HX64061477 
 QM25 M61 Q An alias of anatomy 
 
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Columbia (MnttJersittp 
 
 tntl)f€itpofi^fttigork 
 
 College of l^hpsitiani anb burgeons 
 Hifararp 
 
Digitized by the Internet Archive 
 
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AN 
 
 ATLAS OF ANATOMY 
 
 OR 
 
 PICTURES OF THE HUMAN BODY 
 
 IN TWENTY-FOUR QUARTO COLOURED PLATES 
 
 COMPRISING ONE HUNDRED SEPARATE FIGURES 
 
 WITH DESCRIPTIVE LETTERPRESS 
 
 Mrs. FENWICK MILLER 
 
 MEMBER OF THE LONDON SCHOOL BOARD ; OF THE LADIES' MEDICAL COLLEGE, WITH HIGHEST CLASS HONOURS ; AUTHOR OF THE 
 
 PHYSIOLOGICAL SECTIONS OF ' SIMPLE LESSONS FOR HOME USE,' AND OF 'THE HOUSE OF LIFE,' ETC. ; 
 
 AND LATE LECTURER ON PHYSIOLOGY TO THE WORKING WOMEN'S COLLEGE 
 
 AND THE NATIONAL HEALTH SOCIETY 
 
 LONDON 
 EDWARD STANFORD, 55 CHARING CROSS, S.W. 
 
 1879 
 
a 
 
 
PKEFACE. 
 
 It is hoped that this work, being issued at a comparatively low price, may be found useful 
 both to science teachers and to students of all kinds. To the private student, whose access to 
 anatomical preparations and physiological laboratories is Limited, such a book is indispensable. 
 Students of medicine, although they have seen with their own eyes, yet know the use of Pictures 
 and Diagrams, both for accurate comprehension of Text-books, and for aid to the memory in its 
 heavy task ; for example, they will find the three drawings of the brain, two being sections such 
 as would frequently not be made by the student himself, valuable to them in assisting both under- 
 standing and recollection of Anatomy. Again, children, with theii- keen interest in the facts of 
 Nature, and with their fresh undistracted minds full of curiosity about what is around them, are 
 almost always found to take a deep interest in the wonderful structure and functions of their own 
 bodies. The subject has been introduced into many of the London Board Schools, and has been 
 found to be surprisingly popular among the children themselves ; one of our Inspectors records 
 that he has often been much struck with the alacrity with which boys rush to their seats for an oral 
 examination in Physiology, even at the very end of a long and tiring day of inspection. Thus, this 
 volume would generally be found an acceptable gift to an intelligent youth of twelve or fourteen, 
 and would afford him useful instruction for his adult life in any case, but most of all where it 
 was designed that medicine should hereafter be studied as a profession. 
 
 As I have not, of course, either di-a\\Ti or lithographed the Plates, I may be allowed to say 
 that many of them are quite admirably executed. Nearly all of them are new drawings, never 
 before published in any form in England. Some of them are taken from the recent famous Ana- 
 tomischer Atlas of Dr. Heitzmann ; others are newly drawn from preparations in the Vienna 
 Museum of Anatomy, and other places. Most of them are, therefore, quite modern, and some 
 obtain special value from that fact as embodying the latest results of anatomical research. In 
 this connection attention may be specially drawn to the Structure of the Ear, Plate XXII. 
 
 In writing the Letterpress I have had mainly in view the requirements of young and indi- 
 vidual students, and have not assumed that my readers would possess any knowledge of the sub- 
 ject. At the same time, in order to avoid undue length, I have made the Index to the Plates as 
 fully explanatory in itself as possible. For this reason I would advise beginners of the study to 
 first carefully look out on each Plate the parts referred to by each number in the Index, and 
 afterwards to turn to the Letterpress about the Plate, and in reading it not to spare continual 
 reference from the text to the picture. 
 
 FLOEENCE FENWICK MILLER 
 
 London, March 1879. 
 
AN ATLAS OF ANATOMY. 
 
 Preliminary Observations. 
 
 The luimnH body is exceedingly complex in structure, 
 and marvellous in function ; and yet, like a beautiful pic- 
 ture, it is composed of comparatively few materials. It 
 contains fourteen of the sLxty-six " chemical elements " into 
 which all matter in nature can be separated, and those 
 fourteen elements in combination foi"m all the tissues of the 
 body, and build up the numerous organs by which the vital 
 processes are carried on. 
 
 The knowledge of the structure and positions of those 
 tissues and organs forms the science of Anatomy ; the facts 
 of the vital processes performed by those tissues and organs 
 make up Plii/siology. 
 
 The sister sciences of Anatomy and Physiology are as 
 closely connected as the Siamese twins. They are almost 
 one ; there is an indivisible connection between them, but, 
 at the same time, they are distinct subjects for study. 
 
 A knowledge of Anatomy is an absolutely essential pre- 
 liminary to the study of Physiology. For many hundreds 
 of years this truth was not recognised, and the ancient 
 physiologists tried vaguely to guess at the functions of the 
 various organs, without the aid of the clue which they 
 might have found in even a rough examination of the 
 structure of the parts. It must be acknowledged, however, 
 that small progress could ever have been made in ana- 
 tomical research before the discovery of the microscope. 
 Throughout the plates of this volume, the work of the 
 microscope is discernible, and those young students who 
 are not accustomed to the use of that instrument must be 
 careful not to get their ideas confounded as to the relative 
 size of the objects represented, by neglecting to note whether 
 they are magnified or not, and where they are so, to what 
 extent they are enlarged. 
 
 In ^vriting a description of the plates in this book, my 
 subject is necessarily Anatomy ; but I shall not, therefore, 
 consider myself excluded from briefly describing also, wher- 
 ever possible, the work of the various structures. On the 
 contrary, I shall endeavour to include in these pages a 
 brief sketch of the physical life of man ; so that the young 
 student, by reading attentively, and constantly referring to 
 the plates, may gain a general knowledge of the living 
 human body. 
 
 The Chemical Elements which are normally found in 
 the structure of the body are the following : — Oxygen, Hy- 
 drogen, Nitrogen, Carbon, Sulphur, Phosphorus, Sodium, 
 Potassium, Lime, Chlorine, Magnesium, Iron, Silicon, and 
 Fluorine. No one of these is found by itself, as an element ; 
 but, mixed one with another, they form every particle of 
 the body. 
 
 The most important of tliese fourteen elements are 
 the four first named. The physiological chemist in his 
 laboratory finds that he can anal3-se nearly every part and 
 tissue of the body into these four elements — Oxygen, Hydro- 
 gen, Nitrogen, and Carbon — with a mere infinitesimal portion 
 of some of the other substances named. Suppose he thus 
 analyses the entire body of a man weighing eleven stone 
 (154 pounds), only about one stone (14 pounds) would be 
 found to consist of the last ten elements named above ; 
 
 and of even that one stone, by f<ir the greater portion 
 would consist of the ashes of the bones ; so that the softer 
 parts of the body contain only a very small proportion of 
 the other elements, besides the combinations of Oxygen, 
 Hydrogen, Carbon, and Nitrogen of which they are mainly 
 formed. 
 
 Everywhere in the living body there is found a remark- 
 able substance which is composed of those four principal 
 elements, together with a very little of some few others. 
 This is called Pwtoplasm, from Greek words meaning the first 
 formative material, because it is the earliest condition of 
 living matter ; and it has very remarkable vital properties. 
 
 The word " vital " is derived from the Latin for life, and 
 " vital force" simply means, therefore, the force of life. Living 
 matter, in whatever form, from the lowest up to the highest 
 organism, has certain powers inherent in itself as ^ital 
 properties ; the product of some force peculiar to it, which 
 therefore receives the name of vital force. We cannot 
 produce vital force apart from living matter ; that is, pro- 
 bably, impossible for ever. The chemist can put together 
 the elements of protoplasm, but he cannot thereby produce 
 the force of life. To talk about vital power is thus only 
 one way of concealing our practical ignorance of nature's 
 secrets. 
 
 But if we cannot produce the force, we can study it ; 
 and this can be done quite as effectually by considering 
 the tiniest individual particle of living protoplasm, as by 
 the largest mass of it. As Tennyson says, apostrophising 
 a tiny flower — 
 
 " If I could understand 
 ■What j'ou are, root and all, and all in all, 
 I should know what God and man is." 
 
 The lower animal organisms, such as the jelly-fish, for 
 instance, which may sometimes be seen on the sea-shore 
 (where I remember when I was a very little girl I found 
 one, and an impertinent boy tried to persuade me it was the 
 moon fallen down) are little more than lumps of simple pro- 
 toplasm. There are tiny microscopic animal forms even 
 simpler than the jelly-fish. Now, when one of these is 
 inspected and watched, it is found that the minute speck 
 of matter is endowed with certain powers, produced by an 
 inherent vital force which is practically and essentially the 
 same as that which is observed in all living creatures. If a 
 chemist could (but he cannot, as we all know) make in his 
 laboratory one of those tiny specks of living protoplasm, 
 his making any other animal would be possible, for the prin- 
 ciple of life exists equally in that speck and in a man. 
 
 These vital powers consist, to speak broadly, of the 
 power of movement ; of the power of receiving from the 
 outside matter which serves it as food, and of converting 
 that food into its own substance ; and of the power of in- 
 creasing in size, or reproducing itself, in consequence of its 
 conversion of food into living protoplasm. 
 
 The protoplasmic speck can move about in the fluid in 
 which it is found by means of a shifting of its substance ; 
 the whole mass of protoplasm is moved by the movement 
 of first one atom and then another atom of it. When a 
 particle of food comes against it, the protoplasm flows round 
 the food, so to speak, takes it in, and by vital action upon 
 
AX ATLAS OF ANATOMV. 
 
 it, turns as much as possible of it into now protoplasm. 
 By and by tlie one speck becomes two, eiilier by breaking 
 in halves, or by a new speck j,Towing out at the side, which 
 presently becomes a new individual. 
 
 Such a minute portion of protoplasm is called a Cell. 
 Generally, a darker and even more minute speck can be 
 detected somewhere in the substance of the cell, which is 
 called its nucleus. The ordinary way of growth and 
 reproduction of cells is for the nucleus to divide into two 
 parts, each part gathering around it an equal quantity of 
 cell-substance ; and then I'ach newly-separated nucleus and 
 its surrounding protoplasm absorbs nourishment, and in- 
 creases in size, until tlie two cells are each as large as the 
 one origiiud cell ; and then each repeats the same process. 
 
 It may be useful that I should mention that the simplest 
 animal form to which the description given above applies, 
 is a microscopic organism found in stagnant water. There, 
 each individual cell leads its individual life, absorbing 
 nourishment, showing the power of vital movement in its 
 substance, growing, and reproducing itself; and yet being, 
 so far as can be discovered, a simple speck of protoplasm. 
 This minute living unit has been called the ainceha ; and 
 consequently, the vital properties of a cell, as described 
 above, are often spoken of as aiiuehoid. 
 
 Now, it is not possible to watch the growth of the tissues 
 in a higher animal, in the same way in which the whole 
 growth and vital manifestations of these very low animal 
 existences may be watched. But there is every reason to 
 believe that the tissues of man grow and are reproduced, in 
 a broad sense, exactly like the whole bodies of these lower 
 forms of animal life. 
 
 The simpler tissues are distinctly found to be formed of 
 cells, which obtain their nourishment from the blood, and 
 which, doubtless, gi'ow and develop like cells outside the 
 body. When these ultimate tissues are examined under 
 the microscope, the cell-nuclei can be discovered in them. 
 Each cell — or probablj' it is more exact to say each nucleus — 
 has the power of drawing from the blood, by which nutri- 
 ment is carried to the whole body, exactly the elements 
 required to make its own particular tissue, and none other. 
 Thus, one fat-cell will draw from the blood the elements 
 necessary to increase fat, and enable tlie one cell to multiply 
 itself; one of the cells of the skin will draw out of the 
 blood the special matter for ils growth and reproduction ; 
 and so on, in accordance with the mysterious vital laws of 
 their being. 
 
 The Elementary Tissues are those which cannot be divided 
 without destroying their construction ; they are the first 
 results of the grouping together of cells, and theii- subse- 
 quent development. The following is an enumeration of 
 them ; they will be frequently referred to hereafter : — 
 
 1. Epithelium (Plate XVIII. F, G) consists of simple 
 cells, placed side by side, and generally so tmited as to form 
 a continuous layer, termed a Mtmhrane (skin). These cells 
 are reproduced in the manner above described ; besides sepa- 
 rating from the blood matter for its own sustenance, each 
 cell generally secretes a little spare fluid. The membrane 
 (called mucous) which covers the inside of the lips, and which 
 is contiuued aU through the alimentary canal and other spaces 
 opening outside the body, is only slightly modified epithe- 
 lium ; so is tlie membrane (serous), which forms sjiut bags 
 \vithin which various organs are inclosed, as will be descril)ed 
 in speaking of the heart ; and so, indeed, is the external skin 
 which covers tlie outside of the body. This consists essen- 
 tially of cells, which are soft and plump in the lower layer, 
 where they are produced from the blood, and being gradu- 
 ally pushed upwards by constant growtli below become 
 flatter and harder as they ajjproach the surface, and having 
 reached it are gradually rubbed awa)- in the form of an 
 impalpable! dust. 
 
 -■ Cartilage, commonly known as gristle. This is 
 
 seen, under the microscope, to consist of cells imbedded in 
 a hard substance, which is called the malrk. 
 
 3. Adipose or Fatty Tissue. — The fatty tissue con- 
 sists of a collectiiin of ct^lls, each containing a nucleus and 
 a quantity nf fatty matter. 
 
 4. Connective Tissue (sometimes caWcd JiLivus tissue), 
 which is so named because this tissue passes through all 
 parts of the body connecting the one with another. In it 
 cells seem to stretch out into long fibres, of which the tissue 
 is made up. 
 
 5. Pigment-cells, in which the cell contains a (juantity 
 of colouring matter. Such cells are found in the ej'e, and, 
 as wUl be mentioned again hereafter, in a layer of the skin. 
 
 The structure of nervous tissue and muscular tissue will 
 be spoken of farther on. 
 
 And finally, among these elementary tissues, is 
 
 li. Bone, a figure of the microscopic structure of which is 
 found on Plate III. Fig. E. This beautiful figure represents 
 a slice taken across one of the long bones, such as that of 
 the upper arm, and magnified about 150 times. 
 
 The space in the middle of each of the rings in which 
 the bone is seen to be arranged, is a tiny canal about 
 jig- of an inch in diameter, which runs through the bone in 
 a longitudinal direction. These Haversian canals do not 
 run straight on, however, the whole length of the bone, 
 but diverge in various directions and join into one another, 
 and can always finally be traced to the outside of the bone, 
 where blood-vessels enter them. They are really canals 
 for the blood-vessels to run through ; an artery or vein 
 is found in each shaft. 
 
 The large black spaces surrounding the Haversian canals 
 are called lacuna: In a fresh bone, a nucleus with a little 
 protoplasm around it occupies each of those many spaces. 
 
 The very fine hair-like lines which are seen running in 
 every direction, from one lacuna to another, are exceed- 
 ingly minute tubes excavated in the bone, and are called 
 canalimli. 
 
 By means of this marvellously beautiful and delicate 
 arrangement, the whole of the hard tissue of bone is kept 
 bathed by the blood. The vital fluid runs through the 
 HaversLau canals, and the nutriment is drawn from thence 
 through the minute canals to the living cells in the 
 lacunae. 
 
 Besides these minute cavities, which are only distinctly 
 seen under the microscope, long bones have a canal run- 
 ning straight through their centres, filled ■with that soft fatty 
 substance called marrow. This is verj' plentifully supplied 
 with blood (or, as it is called in technical language, is 
 hiffhly vascular), by means of an artery which passes into 
 it through the bone ; and some of the blood which nour- 
 ishes the substance of the bone is supplied from the mar- 
 row-artery. 
 
 "We may now proceeil to consider 
 
 The Skeleton. 
 
 Plates I. to VI. — Bones are divided into four classes : 
 long, short, flat, and irrc{/ulur. The human skeleton consists 
 of about 200 distinct bones. 
 
 In making this calculation, of course each bone is counted 
 regardless of how firmly it may be jointed to a neighbour. 
 Thus, the spine consists of 26 separate bones, which can 
 be seen best in Plates I. and II. Fig. B. There the 24 ver- 
 tebrre, numbered 6, 7, and 8, can be counted, and the 
 sacrum (9) and its tail-piece the coccy.x (10) are seen to 
 form the twentj'-fifth and twenty-sixth of the number. 
 
 Each vertebra consists of two chief parts. First, a 
 hard solid portion called its lioi:Ji/, which is turned inwards, 
 and is seen in Fig. A. of the plate, with the numbers Ifi, 
 17, and 18 placed upon the respective bodies of three ver- 
 tebrte. These, being placed on top of one another, and 
 
AN ATLAS OF ANATOMY. 
 
 joiuti'il iiriiily togctlior 1i_y the plates of cartilage which are 
 seen iu tlie picture as ilark rings between them, form a 
 strong column which gives support to the trunk. Second, 
 each vertebra has a ring of bone, called its arch, running 
 round liehind the body, so that when the vertebriB are in 
 their natural position, their arches, or rings, form a con- 
 tinuous bony canal, which contains the spinal cord. It is 
 the arches that arc shown in the back view of the spine in 
 Fig. B. 
 
 The first and second vortebra5 are different from all the 
 rest, and they are therefore specially figured on Plate III. 
 (Figs. F and G). The first one, Fig. F, is called the atlas. 
 The ancients had a fable that the globe was supported on 
 the shoulders of a mighty man named Atlas ; and the first 
 cervical vertebra is called after him because it supports the 
 globe of the head. In the figure just above (B) No. 1 .5 
 shows the surfaces of the occipital bone of the skull which 
 come against the depressions made to receive them (5, Fig. 
 F) on the top of the atlas. G. shows the second cervical 
 vertebra, which is called the axis. The point projecting 
 upwards of this bone is called the odontoid process; the 
 figure 2 points out the spot of that process which comes 
 against the spot marked 4 in F. For the odontoid process 
 projects up through the middle of the atlas, and is held 
 there by a ligament that runs across from the projecting 
 point against which the figure 4 stands to the similar point 
 opposite to it. By this means the head is able to turn 
 a little from side to side, and to nod backwards and for- 
 wards, without the whole of the spine moving. The atlas 
 really moves upon the pivot provided liy the odontoid 
 process of tire axis. 
 
 I have made the Index to the Plates as complete as pos- 
 sible, so as to avoid useless repetition here. The majority 
 of the bones in the complete skeleton can be studied by aid 
 of the index alone. 
 
 The Sknll. 
 
 ' ' You are bones ! and what of that ? 
 Every face, however full, 
 Padded round mth flesh and fat, 
 Is but modelled on a skull." 
 
 The skull, even more than the whole of the strange 
 relic of departed existence which a skeleton is, aff'ords a 
 suggestive theme to poets and text to moralists. For the 
 muscles that covered these bones made the face, so full of 
 life and expression ; within the gaping cavity of the jaw- 
 bones moved the tongue, perchance potent to influence, or 
 strong to command, or tender to soothe and cheer ; in that 
 socket flashed or melted the eye ; and protected in the 
 midst of the casket of strong hard bones lay the jewel of 
 the body, the busy wonderful brain, which thought and 
 felt and willed. 
 
 " Once of the ethereal spirit full, 
 This narrow cell was life's retreat, 
 This space was tliought's mysterious seat. 
 What beauteous visions jBlled this spot ! 
 What dreams of pleasure, long forgot ! 
 Nor hope, nor love, nor joy, nor fear, 
 Hath left one trace of record here." 
 
 In the whole skull, including both face and head, there 
 are twenty-two distinct bones ; in the head alone there 
 are eight. Fig. C. of Plate V. shows the bones of the skull 
 of an embryo — a child at a very early period of existence. 
 In connection with this Plate, a few words may be said on 
 the growth of the bones. The figures 3 and 4 are placed 
 in the figure on the membranes which, in this incomplete 
 state of development, intervene between the several bones 
 of the skull. The anterior and posterior fontanelles can 
 both be felt through the skin in the head of a child up to 
 four or six months old ; and the anterior one often remains 
 
 membranous until the child is from one to two years of 
 age. This arrangement enables tiie head to grow. The 
 membrane gradually becomes turned into lione, by the 
 earthy salts being passed into it out of the blood ; and as 
 this goes on, the size of the head gradually increases, until 
 at last the whole membrane is ossified (made into bone, 
 that is), and the development of the cranium is completed. 
 The various bones as they grow present an appearance 
 along their edges like the teeth of a saw ; and the projec- 
 tions of one edge fit into the depressions of its neighbour, 
 and vii:e versa, so that a very firm joint is secured. 
 
 All the bones in the body are developed in practically 
 the same way, only most bones are first modelled in cartilage, 
 not in membrane. Chemically, bone consists of an_animal 
 base — gelatine^ and of certain earthy salts, mostly lime, 
 deposited in the gelatine, and making it hard. The bone 
 exists first, in the very young (embryo) child, as mere 
 cartilage, and a portion of each bone remains cartilaginous 
 until the full growth is attained. The earthy matter is 
 not drawn out of the blood into all parts of the bone at 
 once, but only at certain points, which are called the centres 
 of ossification. The lime begins to appe.ir at these j^oints, 
 and from thence continues to spread. Meantime, the car- 
 tilage grows in length, and the lime does not overtake the 
 growing cartilage (so to speak) until such time as the full 
 size of the bone is attained. Then the cartilage ceases to 
 grow, and the bony salts are deposited throughout it. 
 
 In the long bones, such as the arm and the leg :iud the 
 finger bones, there are usually at least three centres of 
 ossification ; that is to say, three places where growing 
 cartilage is to be found. These are at each end of the 
 bone, and in its centre. The end ossifying cartilages are 
 called the epiphyses, and these remain separated from the 
 shaft of the bone (which ossifies from the middle " centre ") 
 by a portion of unossified and growing cartilage, until quite 
 adult age ; varying in the different bones from the six- 
 teenth to the twenty-fifth year of life. 
 
 Joints and Ligaments. 
 
 Plate VI. The various bones are fastened to one an- 
 other, and these joinings of the bones are called joints, or 
 articulations. The bones are held together by plates of 
 cartilage ; and generally bands of the same tough material, 
 which are called ligaments, pass from one bone of an 
 articulation to the other, helping to keep them connected. 
 
 Joints are divided by anatomists into two great classes : 
 Imperfect or Immovable joints, and Perfect or Movable 
 ones. 
 
 The vertebral column is an instance of the first kind ; a 
 plate of cartilage intervening between the vertebrje, and 
 only allowing as much movement as the spring of that 
 cartilage permits. The sutures of the head also form joints 
 of this class. 
 
 The second class may be subdivided into three kinds — 
 viz. Pivot joints, such as the atlas and axis already de- 
 scribed ; Hinge joints, such as the elbow and the ankle, 
 which are articulated on the same plan as a door is hung 
 on its hinges ; and Ball-and-socket joints, such as the hip 
 and the shoulder. 
 
 It is ob\dous iu a moment that the purpose for which 
 the bones are thus jointed is that they may move upon one 
 another. The power by which such movement takes place 
 must next be briefly studied. 
 
 The Muscles. 
 
 If the outer skin were removed from a man's body, the 
 wonderful and beautiful arrangement shown in Fig. A of 
 Plates VII. VIII. would be seen. There are a multitude of 
 
AN ATLAS OF ANATOMY. 
 
 muscles of all shapes and of all sizes, and running in the 
 most various directions ; but when we come to study those 
 muscles in action, we find that every single one, from the 
 tiniest one in the face to the greatest one in the thigh, is 
 just the shape and the strength that it ought to be for its 
 own special work. Every one Las its office to perform, and 
 is precisely suited to perform it. 
 
 Nor are the muscles seen in this figure all that the l.)ody 
 possesses. This is only the superficial layer, and in many 
 parts (as Fig. B serves to illustrate) the external layer 
 must be quite removed to show the equally powerful and 
 equally needful second or third layers beneath. 
 
 The muscles are fastened on to the bones in the elaborate 
 and wonderful manner shown in C, D, E, F of this Plate, 
 as well as in A. The ends of the muscles pass almost im- 
 perceptibly into tough, white cords, called tendons, which 
 are attached to the bones. In cases where several muscles 
 are fastened close beside each other, or where they are 
 intermingled one with another (as in the hand, where many 
 muscles are needed to supply the power for the infinite 
 variety of movements of which that meml.ier is capable), 
 the various tendons and sheaths which bind them into 
 place are so complicated, and yet so perfect, that they 
 arouse our wonder and admii'ation. 
 
