO PRACTICAL SURGERY, including numerous Clinical Histories, Drawn from a Hospital Service of 'I'hirty Years. In one Volume, Octavo. Price . . . . ^4.00 OTT (ISAAC), M. D.. Late Demonstrator of Experimental Physiology in the University of Pennsylvania. THE ACTION OF MICDICINES. With Twenty-two Illustrations. Octavo. Cloth. Price ;g2.oo OGSTON (francls and francis, jr.), M. D. Prof'> proud. It will ud 0/ Obstetrics. Royal Col- Edited and Illustrations. . $8.00 roduction to our very page bears / Journal. C. y Lists of Prescriptions, of Prescrip- rms, a Proso- ies of Abbre- ;rms, &c. ; to niabbreviated Medical and ition. Price, . $1.25 27 PARSONS (CHARLES), M. D., Honorary Surgeon to the Dover Convalescent Hotnis, &c,, &c. SEA-AIR AND SEA-BATHING. Their Influence on Health a Practical Guide for the Use of Visitors at the Seaside. i8mo. $0.60 PARKER (i vngston), F. R. C. S. L. THE MODERN TREATMENT OF SYPHILITIC DISEASES. Containing the Treatment of Constitutional and Confirmed Syphilis, with numerous Cases, Formulae, &c.,&c. Fifth Edition, Enlarged. $4.25 PRINCE (david), M.D. PLASTIC AND ORTHOPEDIC SURGERY. Containing i. A Report on the Condition of, and Advances made in. Plastic and Ortho- pedic Surgery up to the Year 1871. 2. A New Classification and Brief Exposition of Plastic Surgery. With numerous Illustrations. 3. Ortho- pedics: A Systematic Work, upon ,he Prevention and Cure of Deformities. With numerous Illustrations. Octavo. Price . . . $4.50 This is a good book upon an itnjirrtant practical subject ; carefully written and abun- dantly illustrated. It goes over the whole ground of deformities — fro 1 cleft-palate and club-foot to spinal curvatures and ununited fractures. It appears, moreover, to be an original book. — Medical and Swrgical Iteportcr. SAME AUTHOR. GALVANO-THERAPEUTICS. A Revised reprint of A Report made to the Illinois State Medical Society. With Illustrations. Price, ;^i.25 PIESSE (g. w.. Septimus), Analytical Chemist. WHOLE ART OF PERFUMERY. And the Methods of Obtaining the Odors of Plants ; the Manufacture of Perfumes for the Handkerchief, Scented Powders, Odorous Vinegars, Dentifrices, Pomatums, Cosmet- ics, Perfumed Soaps, &c. ; the Preparation of Artificial Fruit Essences, &c. Second American from the Third London Edition. With Illus- trations. .......... PIGGOTT (a. snowden), M. D., Practical Chemist. COPPER MINING AND COPPER ORE. Containing a full Descrip- tion of some of tl^e Principal Copper Mines of the United States, the Art of Mining, the Mode of Preparing the Ore for Market, &c., &c. ;gi.oo PAVY (f.-/.),M. D., F.R.S. DIABETES. Researches on its Nature and Treatment. Third Re- vised Edition. Octavo ....... PHYSICIAN'S PRESCRIPTION BLANKS, with a Margin for Duplicates, Notes, Cases, &c., &c. Price, per package, Price, per dozen . I I 28 RINDFLEISCH (dr. edward). Professor of Pathological Anatomy, University of Bonn. TEXT-BOOK OF PATHOLOGICAL HISTOLOGY. An Intro. duction to the Study of Pathological Anatomy. Translated frum the German, by Wm. C. Kloman, M.D., assisted by F. T. Miles, M.D., Professor of Anatomy, University of Maryland, &c., &c. Containing Two Hundred and Eight elaborately executed Microscopical Illustra- tions. Octavo. Price, bound in Cloth, .... ^5.00 *• " Leather, . . . .6.00 This is now confessedly the leading book, and the only coniplote one on the subject in the English language. The London Lancet says of it: " lUnclneiscli's work forms a mine which no patliological writer or student can attord to neglect, wiio desires to interi)ret aright pathological structural changes, and his book is consequently well known to readers of (ier- luan medical literature. What makes it especially valuable is the fact that it was originated, as its autlior liimself tells us, more at the microscope than at the writing-table. Altogether the book is the result of honest hard labor. It is admirably af well as profusely illustrated, furnisiied with a capital Index, and got up in a way tliat is worthy of what must coutiuue to be the standard Ibook of the kind." ROBERTS (FREDERICK T.)., M. D., B. Sc. Assistant Physician and Teacher of Clinical Medicine in the University College Hospital | Assistant Physician Brompton Consumption Hospital, &c. A HAND -ROOK OF THE THEORY AND PRACTICE OF MEDICINE. Second Edition, Revised and Enlarged. Cloth, ;^5.oo Leather, 6.00 This work lias been prepared mainly for the use of Students, and its object is to present in as condensed a form as the present extent of Medical Literature will permit, and in one volume, such information with regard to the Principles and Practice of Medicine, as shall be sufficient not only to enable them to prepare for the various examinations which they may have td undergo, but also to guide them in acquiring that Clinical Knowledge which can alone properly fit them for assuming the active duties of their profession. The work is also adapted to the wants of very many members of the profession who are already busily engaged in general Practice, and consequently liuve but little leisure and few opportunities for the psrusal of the larger works on Practice or of the various special monographs. REYNOLDS (j. russell), M. D., F. R. S., Lecturer on the Principles and Practice of Medicine, University College, London. lecturp:s on the clinical uses of electricity. Delivered at University College Hospital. Second Edition, Revised and Enlarged. Price $1.00 RYAN (MICHAEL), M. D. Member of the Royal College of Physicians, PHILOSOPHY OF MARRIAGE, in its Social, Moral, and Physi- cal Relations ; with an Account of the Diseases of the Genito-Urinary Organs, &c. Price ........ $1.00 This is a i)hilosophioal discussion of the whole subject of Marriage, its influences and results in all their varied aspects, together with a medical history of tlie reproductive func- tions of the vegetable and animal lungdonis, and of the abuses and disorders resulting from it iu the latter. It is intended both for the professional and general reader. 11 29 An Intro* =d from the ILES, M.D., Containing ical lUustra- 6.00 the subject in L forms a mine interpret arij^ht readers of tier- ; was originated, )le. Altogether isely illustrated, ; must coutiuUB \sslstant Physician CTICE OF Cloth, $5.00 ,eather, 6.00 its object is to ure will permit, md Practice of for the various m in acquiring ling the active of very many |il Practice, and al of the larger ondoni ICTRICITY. ;ion, Revised . $1.00 I, and Physi- jnito-Urinary $1.00 influences and |l>roductive func- >s resulting from RADCLIFFE (CHARLES bland), M.D., Fellow of the Royal College of Physicians of London, &.c. LECTURES ON EPILEPSY, PAIN, PARALYSIS, and other Disorders of the Nervous System. With lUustraticns. . . $1.50 The rc|)utati()n which Dr. RadclifTe possesses as a very able authority on nervous affections will coniniend liis work to every medical i)ractitioner. AVe recommend it as a work that will throw much li,i,dit upon the Physiology and Pathology of the Kurvous System. — Canada Medical Journal, A ROBERTSON (a.), M.D., D.D.S. MANUAL ON EXTRACTING TEETH. Founded on the Anatomy of the Parts involved in the Operation, the