 Thus, in the hand and foot, which may be studied care- 
 fully in the Plate before us, the tendons are very numerous 
 and carefully arranged. The muscles which bend (or flex) 
 and open (or extend) the fingers, are situated in the lower 
 arm — the extensor muscles at the back, and the flexors at 
 the front. In the same situation are also the muscles 
 which move the whole of the lower arm in certain direc- 
 tions, and those which flex and extend the wrist. Now 
 the tendons of the muscles which move the fingers have a 
 long distance to run (see Fig. A, 23, 2 i, 25), so that if they 
 were not carefully bound down, they would start out in 
 every direction when the muscles acted, in the most ex- 
 traordinary manner. The fingers are flexed by two distinct 
 muscles, which lie on the front of the forearm (as the aim 
 below the elbow is called), one below the other. In the 
 right forearm of Fig. A the second or under layer of 
 muscle is shown ; and the large muscle marked 23, which 
 is seen to di-sdde into four tendons, is the deep flexor of 
 the fingers. Anatomists always use Latin or Greek terms ; 
 and as any one who means to study Anatomy in detail 
 must learn the Latin names, the muscles are described in 
 that language in the Index to the Plates. The name which 
 I have just given to this muscle is merely a literal trans- 
 lation of the name that will be found there. The deep 
 flexor of the fingers has the end of its tendons attached to 
 the tip of the fingers in front, as shown in Fig. A. The 
 upper flexor of the fingers has its tendons attached to the 
 second finger-joint (Fig. C, 6). 
 
 Now these tendons are seen to be held down first of all 
 at the wrist, by the anterior and posterior annular ligaments, 
 which pass around the wrist like a broad bracelet. In the 
 palm of the hand is another portion of fibrous tissue, which 
 equally firmly holds the tendons down beneath it, and 
 which is removed in the picture to show the tendons. 
 Finally, the. complex bandage of ligaments around the 
 tendons on the fingers themselves can be studied in Fig. 
 C, where the sheath investing the tendons is left entire on 
 the Uttle and the third fingers, but removed from the first 
 and second fingers, to show the attachment of the tendons 
 of the upper flexor (sublimis digitorum). 
 
 It is not possible, in the brief space at my disposal, to 
 thus describe in detail the arrangements of other muscles. 
 But the reader will understand that this is merely an in- 
 stance of the ver}- elaborate way in which the muscles are 
 arranged and suited to their use in every part of the body. 
 A careful study of the several figures on Plates VII. VIII. 
 Avill show many other obvious instances. 
 
 "Work of Bones and Muscles. 
 
 The offices of bones and muscles are, broadly, two in 
 number — viz. to jyroied the delicate vital organs, and to pro- 
 duce motion and locomotion. 
 
 That they perform the office first mentioned, is seen at a 
 glance. Tlie brain rests fully enclosed in the bones of the 
 skull, and further protected by muscles. The ribs enclose 
 the heart and lungs ; the rectus, the obliquus, and other 
 muscles, close in the cavity of the abdomen, and protect 
 the important organs that lie there (see Plates XIV. XV.), 
 and the pehas shares in the same service. But to under- 
 stand how the muscles and bones produce motion and 
 locomotion, we must study the functions of muscular tissue. 
 
 Plate IX. Fig. D represents a muscular fibre, treated 
 with an acid which has caused its minute structure to 
 become visible, and immensely magnified ; and Fig. E shows 
 a muscular fibre of quite a ditterent kind. You will 
 notice at a glance that D is marked with stripes both 
 longitudinally and running round, the latter being rather 
 the more distinctly seen, while E is perfectly smooth, and 
 contains a nucleated cell in its midst. 
 
 Physiological research has shown that the striated (/.«. 
 striped) muscular fibre composes all the muscles that are 
 under the control of the will, which includes, of course, all the 
 muscles of the limbs ; we move our limbs by our volition. 
 The unstriped fibres are found in the gullet, in the coats of 
 the blood-vessels, and in other situations where muscular 
 action takes place without the order of the will. Striped 
 muscular tissue is therefore often called roluntary, and un- 
 striped involuntary muscle. 
 
 Fig. D, 1, shows at the torn end of the fibre that the 
 fibre really consists of a great number of smaller fibrils ; 
 while at 5 it is seen that the fibre readily splits up into 
 discs, which are composed of numerous little rounded 
 particles. Each fibre is about ^-g- of an inch in breadth ; 
 each of its fibrils is only about tttwo to x^luo o^ ''^■^ i"*^!* 
 across — a smallness cjuite unimaginable to anybody not 
 accustomed to microscopic work. The fibrils are found to 
 be fastened together to form a fibre by a fine membrane 
 (not seen in the figure), called the sarcolemma. Then a 
 number of fibres are in like manner bound together by a 
 fine membrane into bundles, and a number of these bundles 
 are again fastened up with each other to form a muscle. 
 To carefully dissect an orange will give one some idea of 
 this repeated binding up of bundles to form one whole. 
 
 The muscles are plentifully supplied with blood-vessels, 
 which run aU through amongst the fibres, forming a net- 
 work around them, but never penetrating through the sar- 
 colemma which binds together the fibrils. 
 
 Nerves also enter the nniscles, but they are so exceed- 
 ingly delicate that it is still far from certain how they end. 
 Fig. C shows what is lielieved to be the method of the ter- 
 mination of nerve in a voluntary muscular fibre. 
 
 This same figure, C of Plate IX., also introduces us to 
 the action of the muscles whose structure we have now fully 
 studied. 
 
 The special power peculiar to muscular tissue is that of 
 contraction. AVhen a muscle contracts, it becomes shorter and 
 thicker. If you lay one hand upon the biceps muscle (Plate 
 VII. Fig. A, 1) of the opposite arm, and then draw up the 
 lower part of the arm towards the shoulder, you distinctly 
 feel the biceps grow thicker and shorter under your hand. 
 And by looking at it in the Plate just named, you can see 
 at once that, since one end of the muscle is fixed to the 
 shoulder, and the other end to the forearm just below the 
 elbow-joint, the efi'ect of its growing thicker and shorter 
 must needs be to draw up the forearm. 
 
 The entire muscle contracts by the contraction of each of 
 its fibres. ]\Iost probably, every one of the tiny particles into 
 which the fibre can divide transversely (PI. IX. Fig. D, 5) 
 
AX ATLAS OF ANATOMY. 
 
 becomes closer and wider ; so that the whole fibre is made 
 shorter, and correspondingly wider or thicker ; and by the 
 simultaneous action of all its fibres the entire muscle is thus 
 altered in shape for as long as the state of contraction is 
 kept up. This is very well represented (diagramatically) in 
 Fig. C, Plate IX., where 1 shows the muscle at rest, and 2 
 in a state of contraction. 
 
 The bones are jointed together on definite mechanical 
 principles, so that they form a system of levers ; and the 
 muscles, by their contractions, furnish the moving power to 
 act upon the bones, and to produce motion and loco- 
 motion. 
 
 The Heart. 
 
 This organ, as is seen at once by a glance at Fig. B of 
 Plate IX., is made of muscle. Now, the heart is an iii- 
 vohintdri/ nmsch, and in connection with it. the necessity for 
 the muscles of organic life being removed from the control 
 of the will becomes at once most strongly apparent. For 
 what a terrible thing it would be if the will were in any 
 degree required to maintain the increasing muscular con- 
 tractions, the stoppage of which, for a few instants, means 
 death, and the irregularity of which is painful disease. 
 
 " No rest that throbbing slave may ask, 
 For ever quivering o'er his task." 
 
 But it has to be particularly noted that tlie heart is 
 made of striated muscular fibres. The stripes are less 
 distinct, and the fibres are shorter, than in voluntary 
 muscles ; but nevertheless it is a curious fact that the heart 
 is the solitary instance in the body of striped muscle being 
 outside the control of the will. 
 
 All involuntary muscles are excited to act, through the 
 agency of the nervous system, by some cause, differing for 
 each muscle, which is called the stimulus. Thus, the stimu- 
 lus to the gullet is food coming into it ; the stimulus to the 
 heart is the filling of its cavities with blood. 
 
 To study the internal arrangement of the heart we must 
 turn to the next plate (Plate X. Figs. B, C, D). 
 
 The heart is divided inside into four distinct cavities. 
 It is divided first longitudinally (from base to apex : the 
 broad end being the former, and the point the latter) by a 
 thick muscular wall, or septum. Fig. C is the representa- 
 tion of the heart cut across, at about the part where the 
 figure 1 is placed in B of Plate IX. This is the portion of 
 the heart which comes below that figure, and we are sup- 
 posed to be looking down into it. The septum is marked 
 3, and you will observe that it is very thick and strong. 
 It runs the whole length of the heart, and it has no orifice 
 in it anywhere ; so that the heart is completely divided into 
 two halves — a right and a left half. (See diagram of this 
 division in Plates XII. XIII. Fig. A, where the left half is 
 coloured red, and the right half blue.) Then each half is 
 again divided into two parts — an upper and a lower — by 
 means of a strong fibrous membrane. The two top parts 
 thus formed are called the auricles, and the two bottom parts 
 the ventricles — one of each right and one left. The auricles 
 are much smaller than the ventricles. In Plate IX. Fig. 
 B, the whole of the part coloured red is composed of the 
 ventricles ; the paler portion above indicates the size of the 
 auricles. The left ventricle is thicker and longer than the 
 right, and by projecting a little below the latter it forms the 
 apex, or point, of the heart, as shown in Plate X. B. where 
 the whole of the right half of the organ, together with the 
 septum, is cut away, and yet the extreme tip of the heart is 
 seen. 
 
 The septum completely divides the right auricle and ven- 
 tricle from the left auricle and ventricle ; not a drop of 
 fluid can possibly pass through from the one side of the 
 heart to the other. But the partition between each auricle 
 
 B 
 
 and its corresponding ventricle is not complete ; fluid does 
 pass from the auricle into the ventricle. The fibrous 
 membrane which forms the fixed partition is arranged as 
 a ring round the interior wall of the heart at the point 
 where the auricle ceases and the ventricle begins ; and the 
 centre of this ring is a hole about large enough to admit 
 the tips of three fingers. That hole is called the auriculo- 
 ventricular aperture. It may be compared to a doorway be- 
 tween the auricle and ventricle ; and it has doors which 
 are alternately open and shut. These doors, which can com- 
 pletely close the aperture, are called the valves uf the heart. 
 
 The heart is covered outside and inside alike with a tough 
 shining membrane. That outside is called the. pericardium ; 
 that inside, the endocardium. 
 
 The doors which fill up the two auriculo-ventricular aper- 
 tures are simply flaps of the endocardium, attached by one 
 end to the fibrous rings surrounding the apertures, but free 
 at their tips, so that they hang loosely down in the ven- 
 tricle when the heart is empty, as after death. 
 
 On the right side of the heart there are three flaps, so 
 shaped that when they are lifted up they completely close 
 the aperture, their points and sides coming together. This 
 is the tricuspid {i.e. three-pointed) valve. 
 
 On the left side there are only two flaps, which, however, 
 just as efl'ectually as the three close the aperture. As its 
 shape somewhat resembles that of a bishop's mitre, this 
 valve is called the mitral valve. 
 
 The free sides and tips of each of these flaps have fine 
 tendinous cords fastened to them ; and those clwrdce tendinm 
 are affixed at the other end to small muscular projections, 
 which stand out on the inside of the ventricle, and which are 
 called ihejMpillari/ muscles. The cords are just long enough 
 to keep the sides and tips of the flaps in juxtaposition 
 when they are raised up to close the apertures. But for 
 this the flaps might be pushed right up through the apertures 
 into the auricles, and so become useless as doors. The ar- 
 rangement is, in short, like that of the swing doors often 
 seen in banks, which would go right in and right out of the 
 doorway, were it not for the leathern band which prevents 
 them from opening in the direction opposed to it, while 
 allowing them to come freely towards the wall where it is 
 attached. This arrangement will be presently further 
 explained. 
 
 Large pipes are found to lead out of both the auricles 
 and both the ventricles (Plate IX. Fig. B, 7, 8, 10 ; also 
 Plate X. Fig. B, 5). These pipes are 
 
 The Blood-vessels. 
 
 Blood-vessels are found in every part of the body ; they 
 are pipes which contain the fluid called blood. 
 
 Three kinds of blood-vessels are found in the body, viz. 
 Arteries, Capillaries, and Veins^ The arteries and veins | 
 are all good-sized tubes, though some of them are much 
 larger than others ; but the capillaries are generally micro- 
 scopic, and cannot be seen at all with the naked eye. 
 
 Now what are the distinctions between arteries and veins 1 
 
 In the first place, there are differences of structure. 
 The arteries are stronger and thicker tubes than the veins, 
 having more elastic tissue in their coats ; on the other 
 hand, the veins have valves in them, while the arteries 
 have not. 
 
 Fig. E, Plate X., shows the valves of veins to be merely 
 pouches of membrane, with all their mouths turned in one 
 direction — viz. open towards the heart. Obviously, fluid 
 would flow along those pipes over the back of the valve 
 pouches (that is, towards the heart) without finding any 
 obstruction from them; but if the fluid attempted to run 
 back in the opposite direction, it would catch in the 
 pouches, and swell them out so that they would fill up 
 the tube. They thus eflfectually prevent the flow of the 
 
AN ATLAS OF ANATOMY. 
 
 Wood in a baokwanl direction, and compel it to pass 
 always on one waj-. 
 
 Now, wherever j-ou may commence in a body to trace 
 out the course of either an artery or a vein, you inevitably 
 discover one thing — that is, that you come to the heart at 
 last. Starting with the finest twig, either arterial or 
 venous, that can be seen in any part of the body, and 
 tracing its coui-se, you would soon find that it joined witli 
 a second twig, that the two made a somewhat larger stem, 
 find that this in its turn soon joined into another and thus 
 formed a yet larger branch, and so on. (See Plate X. Fig. 
 A, and trace one of the .small venous twigs at the top of 
 the head until it is seen to communicate with the large 
 vein marked 18.) And at last, following the joinings of 
 the vessels into one another on and on, and noting how a 
 larger tube results from each junction, we finally come to 
 the largest veins and the largest artery of the body, and 
 find that these lead straight into the heart. (Plates XII. 
 XIII., 4, 5, largest veins ; 12, largest artery.) 
 
 Tlie best way to completely study the " distribution," as 
 the arrangement and division of the blood-vessels is ana- 
 tomically called, is, therefore, to begin at the heart. 
 
 The largest artery of the body, the Aorta, rises out of 
 the left ventricle. Fig. D, Plate X. diagrammatically 
 represents the ventricle cut across so that the valve which 
 guards the mouth of the aorta is shown (.5, which is intended 
 to indicate the three half-moon-shaped flaps of membrane, 
 nearly closed, but still allowing a glimpse of the red inte- 
 rior of the heart between their edges) ; and there it is 
 seen that the great blood-vessel goes out from the very 
 top of the cavity, close up beside the mitral valve. The 
 aorta first rises upwards towards the neck, immediately 
 behind the breast-bone ; but when it has ascended to oppo- 
 site the second rib cartilage, it arches over towards the 
 back, and then runs downwards close against the spine. 
 Several smaller arteries arise out of the aorta all down its 
 course (see, for instance, Plate XII. 14, 15, 16), these going 
 to the head, the upper extremities, the liver, stomach, etc. 
 Opposite the fourth lumbar vertebra, the aorta itself divides 
 into two branches, called the common iliac ur/crics, which run 
 towards the legs. Presently, each of these dirides into 
 two others ; and each of those again subdivides, and so on, 
 in the same manner as the external carotid artery maj' be 
 traced in doing in A, Fig. X. 1. And -svith every division, 
 the tubes become less in circumference, and also their coats 
 become less thick and strong. 
 
 Calling in the aid of the microscope, the anatomist sees 
 that the smallest arteries pass into — or, in fact, make by 
 yet further subdivision of themselves — excessively fine 
 tubes, which are much smaller than the hairs of the head, 
 and which are arranged in a network, running into one 
 another (Plate XII. Fig. C). These are the Capillarks, so 
 called because of their extreme fineness (Latin, capHlus, a 
 hair). The capillary network is found in every organ and 
 nearly every tissue of the body. Its meshes are in some 
 parts even closer than the size of the capillaries themselves. 
 In the skin, the interspaces of the network are from three 
 to four times as large as the capillaries of which the net- 
 work is made ; and yet we can scarcely put the point of 
 the finest needle through the skin without breaking open 
 a capillary and letting the blood flow out of it The 
 average diameter of a capillary vessel is jy^T) "^ *'^ 
 inch. 
 
 Tracing along the capillary network, the anatomist 
 discovers that these minute vessels are connected at their 
 other end \vith the veins ; or, to put it in another way, 
 after a time two capillaries of the network join together 
 and make one tube, somewhat larger than the two indi- 
 vidually were, and this larger one joins with another 
 similarly made by two capillaries to form a yet larger tube, 
 and so on, over and over again, till at last this process 
 
 ends in the two great veins of the body — the venae cavse, 
 which open into the right auricle (Plate XII. A, 4, 5). 
 
 Rising out of the right ventricle, another great tube 
 is discovered. Thi.s is ea.sily trace<l away from the heart 
 into the lungs (Plate XII. A, 8), and is therefore called 
 the ruhmnarii (i.e. lung) arlerij. It divides (not shown in 
 this- diagram) into a branch for each lung immediately it 
 leaves the heart, and within the lung each branch divides 
 and subdivides into capillaries, which are especially small 
 and close meshed. 
 
 The lung capillaries join to make veins, just as these 
 tiny vessels do elsewhere ; and finally four great veins come 
 out of the lungs (two from each), and enter into the left 
 auricle (Plate X. Fig. B, 5). These are the Pulmonary 
 veins. 
 
 Thus there is a complete round of pipes in the body, 
 with the heart as a centre. Ciradaiion literally means 
 going rovnd ; and the blood passes round the body to get 
 from the left ventricle (where the aoria rises) to tlie right 
 side of the heart ; and passes round through the lungs to 
 get from the right ventricle (where the pulmmiary artery 
 rises) to the left side of the heart, from whence it starts 
 oft" through the aorta again. The going round the whole 
 body is called the systemic or greater circulation ; that 
 through the lungs is the pulmonary or lesser circulation. 
 
 It will have been noticed that the vessels which take the 
 blood away from the heart are called arteries, while those 
 which biing bai'k the blood to the heart are called veins. 
 This is the proper distinction between arteries and veins : 
 all tubes which carry blood away from the heart are arteries, 
 all which bring blood to it are veins. 
 
 Besides these diff"erences in the structure of the tubes 
 and in their ofiice in relation to the heart, there is also a 
 difference in the blood which they carry. One point of 
 this diff"erence is visible at a glance. When blood is shed 
 from an artery, anywhere in the system, it is found to be 
 of a bright scarlet tint, whUe that which is drawn from a 
 vein is a very dark crimson. This change of hue is, how- 
 ever, only an outward and visible sign of important chem- 
 ical changes which closer examination discovers to have 
 taken place. 
 
 Now, since the blood goes always round in the circle of 
 arteries, capillaries, and veins, with the heart as a centre, 
 it is clear that the alteration in the blood which causes it 
 to be darker in the veins than in the arteries of the system, 
 must take place as it passes through the capillaries of the 
 system ; and, on the other hand, since the blood returns 
 to the right side of the heart through the ven;e cava; of a 
 dark tint, and leaves the left side of the heart again through 
 the aorta of a bright tint, it is equally clear that the lilood 
 is changed from the venous to the arterial condition in pass- 
 ing through the lungs. The full explanation of this cannot 
 be given until we have studied the lungs. But, mean- 
 while, it must be noted here that in consequence of the 
 venous blood being carried awaj' from the heart to be 
 changed in the lungs to arterial, the pulmonary arterj^, 
 with its branches within the lung, is the onlj- artery in the 
 body which carries dark blood, and conversely the pul- 
 monary veins are the onlv veins which carry bright blood 
 (Plate XII. A, 8, 9). In Plate X. Fig. B, the pulmonary 
 veins are shown injected with a blue preparation. 
 
 And now, having studied both the heart and the blood- 
 vessels of which it forms the centre, we may proceed to 
 briefl}- review the mechanism of 
 
 The Circulation of the Blood. 
 
 Let us begin at the left auricle, at the instant when the 
 heart is taking its momentary rest after its contraction — 
 i.e. between two lieats. In this brief pause, the blood 
 pours out of the four pulmonary veins into the left auricle. 
 
AN ATLAS OF ANATOMY. 
 
 The stimulus to the nuiscul.ir contraction of each part of 
 the heart is its becoming filled with blood ; as soon, there- 
 fore, as the auricle is filled from the pulmonary veins, it 
 suddenly and sharply contracts. That is to say, all its 
 sides become thicker and shorter. Now a moment's thought 
 shows us that the result of this must be that the size of 
 the cavity is greatly reduced ; the sides of the auricle must 
 draw nearly close together. The blood which filled the 
 space while the muscle was uncontracted must, therefore, 
 be pushed out when it contracts. There are two directions 
 in which it is possible for it to run— there are the mouths 
 of the veins by which it came in, and there is the auriculo- 
 ventricular aperture. But, of course, it goes where there 
 is least resistance, and that is through the aperture ; for 
 the ventricle is empty, waiting to receive it, while the pul- 
 monary veins are still full of blood pressing on to enter the 
 auricle. The contraction of the auricle, therefore, drives 
 the blood do^vn into the ventricle. 
 
 As the ventricle fills, the fluid gets behind the flaps of 
 the valves and floats them up, so that when the ventricle 
 is filled they just meet in the centre of the auriculo-ventri- 
 cular aperture and close it up. Thus, when the ventricle 
 contracts, as it does the moment it is full, the valve closes 
 the aperture, and the blood cannot run back into the auricle. 
 
 The flaps of the valve, you remember, are fastened to 
 muscular projections on the walls of the heart by tendinous 
 cords, which are just long enough to hold the valve in 
 place when the ventricle is quiescent. But when it con- 
 tracts, and the sides draw so near together as almost to 
 touch each other, it is clear that the tendinous cords 
 would naturally become slack, and permit the valve to be 
 pushed by the squeezing blood right through into the 
 auricfe. To prevent this is why the tendinous cords are 
 fastened to the projecting fleshy pillars ; these latter con- 
 tract at the same time as the sides of the ventricle, and 
 thus draw down the ends of the tendinous cords affixed to 
 them, just so far as is necessary to keep them " taut," and 
 to hold the edges of the valve firmly against the pressure 
 of the blood till the contraction ceases. 
 
 The blood being thus prevented from returning into the 
 auricle, is compelled to enter the aorta. The aorta is, of 
 course, already full of blood ; but the contraction of the 
 left ventricle is so strong, and the fresh portion of blood is 
 pumped out with such vigour bj' it, that the shock thrusts 
 the additional quantity of blood into the aorta, and so 
 throws along the whole of the blood in all the vessels. The 
 elastic coats of the arteries are distended by this sudden 
 push of the blood inside them ; and that distension makes 
 what we call the pulse. 
 
 So the impulse of the throw of the blood out of the left 
 ventricle into the aorta passes over all the arterie.';, and the 
 blood is thus driven along through them all, and into the 
 capillaries ; the blood already in the capillaries is pushed 
 onward into the veins, and so up through the veins the 
 blood presses toward the other side of the heart. 
 
 But the impulse given to the blood by the stroke of the 
 left ventricle becomes weakened before it reaches the veins, 
 by being diffused all over the multitude of capillaries. 
 This is the main reason why the veins are provided with 
 valves, while the arteries are not ; the valves being so 
 placed as to allow of movement of the blood toward the 
 heart, but to obstruct its running the other way. 
 
 There is enough force left, however, to push the blood 
 along the whole of the veins, and to thus drive a portion 
 of that which was in the venje cavse into the right auricle. 
 This at once contracts, and the portion of blood passes on 
 into the right ventricle, and so into the pulmonary artery, 
 and thus through the lung capillaries, and round into the 
 pulmonary veins to the left side of the heart once more. 
 And so the circulation continues unceasingly while life 
 lasts. 
 
 About a wine-glassful of blood is sent along by each con- 
 traction of the heart. 
 
 The two auricles contract at one instant, and the two 
 ventricles likewise together immediately after. On an 
 average, the whole process described above is gone through 
 70 to 80 times in each minute. The whole of the blood 
 in the body is thus passed through the heart in about the 
 course of each minute. 
 
 The Blood. 
 
 The fluid which is thus pumped into every tissue and 
 every corner of the organism is much more complex than 
 appears at first sight. The clotting of blood shows that it 
 consists of a fluid called jilasnui, and of a great number of 
 little bodies which float in the plasma, and are called the 
 corpuscles. The plasma may again be separated into twr) 
 parts — a fibrous material which forms itself into strings an<l 
 is c&WeAfih-'m, and a clear liquid called blood serum. The 
 corpuscles are of two kinds — the red and the white. 
 
 The white ones are the larger and the more numerous, 
 and they are remarkable because, in living blood, they are 
 in a continual state of internal amceba-lLke vital movement. 
 They are, in fact, tiny masses of living protoplasm. Each 
 colourless corpuscle contains a nucleus, and it is believed 
 by anatomists, though it is not yet certain, that the red 
 corpuscles are simply the nuclei of the white ones enlarged 
 and more fully developed. The white corpuscles them- 
 selves are probably to a large extent the immediate pro- 
 ducts of the digestion of food. 
 
 The red corpuscles are shown in Fig. F of Plate X. 
 Seen singly, they are of a pale yellow colour, but it is to 
 the presence of a vast number of them that the blood owes 
 its hue. The darker colour in the middle is simply the 
 effect of an optical peculiarity, which cannot be avoided in 
 looking through a microscope at so minute an object. The 
 corpuscle really is alike throughout every part of its sub- 
 stance. Each is about one three-thousandth of an inch 
 in diameter. 
 
 The plasma and the corpuscles together contain all the 
 elements of the body. The blood is like a carrier, bearing 
 to each organ of the body the supply of nutrition which it 
 needs, and bringing away from each organ the waste matter 
 that it requires to get rid of. Each tissue is bathed by the 
 blood as the blood passes through the exceedingly thin- 
 walled capillary vessels ; and each tissue then draws out of 
 the blood exactly what is required for its own life and 
 growth, and returns certain waste substances wliich the 
 blood carries away. 
 
 The difference in colour between the blood in the arteries 
 and that in the veins of the system is thus accounted for. 
 The arterial blood is going to supply the tissues with 
 nourishment; the venous blood is bringing away their 
 waste. 
 
 Part of that waste is passed out of the body through the 
 lungs, and so the blood is made bright and arterial once 
 
 The Lungs. 
 
 The exterior of the lungs is shown in Plate XI. Fig. A. 
 They are seen to lie one on either side of the heart, the 
 right lung being marked off' into three lobes, the left mto 
 only two. They are covered with fine serous membranes, 
 the pleurce ; and each pleura turns backwards at either of 
 its ends, so as to form a closed bag, the outer half of which 
 adheres to the wall of the ciicst, while the lung is wrapped 
 up in the inner half, and a little fluid is secreted in the 
 bag, just enough to keep it moist and allow of easy move- 
 ment. 
 
AN ATLAS OF ANATOMY. 
 
 For the internal stnicture of the lung we must turn to 
 the next plate (Plates XII. XIII.) Each lung is composed 
 mainly of three things — 
 
 1. Blood-vessels. 
 
 2. Air-vessels. 
 
 3. Elastic fibrous tissue, bindin" 
 
 the others together. 
 
 In Fig. A the left lung is dissected so as to show the 
 pulmonary arteries and veins, the capillaries connecting 
 them being, of course, too small for the naked eye to see ; 
 and the right lung is dissected so as to show the air-tuV)es 
 as far as possible. Like the blood-vessels, however, the 
 air-pipes continue diWding until their smallest twigs are 
 too minute to be examined with the naked eye. 
 
 The Windpipe or Trachea (2) is the stem from 
 ■which all the air-pipes branch out. The trachea divides 
 into two branches in the chest, and one of these goes into 
 each lung, and there divides and subdivides exactly as the 
 arteries do. The two first branches of the windpipe are 
 called the bronchi, and their subdivisions are the 
 bronchial tubes. 
 
 The bronchial tubes all end as shown in Fig. B. The 
 smallest tubes are very minute, and each one at its verj' 
 end spreads out into a small dilatation, not quite round, 
 but generally rather funnel-shaped. This dilatation is not 
 perfectl}" smooth, but, on the contrarv, its walls everywhere 
 pouch out, so as to show a great number of tin}' projections 
 when the bronchial tube is v-iewed from the outside, as it 
 is in Plates XII. XIII. Fig. B ; or of caverns when it is 
 cut open and v-iewed from the inside. These little recesses 
 are the air-cells. Of course all the air-cells of one group 
 communicate with the one central passage from which they 
 pouch out. Their walls are of exceedingly thin skin. Each 
 group of air-cells averages onl}' ^\r of an inch in diameter. 
 
 Figs. C and D of this Plate show the close relation 
 between the capillaries and the air-cells. Each cell is 
 covered with a xery close network of capillaries, which 
 completely surrounds it ; and generally, where the capil- 
 laries dip down between two air-cells, there is only one set 
 of the blood-vessels, so that they have air-cells on either 
 side of them. The coats of the pulmonary capillaries are 
 except ionall}" fine and delicate. 
 
 Respiration. 
 
 The air-cells just described are always full of air. The 
 act of respiration or breathing consists of a continual 
 drawing into the lungs of the air which surrounds us {i.e. 
 i)iS2>iration) and expelling it again [expiration). But every 
 breath only passes in and out of a certain portion of the 
 bronchial tubes ; the smaller tubes with the air-cells can 
 never be emptied by the most complete expiration. The 
 air which they contain in them is constantly renewed, 
 however, because with every breath some portion of the 
 fresh air remains in the lungs to mix by degrees with 
 the whole of the air that it finds there, while an equi- 
 valent quantity of the stale air comes out at the expiration. 
 
 Tims the blood in the capillaries of the lungs is con- 
 stantly in contact with air in the air-cells, the blood and the 
 air Ijeing only kept apart by the two very thin skins of 
 which the vessels and cells are made ; and the air is con- 
 stantly renewed b)' the act of breathing. 
 
 Now it is proved by direct experiment outside the body 
 that gases are not prevented from uniting with one another 
 by being enclosed in a thin moist skin. 
 
 Fresh air is composed mainl)- of three gases — Oxygen, 
 Nitrogen, and a very little Carbonic Acid. Thus there are 
 gases in the air-cells. There are likewise gases in the blood. 
 Gases can be united with fluids. Liquid ammonia, for 
 instauce, is merely ammonia gas in water : and the blood 
 in the bodv carries about gases mixed with it. 
 
 You will remember that it is in the lungs that the blood 
 becomes changed from dark venous to bright arterial 
 red. 
 
 That change in colour is merely a sign that the blood 
 has parted with some portion of one gas that it had in it, 
 and has taken up an equal quantity of another gas. 
 
 Various experiments, which I have not space now to 
 detail, show that the gas taken up by the blood out of the 
 air in the air-cells is Oxygen ; and the gas which tlie 
 blood passes out into the air-cells in exchange is Carbonic 
 Acid Gas. These gases are held in the red corpuscles, 
 and the effect upon them of being charged with oxygen is to 
 cause them to become lighter in tint, while the effect upon 
 them of being full of carbonic acid is to deepen their colour. 
 
 The carbonic acid passed out of the blood into the air- 
 cells mixes with the stationarj' air in the bronchial tubes, 
 in Uke manner that the oxygen does in the opposite 
 direction ; and so the waste gas presently gets into the 
 larger bronchial tubes, and through the windpipe out of the 
 mouth. 
 
 This is the explanation of the change from venous into 
 arterial blood in the lungs ; and as there will not be 
 another opportunity, I will here briefly refer to the 
 opposite change in the blood which takes place as it passes 
 through the capillaries of the system. 
 
 Oxygen is carried away from the lungs in the arterial 
 blood. The element Carbon is a part of every living tissue 
 of the body (see p. 1). As the great stream of the 
 blood flows through the systemic capillaries, the oxj-gen 
 passes out through the thin coats of the minute vessels, 
 and acts upon the carbon of the tissues, combining with 
 it : and the product of the combination of carbon and 
 oxygen is Carbonic Acid Gas. This is waste, like the 
 ashes from a fire, and has to be got rid of; and, therefore, 
 the blood flows on to the lungs, to pass away that gas, 
 and take in fresh oxigen. 
 
 ^^Tiy does this combination take place ? will be the im- 
 mediate question of every thoughtful reader. 
 
 In the first place, the Force of the human body is pro- 
 duced by the combining of the oxygen, which is taken 
 from the blood as it passes through the capillaries, with 
 the substance of the tissues : the chemical change which 
 then takes place making itself visible as force, and the 
 products of the change being waste matter. Part of this 
 waste is carbonic acid, produced by the oxidising of 
 carbon. 
 
 Secondly, our Animal Heat is produced by the uniting 
 of oxvgen with carbon and hydrogen. Such uniting is 
 the essence of combustion. When a candle or anj' other 
 substance burns outside the bodj-, it does so l>ecause the 
 carbon and hydrogen which it contains unite with the oxy- 
 gen of the aii\ This can be very easUj- proved by com- 
 pletely shutting off a small piece of lighted candle from 
 the air by turning a tumbler down over it ; the oxygen 
 in the small portion of air confined under the tumbler will 
 soon be used up, and then the candle will go out. Now, 
 as burning outside the body produces heat, so it does in- 
 side ; and the respiratory process in the body is chemically 
 identical with burning. But in the body, the burning is 
 very slow, and is also damp ; and thus, as with a smoulder- 
 ing fire, we do not have any flame, though we have heat 
 from tlie combustion. 
 
 The Mechanism of Breathing. 
 
 Eespiration is accomplished mainly by three several 
 powers, viz. — 
 
 0. The Diaphragm. 
 
 1. The Muscles of the Ribs. 
 
 c. The Elasticity of the Lung Tissue. 
 
AN ATLAS OF ANATOMY. 
 
 The Diaphragm is a great muscle which separates 
 the chest from the abdomen. The heart and lungs lie 
 above it, and all the other organs of the trunk beneath it ; 
 the great blood-vessels and the gullet pierce through its 
 substance. It is in the shape of an arch, with the con- 
 vexity turned upwards towards the chest, and the con- 
 cavity towards the abdomen. Its situation can be pretty 
 accurately judged from the outside by the ribs ; it arches 
 up just beneath the lowest true ribs (see Plates XII. XIII. 
 Fig. A, aud Plates XIV. XV. Fig. A, 1). 
 
 The pleurre, the covering membranes of the lungs, are 
 afBxed at their ends to the diaphragm. That great muscle 
 contracts continuously and regularly, as the breath is 
 drawn. It necessarily draws down in the centre when it 
 contracts — its arch becomes less — and the pleurte being 
 fastened to it, it drags them, and consequently the lungs, 
 down with it. A space is thus made in the bronchial 
 tubes, which the air rushes in to fill. Then the muscle 
 ceases contracting, and as it rises up to its former arched 
 shape, the lungs return to their unstretched condition and 
 the breath is pushed out. 
 
 The External Intercostal Muscles, which run 
 across from each rib to the one next to it, act by lifting 
 the ribs, and the breastbone to which they are fastened, 
 outwards. This increases the capacity of the chest from 
 before to behind ; and as the pleurae are fastened to the 
 chest wall, the bronchial tubes are stretched open by this 
 action, and the air enters the space. The Uiternal inter- 
 COStals run across in the reverse direction from that taken 
 by the external ones, and perform a directly opposite action, 
 so that they aid expiration. 
 
 The Elastic Tissue of the lungs, which binds 
 together the blood-vessels and air-cells, always assists 
 expiration, by its constant tendency to spring together 
 again, after it has been forcibly expanded by the action of 
 the diaphragm and the external intercostals. Thus it 
 presses on the bronchial tubes, and assists the internal 
 intercostals, the rising diaphragm, and the abdominal 
 muscles, in pushing air out of the lungs. 
 
 Now listen, as a conclusion to this part of the subject, 
 to the poet-anatomist's recapitulation of it. 
 
 "The .smooth, soft air, with pulse-like waves, 
 Flows murmuring through the hidden caves, 
 Whose streams of brightening purple rush 
 Fired with a new and livelier blush. 
 While all their burden of decay 
 The ebbing current steals away, 
 And red with Nature's flame they start 
 From the warm fountains of the heart. 
 
 " No rest that throbbing slave may ask. 
 For ever quivering o'er his task. 
 While far and wide a crimson jet 
 Leaps forth to fill the woven net. 
 Which in unnumbered crossing tides 
 The flood of burning life divides, 
 Then kindling each decaying part 
 Creeps back to find the throbbing heart." 
 (Dr. Olivek Wendell Holmes : '■ The Liviiig Temple") 
 
 Digestion. 
 
 Since the heat oPthe human body, and the force by 
 which it performs all its functions (both vital and voli- 
 tional) are produced by the using up of the tissues, it is 
 clear that those tissues must be continually reproduced ; 
 else the body would shortly be entirely burnt away, like a 
 fire when it is not replenished. 
 
 The fuel of the body is Food. The substances which 
 we use as food, whether animal or vegetable, are made of 
 the same elements as our own bodies are. Those substances 
 can, therefore, supply the needs of every tissue. To enable 
 
 them to reach the whole of the organism, food-substances 
 have first to be reduced into such a condition that they 
 can be taken up by the blood, and carried by it into every 
 part of the system. The preparation of food for its entry 
 into the blood is Digestion. 
 
 Plates XIV. XV. and XVI. show the principal organs 
 of digestion, which are — the Stomach, the Liver, tlie Pancreas, 
 and tlie Intestines. 
 
 The process of resolving the food into such a condition 
 that it can be taken into the blood really begins, however, 
 in the mouth. The Teeth, which are figured among the 
 bones of the body (Plate III. C), are the first in order of 
 action of the digestive organs. They receive the food be- 
 tween them, and tear and crush it into small particles. 
 People who have lost their teeth nearly always suffer from 
 indigestion, because the preparation of the food in the 
 mouth is insufficient, and the labour which ought to have 
 been performed by the teeth is thrown on the stomach. 
 
 While the teeth — acted upon by the powerful muscles 
 of the jaws— are crushing the food up, the Salivary 
 Glands are busily employed in pouring out upon it the 
 fluid which they separate from the blood — the Saliva. 
 These little bodies are six in number, and are arranged in 
 pairs, three on either side of the face. The Parotid pair 
 lie just under and in front of the ears (Plate XVII. E). 
 The other two pairs are smaller ; they are figured in con- 
 nection with the under side of the tongue on Plate XXI. 
 (B). The Suh-maxillarij Glands lie just underneath the lower 
 jawbone ; the Sub-linijaal Glands are under the tongue. 
 The saliva not only moistens the food, and enables the 
 tongue to form it into a compact bolus, but, in addition, 
 has an important chemical action, turning what starch 
 there may be in the food into sugar ; sugar being very 
 readily absorbed into the blood, while starch cannot be 
 taken up into it at all. 
 
 The tongue pushes the mass of food backwards, and it 
 passes between the tonsils (Plate XVIII. A, 30) under the 
 soft palate with its central flap the Uvula (22), which 
 protects the back openings of the nose. The food then 
 passes over a gristly lid, called the epiglottis, which guards 
 the top of the trachea by bending down so as to cover 
 that opening during the instant that the food is being 
 passed into the gullet, the opening of which lies immedi- 
 ately behind that of the wmd-pipe (33, 34-, 40). 
 
 The (Esophagus, or gullet, is a tube made of invo- 
 luntary muscular fibres. The stimulus to their action is 
 the coming against them of the small bolus of food. The 
 ring of muscle which the mouthful touches at once contracts 
 above it, and so pushes it down into the next portion, 
 which similarly contracts and sends it lower down, and so 
 on. This is called vermicular (i.e. worm-like) action, because 
 a worm moves by consecutive contractions of its whole 
 length in this manner. 
 
 Now we return to Plates XIV. XV., where the oeso- 
 phagus is seen to pierce through the diaphragm and enter 
 or merge into the stomach. 
 
 The Stomach is a muscular bag, covered outside by 
 the peritoneum (a membrane which invests all the abdo- 
 minal organs), and lined within by mucous membrane. In 
 Fig. A of this Plate (XIV. XV.), the stomach is shown in 
 the position which it occupies in the body ; the liver, how- 
 ever, which is here turned back upon itself to show how 
 the small intestine is joined to the stomach, is in its natural 
 position laid upon the stomach at that end. In Fig. B 
 the muscular coat of the stomach is shown ; and in Fig. C 
 the organ is laid open, and the mucous membrane is seen. 
 The Omenta shown in connection with this figure are simply 
 folds of the peritoneum by which the stomach is held in 
 position. 
 
 The Mucous Membrane of the stomach demands our atten- 
 tion. It is seen in this figure to be laid in folds ; but when 
 
10 
 
 AN ATLAS OF ANATOMY. 
 
 the stomach is distended with food the folds disappear, 
 stretching out to accommodate the demand for space. 
 
 All over the mucous membrane are seen the openings of 
 the Gastric Glands. These glands are tubes of membrane, 
 lined with epithelium, and covered outside by a fine capil- 
 lary network (Plate XVI. A 5). Sometimes they contain 
 a mass of nucleated cells in their lower part (4), and some- 
 times they are branched into two or more ends, ivith one 
 common opening (3). 
 
 When food enters the stomach, two immediate effects 
 are produced. 
 
 In the first place, the stomach at once receives an in- 
 creased blood-supply, so that the mucous membrane becomes 
 of a deep red colour ; and the glands above described hav- 
 ing dra^^ni from the blood which is circulating actively 
 through the capillaries around them a peculiar fluid, called 
 the gastric juice, pour it out, drop after drop, upon the food. 
 Secondly, the muscular fibres of the stomach are stimu- 
 lated to contract; and they do so in a manner which keeps 
 up a constant movement of the food along the organ, back- 
 wards and forwards, by which the gastric juice is enabled 
 to mix more thoroughly with the food, and also the digested 
 portions are brought against the orifice through which they 
 are to pass. 
 
 That orifice is at the opposite end of the stomach from 
 the opening of the oesophagus (see Plates XIV. XV. C, 2). 
 At that place muscular fibres pass circularly, so as to form 
 a ring around the orifice. The touch of a portion of undi- 
 gested food causes this ring to contract so tightly that no- 
 thing can pass through it ; and, for this reason, the ring 
 is called the j^ylorus (i.e. doorkeeper), and the opening which 
 it guards is named the pyloric orifice. 
 
 The Gastric Juice is the agent by which that dis- 
 solving of the food which commenced in the mouth is con- 
 tinued in the stomach. The gastric juice is a watery fluid, 
 white and thm, and acid to the taste. Chemical analysis 
 shows its two principal ingredients to be hydrochloric acid, 
 and a peculiar substance, not found elsewhere, to which 
 the name of j^fpsin has been given. This latter is probably 
 the principal agent in the digestive process. The efiect 
 which the gastric juice has upon the food is to dissolve it, 
 and to so far change the nature of some portions of it that 
 they become " diS'usible ;" that is, they will pass through 
 fine membranes. The portions of the food thus completely 
 digested are, probably, at once taken up into the blood, 
 passing through the coat of the stomach into the veins. 
 The remainder of the food is merely dissolved into smaller 
 particles, so that it forms a thick liquid ; and this, which 
 is called Chyme, passes out through the pylorus. If an 
 undissolved lump approaches the orifice, the pyloric ring 
 contracts and retains that in the stomach for further diges- 
 tion ; but no obstacle is ofiered to the passage through the 
 pylorus of the chyme. 
 
 \\Tien the food has passed through the pyloric orifice, it 
 is in the small intestine (Plates XIV. XV. A, c and 4). 
 The Intestines form one long tube, about 30 feet in 
 length in an adult person. The part nearest to the stomach 
 is much narrower than the opposite end ; hence, the first 
 portion is called the small intestine, the latter the larc/e 
 intestine. The small intestine is doubled backwards and 
 forwards many times, to get it into the space allotted to 
 it, which is that enclosed by the large intestine (Fig. A). 
 In this figure it is shown drawn out, to exhibit its length ; 
 the large intestine, however, is in its natural position. 
 
 For convenience of description, the small intestine has 
 been marked off' into three divisions, viz. — the duodenum (d), 
 the jejunum (e), and the ileum (f), but there are not any 
 important anatomical diff'erences between the three portions. 
 In like manner, the large intestine is divided into the ca'cum 
 (g), the colon (i, k, 1), and the rectum (n). 
 
 The internal structure of the small intestine is very note- 
 
 worthy. The first point that strikes the naked eye (Plate 
 XIV. XV. C, 8) is, that a short distance below the pylorus 
 the internal membrane of the duodenum is doubled up into 
 innumerable folds. These are most numerous and largest 
 in the part of the intestine here shown, just below the 
 common entrance of the bile and pancreatic ducts (9 and 
 10). They are called the ralvulm conniventce, and their 
 purpose appears to be to cause the food to move more 
 slowly. 
 
 Noting, before we pass on, the spot at which those tubes 
 enter through which the bile and the secretion of the 
 pancreas are passed on to the food, and leaving further 
 mention of the organs which secrete those fluids till 
 by and by, let us turn to the next plate. Fig. D, Plate 
 XVI., gives a diagrammatic view of the peculiar struc- 
 tures of the small intestines. This is a fine picture, and 
 merits looking at carefully, with the aid of the index. 
 The little depressions of the mucous membrane named Lie- 
 berkuhn's crypts secrete a thin fluid called the intestinal 
 juice, the action of which is not yet fully understood. The 
 Solitary Glands (13) are the same bodies as when gathered 
 in groups form what are called Peyers Patches (C, 2). The 
 exact use of these glands is not yet made out clearly. It 
 is thought that they exercise some influence upon the action 
 of the lymphatic vessels, and that they are similar in struc- 
 ture to the lymphatic glands of the rest of the body, of 
 which I shall presently proceed to speak. 
 
 But most interesting and important of all these details 
 of the minute structure of the small intestine are the Villi 
 (C, 1 ; and D, 7). The interior of the small intestine pre- 
 sents an appearance resembling the pile of velvet, so closely 
 are these little bags, or projections, set over it. In the 
 whole course of the intestine there are calculated to be 
 about four millions of them. Each villus contains inside 
 it an artery and a vein (D, 8), with their connecting capil- 
 lary network ; and also, enclosed by the blood-vessels, the 
 blind end or ends of a lymplmtic vessel (10). It will be 
 understood that each villus contains all three, although in 
 this diagram, for clearness' sake, they are severally shown. 
 
 Now, what is a lymphatic vessel ? 
 
 In almost every part of the body, and entering into 
 nearly every tissue, are found small and delicate tubes, 
 which contain an almost colourless fluid. These tiny ves- 
 sels begin blindly in the tissues, so far as is at present 
 made out. They join into one another frequently (or 
 anastomose, as the anatomists call it), but they do not by 
 this means form large trunks. Every here and there the 
 tubes enter small round bodies, which lie in their course, 
 and which are called the lymphatic glands. In those glands 
 the vessels divide and subdivide, and then ajjpear as one or 
 two tubes again on the opposite side of the gland. Finally, 
 all the IjTnphatic vessels end in two tubes, the thoracic duct, 
 which opens into the left subclavian vein (as shown at 
 Plate XI. A, 21, 23), and the hjmplmtic duct, which enters 
 the corresponding vein on the right side. These two veins 
 immediatelj- pour their contents into the supei'ior vena 
 cava, and so the fluid which enters them from the lympha- 
 tics is at once thrown into the heart, and so into the gene- 
 ral current of the blood. 
 
 The lymphatic vessels, taking the body as a whole, have 
 the office to perform of gathering up the excess, so to 
 speak, of the blood which the various tissues have drawn 
 out of the capillaries for their use. There is no doubt 
 whatever that the fluid portion of the blood passes out 
 through the capillaries to bathe the tissues, anil it is pos- 
 sible that the same happens to some extent witn the cor- 
 puscles themselves. Whatever cannot be used by the tis- 
 sues is gathered up by the lymphatics, and restored through 
 them to the general course of the circulation. 
 
 But those particular lymphatics which we have seen 
 beginning in the villi of the intestine do more than gather 
 
AN ATLAS OF ANATOMY. 
 
 11 
 
 up the overflow. Through them the new matter of tlie 
 digested food chiefly passes, to reach the blood, by which 
 it is carried around to form part of the tissues. 
 
 The lymphatics arising in the small intestine are called 
 Ladeals, which means milky, because of the milky appear- 
 ance of the fluid which they contain immediately after a 
 meal ; but they do not differ in any other resjject from the 
 other lymphatics. They pass away from the intestine, and 
 enter numerous lymphatic glands that lie in the midst of a 
 broad fold of the peritoneum which holds the small intes- 
 tines up to the back wall of the abdomen, and which is 
 called the Mesentery. After ramifying here, the lacteals 
 finally enter the thoracic duct at its lower part, and so 
 their contents pass through that duct to the heart. 
 