kinds and proper construction of the instruments to be used, the accidents likely to occur from the operation, and the proper remedies to retrieve such accidents. A New Revised Edition. ....... The author is well known as a contributor to the literature of the profession, and as a clear, terse, and practical writer. The subject is one to which he has devoted c<)nsiilera!)le attention, and is treated with his usual care and ability. The work is valuable not only to the dental student and practitioner, but also to the medical student and surgeon. — Denial Cosmos, REESE (JOHN J.), M.D., Professor of Medical Jurisprudence and Toxicology in the University of Pennsylvania! AN ANALYSIS OF PHYSIOLOGY. Being a Condensed View of the most important Facts and Doctrines, designed especially for the Use of Students. Second Edition, Enlarged. . . . ;^i.5o SAME AUTHOR. THE AMERICAN MEDICAL FORMULARY. Price . ^1.50 A SYLLABUS OF MEDICAL CHEMISTRY. Price . ^i.oo RICHARDSON (joseph), D.D.S. Late Professor of Mechanical Dentistry, Slc, &c. A PRACTICAL TREATISE ON MECHANICAL DENTISTRY. Second Edition, much Enlarged. With over 150 beautifully executed Illustrations. Octavo. Price, in cloth, ^4.00; in leather, . $4.50 This work does infinite credit to its author. Its comprehensive style has in no way in- terfered with most elaborate details where this is necessary ; and the numerous and beautifully executed wood-cuts with which it is illustrated make the volume as attractive as its instruc- tions are easily understood. — Edinburgh Med. Journal, ROBERTS (lloyd d.), M.D., Vice-President of the Obstetrical Society of London, Physician to St. Mary's Hospital, Manchester! THE STUDENT'S GUIDE TO THE PRACTICE OF MID- WIFERY. With 95 Illustrations. Price .... $2.00 RUTHERFORD (william), M. D., F. R. S. E. Professor of t'le Institutps of Medicine in the University of tciinljurgh. OUTLINES OF PRACTICAL HISTOLOGY FOR STUDENTS AND OTHERS. Second Edition, Revised and Enlarged. With Illus- trations, &c. Price $2.00 30 RIGBY AND MEADOWS. DR. RIGBY'S OBSTETRIC MP:M0RANDA. Fourth Edition, Revised and Enlarged, by Alkrku Meadows, M. D., Author of "A Manual of Midwifery," ike. Price jSo.50 ROYLE'S MANUAL OF MATERIA MEDICA AND THERA- PEUTICS. The Sixth Revised and Enlarged Edition. Containing all tiie New Preparations according to the New British, American, French, and German Pharmacopoeias, the New Chemical Nomencla- ture, etc., etc. Edited by John Harley, M. D., F. R. C. P., Assistant Physician and Lecturer on Physiology at St. Thomas's Hospital. With 139 Illustrations, many of them new. One vol., Demy Octavo. ;^5.oo STOCKEN (jAMEs), L D. S. R. C. S., Lecturer on Dental Materia M dica and Therapeutics and Dental Surgeon to National Dental Hospital. THE ELEMENTS OF DENTAL MATERIA MEDICA AND THERAPEUTICS. With Pharmacopc^eia. Second Edition. $2.25 I I SANDERSON, KLEIN, FOSTER, and BRUNTON. A HAND-BOOK FOR THE PHYSIOLOGICAL LABORATORY. Being Practical Exercises for Students in Physiology and Histology, by E. Klein, M. D., Assistant Professor in the Pafhological Laboratory ot the Brown Institution, London; J. Buruon Sanderson, M. D., F. R. S., Professor of Practical Theology in Ui.iversity College, Lon- don; Michael Foster, M.D., F.R.S., Fellow of and Prcelector of Phys- iology in Trinity College, Cambridge; and T. Lauuek Brunion, M.D., D.Sc, Lecturer on Materia Medica in the Medical CoUe^^e of St. Bar- tholomew's Hospital. Edited by J. Burdon-Sanderson. The Illus- trations consist of One Hundred and Twenty-three o:tavo pages, including ovei* Three Hundred