 The contents of the lacteals are the final products of the 
 digestion of the food. As the chyme passes over the com- 
 mon orifice of the bile and pancreatic ducts, it excites a gush 
 of fluid, which mixes with it, and continues the digestive 
 process upon it. The food is now called Chijle, and is passed 
 along the length of the intestine by movements similar to 
 those of the esophagus, already described. As it is thus 
 pushed along, the lymphatics of the villi draw it through 
 the membrane into themselves, and carry it away to the 
 thoracic duct. No doubt the capillaries which surround 
 the lacteals carry away some of the food ; but the fatty 
 matters especially are passed through into the lymphatic 
 roots themselves. 
 
 But all food has certain husks and fibres which cannot 
 be so dissolved, and which are useless as food ; and by the 
 time the chyle has passed through the length of the small 
 intestine, these waste matters alone, or almost alone, remain, 
 the whole of the good and useful parts of the chyle having 
 been absorbed by the lacteals. 
 
 Where the ileum joins into the csecum (Plates XIV. XV. 
 D) there is a valve which prevents the mass that has 
 once passed it from retrograding into the small intestine. 
 Attached to the csecum is a curious pipe-like appendix, 
 which is of no use in man, and seems to be only a relic 
 of the long caecum which is found in other mammals. 
 
 As the mass of digested food passes along the large 
 intestine, in which there are no villi, the veins in its coats 
 doubtless suck up any portions of useful matter that may 
 remain, and finally the waste remainder is expelled from 
 the body. 
 
 We must now return to the two organs which we have 
 already seen are part of the digestive apparatus, though not 
 in the course of the alimentary canal — viz. the Pancreas 
 and the Liver. 
 
 The Pancreas. 
 
 Plates XIV. XV. A, 9, show this viscus in its natural 
 position, with its duct joining with the common bile duct, and 
 immediately entering the duodenum. Sometimes, how- 
 ever, the pancreatic duct and the bile duct are found to 
 open into the duodenum separately, and this peculiarity is 
 shown in the figure of the pancreas laid open, on Plate 
 XVI. E. The fluid which the pancreas draws out of the 
 capillaries, and passes through its duct into the intestine, 
 is very similar to saliva. It appears to act mainly upon the 
 fats of the food. 
 
 The Liver 
 
 has a very complicated structure, and performs a very im- 
 portant work. It is the largest organ in the body, weigh- 
 ing about four pounds (50 to 60 ounces). It lies imme- 
 diately below the diaphragm, partly covering the stomach. 
 In Plates XIV. XV. it is shown partly turned up, so that 
 its under surface is seen. The liver is divided by five 
 fissures upon its under surface into as many portions of 
 unequal sizes, which are called its lobes. The smallest sub- 
 
 divisions of the liver are called lolmlcs, and each of these 
 is a many-sided body about the size of a mustard-seed. 
 
 Fig. B is a greatly magnified and diagrammatic section 
 of a portion of a lobule. The final branches of the j^ortal 
 vein (D) and of the hepatic artery (E) are seen to run round 
 the margin of the lobule, and to break up within it into a 
 multitude of capillaries, which themselves are seen in the 
 opposite corner of the picture (which would be really the 
 centre of the entire lobule) to unite into a central hepatic 
 or intT&-lobular win (F). The little bodies which crowd the 
 meshes of the capillaries are the liver-cells (H), and the lile- 
 duct (A), partly injected with a yellow preparation, is shown 
 mingling with the capillaries and surrounding the cells. 
 
 Now let us examine these various structures, which all 
 together make up the lobule — viz. Portal vein, Hepatic 
 vein, Hepatic duct, Hepatic artery, and Liver-cells. 
 
 Three of the four tubes just named enter the liver side 
 by side at a spot on its under surface called the porta, or 
 gate, of the liver. Hence the name given to one of the 
 three vessels, the portal vein. The portal vein is, as its 
 being called a veiti implies, formed by the joining together 
 of capillaries. The blood which is in it is that which has 
 circulated in the capillaries of the stomach, the spleen, 
 and the intestines. The other two vessels which enter 
 the liver at the same place as the portal vein are the 
 hepatic artery, which brings blood from the aorta to nourish 
 the substance of the liver, and the hepatic duct, which comes 
 from the gall-bladder (Plates XIV. XV. A, w). 
 
 These three tubes enter the liver side by side, and keep 
 together throughout their course. The portal vein, though 
 a true vein in that it is made by the joining together of 
 capillaries, and is conveying blood towards the heart, yet 
 behaves like an artery ; it divides and subdivides into 
 capillaries again. The hepatic artery of course divides 
 also, and the hepatic duct does the same, the three vessels 
 always accompanying one another, and dividing and sub- 
 dividing in the substance of the liver in canals made for 
 the purpose. Finally, a network of small portal veins 
 (Plates XVI. Figs. B, D) is made, which surrounds and 
 marks ofl' each lobule from the rest, and these veins are 
 called the inter-lohular veins {i.e. bctiveen the lobules). 
 From that surrounding network small veins enter tntlun 
 the lobule, and immediately break uji into capillaries. 
 The hepatic artery sends a branch into the lobule with 
 each of these veins, and the capillaries of the artery and 
 those of the vein inside the lobule join together, so that 
 the blood in the lobular capillaries is a mixture of that 
 brought in by both portal vein and hepatic arter}^ The 
 meshes of that network inside the lobule are filled with 
 the minute cells called hepatic cells (Plate XVI. Fig. B, 
 H). Thus the blood is in very close relation with the cells, 
 only the fine skin of the capillaries keeping them apart ; 
 and while the blood is slowly passing along the capillaries, 
 the cells draw out of it the peculiar constituents of the Bile. 
 
 Now, does the hepatic duct, which certainly accompanies 
 the portal vein and the artery so far as to the outside of 
 the lobules, also enter into the lobules with them % Upon 
 this point there is some difference of belief. It must be 
 remembered how very small the lobules each are (about 
 the size of a mustard-seed), and then the difficulty of 
 deciding the point with absolute certitude will be under- 
 stood. It is most probable, and is now generally held, that 
 what is shown in Fig. B of Plate XVI. is what really hap- 
 pens to it, viz. that it enters the lobule with the blood- 
 vessels, and there breaks up into a network much finer even 
 than the capillary one, generally enclosing only one or two 
 cells in each mesh. Thus the cells can readily discharge 
 the bile which they secrete, so that it passes through into 
 these tiny tubes. 
 
 Whether this is the exact method of their termination 
 or no, certainly the bile finds its way into the hepatic duct 
 
12 
 
 AN ATLAS OF ANATOMY. 
 
 at the exterior of the lobule, .and passes along that tube 
 until it comes to the outside of the liver, where it goes 
 domi and enters the common bile duct (Plate XIV. A, w), 
 and either at once passes into the intestine or goes up to 
 the gall-bladder to be stored till required. The secretion 
 of bile is continuous, but its discharge into the intestine 
 oidj' takes place while digestion proceeds. 
 
 Now we must return to Plate XVI. Fig. B, to see what 
 becomes of the blood that is poured into the capOlaries 
 within the lobule. In the very centre of each lobule is a 
 small vein (F), which is called the irAvSu-lohular vein, and 
 which is really the smallest branch of the venous system 
 that gathers up the liver capillaries. The tiny vessels in 
 the lobule all ramify towards this central vein, and pour 
 their contents into it. This veinlet passes out of the 
 middle of the lobule into a somewhat larger hepatic vein ; 
 and several of those join to make yet larger tubes, and so on 
 over and over again, as veins always do, until at last all the 
 blood is carried to four great hepatic veins, which open into 
 the vena cava inferior, and so convey the blood to the heart. 
 
 Besides secreting bile, the Uver-cells act upon certain 
 constituents of the blood, and turn them into sugar, but 
 this process is very complicated, and not yet fully under- 
 stood. 
 
 The Excretory Organs. 
 
 Throughout the last few pages the term " Secretion " has 
 been repeatedly used, and it would be gathered by the 
 reader that the meaning of this word was the separating of 
 some substance from the blood. Excretion is an analogous 
 process, with the difference that an excretion is cast out of 
 the body as waste, while a secretion is used again for some 
 physiological purpose. Thus, bile and pancreatic juice are 
 secretions, while perspiration and carbonic acid gas are 
 excretions. 
 
 All organs which either secrete or excrete receive the 
 generic name of Glands ; and all glands have one funda- 
 mental structure. They consist essentially of a simple 
 membrane with epithelial cells on one side of it and blood- 
 vessels on the other. The epithelial cells are the active 
 agents in the work ; they draw the peculiar secretion out 
 of the capillaries, which are on the opposite side of the 
 basement membrane which they cover. How they do this 
 in any given case is a vital mystery : the cells are to all 
 appearance identical in every situation, yet the cells of a 
 sweat gland never produce saliva, the cells of the salivary 
 glands never secrete bile, etc., but everywhere the cells pro- 
 duce the proper secretion of the gland in which they are 
 found. 
 
 We have already seen that glands vary greatly in form 
 and in respect of the complexity of their structure, from 
 the simple depressions of the membrane in the intestine to 
 the elaborate arrangement of the liver-cells in their lobules. 
 But however wide the apparent differences, careful exami- 
 nation shows the elementarj' structure just described to be 
 always present. 
 
 The Excretions of the body are those waste matters 
 which are produced by the chemical changes of the tissues. 
 They are finally, when they leave the body, reduced to 
 three principal forms, viz. TVater, Carbonic Acid, and Urea. 
 The first-named is the product of mixing together oxygen 
 and hydrogen, the second of oxygen and carbon, and the 
 third of oxygen and nitrogen ; so that the principal ele- 
 ments of the tissues, which are also necessarily the principal 
 elements of our foods, after producing force and heat by 
 their chemical change within our bodies, are thus cast out 
 in those changed forms, and are thrown away like the soot 
 and the ashes of a fire, ilinute quantities of the other 
 elements of the body are also passed away as excretions, 
 but of course the quantity of these in the sweat and in the 
 urine is proportionately small compared to the matters 
 
 above named, just as is their quantity in the body compared 
 to that of the oxygen, nitrogen, carbon, and h3'drogen. 
 
 The Excretory Organs are the Lunfjs, which we 
 have already studied, and wliieh we know to pass away 
 much carbonic acid with a little water ; the Kidni'ijs, which 
 pass away most urea, ^vith a good deal of water ; and the 
 Skin, whicli gets rid of a considerable quantity of all three 
 waste products. 
 
 The Kidneys. 
 
 Plate XVII. is entu'ely devoted to showing the structure 
 of the kidney, with the exception of one figure of the parotid 
 gland (E). In Fig. A the kidney is drawn in its natural 
 position, with its external capsule partly turned back to 
 show bow the blood-vessels enter. The blood is seen to 
 go into the kidney direct from the aorta. In Fig. B a 
 section through the midst of the organ is shown. 
 
 At a glance, it is seen that the interior of the kidney 
 may be divided into two parts, one much firmer in texture 
 than the other. The external hard portion is called the 
 ciirtcx (bark), and the internal softer portion the medulla 
 (marrow) of the kidnej". The microscope shows the reason 
 for this diflerence in the naked-eye appearance : the cortex 
 contains in its substance a great number of tiny round 
 bodies, the medulla consists almost wholly of a multitude 
 of fine tubes, which run (14) towards the concave part of 
 the kidney, gathering into bundles as they approach there 
 in such a fashion as to form pyramids. The pjTamids end 
 by a small nipple-like projection into the central open space 
 of the kidney, each projection being called a papilla. (13), 
 and each one of tliem having the orifices of about a thousand 
 tubes upon its summit. 
 
 The tubes which open upon the papUlffi are the true 
 secreting apparatus of the kidney : they are called the 
 uriniferous tubules, and are lined throughout (D, 2, 4) with 
 secreting epithelial cells. Fig. C traces diagrammatically 
 the course of a single tubule backwards from the spot 
 where it (7) opens on the papilla. The tubule is seen to 
 branch out, and to become continuous with a number of 
 iuterlooped and convoluted smaller tubules, which in their 
 turn finally end in (4) somewhat enlarged tubes in the 
 cortical part of the kidney. At the end of each of these 
 larger tubes there is a dilatation (see D, 2) of the tube 
 into a round body, called the Malpigliian capsule, shown 
 in Fig. C, 2. Into that capsule an artery penetrates. This 
 arrangement wUl be better understood by turning to Fig. 
 D, which is a verj^ greatly enlarged representation of the 
 terminal tubules and the blood-vessels within them. The 
 convoluted tubule is seen to become wider, and to spread 
 out into the ^lalpighian capsule, into which enters a branch 
 of (1) the renal arterij (the arterj' which we saw in A, 7, 
 entering the kidney), and immediately within the capsule 
 divides and subdivides into a multitude of capillaries, form- 
 ing a tuft which is called a glomeridus. The blood passing 
 through these is in immediate relationship with the cells, 
 and here a portion of the excretion which the kidneys 
 separate, the urine, is drawn out. But as though this could 
 not do the whole work, a very peculiar arrangement of the 
 blood-vessels and tubules is made, so that after the blood 
 has passed through the glomeruli it is again submitted in 
 capOlaries to the action of cells. The capillaries in the 
 Malpighian capsule join together and make a small vein, 
 which issues from the capsule near where the artery enters ; 
 but instead of joining with other similar vessels to make 
 one larger tube, as veins commonly do, this little vein again 
 breaks up into a number of capillaries which completely 
 surround the uriniferous tubules in the cortex (C, 2). and 
 onl3" after thus a second time passing through capillaries can 
 the blood reach the small renal vein (C, 3) bj- the joinings 
 and communications of which it is carried out, through the 
 principal renal vein (A, 10) and into the vena cava inferior 
 
A^'^ ATLAS OF AXATOMV 
 
 13 
 
 (A, 9). There is no doubt that the secretion of the urine 
 takes place from the second set of capillaries, and by the 
 tubules, as well as from the glomeruli. 
 
 The fluid thus secreted consists mainly of water and 
 urea, the waste product of the using up of nitrogen in the 
 tissues. It contains, also, small quantities of several salts, 
 which, like the urea, are dissolved in the water. 
 
 The fluid passes down tlie minute uriniferous tubes by 
 which it is secreted from the blood, and out at the openings 
 of the pyramids on the papillie. The papilla; project into a 
 space of considerable size, called thepcfcw, or basin of the kid- 
 ney (B, 17), which is divided into parts called calices, for the 
 reception of the tips of the pyramids (B, 12). The pelvis 
 is continnous in each kidney \\\i\\ a tube, the ureter (A, 5, 
 B, 5), which runs down and opens into a bag of muscle and 
 skin that lies in the bony pelvis, just above the os pubis, 
 and serves as a receptacle for the urine. This is the 
 urinary bladder ; and from it the excretion of the kidneys 
 is passed out of the body through the urethra. Thus the 
 uriniferous tubules are indirectly in communication with 
 the outside of the body. 
 
 Ductless Glands. 
 
 One of the ductless glands being shown in Fig. A, this 
 appears the best place for saying a few words about those 
 bodies. The ductless glands comprise the Spleen (Plates 
 XIV. XV. Fig. A, 7), the Thymus and the Thyroid 
 glands (Plate XI. A, 3 and .5), and the Supra-renal 
 Capsules (Plate XVII. A, 4). These bodies are all alike 
 in one respect, viz. that they receive a full blood-supply, 
 and yet have no ducts through which any secretion is 
 passed out of them. ^^Tiatever change they work in the 
 blood, therefore, they return at once to the blood itself 
 It is thought that they are probably manufactories, so 
 to speak, of the blood-corpuscles ; and this theory is 
 strengthened by the fact that the thymus gland is active 
 and large during childhood while the body is growing, but 
 wastes away and becomes quiescent when the body is fully 
 developed. Xo certainty has yet been reached upon this 
 point, however. 
 
 The Skin 
 
 performs two functions ; it is both the seat of the organ of 
 touch and a part of the excretory apparatus. It is figured 
 among the organs of sense, but it wUl be more convenient 
 to briefly consider it now. 
 
 Plate XXI. Fig. E, is a diagram to show the various 
 structures which are to be found in the skin. These are 
 not, of course, found consecutively in every part of the skin ; 
 it is a diagram, not a section from one particular place. 
 
 The skin can be divided, anatomically, into two layers : 
 the dermis, or true skin, beneath ; the ejiidermis, or cuticle, 
 externally. Each of these, again, is readily divisible into two 
 portions. The epidermis consists of a lower layer of soft 
 cells (2) somewhat rounded in form, which have just been 
 born from the blood, as cells are reproduced (see p. 2) ; and 
 an upper layer, consisting of similar but older cells, which 
 have been pushed upwards by the constant growth beneath 
 of the new cells, and have become harder and flatter as they 
 neared the surface (1). The dermis consists of a narrow 
 upper layer of fibres in which the nerves of the skin are 
 distributed, and a lower layer of fibrous tissue fibres, not 
 well seen in the diagram, which intertwine so as to make 
 a sort of a network. 
 
 The uppermost layer of the dermis (3) is called the 
 jmpiUarii layer, because it is elevated into minute cone- 
 shaped eminences, the papiUce., which contain the ends of 
 nerve-fibres, and also one or more capillary loops. "Wliere 
 the sense of touch is weak, the papillse are small, and com- 
 paratively few in number ; where the sense is very acute, 
 
 D 
 
 they are both numerous and large, and in addition contain 
 within them curious bodies, shaped something like a fir-cone, 
 upon which the nerves end, in the manner shown in Fig. 
 F of Plate XXI. These are the tadile-corptiscles. This 
 layer of the dermis, therefore, is the one which contains 
 the sense of touch. The whole epidermic layer appears de- 
 voted merely to preserving the more sensitive parts beneath 
 it from pain and injury ; and the secreting apparatus must 
 be looked for in the lower part of the dermis. 
 
 There we note first the sebacsous, or oil glands 
 (8), which are found very sparingly in most parts of the 
 skin, and are usually connected with the hair-ducts, or 
 placed around the joints. Lower down, embedded in fat, 
 are seen the coils of fine membrane which constitute the 
 S"weat glands (G), with their ducts running up to the 
 surface of the skin, and opening upon the exterior (7). The 
 membrane which is thus coiled round to form the gland is 
 a true secreting membrane, being lined inside by cells ; and 
 each coil is surrounded by a network of capillaries, not 
 shown in the diagram, from the blood within which the cells 
 draw the secretion — the sweat ov pcrspiratinn. There are cal- 
 ctdated to be about three million sweat glands in the body. 
 In the palm of the band there have been ascertained to be 
 as many as three thousand of these openings on a square 
 inch of skin. 
 
 Sweat is constantly secreted by the glands, and evapo- 
 rates from the skin insensibly ; it is only when the quantity 
 is increased beyond the ordinary amount that it foi-ms drops, 
 and that we become sensible of it. Perspiration, like the 
 kidney and the lung excretions, contains, and passes out of 
 the body, water, carbonic acid, and urea, and small quan- 
 tities of various waste salts. 
 
 The Nervous System. 
 
 AVe have already seen that various muscular movements 
 of the body are executed at the command of the will ; and 
 we have just noted that the skin contains a provision for 
 sensation. We are now naturally led to enquire into the 
 mechanism of will and of sensation. 
 
 The Nervous System is composed of a multitude 
 of fine cords, found in every part of the body — the Nerves ; 
 and of central parts to which those cords lead. The cen- 
 tral portions are two — the Cerebro-Spinal Nervous 
 
 Centl'e, which consists of tlic hniin and tlie fpiii/il curd; 
 
 and the Ssonpathetic Nervous Centre, which is 
 composed of two rows of lumps (called (janglia) of nervous 
 matter, joined into chains by cords which run from one to 
 another, and lying along each side of the backbone. 
 
 Nerve-Matter, of which both nerves and nerve-centres 
 are composed, is a delicate soft tissue, of which there are 
 two kinds — grey and u'hite. The distinction in the oflSce 
 of these is not clearly made out ; but the grey appears to 
 be the more highly organised, inasmuch as in the brains of 
 the most intellectual persons there appears to be a greater 
 cpiantity of it than in those of less gifted ones ; and, more- 
 over, the grey is found only in the nerve-centres, whUe 
 the white alone makes the nerv'es, and mingles with the 
 grey in the centres. 
 
 Close microscopic exammation shows that the grey 
 matter is chiefly made up of cells, while the white matter 
 is formed of fibres. The nerve cells have various shapes ; 
 very frequently they are star-shaped, sometimes they are 
 oval. They always contain a nucleus. The nerve-fibres, 
 the constituents of the white matter, separate soon after 
 death into two parts ; a white substance, supposed to be a 
 fluid fatty matter, surrounding and protecting a delicate 
 firm interior, which is belie\'ed to be the essential part of 
 the nerve. This latter is called the axis-cylinder ; the fatty 
 protection is the ivhite substance of Schwann. The two parts 
 are enclosed within a fine membrane, called the tubular 
 
1-4 
 
 AiV ATLAS OF AXATOMT 
 
 sheath. These three parts make up a nerve-fibre. Of 
 course the nerves generallj-, like muscles, are composed of 
 bundles of these primitive fibres. Fig. D, 2, of Plates 
 XIX. XX. represents an appearance often seen in nerve- 
 fibres, from the tendencj' of the white substance on the 
 least pressure to run together, while the delicate tubular 
 sheath sinks in. 
 
 The chemkal analysis of nerve-matter shows that it is com- 
 posed of water (85 parts in a hundred), albumen, fat, and 
 salts. Phosphorus is the salt which is present in the largest 
 quantity, there being about one part of it in a hun<lred 
 parts of nerve-matter. Indeed, phosphorus appears to be 
 distinctlj- connected with nervous action, since increased 
 exercise of the brain adds to the quantity of waste phos- 
 phrirus jiassed away by the kidneys. 
 
 The Ssmipathetic nervous system is of less impor- 
 tance than the cerebro-spinal. It must not be supposed 
 that there is a complete distinction between the sympa- 
 thetic and cerebro-spinal systems ; on the contrary, some 
 of the fibres which take their rise in the sympathetic 
 ganglia running down on either side of the spine, pass into 
 the spinal nerves, and are distributed with them ; while, 
 on the other hand, the sympathetic nerves generally con- 
 tain some fibres supplied by the cerebro-spinal system. 
 Notwithstanding this, however, the s3-mpathetic nerves are 
 liroadly distinct from the others, and have their special 
 office to perform. They control or influence the functions 
 of the vital organs. These organs, as we have already 
 seen, are quite outside the control of the will, and yet 
 are governed by the nervous system ; for they act when 
 a certain stimulus is applied to them, and are quiescent 
 when the stimulus is absent. This unconscious watchful- 
 ness is the work of the ganglionic centres. That they are 
 to a considerable extent independent of the cerebro-spinal 
 centre is shown by the fact that the organs supplied by 
 them will continue their normal motion for some time after 
 being severed from the bodJ^ The sympathetic nerves 
 also send filaments to the coats of the blood-vessels, regu- 
 lating the degree of their contraction, and so determining 
 the blood-fupply of any part. 
 
 The Cerebro-spinal System is by far the more 
 important. It is composed of the Brain, which is the seat 
 of Consciousness, — thought, emotion, sensation, and will ; of 
 the spinal cord, which controls and directs many of those 
 motions which seem to be voluntary, but are half automatic; 
 and of the nerves of sensation and of motion, which go to 
 and from the various organs of the senses, the muscles, 
 and the skin. We will briefly view the cerebro-spinal 
 system in each of these parts. 
 
 The Brain, 
 
 . . " The cloveu sphere th.at holds 
 All thought in its mysterious folds, 
 That feels sensation's faintest thrill 
 And flashes forth the sovereign will," 
 
 is enclosed within the cavity of the skull. Plate XVIII. 
 Fig. A, shows the brain in its natural position, but cut 
 longitudinally, exactly through its centre. The great top 
 mass (1, 2, 3) is the principal part of the brain, the Cerebrum. 
 In the cerebrum the grey matter is external to the white, 
 and is doubled up into a great number of folds, or con- 
 volutions, which are seen better in the next Plates, XIX. 
 XX. Fig. A- The effect of this is to increa.se the surface 
 of grey matter ; and it is a noteworthy fact that as animals 
 descend in the scale of intelligence their brains contain 
 fewer and fewer convolutions, while men of exceptional 
 ability have been found, by post-mortem examination, to 
 possess brains remarkable for the numerous convolutions, 
 and for the depth of the intervals between the folds, the 
 sulci. The cerebrum is divided nearly into two halves by 
 
 a central longitudinal fissure ; in Plate XVIII. A, the cut 
 has been made through the direct centre, so that the knife 
 has passed down the fissure without cutting into the con- 
 volutions. They can be seen cut through on Plate XXII. 
 Fig. A. The bridge of white matter at the bottom of the 
 fissure by which the two halves of the cerebrum are joined 
 together is seen cut through (4, cwpus callosum). Each 
 half of the cerebrum is further marked off into three lohes, 
 by fissures extending some distance down into its centre. 
 