and Fifty Figures, with appropriate letter-press explanations attached and refeiences to the text. Price, in one volume. Cloth, $6.00 ; in Leather, $7.00 ; or in two volumes, Cloth, $7.00. Vol. I., containing the Text, sold separately, ^4.00. We feel that we cannot recommend this work too highly. To those engaged in physiologi- cal work as students or teachers, it is almost indis|)L'nsid)le : and to tiiose wiio are not, a perusal of it will by no means l)e unprofitable. The execution of the plates leaves nothing to be desired. They are mostly original, and their arningenient in a se]>arate volume haa great and obvious advantages. — Dublin Journal of Medical /Sciences. SIEVEKING (e. h.), M.D., F.R.C.S. THE MEDICAL ADVISER IN LIFE ASSURANCE. Price $2.00 This book supplies, in a concise and available form, such facts and figures as are required by the Physician or Examiner to assist him in arriving at a correct estimate of the many conliugencies upon which life insurance rests. SWAIN (WILLIAM PAUL), F.R.C.S., Surgeon to the Royal Albert Hospital, Devonport. SURGICAL EMERGENCIES: A MANUAL CONTAINING CONCISE DESCRIPTIONS OF VARIOUS ACCIDENTS AND EMERCENCIES, WITH DIRECTIONS FOR THEIR IMME- DIATE TREA TMENT. With numerous Wood Engravings. In one volume, i2mo. Cloth. Price ...... |2.oo 31 I Edition, lior of " A 50.50 THERA- Containing American, Nomencla- \, Assistant lital. With ivo. $5-oo STILLE (ALFRED), M. D. Professor of the Theory and Practice of Medicine in the University of Pennsylvania, &c. EPIDEMIC MENINGITIS; or, Cercbro-Spinal Meningitis. In one volume. Octavo. ......... $2.00 This nioiKij^mph is a timely jmblieation, comprehensive in its scope, and presentiiif? wltliin n sinnll conipiuss a fair digest of our existint,' le present time. It is just sueli a one as is needed, at>d muy be tulien as u luudel for similar works. — American Journal Medical /Sciences, SMITH (WILLIAM ROBERT), Resident Surgeon, Hants County Hospital. LEC IRES ON THE EFFICIENT TRAINING OF NURSES FUR HOSPITAL AND PRIVATE WORK. With IHustratioMs. i2mo. Cloth. Price . . . . . , . . $2.00 ntai Hospital. ICA AND 52.25 on. TON. RATORY. listolopj, by Laboratory :soN, M. D., ;ollege, Lon- ctor of Phys- NION, M.D., e of St. Bar- The Illus- tavo pages, appropriate Price, in o volumes, , $4-oo. inphysiologi- lio are not, a uaves nothing ate volume has Price $2.00 as are required to of the many sITAINING LN'i'S AND IR IMME- ugs. In one . >2.00 SMITH (heywood), M. D., Physician to the Hospital for Women, iSic. PRACTICAL GYNAECOLOGY. A Hand-Book for Students and Practitioners. With Illustrations. Price . . . . $i-5o " It is obviously the work of a thoroughly intelligent i)ractitioner, well versed iu his art." — British Medical Journal. SANSOM (ARTHUR ERNEST), M.B., Physician to King's College Hospital, &c. CHLOROFORM. Its Action and Administration. Price BY SAME AUTHOR. LECTURES ON THE PHYSICAL DIAGNOSIS OF DISEASES OF THE HEART, intended for Students and Practitioners. $1.50 $1.50 SCANZONI (f. w. von), Professor in the University of Wurzburor. A PRACTICAL TREATISE ON THE DISEASPIS OF THE SEXUAL ORGANS OF WOMEN. Translated from the French. By A. K. Gardner, M.D. With Illustrations. Octavo. . ^5.00 STOKES f William), Regius Professor of Physic in the University of Dublin. THE DISEASES OF THE HEART AND THE AORTA. Octavo. $3.00 SYDENHAM SOCIETY'S PUBLICATIONS. New Scries, 1859 to 1878 inclusive, 20 years, 81 vols. Subscriptions received, and back years furnished at ^9.00 per year. Full prospectus, with the Reports* of the Society and a list of the Books