 Beneath the cerebral lobes and the corpus callosum are 
 various layers and masses of nerve substance, to each of 
 which a distinct name has been given. The student who 
 wishes to master these minute details must do so by refer- 
 ring from one to another of the following figures : — Plate 
 XVIII. A ; Plates XIX. XX. A ; Plate XXII. A. In 
 one of these figures the structures are shown in a longi- 
 tudinal section, in another in a transverse and vertical 
 section, and iu the other the brain is exhibited as removed 
 from the skull and turned upside down, wthout any dis- 
 secting away. By careful study, with the aid of the index, 
 these three plates will serve to make the relationship of 
 the parts quite clear. 
 
 The spinal cord is seen to run up into the brain, widen- 
 ing out at its upper end into (Plates XVIII. and XIX. 
 XX. 12) a broad jiortion of nervous matter called the 
 medulla oblongata. The medulla is about an inch and a 
 quarter long. It contains a central canity — it is hollow, 
 to put the matter more simply — and that cavit}- is called 
 the fourth ventricle of the brain. The medulla is divided 
 by central grooves into two halves, and each half is again 
 marked off into four columns ; the one nearest the front 
 being called the anterior pijramid, the next the olivary body, 
 the next the restiform body, and the one next to the back 
 groove the posterityr pyramid (Plates XIX. XX. A, 21). 
 
 Immediately above the medulla is the pons Varolii, or 
 biidge of Varolius (11), so called because it connects toge- 
 ther the medulla, the cerebellum, and the cerebrum. It 
 contains both transverse and longitudinal fibres. The 
 transverse fibres enter the pons from the cerebellum, from 
 either side of which they sweep across the top of the me- 
 dulla (XIX. XX. 11), and so form a bridge from the one 
 to the other half of the cerebellum. The longitudinal 
 fibres enter into the substance of the pons from the medulla 
 itself ; and from the pons those fibres go on their way to 
 the cerebral hemispheres. 
 
 In front of and above the pons again appear two thick 
 bundles of nervous fibres, the crura cerebri, which on close 
 examination are seen to be the longitudinal fibres that have 
 passed through the pons. These bundles spread out as they 
 pass forwards (Plates XIX. XX., the dark diverging portion 
 between the III. and IV. nerves), and then enter into the 
 under part of the cerebral hemispheres, some distance 
 below (as Plate XVIII. 1 0, shows) the level of the corpus 
 callosum. The fibres pass through what are sometimes 
 called the ganglia of the brain — two large masses of grey 
 matter named respectively the optl: thalami and the corpora 
 striata. 
 
 The figure 9 iu the plate just referred to is intended to 
 indicate the narrow passage close to the left of which it is 
 placed. That passage, the aquedud of Sylvius, runs from 
 the fourth ventricle in the medulla up to the much larger 
 third ventri'-le in which the figure 5 is placed. This figure 
 stands on one of the two masses of nervous matter into 
 which the fibres from the crura cerebri first pass, and which 
 are named the optic thalami. Of course the other optic 
 thalamus has been cut off with the half of the brain which 
 is entirely removed in this figure. When they are both in 
 their natural positit)n, however, there is a space between 
 these two thalami, and that space is called the third ven- 
 tricle, (Consult Plate XXII. A, 11.) 
 
 The plaited appearance just above the figure 5 is the 
 
AN ATLAS OF ANATOMY. 
 
 If) 
 
 choroid plexus ; while just beneath and in front of it is the 
 corpus striatum, And below the curious little projection called 
 the pituitary body (7). 
 
 The fornix (6) is a longitudinal portion of white matter, 
 which forms the foundation, as it were, for the corpus cal- 
 losuni, and also, in part, serves as a floor for the largest 
 of the ventricles of the brain — the lateral ventricles. 
 
 These spaces (the lateral ventricles) extend right into 
 the cerebral hcmispheies. A portion of one is seen in the 
 figure before us — the triangular opening beneath the corpus 
 callosum, and close beside the figure 6. The third ventricle 
 opens by a narrow aperture at either end of its anterior 
 bounding membrane into the lateral ventricles. Thus we 
 see that all these spaces communicate with one another, 
 just as, by the passing of fibres from one part to another, 
 the whole brain substance communicates. In fact, no por- 
 tion of the entire nervous system, of whatever structure 
 or office, stands by itself; all the parts are joined into 
 one great whole. The importance of this is seen at once 
 when the office of the nervous system is understood. 
 
 Twelve pairs of nerves arise out of the brain at its base, 
 and, passing out of the skull through foramina (windows) 
 provided for the purpose (XIX. XX. C), go to various 
 parts of the body. Their names and functions I have given 
 in the index, and they need not all be repeated here. One 
 or two points only must be remarked upon. 
 
 It will be seen that the nerves of smell (I) are the most 
 intimately connected with the cerebral hemispheres. The 
 next pair of nerves, the ojitic, arise back in the optic 
 thalami, and pass forward in the direction shown in Plates 
 XIX. XX. (being so far called the optic tract), until at (10) 
 tlie fibres from each side meet and cross over. This junc- 
 tion is the ojjtic chiasma or commissure. This remarkable 
 crossing of the nerve fibres, doubtless, has something to do 
 with our seeing only one object, though we look at a thing 
 with two eyes. All the other nerves except these two arise, 
 dii'ectly or indirectly, out of the medulla. The spinal acces- 
 sory is the only one needing a word of special notice ; it 
 arises in a very remarkable manner (XI.) Its roots origin- 
 ate in the spinal cord, at the side of the spinal nerves, 
 even as low down as the sixth cervical nerve (Ij. II,. Illg.) 
 Passing upwards and joining, the fibres enter the skull, and 
 emerge from it again by the same foramen as the pneumo- 
 gastric (XIX. XX. C, X. XL) 
 
 The Cerebellum, 
 
 or little brain, lies at the liack of the skull, completely 
 overhung by the posterior lobes of the cerebrum, and itself 
 partly overhanging the medulla, but extending also quite 
 into the back of the skull behind the medulla. It, like the 
 cerebrum, is divided by a deep fissure into two hemispheres. 
 It is not convoluted, but is marked by numerous curved 
 lines upon its outer surface. The grey matter is external 
 to the white, as in the cerebrum ; and the white is so 
 curiously arranged within the grey as to give an appearance 
 like a branching tree when the cerebellum is cut through 
 (XVIII. 13). This arrangement is hence called the arhor 
 vitic (tree of life). 
 
 The Spinal Cord, 
 
 which runs down from the brain through the centre of the 
 vertebral column, contains both grey and white matter, but 
 arranged in precisely the opposite manner from that of 
 the cerebrum and cerebellum. In the cord the white 
 matter is external, and the grey is inside arranged like two 
 half-moons with their backs turned toward each other. 
 A narrow canal, called the central caned, runs right through 
 the centre of the cord, and is continuous with the fourth 
 ventricle. 
 
 Thirty-one pairs of Spinal Nerves arise from the 
 spinal cord (XIX. XX. — 1. to XXXI.) by a number of deli- 
 cate filaments down each half of the cord. These roots 
 join into bundles, which coalesce into the trunk of a nerve. 
 The nerve passes out of the backbone through a space left 
 for it between the vertebra; (the intervertebral foramen), 
 and passing onwards in its proper direction divides and sub- 
 divides into a multitude of fine filaments, which supply the 
 skin and the muscles of every part of the body except those 
 supplied liy the cranial nervfs. 
 
 Protecting Membranes cover both brain and 
 spinal cord. The external one is close to the bone, and is 
 called the dura mater (Plates XIX. XX. A, 15). The 
 next beneath is a fine membrane, which is reflected on 
 itself like the pleura and the pericardium ; this is the 
 arachnoid (16). Finally, a delicate membrane called the 
 pia mater envelopes the brain and cord closely (17). 
 
 Functions of the Nervous System. 
 
 When the trunk of a nerve is cut or otherwise injured 
 immediately after its issue from the spinal column, two 
 results invariably are found to follow. The part to which 
 the filaments of that nerve go, becomes incapable of feeling, 
 and cannot be moved by the will. From this fact we learn 
 that the nerves are simply like telegraph wires ; they con- 
 vey messages to and from the nervous centres, but they 
 themselves, by themselves, have no more sensation or will 
 than any other structure has. The nerves which convej' 
 the message of sensation from their terminations to the 
 nerve centres, can be distinguished from those which carrj' 
 the message of command for movement back to the place 
 where the terminations are. The former are called sensory, 
 the latter moim- nerves. 
 
 Consciousness — under which general name we include 
 sensation, will, emotion, and thought — resides in the cere- 
 bral hemispheres. This we know, firstly, because any injury 
 which crushes the spine so as to disorganise it places all 
 those parts which are supplied by nerves from below the 
 seat of the injury outside the control of the will, and 
 deprives them of sensation. Thus when the lower part of 
 the spine is so injured that messages cannot pass along it 
 from the nerves supplying the lower limbs, not only is the 
 patient unable to move his legs and feet by his will, but 
 also he does not feel if they are cut or burnt. Moreover, 
 when the cerebral hemispheres are themselves injured, 
 intelligence and volition are lessened or altogether lost. 
 
 The cerebeJhim appears to order the combined movements 
 which we often perform, not quite automatically but also 
 hardly consciously. Its functions, however, as well as 
 those of the neighbouring parts of the brain, are very im- 
 perfectly understood at present. 
 
 Nervous Force, by which messages i^ass along the 
 nerves, is, like most other similar existing facts of nature, 
 ultimately a mystery. It is very likely somewhat related 
 to electricity, but it is not the same thing, and rapidly 
 though messages appear to fly from the peripheral termi- 
 nations of the nerves to the centres and back again, yet 
 nerve-force is found to be considerably less rapid in its 
 movement than electricity. 
 
 The Organs of Sense. 
 
 All the nerves, both cranial and spinal, terminate in 
 innumerable spread-out fibres, which form what are termed 
 the peripheral extremities of the nerves. The sensory nerves 
 generally are so arranged that they receive impressions 
 from the outer world, and the peculiar structures in which 
 their peripheral extremities are found are called the organs 
 
16 
 
 ^.V ATLAS OF AXATOMY. 
 
 of the senses. Each sense has its own special organ. Xo 
 diflferences, or at most very slight ones, can be discovered 
 in the nerves of the various sense-organs ; but the arrange- 
 ments in the midst of which their terminations are placed 
 are different in each organ, and no one sense-organ ever did 
 the work proper and peculiar to another. 
 
 We will proceed briefly to study the sense-organs in the 
 order in which they are figured upon the plates; by so 
 doing we consider first the simpler structures of the nose, 
 the tongue, and the skin, and reserve the very elaborate 
 and interesting details of the ear and the eye for our final 
 subject. 
 
 The Organ of Smell. 
 
 The ethmoid bone, which is situated at the top of the 
 nose between the two eyes, has its lower surface next to 
 the nose perforated with a number of holes like a sieve. 
 The bulbs of the olfactory nerve run on to the cribriform 
 plate, as this piece of bone is called, and then divide up 
 into tiny filaments, which penetrate through the holes into 
 the nose (Plates XIX. XX. Fig. E, 7, 8). The filaments 
 then spread out in a certain part of the mucous membrane 
 which covers the internal cavities of the nose. In this 
 mucous membrane also a German observer has lately dis- 
 covered the peculiar rod-shaped filaments attached to cells 
 which are figured below (Fig. J). The filaments of the 
 olfactory nerve do not, however, extend through the whole 
 of the mucous membrane. The fifth nerve also enters the 
 nose (E, 9 and 15), and its filaments are distributed to the 
 lower part of the nasal cavities. 
 
 The septum, which divides the nostrils below, is continu- 
 ous through the nose up to its root at the brow. But, 
 beside the two cavities thus made, the peculiar shape-of the 
 bones which form the sides of the nose (within the cheek, 
 as it were) separates it into somewhat elaborate passages. 
 These may be studied in section in Fig. H. The olfactory 
 nerve, as Fig. E shows, only descends upon the uppermost 
 two of the three turbinated scroU-shaped bones. The 
 olfactory nerve distributes fibres also on each side of the 
 septum. 
 
 Odoriferous particles float into the nasal chambers with 
 the air, and, striking upon the termination of the olfactory 
 nerve, excite it, and the excitement passing on through the 
 olfactory lobes to the brain, there becomes recognised by 
 consciousness as a sensation. 
 
 The shape of the nasal passages shows why a person 
 sniffs up the air when he wishes to detect a faint odour. 
 The back openings of the nose (posterior nares) have 
 already been seen on Plate XYIII. A — that large space 
 between the Fig. 22 and the bone above, in which the Xo. 
 32 is placed. ^^^liIe the breath is drawn quietly it passes 
 straight through the lower part of the nose, not much of it 
 ascending to the upper cavity where the olfactory nerve is 
 spread out. But a snift" is really a sudden inspiration 
 through the nostrils ; and when this inspiratory eff'ort is 
 made air is drawn out of the upper cavities into the lungs, 
 and the fre.sh air from outside, laden with the odour, rushes 
 in and fills the space thus left, as well as agitating the 
 whole of the air there, and setting up a current like a wind 
 on a small scale. 
 
 What is commonly meant by " the nose," that portion of 
 it which is seen on the face, is shown in Figs. F and G to 
 be composed of two small bones and of cartilage. 
 
 The Organ of Taste. 
 
 The Tongue (like the skin) serves two jiurposes. Xot 
 only is the tongue the seat of the jjeripheral terminations 
 of the nerves of taste, but it is also the principal organ of 
 speech. It will be necessary to briefly consider it in each 
 capacity. 
 
 Two nerves supply filaments to the tongue — the glosso- 
 pharyngeal (9th), and a branch of the trigeminus (5tb) named 
 the limjual or gushitvry. These nerves end in little emi- 
 nences called papillre, which are scattered over the surface 
 of the tongue (Plate XXI. Fig. A). The papilla are of 
 three kinds. Fig. C shows diagrammatically each of these, 
 with the nerve filaments entering and ending in them. 
 The filiform papilla; (2) are most numerous at the tip of 
 the tongue; farther back, the fungiform (1) and filiform 
 are mingled ; and the circumvallate (3), few in number, are 
 arranged in the form of the letter V at the root of the 
 tongue (A, 6). 
 
 A perfectly dry substance has no flavour at all ; and 
 since it is necessarj' for taste that a substance should be 
 dissolved, it is found very diflicult practically to experiment 
 so as to discover in which part of the tongue the sensation 
 resides, or which papill* possess the most acute nerves. 
 German physiologists have latel)' assigned the principal 
 power to curious little bodies called tastc-gMcis or gustatory 
 bidbs (Fig. D). These are found in the hollow around the 
 V formed bj- the circumvallate papillte, on those papillae 
 themselves, and also on the upper surface of the fungiform 
 papillae. It appears certain that they must perform some 
 office in connection with the sense of taste. An eminent 
 English physiologist (M. Foster) has, however, denied 
 that they are the " specific organs of taste," and so the 
 exact nature of their function must be considered as still 
 uncertain. 
 
 Speech, is articulate sound, and must not be confounded 
 with ivice. The organ by which voice is produced is figured 
 on Plate XYIII. B, C, D, and E. It consists of a cartila- 
 ginous box, called the larynx, which is seated on the top of 
 the windpipe, having the epiglottis above it. Across it, 
 from back to front, Tun two fleshy bands, the rond cords ; 
 they are afiLxed to the centre of the thyroid cartUage in front, 
 and to the corners of the aryitnoid cartdages behind. While 
 the muscles connected with them (C) are quiescent, the two 
 corners of the arytenoid cartilages are some little distance 
 apart, and the vocal cords are necessarily also kept away 
 from one another by this means. But by the contraction 
 of various muscles, the tips of the arytenoid cartilages are 
 brought together, so that the vocal cords lie straight beside 
 each other, and are made tense. In this condition, the air 
 breathed out over them causes them to vibrate, and give 
 forth a sound, which varies in pitch according to the degree 
 of their tension. This sound is voice. 
 
 Voice is made into speech by the conjoint action of the 
 tongue and the lips, with the aid of the teeth and the hard 
 palate. The tongue has much to do with this forming 
 articulate sounds, but it is not absolutely essential to the 
 production of many sounds, and persons whose tongues 
 have been removed have been found to be able to make 
 their speech understood. 
 
 The Sense of Touch has already been spoken of (p. 
 13) at sufficient length, and we may now proceed to the 
 more complex 
 
 Organ of Hearing. 
 
 Plate XXII. A, somewhat diagrammatic, shows the ear 
 in its natural position ; for the organ of hearing does not 
 consist only, or even essentially, of that outside portion of 
 it which is commonh" called the ear. The essential parts 
 of the organ, indeed, are set deep in the head, place for 
 them being excavated in the petrous portion of the tem- 
 poral bone, near the base of the skull. 
 
 The ear is divided into three parts : the external ear, 
 the middle ear or tympanum, and the internal ear or laby- 
 rinth. 
 
 The external ear consists of the outside cartilase, which 
 
AN ATLAS OF AX ATOMY. 
 
 17 
 
 serves iiuicly ;is a sort of natural ear-trumpet, collecting 
 sounds and aiding them to enter the ear ; and of the pass- 
 age which leads from the exterior to the membrane of 
 the drum of tiie ear. In the external auditory meatus (14, 
 15) are several small glands which secrete the ear-wax. 
 
 At the bottom of the meatus a membrane (the viem- 
 bnina lijmpiini, IG) is stretched tightly across, and encloses 
 a cavity full of air (IS) like a drum. The tympanic cavity 
 is not wholly closed on the opposite side from the raem- 
 l)raiia tym]iani ; a small jiassage, the Eustachian lube, runs 
 up from the pharynx, and opens into the tympanic cavity, 
 and through this air can enter. 
 
 liunniug across the cavity of the drum (as best seen on 
 the left side in this figure) are three small bones, united 
 together into a chain. They are shown about the natural 
 size in the natural situation ; but below (Fig. B) they are 
 somewhat enlarged, and separated, in order that the curious 
 shape of each may be seen. The first one (Fig. B, a) is 
 attached to the middle of the membraua tympani ; its 
 shape is something like that of a hammer (malleus), after 
 which implement it is therefore named. The next one 
 (incus) is called the avvil. It has a depression at the top, 
 into which the head of tlie hammer is inserted. The third 
 little bone is exactly like a .stirrup, and is thence named 
 the stapes. Its top fits into one of the feet of the anvil, 
 and its lower part, answering to the foot-plate of the stirrup, 
 is fixed into a membrane which closes up an aperture in 
 the opposite wall of the cavity (A, 20). Thus the tympanic 
 cavity is completely bridged across by these tiny ossicles. 
 
 In the opposite wall from the membrane of the drum 
 are two openings, each filled in with membrane, like a 
 window with glass. One has already been mentioned as 
 having the stirrup fastened to it : that is the oval window, 
 OT fenestra ovalis. The other is lower down (shown just to 
 the right of the figure 19), and is round in shape; it is 
 called the fenestra rotunda, or round window. 
 
 Past those windows, on the other side of the bone in 
 which they are, is the internal ear, or lalnjrinth. The latter 
 name has been given to it from the exceeding complexity 
 of its detailed structure. 
 
 It is partly made of bone and partly of membrane ; or, 
 as it might be put, there are certain excavations made in 
 the bone of the head, and membranous structures are 
 found within those bony passages. 
 
 Fig. C shows the bony labyrinth laid open. It is divisible 
 into three parts : on the one side the semieircular canals 
 (9, 10, 11) ; on the other the cochlea (2, .3, 4) ; and a central 
 part with which both the others communicate, the vestibule 
 (5, 6, 7). _ 
 
 The semicircular canals, three in number, open into the 
 vestibule by only five ends, two of them joining together, 
 and so having one common aperture. Within them, in the 
 natural state, lie membranous semicircular canals, which 
 open into a membranous vestibule enclosed in the bony 
 one. These membranous structures form closed bags. They 
 are considerably smaller than the bone in which they lie, 
 and are separated from it by a surrounding fluid (the peii- 
 hjmph), in which they float. The membranous canals and 
 vestibule also contain a fluid inside them (the endohjmph), 
 in which are found minute particles of stone. The mem- 
 branous canals, like the bony ones (Fig. C), widen out a 
 little near their ends where they enter the vestibule ; those 
 expansions are called the ampullce, and inside them are 
 found cells, which have attached to their ends little stiff 
 hair-like projections that stand out into the cavity of the 
 ampulla\ A part of the nerve of hearing is spread out in 
 a network in the midst of the cells of the ampullse. 
 
 The Cochlea also consists of a bony portion and a 
 membranous portion, but these are more intricate in arrange- 
 ment. The cochlea receives its name from its general 
 resemblance to a snail's shell. It consists, in the first place. 
 
 of a roundabout passage, excavated out of the hard bone of 
 the head so as to turn upon itself (as a spiral staircase 
 does) two and a half times (A, 19 ; C, 2, 3, 4). The exact 
 middle of this e.xcavated coil is occupied by a straight 
 pillar of bone, which stops a little short of the very top of 
 the coil, so as to leave above it a dome called the cupola 
 (D, 8). The pillar itself is called the modiolus. It is not 
 perfectly solid, but is channelled by numerous small pass- 
 ages through which the auditory nerve fibres pass (D, 7). 
 
 A tliin plate of bone, the lamina spiralis ossea, twines 
 around the modiolus, its twists corresponding to those of 
 the sides of the cochlea. It is clear that if this bony 
 spiral went right across from the modiolus in the centre to 
 the side, each twist of the cochlea would be divided into 
 two halves — one above and one below the lamina spiralis. 
 But it does not go more than half-way across ; then the 
 bone ends, and two delicate membranes start from it, and 
 continue across to the sides. These membranes diverge as 
 they go, and are affixed to the outer bone at some dis- 
 tance (microscopicallj-, of course) from one another, so that 
 another passage is enclosed between them. Each turn of 
 the cochlea is thus divided into three passages — one above 
 the lamina spiralis, one beneath it, and the third enclosed 
 within the membranes which arise from the edge of it. 
 (Consult carefully D, 1, 2, 3.) 
 
 The space contained between the two membranes, being 
 the centre one, is called the scala media. The passage 
 beneath this communicates with the cavity of the drum by 
 means of the round window (C, 1), and is therefore called 
 the scala tympani. The passage above the scala media 
 opens into the vestibule, and is therefore named the scala 
 vestibuli. 
 
 In Fig. E we have a diagrammatic representation of a 
 transverse section of the cochlea, and this merits careful 
 study. 1 is the scala tympani, and above it, 5, is the basilar 
 membrane, by which it is separated from 2, the scala media. 
 6 is the other of the two membranes which take their 
 rise from 4, the lamina spiralis. It is named the mem- 
 brane of Ileissner, and it separates the scala vestibuli, 3, 
 from the scala media. 
 
 The lamina spiralis is here (4) seen to be composed of 
 two thin plates of bone, between which the auditory nerve's 
 branches run to be finally distributed on the basilar 
 membrane, and in close connection with those remarkable 
 structures which are figured lying upon the basilar mem- 
 brane. These elaborate and curious structures form Corti's 
 organ. They are, of course, excessively minute ; so minute, 
 indeed, that their anatomy and physiology are stUl some- 
 what uncertain. The organ of Corti is bounded above 
 by a delicate membrane (9), between which and the basilar 
 membrane (5) are seen splierical cells (10, 13, 17); cells 
 which bear along their tops a number of fine hair-like 
 processes, and which are therefore called the hair-cells (1.5) ; 
 and finally the curious rod-like bodies called the fibres 
 or rods of Corti. These latter are club-shaped bodies, set 
 up on end so as to lean against one another and leave a 
 triangular space beneath them (11, 12). It is believed 
 that filaments of the nerve project into the triangular space. 
 The latest investigations, indeed, lead to the belief that the 
 nerve ends in the hair-cells. In any case the terminal 
 fibres of the nerve are certainly in close relation ivith the 
 rods of Corti. There are an immense number of Corti's 
 rods set all .along the basilar membrane, from top to bottom 
 of the length of the spiral coil, giving it an appearance like 
 the key-board of a piano. 
 
 Such, leaving aside a few exceedingly minute details, is 
 the structure of the organ of hearing. A few words will 
 explain as much of the physiology of the sense as is at 
 present clearly known. 
 
 Sound is the result of vibrations of the atmosphere 
 striking upon the terminations of the auditorj- nerve in their 
 
li 
 
 AX ATLAS OF AX ATOMY 
 
 functional relationship with tho special structure of the organ 
 of hearing. Any body vhieh gives forth a sound, does so 
 by throwing the air which surrounds it into waves. Thosi' 
 waves are continued through the atnios])here, and for some 
 distance remain strong enough to set the membrana tyra- 
 pani also in a state of vibration when they strike upon it. 
 The vibration is continued across the tympanic cavity, 
 partly through the air which it contains, and partly by 
 moans of the chain of little bones. The sound-wave is 
 thus caused to strike upon both the round window and 
 the oval window ; through one of which it agitates the 
 fluid in the semicircular canals, and so afiects the nerve- 
 fibres there distributed ; through the other it reaches the 
 scala tympani, and so directly strikes against the basilar 
 membrane and throws the organ of Corti into vibrations, 
 ■which affect the nerve-fibres that end there. The agitation 
 is earned on through the nerve into the brain, and con- 
 sciousness of the sound is produced. 
 
 The organ of Corti has been known for only a very few 
 years. In an edition of one of the finest English works 
 on Anatomy published only ten years ago, the membrane 
 of Eeissner and the basilar membrane are described as 
 only one membrane, the scala media being unknown ; and 
 that single membrane which the author said extended from 
 the edge of the lamina spiralis to the side of the cochlea 
 was, he informed the reader, stated by one authority to 
 be a muscle, and by another to be connective tissue ! 
 I mention this chiefly to try to convey some idea to 
 the reader's mind of how very minute and delicate the 
 wonderful structure of the organ of Corti is. This fact 
 may explain how it is that we still do not know with 
 any certainty what office its various structures perform. 
 "We know that we are capable of distinguishing an im- 
 mense variety of notes and sounds. Even those of us most 
 destitute of " a musical ear," as the power of recognising 
 shades of tone is commonly called, yet know our friends 
 by their voices, and are conscious of innumerable variations 
 of sound. When we survey the structure of the organ of 
 Corti, with its hundreds or even thousands of fibres set so 
 regularly side by side, and gradually shortening from one 
 end to the other, we are irresistibly compelled to infer 
 that this must be the mechanism by which the waves of 
 sound are made to vibrate into the brain as so many 
 musical notes. But we do not really knoiv at present that 
 this is tlie case. 
 
 The Organ of Sight. 
 
 The Eye, if not quite so complex in arrangement as 
 the ear, is certainly equally wonderful. In it, again, we 
 find an exceedingly thin and delicate membrane, proving 
 under the microscope to contain elaborate structures, which 
 are provided for the special excitement of the end fibres of 
 the nerve ; and we find also external to that, careful an-ange- 
 ments for bringing outside imjiressions against the structures 
 just mentioned. 
 
 The eyeball is protected by being placed in the bony 
 cavity of the skull called the orbit. The entire eyeball 
 moves in the orbit, in all directions ; and so many and 
 delicate are the variations required in its movements, that 
 sLx separate muscles are employed in the work (Plate 
 XXIII. A, 2-7). The orbit is padded with fat ; and the 
 bone is pierced with several openings through which pass 
 the nerves and blood-vessels. 
 
 Fig. B, the diagrammatic section of an eyeball, gives a 
 general view of its structure on the one side, and shows 
 the remarkable capillary plexus of the middle coat of the 
 eyeball on the other side. 
 
 The external coat of the eyeball is a tough fibrous 
 membrane behind, with a transparent glittering portion in 
 front. The former (B, 1) is called the sclerotic coat. The 
 
 latter is the part which is seen in front of the eye, and is 
 called commonly "the white of the eye;" its technical 
 name is tlie corner (B, 2). It will be noticed that the 
 cornea is more eon\cx than it would be if the eye were a 
 perfect globe ; it projects out as a watch-glass does from 
 its case. The cornea is covered outside by a delicate 
 membrane (17) called the conjunctiva, which is reflected 
 over the eyelids and lines them internally. 
 
 Behind the cornea is a space called the anterior chamber, 
 (G) which contains a w^hite watery fluid called the aqueous 
 humour. 
 
 The second coat of the eye comprises several important 
 structures. Over the posterior four-fifths of the eyeball, 
 this second coat, just under the sclerotic, consists of a 
 membrane called the choroid coat (3), which contains a very 
 great many blood-vessels (20), and is lined inside by a layer 
 of dark pigment-cells. At the front of the eye, the choroid 
 ends in the remarkable manner shown at 11 in this figure, 
 and more enlarged and exact on the next plate. Fig. B. 
 Near the point where the sclerotic merges in the cornea, 
 the choroid coat ends by doubling up into a numljer of 
 folds or plaits, which receive the name of the cUiary pro- 
 cesses. The pigment-cells which cover these are continuous 
 with those dark pigment-cells which cover the back of 
 the iris, or coloured part of the eye (XXIV. B, 11). The 
 iris (rainbow) is a muscular curtain with a hole, the 
 pupil, in its centre ; and being affixed to the front ends 
 of the choroid, it may be described as the front part of 
 the second coat of the eye. It is, however, also con- 
 nected with the sclerotic and cornea by a band of mus- 
 cular fibres (G), which runs right round the iris, arising, 
 as shown, from the point of junction of the sclerotic and 
 cornea, and passing backwards over the ciliary processes 
 (to which it is affixed), and finally being fastened behind 
 on the outer surface of the choroid coat. It is clear 
 that when this ciliary muscle contracts, it will pull the 
 choroid coat and ciliary processes forward towards the point 
 of junction of the cornea and sclerotic. This would be the 
 natural result of the shortening of the ciliarj' muscle, inas- 
 much as this would be more easily accomplished than would 
 the dragging downwards of the cornea to which the other 
 end of the muscle is fixed. The reason for this muscle's 
 existence and action we will see presently. 
 
 The 2'ostcrior chamber (7) is a small space, filled with the 
 same aqueous fluid as the anterior chamber, and intervening 
 between the back of the iris and the crystalline lens. The 
 anterior and posterior chambers communicate through the 
 pupil. 
 
 The crystalline lens (XXIII. B, 9) is a beautifully clear, 
 transparent, hard body, like crystal. It is placed behind 
 the iris, and is covered at its edges by the ciliary processes. 
 The lens is doubly convex — i.e. is bowed outwards both 
 before and behind. It is enclosed in an elastic and trans- 
 parent membrane called the capsule of the lens, and is 
 held in its place by a thin membrane called the suspensory 
 ligament, which passes from the capsule to the inner side 
 of the choroid, on to which it is affixed. It passes under- 
 neath the ciliary processes, and just as the ciliary muscle 
 fits into their folds above, so the suspensory ligament fits 
 into their folds below, the ligament having projections 
 where the processes are depressed, and vice versa. 
 
 Now let us see what happens to all these structures when 
 the ciliarj^ muscle contracts. The lens is held constantly 
 in a flatter state than its shape would be, liy the tightness 
 of its suspensory ligament. When the ciliary muscle con- 
 tracts, it necessarily drags forward the edge of the choroid 
 and the ciliary jirocesses to which it is affixed. The sus- 
 pensory ligament is also affixed to the same structures, and 
 thus must be pulled forward by them ; and its tension is 
 necessarily slackened by this means. Immediatel}', the 
 elasticity of the lens comes into play, and it bows more 
 
^^V ATLAS UF ANATOMY. 
 
 19 
 
 outwards (Ijccomes more convex). When the contraction 
 of the ciliary muscle ceases, the suspensory ligament is 
 carried back to its former position, and so again exercises 
 pressure upon the lens and lessens its convexity. 
 
 This proceeding is the mechanism by which the eye 
 accommodates itself to distances. It is known to be neces- 
 sary, by the laws of optics, to liave a more convex lens to 
 throw the image of a near object upon the back of the eye, 
 than is required to throw the image of a distant object 
 upon the same "spot. Thus, the nearer the object at which 
 we wish to look, the more we contract the ciliary muscle; 
 and conversely, the farther otf the object is, the less the 
 muscle needs to act. 
 
 Behind the lens is a great cavity, filled with a clear jelly- 
 like matter, which is called the vitreous humour (10). It is 
 enclosed in a very delicate membrane called the hyaloid 
 membrane, represented here by the narrow yellow line 
 against which the figure 14 is placed. 
 
 The vitreous humour supports and holds out the inner- 
 most coat of the eye, and the really essential part of the 
 organ — the retina. To the naked eye, the retina is a thin 
 delicate silvery membrane ; and it is wonderful to learn 
 from the microscope how elaborately constructed this fra- 
 gile and thin membrane is. 
 
 The retina extends over the back and sides of the inte- 
 rior cavity of the eyeball, and ends, not far behind the 
 ciliary muscle, by a jagged edge, having gradually dimin- 
 ished in thickness from behind to this point. Exactly at 
 the back of the eye a slight depression is noticed in the 
 retina (XXIII. A, 14). This is called the macula lutea, or 
 yellow spot. A little more to the nasal side of the eyeball 
 is the point at which the optic nerve pierces the external 
 coats of the eye, and spreads out in fibres which form the 
 internal layer of the retina. 
 
 Fig. C on Plate XXIII. shows the structure of the retina 
 and the entrance of the ojitic nerve. The nerve is seen to 
 enter (all the other structures of the retina disappearing at 
 that exact spot) and immediately to spread out on either 
 side to form a layer (a) of (7) the retina, and a very thick 
 layer in comparison with all the others (5 to g). The 
 minute structure of the retina is best seen on the next 
 Plate, XXIV. Fig. A. The various delicate structures 
 which are seen to lie between the fibres of the optic 
 nerve and the outermost layer (9) of the retina, are jiartly 
 connective and partly nervous. The connective elements 
 begin at 1, the anterior limiting membrane, and end at 8, 
 the posterior limiting membrane ; and they pass under and 
 amidst the granular layers (4, G), and the ganglionic cor- 
 puscles (3), supporting and bearing up these nervous struc- 
 tures. The outermost layer of the retina — that is to say 
 the layer nearest tlie choroid — is seen to be outside these 
 connective elements. This important and remarkable 
 layer is, however, embedded at its tips in the pigment- cells 
 already described as lining the choroid ; and indeed it has 
 
 lately been claimed by some anatomists that the pigment- 
 cells ought really to be described as belonging to the retina, 
 because they are thus closely connected with it. The layer 
 which meets the pigment cells (9, 10) is called the layer of 
 rods and cones. It consists, as seen, of a number of rod-like 
 and sugar-loaf-shaped bodies, from the ends of which 
 nervous filaments pass forward into the outer layer of 
 granules. The rods and cones are thicker and longer over 
 the yellow spot than they are elsewhere ; while, on the 
 other hand, all the other layers of the retina liecome 
 exceedingly thin there, and the fibres of the optic nerve do 
 not pass over it at all. At the point of entrance of the 
 optic nerve, on the contrary, as we have already seen, only 
 the fibres of the nerve are to be found, all the other layers 
 being absent. From this anatomical arrangement, we 
 learn the remarkable physiological fact that the fibres of 
 the optic nerve are absolutely blind, and that the rods and 
 cones are the essential intermediaries between the impulse 
 which can arouse the sense, and the nerve by which the 
 sense is carried to the brain. To put it in another way — 
 light cannot excite the optic nerve itself ; but light excites 
 the rods and cones, and they excite the end fibres of the 
 nerve. We know this to be the case because when the 
 reflection of an object falls into the eye so that, on optical 
 principles, it falls on the yellow spot, vision is most perfect ; 
 while when the image is so thrown as to fall on the point 
 of entrance of the nerve, no sensation of seeing is aroused 
 in the brain. 
 
 The Appendages of the Eye are the eyebrows 
 and lids, and the lachrymal apparatus. The eyelids are 
 chiefly composed of cartilage, covered externally with skin 
 and internally with the mucous membrane called the con- 
 junctiva, before mentioned as being reflected from over the 
 surface of the cornea. Along each eyelid runs a row of 
 small glands, the Meibomian glands (Plate XXIV. D, 2 ; 
 E, 3), which secrete a little fluid that prevents the adhesion 
 of the lids to each other. 
 
 The lachrymal glands are lodged in depressions in the 
 bone of the orbit, at the top of the eyeballs (Fig. D, 3). 
 Each eye has one gland, which opens by six or seven little 
 ducts on the interior of the upper eyelid. The tears are 
 secreted by the lachrymal gland, and are generally only 
 sufficient in cpiantity to moisten the conjunctiva, and 
 enable the lids to move without pain or difficulty ; after 
 which the excess is passed through the canals (6, 7) into 
 the lachrymal duct (9), down which it passes into the nose. 
 Painful emotion has the very curious eff'ect of so increasing 
 the secretion of the lachrymal glands that it can no longer 
 be all passed away through the duct, but overflows the 
 eyelids in the drops called tears. 
 
 The upper eyelid is raised by the action of a special 
 small muscle, the levator palpehroi svperioris. The eyelids 
 are closed by the action of a muscle called the orbictdaris, 
 the fibres of which pass circularly within the eyelid. 
 
INDEX TO THE PLATES. 
 
 Plates I. and II. 
 
 Plate IV. 
 
 A. SKELETON— Front View. 
 
 1. Frontal bone. — ^ 
 
 2. Parietal bone. - " 
 
 3. Temporal bone. ' 
 
 4. Superior maxillary. 
 
 5. Inferior maxillarj'. 
 
 6. Cervical veitebixe. .. - • 
 
 7. Humerus. 
 
 8. Radius. 
 
 9. Ulna. 
 
 10. Bones of the hand. 
 
 11. ClaTicle. 
 
 12. Sternum, or breast bone. 
 
 13. Ensiform proeesss ; cartilagi- 
 
 nous end of the breast-bone. 
 1 i. True ribs (which are fastened 
 immediately on to the ster- 
 num). 
 
 15. False ribs (so called because 
 
 attached only to a piece of 
 cartilage, and by its means 
 to the sternum). 
 
 16. Thoracic vertebrae. — /- 
 
 17. Lumbar vertebrae. ~ ^-i " 
 IS. Sacnim. -^_ 5~ 
 
 19. Ilium (part of the Innominate 
 
 bone). 
 19«. Ischium. 
 196. Os pubis. 
 
 20. Femiu'. 
 
 21. Patella. 
 
 2-2. Tibia. 
 
 23. Fibula. 
 
 24. Bones of the foot. 
 
 B. SKELETON, seen from 
 
 BEHIXD. 
 
 1. Occipital bone. 
 
 2. Parietal bones. 
 
 3. Temporal bone. 
 
 4. Malar bone. 
 
 5. Inferior maxillary. 
 
 6. Cervical vertebrae. - 
 
 7. Thoracic vertebrae. / '- 
 
 8. Lvmibar vertebrae. ^' 
 
 9. Sacrum. 
 
 10. Coccyx. 
 
 11. Clavicle. 
 
 12. Scapula. 
 
 13. True ribs. 
 
 14. False ribs. 
 
 15. Innominate bone. 
 
 16. Ischium. 
 
 17. Humerus. 
 IS. Eadius. 
 
 19. Ulua. 
 
 20. Bones of the hand. 
 
 21. Femur. 
 
 22. Tibia. 
 
 23. Fibula. 
 
 24. Bones of the foot. 
 
 A. MONGOLIAN SKULL, 
 Lateral Aspect. 
 
 C. NEGRO SKULL, 
 Lateral Aspect. 
 
 Plate III. 
 
 A. SKULL, FROM IX front. 
 
 1. Frontal bone. 
 
 2. Parietal bones. 
 
 3. Sphenoid bones. 
 
 4. Temporal bones. 
 
 5. Jlalar bones. 
 
 6. Nasal bones. 
 
 7. Nasal septum. 
 
 8. Superior maxUlary, facial part. 
 
 9. Inferior maxillary. 
 
 B. SKULL, FROM BELOW. 
 
 1. Superior maxillary, palatine, 
 
 and alveolar processes. 
 
 2. Superior maxillary, facial sur- 
 
 face. 
 
 3. Palate bones. 
 
 4. Siihenoid. 
 
 5. Vomer. 
 
 6. Temporal bones. 
 
 7. Temporal bone, petrous por- 
 
 tion. 
 
 8. Occipital bone, basilar process. 
 
 9. Occipital bone, occipital part. 
 
 10. Foramen magnum, through 
 
 which the spinal cord passes 
 into the brain. 
 
 11. Posterior nares. 
 
 12. Temporal bone, styloid pro- 
 
 cess. 
 
 13. Malar or cheek bones. 
 
 14. Parietal bones. 
 
 15. Condyles of occipital hone ; 
 
 for articulation with first cer- 
 vical vertebra. 
 
 C. THE TEETH. 
 
 1, 2. Incisors. 
 
 3. Canine. 
 4, 5. Bicuspids. 
 6, 7. Molars. 
 
 8. Wisdom tooth. 
 a. Crown. 
 I. Neck, 
 c. Fang. 
 
 D. SECTION THROUGH A TOOTH. 
 
 1. Dentine. 
 
 2. Enamel. 
 
 3. Pulp cavity with canal. 
 
 4. Cement. 
 
 5. Nerves and blood-vessels enter- 
 
 ing 
 
 6. Jawbone. 
 
 7. Gum. 
 
 E. SECTION OF BONE. 
 
 1. Haversian canals. 
 
 2. Lamellie, showing lacunoe and 
 
 canaliculi. 
 
 F. FIRST CERVICAL VERTE- 
 
 BRA (ATLAS), FROM above 
 
 AND BEHIND. 
 
 1. Anterior arch. 
 
 2. Posterior arch. 
 
 3. Transverse processes. 
 
 4. Articulating surfaces for odon- 
 
 toid process. 
 
 5. Articulating surfaces for occi- 
 
 pital condyles. 
 
 6. Spinal canal. 
 
 G. SECOND CERVICAL'(AXIS), 
 
 FROM IN FRONT. 
 
 1. Odontoid process. 
 
 2. Its articulating surface. 
 
 3. 4. Superior and inferior articu- 
 
 lating surfaces. ■ 
 5. Transverse process. 
 
 B. MONGOLIAN SKULL, D. NEGRO SKULL, 
 
 Anterior Aspect. Anterior Aspect. 
 
 E. PREHISTORIC CRANIUM from a Belgian Gave. 
 
 Plate V. 
 
 A. HYOID BONE. 
 
 Greater cornua. 
 Lesser cornua. 
 
 B. ATTACHMENTS of MUS- 
 CLES AND CARTILAGES 
 to the HYOID BONE. 
 
 1. Body of the hyoid bone. 
 
 2. Greater cornua, left. 
 
 3. Laryux. 
 
 4. Two sterno-hyoid muscles. 
 
 5. Thyro-hyoid muscles. 
 
 6. Hyo-glossus muscles. 
 
 7. Stylo-hyoid muscle. 
 
 8. Stemo-mastoid. 
 
 C. SKULL OF A VERY YOUNG 
 
 CHILD. 
 
 1. Anterior fontanelle. 
 
 2. Posterior fontanelle. 
 
 3. Anterior lateral fontanelle. 
 
 4. Posterior lateral fontanelle. 
 
 D. SKULL OF A CHILD with 
 
 THE Milk Teeth and the 
 germs of the permanent 
 Ones. 
 
 1. Milk teeth, lower jaw. 
 
 2. Milk teeth, upper jaw. 
 
 3. Germs of permanent teeth. 
 
 B. SKELETON of GORILLA, 
 to compare with that of 
 Man. 
 
 Plate VI. 
 
 A. SKELETON OF RIGHT 
 HAND — DORSAL SUR- 
 FACE. 
 
 1. First row of phalanges. 
 
 2. Second row of phalanges. 
 
 3. Third row of phalanges. 
 
 4. Metacarpal bones. 
 Carpal Bones — 
 
 5. Trapezium. 
 
 6. Trapezoid. 
 
 7. Os magnum. 
 
 8. Unciform. 
 
 9. Scaphoid. 
 
 10. Semilunar. 
 
 11. Cuneiform. 
 
 12. Pisiform. 
 
 13. Radius i 
 
 14. Ulna J 
 
 >- Bones of the forearm. 
 
 B. LIGAMENTS and JOINTS 
 
 OF THE 4tH and 5TH 
 
 FINGERS OF the RIGHT 
 HAND — Palmar Surface. 
 
 1. First phalanx. 
 
 2. Second phalanx. 
 
 3. Third phalanx. 
 
 4. Metacarpal bones. 
 
 5. External lateral ligament. 
 
 6. Internal lateral ligament. 
 
 7. Capsular ligament. 
 
 8. Transverse metacarpal liga- 
 
 ment. 
 
 C. SKELETON of RIGHT 
 FOOT — Plantar Surface. 
 
 1. First phalanx. 
 
 2. Second phalanx. 
 
 3. Third phalanx. 
 
 4. Metatarsal bones. 
 
 Tarsal Bones — 
 f 5. Internal cuneiform. 
 I 6. Middle cuneiform. 
 I 7. External cuneiform. 
 -{ 8. Cuboid. 
 I 9. Scaphoid. 
 I 10. Astragalus. 
 1.11. Os calcis. 
 12. Sesamoid bones, external and 
 internal. 
 
 D. LIGAMENTS and JOINTS 
 
 of the 4th and 5th 
 TOES OF THE RIGHT 
 FOOT — Plantar Supj ACE. 
 
 1. First phalanx. 
 
 2. Second phalanx. 
 
 3. Third phalanx. 
 
 4. Metatarsal bones. 
 
 5. External lateral ligament. 
 
 6. Internal lateral ligament. 
 
 7. Transverse metatarsal liga- 
 
 ment. 
 
 E. PATELLA— Posterior View. 
 
 1. Apex. 
 
 2. Ai-ticular surfaces for the con- 
 
 dyles of the femur. 
 
 F. LIGAMENTS of the 
 KNEE JOINT. 
 
 1. External condyle of the femur. 
 
 2. Internal condyle of the femur. 
 
 3. Tibia. 
 
 4. Patella, thrown downwards. 
 
 5. Insertion of the quadriceps 
 
 extensor muscle (forming 
 part of capsule of joint). 
 
 6. Ligaments, crucial and alar. 
 
 7. Lateral ligaments. 
 
22 
 
 INDEX TO THE FLATEB. 
 
 Plates VII. and VIII. 
 
 A. THE MUSCLES. 
 
 1. Facial muscles. 
 
 2. Sterno-cleido mastoid. 
 
 3. Trapezius. 
 
 4. Deltoid. 
 
 5. Pectoralis major. 
 
 6. Serratus magnus. 
 
 7. Latissimus dorsi. 
 
 8. Rectus abdominis. 
 
 9. Obliquus externus. 
 
 10. Glutieus maximus. 
 
 11. Kectus femoris. 
 
 12. Sartorius. 
 
 13. Vastus externus. 
 
 Vastus internus and cniscus. 
 
 14. Tibialis anticus. 
 
 15. Extensor longus digitomm. 
 
 16. Soleus. 
 
 17. Gastrocnemius. 
 
 18. Flexor longus digitorum. 
 
 19. Muscles of the foot. 
 
 20. Triceps. 
 
 21. Biceps. 
 
 22. Brachialis anticus 
 
 23. Flexor digitorum ~i Deep layer 
 
 profundus I of muscles 
 
 24. Flexor poUicis f "'^'Af™"' 
 
 longus ) forearm. 
 
 25. Extensor communis digitorum. 
 
 26. Extensors of the thumb. 
 
 27. Supinator longus. 
 
 28. Muscles of the back of the 
 
 hand. 
 
 B*. MUSCLES OF THE BACK. 
 a-g — Cervical Vertebr.e. 
 I.-Xn. — Dorsal VERTEBRiE. 
 
 1. Sterno-mastoid. 
 
 2. Splenius capitis. 
 
 3. Trapezius. 
 
 4. Levator anguli scapulae. 
 
 5. Latissimus dorsi. 
 
 6. Deltoid. 
 
 7. Rhomboideus major. 
 
 8. Infraspinatus. 
 
 9. Teres major. 
 
 10. Rhomboideus miuor. 
 
 11. External intercostals. 
 
 12. Serratus posticus inferior. 
 
 13. Sacrolumbalis. 
 
 14. Longissimus dorsi. 
 
 15. Spinalis dorsi. 
 
 16. Supraspinatus. 
 
 • To the right hand of the student the 
 superticial layer of muscles is shown ; to 
 the left, some of the muscles ,of the 
 lower layers are displayed by the laying 
 back of part of the superBcial layer. 
 
 C. MUSCLES AND LIGAMENTS 
 OF THE HAND — Palmar 
 
 Surface. 
 
 Annular ligaments. 
 
 Anterior annular ligament of 
 the wrist joint. 
 
 Flexor brevis minimi digiti. 
 
 Tendons of flexor sublimis 
 digitorum. 
 
 Lumbricales. 
 
 Piilmaris brevis. 
 
 Adductor poUicis. 
 
 Flexor brevis pollicis. 
 
 Opponens pollicis. 
 
 Abductor pollicis. 
 