published, furnished free upon application. SANKEY (w. iL o.), M. D., F. R. C. P. LECTURES ON MENTAL DISEASES. Octavo . ;^3.oo 82 I m I r ■ I SWERINGEN (hiram v.). Member American Pharmaceutical Association, Sic, PHARMACEUTICAL LEXICON. A Dictionary of Pharmaceu- tical Science. Containing a concise explanation of the various subjects and terms of Pharmacy, with appropriate selections from the collateral sciences.' Formulae for officinal, empirical, and dietetic preparations; selections from the prescriptions of the most eminent physicians of Europe and America; an alphabetical list of diseases and their defini- tions; an account of the various modes in use for the preservation of dead bodies for interment or dissection; tables of signs and abbrevia- tions, weights and measures, doses, antidotes to poisons, &c., &c. Designed as a guide for the Pharmaceutist, Druggist, Physician, &c. Royil Octavo. Price in cloth $3-oo leather . . . . . .4.00 <( SEWILL (h. e.), M. R. C. S., En?., L. D. S., Dentai Surgeon to the West London Hospital. THE STUDENT S GUIDE TO DENTAL ANATOMY AND SURGERY. With 77 Illustrations. Price . . . • ^1.50 SHEPPARD (EDGAR), M. D. Professor of Psyclioiogical Medicine in King's College, London. MADNESS, IN ITS MEDICAL, SOCIAL, AND LEGAL AS- , PECTS. A series of Lectures delivered at King's College, London. $2.25 Octavo. Price SAVAGE (henry), M. D., F. R. C. S. Consulting Physician to the Samaritan Free Hospital, London. THE SURGERY, SURGICAL PATHOLOGY, and Surgical Anat- omy of the Female Pelvic Organs, in a Series of Colored Plates taken from Nature : with Commentaries, Notes, and Cases. Third Edition, greatly enlarged. A quarto volume. Price . ^12.00 « SAVORY AND MOORE. A CONDENSED COMPENDIUM OF DOMESTIC MEDICINE AND COMPANION TO THE MEDICINE CHEST. With En- gravings. i2mo. Cloth. Price . . . . . . ^0.50 SUTTON (FRANCIS), F. C. S. A SYSTEMATIC HAND-BOOK OF VOLUMETRIC ANALYSIS, or the Quantitative Estimation of Chemical Substances by Measure, Applied to Liquids, Solids, and Gases. Third Edition, enlarged. With numerous Illustrations. Now Ready. Price . . ;^5.oo SMITH (EUSTACE), M.D. Physician to the East Lonuon Hospital for Diseases of Children, Sue, CLINICAL STUDIES OF DISEASES OF THE LUNGS IN CHILDREN. Price ;^2.5o harmaceu- ous subjects le collateral reparations; lysicians of their defini- ;ervatioii of id abbrevia- s, &c., &c. ysician, &c. 4-00 5., iMY AND . $1.50 iGAL AS- ge, London. . $2.25 rgical Anat- )lored Plates ases. Third «I2.00 lEDICINE With En- • ^0.50 NALYSIS, by Measure, n, enlarged. .UNGS IN . ^2.50 33 TANNER (THOMAS hawkes), M.D., F.R.C.R, &c. THE PRACTICE OF MEDICINE. Sixth American from the last London Edition. Revised, much Enlarged, and thoroughly brought up to the present time. With a complete Section on the Diseases Peculiar to Women, an extensive Appendix of Formulae for Medicines, Baths, &c., &c. Royal Octavo, over iioo pages. Price, in cloth, $6.00; leather . . . . .' . . . . . $7.00 Tliere is a common character about the writings of Dr. Tanner — a characteristic which constitutes one of tlieir chief vahies : tliey are ail essentially andthorouglily jiructical. Dr. Tanner never, for one moment, allows this utilitarian end to escape iiis mental view. He aims at teaching how to rec(»gnize and how to cure disease, and in this he is thoroughly suc- cessful. ... It is, indeed, a wonderful mine of kiu>wledge. — 3Iedical Times. SAME AUTHOR. A PRACTICAL TRP:ATISE ON THE DISEASES OF IN- FANCY AND CHILDHOOD. Third American from the last Lon- don Edition, Revised and Enlarged. By Alfred Meadows, M.D., London, M.R.C.P., Physician to the Hosi)ital for Women and to the General Lying-in Hospital, &c., Szc. Price .... ^3.00 TANNER'S INDP:X OF DISEASES AND THEIR TREAT- MENT. Second Edition. Carefully Revised. With many Additions and Improvements. By W. H. Broadcent, M. D., F. R. C. P., Phy- sician to the London Fever Hospital, &c,, &c. Octavo. Cloth. ;^3.oo A MEMORANDA OF POISONS. A New and much Enlarged Edition. Price $0'7S TYSON (JAMES), M.D., Lecturer on Microscopy in the University of Pennsylvania, &c, THE CELL DOCTRINE. Its History and Present State, with a Copious Bibliography of the Subject, for the use of Students of Medi- cine and Dentistry. With Colored Plate, and numerous Illustrations on Wood. Second Edition. Price ..... $2.00 BY SAME AUTHOR. A PRACTICAL GUIDE TO THE EXAMINATION OF URINE. For the use of Physicians and Students. With a Colored Plate and numerous Illustrations Engraved on Wood. Second Edition. Just Ready. Price ;^i-25 A TAFT (Jonathan), D. D. S., Professor of Operative Dentistry in tiie Ohio College, &Ci PRACTICAL TREATISE ON OPERATIVE DENTISTRY. Third Edition, thoroughly Revised, with Additions, and fully brought up to the Present State of the Science. Containing over 100 Illustra- tions. Octavo. Price, in cloth, $4.25. In leather, . . ^5.00 TURNBULL (laurence), M. D. THE ADVANTAGES AND ACCIDENTS OF ARTIFICIAL ANi4;STHESIA. A Manual of Angesthetic Agents, Modes of Admin- istration, etc. Second Edition, Enlarged. 25 Illustrations. Cloth. 11.50 COUGHS AND i2mo. Cloth. 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Not only in larp;e cities, hut in every town and hamlet, the Doctor leads in every effort to eradicate the sources of disease. These efforts have i)een ably seconded by intelligent and public-spirited citizens of many callings. The American Public Health Association and the Social Science Association, with their manifold and most useful influences, are organizations which have sprung fiom.and still further extend and reinforce, the efforts to improve the public health. But the great mass of the public scarcely recognize the importance of such efforts, or, if they do, are ignorant of the facts of Anatomy, Physiology, and Hygiene, and of their prac- tical applicatioi. to the betterment of their health and the prevention of disease. Such knowledge does not come by nature. In most cases, in fact, it is a direct result of the most laborious research and the highest skill. Accordingly, it is the object of this series of American Health Primers to diffuse as widely and as cheaply as jwssible, among all classes, a knowledge of the elementary facts of Preventive Medicine, and the bearings and appli- cations of the latest and best researches in every branch of Medical and Hygienic Science. They are not intended (save incidentally) to assist in curing disease, but to teach people how to take care of themselves, their children, their pupils, and their employes. The series is written from the American standpoint, and with especial reference to our Climate, Architecture, Legislation, and modes of Life ; and in all these respects we differ materially from other nations. Sanitary I^egislation especially, which in England has made such notable progress, has barely begun with us, and it is hoped that the American Health Primers may assist in developing a public sentiment favorable to proper sanitary laws, especially in our large cities. The subjects selected, are of vital and practical im]iortance in every-day life. They are treated in as popular a style as is consistent