 Flexor sublimis digitorum. 
 
 Pisifonn bone. 
 
 Tendon of flexor longus pol- 
 licis. 
 
 D. MUSCLES AND LIGAMENTS 
 OF HAND — Dorsal Sur- 
 face. 
 
 1. 
 
 proprius miumii 
 
 Extensor 
 digiti. 
 
 Extensor communis digitorum. 
 
 Transverse ligament. 
 
 Interossei. 
 
 Abductor minimi digiti. 
 
 Extensor primi internodii pol- 
 licis. 
 
 Extensor secundi internodii 
 pollicis. 
 
 Abductor pollicis. 
 
 Posterior annular ligament of 
 wrist joint. 
 
 Radius. 
 
 Ulna. 
 
 1. Oblique ligaments. 
 
 2. Cruciate ligaments. 
 
 E. MUSCLES AND LIGAMENTS 
 OF FOOT— Dorsal Surface. 
 
 1. Extensor longus digitorum. 
 
 2. Extensor brevis digitorum. 
 
 3. Extensor proprius pollicis. 
 
 4. Tibialis anticus. 
 
 5. Interossei. 
 
 6. Abductor pollicis. 
 
 7. Abductor minimi digiti. 
 
 8. Anterior annular ligament of 
 
 ankle joint.' 
 
 F. MUSCLES anb LIGAMENTS 
 OF FOOT— Plantar Sur- 
 face. 
 
 1. Flexor brevis digitorum. 
 
 2. Flexor longus digitorum. 
 
 3. Flexor longus pollicis. 
 
 4. Abductor pollicis. 
 
 5. Abductor minimi digiti. 
 
 6. Interossei. 
 
 7. Lumbricales. 
 
 8. Tendon. 
 
 9. Os calcis. 
 
 Plate IX. 
 
 A. EXTERNAL MUSCLES of 
 THE HEAD. 
 
 Tendon of occipito-frontalis. 
 
 Frontal portion of occipito- 
 frontalis. 
 
 Temporal. 
 
 Orbicularis palpebrarum. 
 
 Zygomaticus major. 
 
 Zygomaticus minor. 
 
 Levator labii superioris et alie 
 nasi. 
 
 Compressor narium. 
 
 Buccinator. 
 
 Orbicularis oris. 
 
 Masse ter. 
 
 Sterno-cleido-mastoid. 
 
 Trapezius. 
 
 Splenius capitis. 
 
 Levator labii superioris pro- 
 prius. 
 
 Levator anguli oris. 
 
 17. Musculus risorius Santorini. 
 
 18. Depressor alse nasi. 
 
 19. Depressor anguli oris. 
 
 20. Depressor labii inferioris. 
 
 21. Levator menti. 
 
 22. Pyramidalis nasi. 
 
 23 i Fibres of orbicularis palpebrse 
 24' i covering upper and lower 
 ( eyelids (Ciliaris Riolaui). 
 
 25. Attollens aurem. 
 
 26. Attrahens aurem. 
 
 27. Retrahens aurem. 
 
 28. Occipital portion of the occi- 
 
 pito-frontalis. 
 
 B. EXTERNAL MUSCLES of 
 THE HEART, from in 
 front. 
 
 1. Muscle of right ventricle. 
 
 2. Muscle of left ventricle. 
 
 3. Muscle of right auricle. 
 
 4. Muscle of left auricle. 
 
 5. Common muscles of the two 
 
 auricles. 
 
 6. Left auricular appendix. 
 
 7. Pulmonary veins. 
 
 8. Superior vena cava. 
 
 9. Inferior vena cava. 
 
 10. Pulmonary artery with conus 
 arteriosus. 
 
 C. STRIPED MUSCULAR FI- 
 BRES, WITH Nerves enter- 
 ing. Dl.A.r,RAMMATIC. 
 
 1. Muscular fibre at rest. 
 
 2. Muscular striaj at moment of 
 
 contraction. 
 
 3. Jlotor nerve. 
 
 4. Terminal plate of nerve. 
 
 6. Nerve nuclei. 
 6. Mu.scle nuclei. 
 
 D. STRIPED MUSCULAR FI- 
 
 BRE, treated with weak 
 AciD.s. Much enlarged. 
 
 1. Primitive fibrils. 
 
 2. Transverse stria;. 
 
 3. Longitudinal stria;. 
 
 4. Cell-nuclei. 
 
 5. Decomposition of muscular 
 
 fibres into discs. 
 
 E. SMOOTH MUSCULAR FI- 
 
 BRE. Much enlarged. 
 
 1. Incompletely formed. 
 
 2. Completely developed. 
 
 Plate X. 
 
 A. BLOOD-VESSELS of FACE 
 AND SCALP. 
 
 1. External carotid. 
 
 2. Internal carotid. 
 
 3. Posterior auricular. 
 
 4. Occipital artery. 
 
 5. Superficial temporal. 
 
 6. Anterior branch of same. 
 
 7. Posterior branch of same. 
 
 8. Internal maxillary. 
 
 9. Facial. 
 
 10. Submental. 
 
 11. Coronary arteries. 
 
 12. Angular artery. 
 
 13. Supra-orbital. 
 
 14. Facial vein. 
 
 15. Superficial temporal veins. 
 
 16. Superficial temporal. 
 
 17. Deep temporal. 
 
 18. External jugular. 
 
 19. Internal jugular. 
 
 20. Occipital vein. 
 
 21. Posterior external jugular. 
 
 B. LONGITUDINAL SECTION 
 
 of HEART. 
 
 1. Left ventricle, with column* 
 
 cornea;. 
 
 2. Mitral valve. 
 
 3. Left auricle. 
 
 4. Auricular appendix. 
 
 5. Pulmonary veins, injected with 
 
 a blue preparation. 
 
 C. TRANSVERSE SECTION 
 
 through heart. 
 
 1. Left ventricle. 
 
 2. Right ventricle. 
 
 3. Septum ventriculorum. 
 
 4. Wall of right ventricle. 
 
 5. Wall of left ventricle. 
 
 6. Coronary vessels and fat in 
 
 anterior inter - ventricular 
 grooves. 
 
 7. The same in posterior furrow. 
 
 D. VALVE OF the AORTA, 
 
 WITH the MITRAL VALVE 
 OF THE Left Ventricle. 
 
 1. Septum between left auricle 
 
 and ventricle, with the 
 mitral valve. 
 
 2. Left ventricle. 
 
 3. Aorta. 
 
 4. Coronary artery. 
 
 5. SemUunar valves of aorta, con- 
 
 sisting of three folds, each 
 with a small nodule in centre 
 of free edge. 
 
 E. INTERNAL ASPECT of a 
 
 VEIN. 
 
 1. Direction of blood current. 
 
 2. Pouch-like valves to prevent 
 
 regurgitation of blood. 
 
 P. BLOOD-CORPUSCLES. Mag- 
 nified. 
 
 1. Corpuscles, treated with water, 
 
 perfectly circular. 
 
 2. Disc-shaped corpuscles. 
 
 3. Side view of the same. 
 
 4. Ordinary shape of the corpus- 
 
 cles. 
 
 5. Fibrin. 
 
 6. Dried blood-corpuscles. 
 
 7. Blood discs running togeth* 
 
 like rolls of coins. 
 
 Plate XI. 
 
 A. THORACIC VISCERA of 
 a CHILD. 
 
 1. Thyroid cartilage. 
 
 2. Cricoid cartilage. 
 
 3. Thyroid gland. 
 
 4. Trachea. 
 
 5. Thymus (well developed only 
 
 up to second year of child- 
 hood, after that only a mere 
 rudiment). 
 
 6. Bronchi. 
 
 7. Superior lobe of right lung. 
 
 8. Middle lobe of right lung. 
 
 9. Inferior lobe of right lung. 
 
 10. Superior lobe of left lung. 
 
 11. Inferior lobe of left lung. 
 
 12. Right ventricle. 
 
 13. Left ventricle. 
 
 14. Right auricle. 
 
 15. Left auricle. 
 
 16. Vena cava superior. 
 
 17. Vena cava inferior. 
 
 18. Pulmonary ai-tery. 
 
 19. Pulmonary veins. 
 
 20. Aorta. 
 
 21. Branches of superior cava. 
 
 22. Diaphi'agm. 
 
 23. Thoracic duct. 
 
 24. Lymphatic vessels. 
 
 B. TRANSVERSE and DIA- 
 GONAL SECTION through 
 THORAX, JUST ABOVE the 
 DIAPHRAGM. 
 
 1. Right lung. 
 
 2. Left lung. 
 
 3. Diaphragm. 
 
 4. Apex of heart (this peculiar 
 
 arrangement of muscular 
 fibres is called the vortex), 
 
 5. Pericardium. 
 
 6. Inferior vena cava. 
 
 7. Aorta. 
 
 8. Qisophagus. 
 
 9. Pneumogastric nerves or vagi. 
 
 10. Thor.-icic duet. 
 
 11. Sympathetic nerve. 
 
 12. Ninth thoracic vertebra with 
 
 its ribs. 
 
INDEX TO TEE PLATES. 
 
 23 
 
 13. Eighth rib (a) and spine of 5. 
 
 eighth vertebra (4). 6. 
 
 14. Seventh rib. 7. 
 
 15. Sixth rib. 8. 
 
 16. Fifth rib. 9. 
 
 17. Liitissimus dorsi. 10. 
 
 18. Senatus maguus. 11. 
 
 19. Trapeziu.s. 
 
 20. Peetoialis major. 12. 
 
 C. TRANSVEKSE SECTION 13 
 
 THitouGH ABDOMEN, jtst 14. 
 
 BELOW THE DIAPHRAGM. 15. 
 
 1. Liver. 16. 
 
 2. Vena portie. 1'' 
 
 3. Inferior vena cava. l^- 
 
 4. Aorta. 19- 
 
 Thoracic duct. 
 
 Stomach. 
 
 Spleen. 
 
 Suprarenal body. 
 
 Sympathetic nerve. 
 
 Diaphragm. 
 
 Eleventh thoracic vertebra and 
 
 its rib. 
 Tenth rib (a) and spine of tenth 
 
 vertebra (A). 
 Ninth rib. 
 Eighth rib. 
 Seventh rib. 
 Si.xth rib. 
 Serratus muscle. 
 Latissimus dorsi. 
 Abdominal muscle. 
 
 A. TRACHEA, BRONCHI, and 
 BLOOD-VESSELS of the 
 LUNGS. Diagrammatic. 
 
 Plates XII. and XIII. 
 
 B. TERMINAL BE.iNCHES 
 OF THE AIR PASSAGES 
 WITH THE PULMONARY 
 VESICLES. Verygkeatlt 
 
 ENLARGED. 
 
 Larynx. 
 Trachea. 
 Bronchial branches in the right 
 
 lung. 
 Superior vena cava. 
 Inferior vena cava. 
 Right auricle. 
 Right ventricle. 
 Left pulmonary artery. 
 Left pulmonary veins. 
 Left auricular appendix. 
 Left ventricle. 
 Aorta. 
 
 I arising from 
 Eight subclavian ) aorta by one 
 
 13, 
 
 14. Right carotid. 
 
 trunk — the 
 innominate. 
 
 Left carotid. 
 
 Left subclarian. 
 
 Liver. 
 
 Stomach. 
 
 Peritoneum. 
 
 Diaphragm. 
 27. True ribs. 
 29. Two false ribs. 
 
 Cartilage of true ribs. 
 
 Cartilage of false ribs. 
 
 Part of pleura. 
 
 1. Branches of the bronchi. 
 
 2. Pulmonaiy vesicles, or air-cells. 
 
 C. TRANSVERSE SECTION of 
 
 PULMONARY VESICLES 
 WITH VASCULAR NET- 
 WORK. Diagrammatic. 
 
 1. Blood-vessel. 
 
 2. Its branches. 
 
 3. Vesicles cut across. 
 
 D. PULMONARY VESICLE 
 WITH ITS VASCULAR NET- 
 WORK. Vert much en- 
 larged. 
 
 1. Septum between vesicles. 
 
 2. Looping capillaries. 
 
 3. Capillaries in which proceeds 
 
 the exchange of carbonic 
 acid for oxygen. 
 
 4. Cell-nuclei of matrix. 
 
 Plates XIV. and XV. 
 
 A. ABDOMINAL VISCERA. 
 
 1. Diaphragm. 
 
 2. Qisophagus. 
 
 3. Stomach. 
 
 a. cardiac orifice. 
 J. fundus. 
 
 c. pylorus. 
 
 4. Duodenum. 
 
 d. entrance of common bile 
 
 and pancreatic duct. 
 
 5. Remainder of small intestine 
 
 drawn out. 
 
 e. jejunum. 
 /. ileum. 
 
 6. Large intestine in its natru'al 
 
 position. 
 g. cfecum. 
 
 h. vermiform appendix. 
 i. ascending colon. 
 Tc. transverse colon. 
 I. descending colon, 
 m. sigmoid flexure. 
 n. rectum. 
 
 7. Spleen. 
 
 8. Liver. 
 
 8. Liver (turned back). 
 
 0. right lobe. 
 
 p. quadratic lobe. 
 
 q. left lobe. 
 
 r. spigelian lobe. 
 
 s. superior or anterior sur- 
 face. 
 
 t u. ligaments. 
 
 V. gall-bladder. 
 
 w. ductus choledochus or bile- 
 duct. 
 
 9. Pancreas. 
 
 10. Right kidney. 
 
 11. Left kidney. 
 
 inferior 
 surface of 
 the liver. 
 
 B. MUSCULAR BANDS of 
 STOMACH— seen from the 
 exterior. 
 
 1. (Esophagus. 
 
 2. Cardiac oiifice. 
 
 3. Central part. 
 
 4. Cardiac end. 
 
 5. Lesser curvature. 
 
 6. Greater curvature. 
 
 7. Pylorus. 
 
 8. Duodenum. 
 
 C. STOMACH AND DUODENUM, 
 
 DIVIDED IN THE MIDDLE LINE. 
 
 1. Cardiac orifice. 
 
 2. Pylorus. 
 
 3. Folds of mucous membrane. 
 
 4. Gastrophrenic omentum. 
 
 5. Gastrosplenic omentum. 
 
 6. Great omentum. 
 
 7. Small omentum. 
 
 8. Duodenum with folds. 
 
 9. Common bile duct. (Cut. ) 
 10. Pancreatic duct. (Cut.) 
 
 D. COMMUNICATION of 
 SMALL INTESTINE with 
 THE LARGE ONE (Valvula 
 B.A.11HIN1, OR Ileo - c^cal 
 Valve). 
 
 1. Small intestine (ileum). 
 
 2. Cfficum. 
 
 3. Vermiform appendix. 
 
 4. Ascending colon. 
 
 Plate XVI. 
 
 A. SECTION of STOMACH- 3. 
 
 WALL. =?«. 4. 
 
 5. 
 
 1. Longitudinal muscular fibres g, 
 
 with cells. 7^ 
 
 2. Mucous-muscular layer. g 
 
 3. Secreting glands (empty) cut 
 
 across. 9_ 
 
 4. The same, full of secreting 
 
 cells. 10. 
 
 5. Secreting glands, surface of. w_ 
 
 6. Orifices of glands on the inner 12. 
 
 surface of stomach, deprived 13. 
 
 of its mucous layer. \ 4_ 
 
 B. DIAGRAM OF PART of a 
 LOBULE OF THE LIVER. 
 
 External circular layer. 
 Internal longitudinal layer. 
 Internal circular layer. 
 Mucous membrane. 
 Villi, covered with epithelium. 
 Blood - vessels branching in 
 
 villi. 
 Lymph network of the mucous 
 
 membrane. 
 Lymph vessels of vUIi. 
 Nerves. 
 
 Lieberkuhn's crypts. 
 A follicle or solitary gland. 
 Lymphatic vessel. 
 
 E. DUODENUM AND 
 PANCREAS. 
 
 A. Hepatic duct, injected with 
 
 yellow. 
 
 B. Hepatic duct, not injected. 
 
 C. Hepatic artery, cut. 
 
 D. Portal vein. 
 
 E. Interlobular branch of portal 
 
 vein. 
 
 F. Intralobular veinlet. 
 H. Hepatic cells. 
 
 C. INNER SURFACE of SMALL 
 
 INTESTINE. V- 
 
 1. Villi. 
 
 2. Elevationsoftheglandsof Peyer 
 
 (when standing singly = soli- 
 tary glands ; when in groups 
 = Peyer's patches). 
 
 3. Lieberkuhn's crypts. 
 
 D. DIAGRAMMATIC SECTION 
 THROUGH SMALL INTESTINE. 
 
 1. Peritoneal covering. 
 
 2. External longitudinal layer. 
 
 1. Apex of pancreas. 
 
 2. Head of pancreas. 
 
 3. Duct of pancreas. 
 
 4. Santorini's duct (seldom pre- 
 
 sent). 
 
 5. Orifice of this duct. 
 
 6. Orifice of bUe duct. 
 
 Note. — The pancreatic duct com- 
 monly joins with the bile duct 
 just before opening into the in- 
 testine, and the two fluids enter 
 the duodenum by the common 
 tube. 
 
 7. Longitudinal folds of duo- 
 
 denum. 
 
 8. Transverse folds. 
 
 P. Shows the two kinds of 
 CAPILLARY VESSELS IN 
 the liver. 
 
 1. Branches of portal vein. 
 
 2. Branches of hepatic vein. 
 
 Plate XVII. 
 
 A. RIGHT KIDNEY and 
 SUPRA-RENAL BODY. 
 XII. Twelfth thoracic vertebra and 
 last rib. 
 I. II. III. Lumbar vertebras. 
 
 1. Kidney, external edge. 
 
 2. Capsule. 
 
 3. Surrounding adipose tissue. 
 
 4. Supra-renal body. 
 
 5. Ureter. 
 
 6. Abdominal aorta. 
 
 7. Renal arteries. 
 
 8. Supra-renal arteries. 
 
 9. Vena cava inferior. 
 
 10. Renal veins. 
 
 11. Supra-renal veins. 
 
 B. LEFT KIDNEY, Longi- 
 tudinal Section. 
 
 D. 
 
 4. 
 
 12. CaUces. 
 
 1 3. PapiUa; with openings of ducts. 
 
 14. Medulla ; pyramids formed of 
 
 the tubules. ■'''• 
 
 15. Boundary of cortical and me- 
 
 dullary portions. 
 
 16. Cortex with Malpighian bodies 
 
 and commencement of uri- 1- 
 nary tubules. 2. 
 
 17. Pelvis. 
 
 3. 
 4. 
 C. STRUCTURE of KIDNEY, 
 somewhat diagrammatic 
 
 5. 
 
 AND SIMPLIFIED. 
 
 1. Branches of renal artery. 7, 
 
 2. The glomeruli (Malpighian 8, 
 
 bodies). 9, 
 
 3. Branches of renal vein. 10. 
 
 Uriniferous tubules, with di- 
 lated ends forming the cap- 
 sules of the glomeruli. 
 
 Looped tubules (of Henle) 
 running down in pyramids. 
 
 Contorted portion of tubules. 
 
 Straight tubules running down 
 to form the pjTtimids and 
 open on their apices. 
 
 Capsule. 
 
 URINARY TUBULES, con- 
 siderably ENLARGED. 
 
 Renal arteriole. 
 
 Urinary tubule, surrounding a 
 bundle of capillaries (a glo- 
 merulus), and showing renal 
 venule leaving the capsule. 
 
 Commencement of a tubule, 
 covered like the glomeruli 
 with cells. 
 
 PAROTID GLAND, dissect- 
 ed OUT, AND the Vesicles 
 somewhat magnified. 
 
 Parotid gland. 
 
 Accessory parotid, rarely pre- 
 sent. 
 
 Steno's duct. 
 
 Its orifice in the mouth on the 
 inner side of the buccinator 
 muscle. 
 
 Gland vesicles. 
 
 Masseter muscle. 
 
 Buccinator muscle. 
 
 Stemo-mastoid muscle. 
 
 Trapezius muscle. 
 
 Facial nerve (VII.) 
 
24 
 
 IXDEX TO THE PLATES. 
 
 Plate XVIII. 
 
 A. LOXGITl'DIXAL SECTION" 
 
 THROUGH MIDDLE OF HEAD 
 AND NECK. 
 
 a-g. Cervical Tertebne. 
 I. II. III. Dorsal vertebrae. 
 
 Brain. 
 
 1. Frontal lobe 1 of the 
 
 2. Parietal low Cerebrum. 
 
 3. Occipital lobeJ 
 
 4. Corpus callosum. 
 
 5. Placed on one of the optic 
 
 th.ilami which form the 
 lateral boundaries of the third 
 ventricle. 
 
 6. FoniL'f (which consists of white 
 
 nerve matter). 
 
 7. Pituitary body. 
 
 8. Corpora albieantia. 
 
 9. Aqueduct of Syh-ius. 
 
 10. Cerebral pedmicles, or crura 
 
 cerebri 
 
 11. Pons varolii. 
 
 12. Medulla oblongata. 
 
 13. Arbor vita;. 
 
 14. Cerebellum. 
 
 15. CaniU of spinal cord. 
 
 16. Openings for spinal nerves. 
 
 Nasal Cavity. 
 
 il7. Nasal bone. 
 18. Suj>erior turbinate bone. 
 19. Middle turbinate bone. 
 20. Inferior turbinate bone. 
 
 Oral Cavity. 
 f 21. Hard palate. 
 I 22. Soft palate and uvula. 
 
 23. Inferior maxillary bone. 
 
 24. Median septum of tongue. 
 J 25. Lingualis muscle. 
 
 26. Genio-hyo-glossus muscle. 
 
 27. Genio-hyoid muscle. 
 
 28. Hyoid bone. 
 
 29. Frenum lingua. 
 t.30. TousiL 
 
 Pharyxx axd Lary>"X. 
 
 31. Back opening of nose. 
 
 32. Eustachian tube. 
 
 33. Epiglottis. 
 
 34. Kima glottidis. 
 
 35. Thyroid cartilage. 
 
 36. Arytenoid cartilage 
 
 37. Cricoid cartilage 
 
 38. Trachea. 
 
 39. Thyroid gland. 
 1 40. Pharj-nx. 
 
 41. (Esophagus. 
 
 42. Sternum. 
 
 B. LARYNX— From is Front. 
 
 1. Body of hyoid bone. 
 
 2. Greater comua of hyoid bone. 
 
 3. Lesser comua of hyoid bone. 
 
 4. Epiglottis. 
 
 5. Thyroid cartilage. 
 
 a. Superior comu. 
 
 b. Inferior comu. 
 
 6. Cricoid cartilage. 
 
 7. Tracheal rings. 
 
 C. L.VPiYNX — From one side. 
 
 1. Left ala of tlijToid. 
 
 a. Comu. 
 
 b. Anterior edge with section 
 
 of the rightala (removed). 
 
 2. Cricoid. 
 
 3. Right arytenoid. 
 
 4. Right cuneifomi cartilage. 
 
 5. Right Snntorini's cartilage. 
 
 6. Articulating surface of lower 
 
 cornu of the right ala. 
 
 7. Tracheal cartilages. 
 
 8. Crico-thjToid muscle tensor of 
 
 vocal cords (cut). 
 
 9. TlijTo-epiglottic muscle (not 
 
 usually described). 
 
 10. Ary-epiglottic. 
 
 11. Transverse and obliijue ary- 
 
 tenoid muscle-s, which ap- 
 proximate the vocal cords. 
 
 12. Posterior crico-arytenoid, and 
 
 13. Thyio-arytenoid do the sjime. 
 
 14. Lateral crico-arytenoid — opens 
 
 the glottis by rotating the 
 arytenoid cartilages. 
 
 15. Membrane of trachea. 
 
 16. (Esophagus. 
 
 17. Epiglottis. 
 
 D. INTERNAL VIEW of AN- 
 
 TERIOR HALF OF LA- 
 RYN X — Seen from behind. 
 
 1. Root of tongue. 
 
 2. Epiglottis. 
 
 3. Prominence of thyroid. 
 
 4. False vocd cords. 
 
 5. True vocal cords. 
 
 6. Lower part of larynx. 
 
 7. Thyroid cartilage. 
 
 a. Right ala. 
 
 b. Left ala. 
 
 8. Cricoid cartilage. 
 
 9. Tracheal cartilage. 
 
 10. An"-epigIottic muscle. 
 
 11. Thyro-arytenoid do. 
 
 12. Hyoid bone. 
 
 E. LARYNX— From abo\-e. 
 
 1. Posterior waU of pharynx. 
 
 2. Pharyngeal cavity. 
 
 3. Ary-epiglotdc fold, with 
 
 4. Wrisberg's (or cuneiform) and 
 
 5. Santorini's cartilages. 
 
 6. Rima glottidis. 
 
 7. False vocal cords. 
 
 8. True vocal cords. 
 
 9. Prominence of epiglottis. 
 
 10. Epiglottis. 
 
 11. Middle glosso-epiglottic liga- 
 
 ment. 
 