with their nature, technical terms being avoided as far as practicable. Eacli volume, if the subject calls for it, will be fully illustrated, so that the text may be clearly and readily understood by any one heretofore entirely ignorant of the structure and functions of the body. The authors have been selected with great care, and on account of special fitness, each for his subject, by reason of its previous careful study, either privately or as public teachers. Dr. W. W. Keen has undertaken the supervision of the series as Editor, but it will be un- derstood that he is not responsible for the statements or opinions of the individual authors. The following volumes are in press, and will be issued about once a month. I. (By CHAS. H. BURNETT, M.D.,of Philada., < Si/>i;i;>ii iiif/icDj^,' of riiila. Disp. for Diseases of (. ///(■ Ear, Aurist to Prcshyterian liosf>ital, etc. Lona Life and How to Reach It JByj. g. RiCHARDSON,M.D.,of Phiiada., l_Ony Lim, dnu now lO nUdCn ll. | rr,f. of Hygiene in University of Pe>tna., etc. ( By WILLIAM S. FORBES, M.D., of Phila., \ Surgeon to the l-fisco/'iit Hospital, etc. ( By JAMES C. WILSON, M.D., of Philada., < Li'cturer on Physical Diagnosis in fcfferson ( Medical College, etc. By GEORGE C. HARLAN, M.D., of Phila., Sii7-geon to tlie II ills (Eye) Hospital. (By J. SOLIS COHEN, M.D., of Philada., -< Lecturer on I israses o/ the Throat in f-ferson (. Medical CoUei;e. ( By HAMILTOI^ OSGOOD, M.D., of Boston, \ Editorial Staff' Boston Med. and Surg. Journal. fByJ. W. WHITE, M.D.,D.D.S., of Philada., \ Editor of the Dental Cosmos. Hearing, and How to Keep It II. III. Sea Air and Sea Bathing. IV. The Summer and its Diseases. V. Eyesight, and How to Care for It. VI. The Throat and the Voice. VII. The Winter and its Dangers. VIII. The Mouth and the Teeth. IX. Our Homes. The Skin in Health and Disease. JBy HENRY HARTSHORNE,M.D., of Phila., I Formerly Prof, of Hygiene in I'niver. of Penna, X. XI. Brain Work and Overwork. By L. D. BULKLEY, M.D., of New York., Phy.fician to tlie SIdn Department of the Ih-inilt Pi.\pensary and of the A'ew \ 'ork J/ospital. ( By H. C. WOOD, Jr., M.D., of Philada., -; Clinical J'rofessor of Nervous Diseases in the y L.tiversity of Pennsylvania, etc. Other volumes are in preparation, including the following subjects: "Preventable Diseases," "Accidents and Eme-gencies," " Towns we Live In," "Diet in Health and Disease," ■ Th Art of Nursing, ' "School and Industrial Hy- giene," " Mental Hygiene," etc., etc. They will be ibnio in size, neatly printed on tinted paper, and bound in cloth, 50 cents. Mailed Iree upon receipt of price. LINDSAY & BLAKISTON, Publishers, Pliihulelphia. pital, &c. at its members them that the ice. Not only ) eradicate the public-spirited Social Science ns which have puhlic health. 1 efforts, or, if of their prac- lisease. Such lit of the most this series of ing all classes, igs and appli- ;ienic Science. teach people yts. erence to our )ects we differ land has made erican Health sanitary laws, fe. They are being avoided illustrated, so tirely ignorant :ed with great evious careful t it will be un- idiial authors. j.,'of Philada., ''.for Diseases of an Hospital, etc. , of Philada., o/ Penaa., etc. .D.,of Phila., a/, etc. , of Philada., is in JcJ/'erson D.,of Phila., bital. " Philada., ■oat in J'-'O'erson D., of Boston, i Siir^. yournal. S., of Philada., i/I.D.,of Phila., iiiver. of Penna. "New York., /.•/ ()/ tlic Dcniilt 'oik Uos/>ital. Philada., Diseases in the •tc. 'reventable ," "Diet in ustrial Hy- ncatly printed oth, 50 cents. iilelphia.