 12. Root of tongue, 
 
 F. SECTION THKorcH the MU- 
 
 COUS MEMBRANE of a 
 VOCAL CORD. 
 
 1. Surface of flat epithelium. 
 
 2. Fibrous framework. 
 
 G. SECTION throcgh MUCOUS 
 
 MEMBRANE or A FALSE 
 VOCAL CORD, 
 
 1. Surface of cUiated epithelium. 
 
 2. Fibrous framework. 
 
 Plates XIX. and XX. 
 
 A. BRAIN. 
 
 B. SPINAL CORD. 
 
 1. Right frontal lobe. 
 
 2. Left frontal lobe. 
 
 3. Right temporal lobe. 
 
 4. Left temporal lobe. 
 
 5. Right half of cerebellum. 
 
 6. Left half of cerebellum. 
 
 7. Pituitary body. 
 
 8. Tuber cinereum. 
 
 9. Corpora albieantia 
 
 10. Optic chiasma (close by the 
 
 entrance of internal carotid). 
 
 11. Pons Varolii. 
 
 (Between III. and IV. are the 
 crura cerebri. ) 
 
 12. Medulla oblongata. 
 
 a. Pyramids. 
 
 b. Olivary bodies. 
 
 13. Vertebral arteries, entering the 
 
 foramen of the sixth cervical 
 vertebra, and uniting to form 
 one trunk at the edge of the 
 pons Varolii. 
 
 14. Spinal cord. "| 
 
 15. Dura mater laid I ^.r^hUmB. 
 
 0Fnatl:,6. Ljembranes. 
 
 16. Arachnoid. 
 
 17. Pia mater. J 
 IS. Cauda equina. 
 
 19. Bracliial plexus. 
 
 20. Sciatic and lumbar plexus. 
 
 21. Section of medulla at (a, b) 
 
 (References as to 12.) 
 
 22. Section of cord between the 
 
 fifth and sixth cervical verte- 
 bne. 
 
 23. Section of cord between fifth 
 
 and SLxth dorsal vertebne. 
 
 24. Section of cord between third 
 
 and fourth lumbar vertebne. 
 
 25. Section of the nerves. 
 
 Cranial Nerves. 
 I. Olfactorv nerve and bulb. 
 II. Optic. 
 
 III. Oculo- motor (moving the 
 
 eye). 
 
 IV. Trochlear (goes to the 
 
 superior oblique muscle of 
 the eye). 
 V. Trigeminal (so called because 
 it arises by three roots : it 
 supplies gustatory nerves 
 to the tongue). 
 VI. Abducens (goes to the ex- 
 ternal rectus muscle of the 
 eve). 
 VII. Facial. 
 VIII. Auditory. 
 IX. Glosso-pharyngeal (nerve of 
 the tongue ; also supplies 
 the pharynx with motor 
 fibres). 
 X. Vagus, or pneumogastric, 
 sends filaments to heart, 
 lungs, liver, and stomach. 
 XI. Spinal accessory ; motor 
 nerve of muscles of neck. 
 XII. Hypoglossal, motor nerves of 
 the tongue. 
 
 Spinal Nerves. 
 I.-VIII. Cervical nerves. 
 IX.-XX. Dorsal nerves. 
 XXI.-XXV. Lumbar nerves. 
 XXVI.-XXXI. Sacral nerves. 
 
 C. BASE OF SKULL, with the 
 
 NERVES LEAVING IT, AND 
 
 VENOUS SINUSES. 
 
 1. Anterior cerebral fossa, for 
 
 frontal lobes. 
 
 2. iliddle.fortemporosphenoidal. 
 
 3. Posterior, for cerebellum. 
 
 4. Venous sinuses. 
 
 5. Internal carotid. 
 
 E. RIGHT NASAL CAVITY, 
 
 WITH SEPTUM REMOVED. 
 
 Expansion of NASAL 
 NERVE ON the Wall op 
 the Right Nostril. 
 
 1. Superior meatus, between the 
 
 superior and middle turbin- 
 ated bones. 
 
 2. Middle, between middle and 
 
 inferior. 
 
 3. Inferior, between inferior and 
 
 floor. 
 
 4. Orifice of antrum of Highmore. 
 
 5. Frontal lobes of brain. 
 
 6. Corpus callosum. 
 
 7. Olfactory bulb, spreading into 
 
 fiilaments which pass through 
 the ethmoid bone into the 
 nasal cavities. 
 
 8. Branches of olfactory nerve in 
 the mucous membrane. 
 
 Meckel's ganglion — connected 
 by filaments with the second 
 division of the trigeminus 
 (XXIV. 0, II. 14) and the 
 sympathetic. 
 
 Nerve for mucous membiane 
 of pharynx. 
 
 For that of nose. 
 
 Posterior palatine. 
 
 Anterior palatine. 
 
 Nerve for incisor teeth. 
 
 Nasal branch of ophthalmic 
 nene, which is a part of the 
 fifth cranial nerve (Plate 
 XXIV. C, I. 4, 5). 
 
 Frontal sinuses. 
 
 Sphenoidal sinuses. 
 
 I. 
 
 II. 
 
 III. 
 
 IV. 
 
 V. 
 
 VI. 
 
 VII. 
 
 VIII. 
 
 IX. 
 
 X. 
 
 XI. 
 
 XII. 
 
 XIII. 
 
 Olfactory nerve. 
 
 Optic. 
 
 Oculo-motor. 
 
 Trochlear. 
 
 Trigeminal. 
 
 Abducens. 
 
 Facial. 
 
 Auditory. 
 
 Glosso-pharyngeal. 
 
 Vagus. 
 
 Spinal accessory. 
 
 Hypoglossal. 
 
 Spinal cord. 
 
 P. CARTILAGES OF NOSE— 
 Seen from Right Side. 
 
 1. Nasal bone. 
 
 2. Frontal bone. 
 
 3. Cartilaginous septum. 
 
 4. Triangular cartilages. 
 
 5. Alar cartilages. 
 
 6. Sesamoid cartilages. 
 
 7. Integument. 
 
 8. Naso-lachrvmal duct (Plate 
 
 XXIV. D, 9). 
 
 G. CARTILAGES of NOSE— 
 Seen from is Frost. 
 
 1. Nasal bone. 
 
 2. Frontal bone. 
 
 3. Cartilaginous septum. 
 
 4. Triangular cartilages. 
 
 5. Alar cartilages. 
 
 6. Sesamoid cartilages. 
 
 7. Superior maxillary. 
 
 H. NASAL CAVITIES— 
 In Section. 
 
 1. Superior turbinate bone. 
 
 2. Middle hirbinate bone. 
 
 3. Inferior turbinate bone. 
 
 4. Ethmoid cells. 
 
 5. Antrum of Highmore. 
 
 6. Superior 1 
 
 7. Middle > meatus. 
 
 8. Inferior ) 
 
 9. Septum. 
 
 10. Ethmoid bone, with apertures 
 
 for olfactory nerve fibres. 
 
 11. Hard palate. 
 
 12. Soft palate. 
 
 D. NERVE-FIBRES, magnified. J. OLFACTORY CELLS. 
 
 Plate XXI. 
 
 A. TONGUE— Upper Surface. 
 
 1. Greater comua of hyoid bone. 
 
 2. Epiglottis. 
 
 3. Root of tongue. 
 
 4. Mucous glands. 
 
 5. Foramen csecum. 
 
 6. Papill* circumvallatse. 
 
 7. Papilla filifonnes. 
 
 S. Papillae fiingiformes. 
 9. Palato-glossus muscle. 
 10. Glosso-pharyngeal nerve. 
 
 B. TONGUE— Lower SrRFACE. 
 
 1. Hyoid bone. 
 
 2. Hyoglossus muscle (depressor 
 
 of tongue). 
 
INDEX TO THE PLATES. 
 
 8. Genio-hyo-glossU8, depressinj 
 and protruding. 
 
 4. Stylo-glossus, withdrawing thi 
 
 tongue. 
 
 5. Thyro-liyoid muscle. 
 <5. Submaxillary gland. 
 
 7. Sublingual gland. 
 
 8. Wharton's duct. 
 
 9. Sublingual fossa. 
 
 10. Kuhn's gland. 
 
 11. Ranine artery. 
 
 12. Hypoglossal nerve. „.,™„.. 
 
 1 3. Gustatory nerve (from the third 1 5. intmial' root s"heath' 
 
 branch of trigeminus (XXIV. 16. Cortex of hair. 
 ,, r,?' ^''- ^*''- 17. Medulla. 
 
 14. t.losso-phiiryngeal nerve, Sen- 18. Hair-bulb. 
 
 sory, IXth cranial. 19. Papilla; of hair, 
 
 15. Frenuni linguie, with a fold of 20. Hair, 
 mucous membrane on each 21. Fat-celle. 
 
 6. Sudoriferous glands (which are 
 in nature surrounded by a 
 capillary network). 
 
 7. Thoir ducts, 
 
 8. Sebaceous gland. 
 
 9. Its duct. 
 
 10. Museulus erector pili. 
 
 11. Longitudinal fibrous tissue 
 fibres. 
 
 12. Transverse ones. 
 
 13. Hair sac. 
 
 1 4. External root sheath. 
 
 side. 
 
 22. Arteries. 
 
 23. Veins. 
 
 C. VERTICAL LONGITUDINAL 
 
 SECTION THROUGH the p. TACTILE CORPUSCLES 
 
 END-ORGANS of TASTE. 
 
 Diagrammatic. 
 
 1. Fungiform papillse. 
 
 2. Filiform papill*. 
 
 3. A circumvallate papilla. 
 
 Highly magnified. 
 
 1. Rete Malpighi with pigment 
 cells. 
 
 2. Fibres of corium. 
 
 3. PapUhe of corium. 
 
 4. Simple papilla (similar to those 4. Tactile corpuscles with nuclei. 
 5. Nerve fibres, surrounding the 
 corpuscles. 
 
 of the organ of touch). 
 
 5. Glands. 
 
 6. Gustatory bulbs, or taste goblets. 
 
 7. Glosso-pharyngeal nerve ftla- q, HAIR- Diagrammatic and 
 
 Enlarged. 
 
 ments. 
 8. Filaments oflingual or gustatory 
 
 nerve (a branch originating 1. Hair sac of the root. 
 
 in the fifth nerve). 2. Sheath. 
 
 3. llembrane of the shaft. 
 D. TASTE GOBLETS with the 4. Cortex of shaft with pigment 
 
 CELLS HIGHLY magnified. cells. 
 
 1. Taste goblet in the wall of a ^- ^^'^""''' ^*'' "'^"^ ''•^^ °^ ^^^^ 
 
 circumvallate papUla, closed 
 at top. 
 
 2. The same, open, with taste cells 
 
 (nervous). 
 3-9. Various forms of taste cells. 
 
 E. 
 
 H. SECTION THROUGH THE TOP 
 
 OF THE THUMB, showing 
 THE NAIL — Magnified. 
 1. Bone. 
 
 DIAGRAMMATIC SECTION ^- *^''*''\* "^ ^f^' ^^^°^ t'^^^^ 
 
 with vessels. 
 
 3. Margin of the bed. 
 
 4. Furrow of the bed. 
 
 5. Papillaj of the bed. 
 
 6. Layer of soft young cells. 
 
 7. Dark boundary layer. 
 
 8. Cutieular layer. 
 
 OF HUMAN SKIN. 
 Epidermis. 
 Rete iilalpighi. 
 PapUlfe with capillary loops. 
 Tactile corpuscles. 
 
 5. Nerve threads. 
 
 Plate XXII. 
 
 A. DIAGRAMMATIC TRANS- 
 VERSE VERTICAL SEC- 
 TION THROUGH THE HEAD. 
 
 a. Through the Brain 
 between the anterior and 
 middle thirds of the Corpus 
 Callosum. 
 
 1. Parietal lobes. 
 
 2. Temporal lobes. 
 
 3. Corpus caUosum. 
 
 4. Fornix. 
 
 5. Corpus striatum. 
 
 6. Thalamus opticus. 
 
 7. Lenticular nuclei. 
 
 8. Claustrum. 
 
 9. Sylvian fissure, which separates 
 
 the anterior and middle lobes 
 of the cerebrum. 
 
 10. Lateral ventricle. 
 
 11. Third ventricle. 
 
 12. Pituitary body. 
 
 h. Ear. 
 
 13. Pinna or outer ear. 
 
 14. External auditory meatus with 
 
 hairs and ceruminous glands. 
 
 15. Osseous portion of same. 
 
 16. Membrana tympani. 
 
 17. Auditory ossicles, malleus, 
 
 incus, and stapes. 
 
 18. Middle ear or tympanic cavity. 
 
 19. Cochlea. 1 labyrinth 
 
 20. Vestibule. \ or inter- 
 
 21. Semicircular canals. ) nal ear. 
 
 22. Auditory nerve. 
 
 23. Eustachian tube. 
 
 c. Oral Cavity. 
 
 24. Soft palate. 
 
 25. Uvula. 
 
 26. Arches enclosing entrance, 
 
 27. Tonsils. 
 
 28. Section of tongue. 
 
 29. Parotid gland, 
 
 30. SubmaxiUary gland. 
 
 31. Sublingual gland. 
 
 B. AUDITORY OSSICLES- 
 Magnified. 
 
 a. Malleus. 
 
 1. Head. 
 
 2. Neck. 
 
 3. Handle. 
 
 4. Long process. 
 
 5. Short process. 
 
 b. Incus. 
 
 1. Short process. 
 
 2. Long process. 
 
 3. Body. 
 
 4. Orbicular bone. 
 
 C. STAPE.S. 
 
 1. Head. 
 
 2. Legs, 
 
 3. Footplate. 
 
 C. LABYRINTH— Opened. V- 
 
 1. Fenestra rotunda. 
 
 2. Scala tympani. 
 
 3. Scala vestilnili (the figure is 
 
 placed on the lamina spiralis). 
 
 4. Cupola. 
 
 5. Vestibule. 
 
 6. Fovasa hemi- 'i „ . . 
 
 spherica. / Hepressions in 
 
 7. Fovffia hemi- r'^^T' o'^tl'^ 
 
 elliptica, ) vestibule, 
 9. Superior semicircular canal. 
 
 10. Inferior semicircular canal. 
 
 11. Exterior semicircular canal. 
 
 D. COCHLEA-Opened, V. 
 
 1. Seala tympani. 
 
 2. Scala media. 
 
 3. Scala vestibuli. 
 
 4, Lamina spiralis ossea, 
 
 5, Membrana basilaris, 
 
 6, Reissner's membrane. 
 
 7, Nerve of the cochlea. 
 
 8, C'upola. 
 
 CORTI'S ORGAN. Diagram- 
 matic. 
 Scala tympani. 
 Scala media. 
 Scala vestibuli. 
 Lamina spiralis ossea. 
 Basilar membrane. 
 Reissner's membrane. 
 Cochlear nerve. 
 Zona denticulata. 
 Corti's membrane. 
 Spherical cells. 
 Inner row of Corti's rods. 
 External row of Corti's rods. 
 Innerganglion cells — hair cells. 
 Membrana reticulata, 
 Corti's hair cells, 
 Deiter's supporting cells. 
 Cells of Claudius. 
 Ligamentum spirale. 
 
 Plate XXIII. 
 
 A. The Two EYES from above, 
 WITH their vessels and 
 MUSCLES. 
 
 1. Optic chiasma. 
 
 2. Rectus superior muscle. 
 
 3. Rectus inferior muscle. 
 
 4. Rectus externus muscle. 
 
 5. Rectus internus muscle. 
 
 6. Superior oblique muscle. 
 
 7. Inferior oblique muscle. 
 
 8. Lachrymal gland. 
 
 9. Section of eyelid. 
 
 10. Internal view of eyelid, 
 
 11. Ophthalmic artery, 
 
 12. Lachrymal artery. 
 
 13. Arteria centralis retinse. 
 
 14. Ciliary arteries. 
 
 15. Supra-orbital arteries. 
 
 16. Frontal arteries. 
 
 17. Ethmoidal arteries — anterior 
 
 and posterior. 
 
 B. TRANSVERSE SECTION of 
 AN EYE. Left Side show- 
 ing VESSELS ; Right, re- 
 lative Thickness of the 
 LAYERS. Diagrammatic. 
 
 1. Sclerotic. 
 
 2. Cornea. 
 
 3. Choroid, 
 
 4. Iris. 
 
 5. Retina, 
 
 6. Anterior chamber, 
 
 7. Posterior chamber. 
 
 8, Pupil, 
 
 9, Crystalline lens, 
 
 10, Vitreous body, 
 
 11, Ciliary muscle, 
 
 12, Canal of Petit, 
 
 13, Optic nerve, 
 
 14, Macula lutea, 
 
 15, Internal and external sheaths 
 
 of optic nerve. 
 
 16, Tenon's fascia. 
 
 17, Conjunctiva, 
 
 18, Descemet's membrane. 
 
 19, Canal of Schlemm. 
 
 20, Tnnica Rnyschiana (or middle 
 
 vascular layer of the choroid). 
 
 21, External rectus. 
 
 C, SECTION through the En- 
 trance OP the OPTIC 
 NERVE. 'f». 
 
 1. Optic nerve. 
 
 2. Arteria centralis retinse. 
 
 3. Edges of the optic disc. 
 
 4. Sheath. 
 
 5. Sclerotic. 
 
 6. Choroid, 
 
 7. Retina, 
 
 a. Nerve fibre layer, 
 
 I. Ganglionic layer, 
 
 c. Internal granular layer. 
 
 d. Internal nuclear layer. 
 
 e. External granular layer. 
 /. External nuclear layer. 
 (/. Layer of rods and cones. 
 
 Plate XXIV. 
 
 A. LAYERS of the RETINA- 
 A'eky greatly enlarged, 
 
 1, Internal limiting membrane, 
 
 2, Nerve fibre layer, 
 
 3, Ganglion cell layer, 
 
 4, Internal granular layer. 
 
 5, Internal nuclear layer, 
 
 6, External granular layer. 
 
 7, External nuclear layer. 
 
 8, External limiting membrane. 
 
 9, Rods and cones. 
 
 10. Pigment layer (generally de- 
 scribed as the internal layer 
 of the choroid coat). 
 
 B. SECTION through the Junc- 
 tion OF THE CORNEA and 
 SCLEROTIC. *r 
 
 1. Anterior chamber. 
 
 2. Posterior chamber 
 
 3. Lens. 
 
 4. A''itreous body. 
 
 5. Corpus ciliare. 
 
 6. Ciliary muscle. 
 
 7. Fontana's spaces. 
 
 8. Schlemm's canal. 
 
 9. Sclerotic. 
 
 10. Cornea. 
 
 11. Iris. 
 
 12. Conjunctiva, 
 
 13. Epithelium, 
 
 C. NERVUS TRIGEMINUS 
 AND ITS Most Important 
 
 BRANCHES, 
 
 I, First Br.\nch (Sen.?oryl, 
 
 1, Frontal, 
 
 2, Supra- orbitaL 
 
 3, Lachrymal, 
 
 4, Infratrochlear, 
 
 5, Nasal. 
 
IXDEX TO THE PLATES, ETC. 
 
 II. Sec»sd Buasch ^Sensory). 
 
 6. Temporo-malar. 
 
 7. Buccal. 
 
 8. lufraorbital. 
 
 9. Xasal, and to upper lip. 
 
 10. Sui>erior anterior deutal. 
 
 11. Boclidaleh's ganglion. 
 
 1 2. Posterior dental. 
 
 IS. Nerve to wisdom tooth. 
 1 4. Meckel's ganglion. 
 
 III. Chiefly Motor Xerves for 
 Muscles of Mastication and 
 
 for the Articulation of the 
 lower Jaw. The following 
 are mainly sensory : — 
 
 16. Lingual or gustatory. 
 
 17. Subniaxillaiy ganglion. 
 
 IS. Nerves for teeth of lower 
 jaw. 
 
 19. Inferior mental. 
 
 20. Labial. 
 
 21. NeiTO for the external rectus 
 
 musde (IV. cranial). 
 
 22. Ciliary ganglion. 
 
 23. Optic nerve (II. cranial). 
 
 D. PROTECTIVE STRUCTURES 
 
 OF THE EYE AND THE 
 
 LACRYMAL APPARATUS 
 
 Somewhat enlarged. 
 
 1. Upper eyelid, with eyelashes. 
 
 2. Lower eyelid (skin and muscle 
 
 removed to show the Meibom- 
 ian glands and their open- 
 ings on the edge of the 
 lids). 
 
 3. Lachrymal glands with their 
 
 ducts. 
 
 4. Plica semilunaris. 
 
 5. Caruncula lachrymalis. 
 
 6. 7. Canaliculi with the puncta 
 
 laolirymalia. 
 
 8. Lachrymal sac. 
 
 9. Lachi'ymal duct. 
 
 E. VERTICAL SECTION 
 
 THROUGH THE UPPER EYE- 
 LID — Enlarged. 
 
 1. Levator palpebra; superioris 
 
 muscle. 
 
 2. Fat tissue, with smooth mus- 
 
 cular fibres. 
 
 3. Meibomian glands. 
 
 4. Conjunctiva. 
 
 5. Sudoriparous glands of the 
 
 corium (external skin). 
 
 6. Hairs of the corium. 
 
 7. Sebaceous glands of the corium. 
 
 INDEX TO THE LETTERPKESS. 
 
 Adipose tisstte, 1. 
 Amoeba, 2. 
 Anatomy, 3. 
 Aorta, 6, 12. 
 Arteries, 5, 6, 12, 17. 
 Auricles, 5, 7. 
 Axis and atlas, 3. 
 Axis-cylinder, 13. 
 
 Basilar membrane, 17. 
 BUe, 11. 
 Blood, 7. 
 
 circulation of, 6. 
 
 vessels, 5. 
 Bones, 2-3, 16, 17. 
 Brain, 13-14. 
 Breathing, 8. 
 Bronchial tubes, 8. 
 
 CANALICULr, 2. 
 Capillaries, 6. 
 Carbon 1, 8. 
 Carbonic acid gas, 8. 
 Cartilage, 2, 3. 
 Centres of ossification, 3. 
 CeUs. 2, 11, 13. 
 Cerebrum, 14. 
 Cerebellum, 15. 
 Chordae tendinse, 5. 
 Ciliary processes, 18. 
 Cochlea, 17. 
 Connective tissue, 2. 
 Conjunctiva, 18, 19. 
 Colon, 10. 
 Csecum, 10. 
 Cornea, 18. 
 Corpuscles, blood, 7. 
 nerve, 13. 
 Crystalline lens, 18. 
 
 Diaphragm, 8. 
 Digestion, 9. 
 Daodenum, 10. 
 
 Ear, 16-18. 
 Elastic tissue, 9. 
 
 Endocardium, 5. 
 Epiphyses, 3. 
 Epithelium, 2, 12. 
 Eustachian tube, 16. 
 Excretion, 11. 
 Expiration, 8. 
 Eye, 18. 
 
 Fenestra of ear, 17, IS. 
 Fibres, muscle, 4. 
 nerve, 13. 
 Fibrin, 7. 
 Fontanelles, 3. 
 Force, vital, 1, 8. 
 Fornix, 14. 
 
 Ganglia, 13. 
 
 Gastric juice, 10. 
 
 Gelatine, 3. 
 
 Glands, 9, 10, 12, 13, 19. 
 
 Gustatory bulbs, 16. 
 
 Haversian canals, 2. 
 Heart, 5. 
 Heat, animal, 8. 
 Hepatic duct, etc., 11. 
 Hydrochloric acid, 10. 
 Hydrogen, 1, 8. 
 
 Ileum, 10. 
 Intestines, 10. 
 Inspiration, 8. 
 Iris, 18. 
 
 Jejunum, 10. 
 Joints, 3. 
 
 Kidneys, 12. 
 
 Lachrymal glands, 19. 
 Lacteals, 10. 
 Lacunae, 2. 
 Ligaments, 3. 
 
 Liver, 11. 
 Lungs, 7. 
 Lymphatics, 10. 
 
 Medulla oblongata, 14. 
 Membrane, 2, 7, 9. 
 Mesentery, 11. 
 Microscope, 1. 
 Muscles, 3-4, 9, 19. 
 
 Nervous system, 13-15. 
 
 force, 15. 
 Nerve-matter, 13. 
 Nerves, cranial, 15, 16, 17, 19. 
 
 spinal, 15. 
 
 sympathetic, 14. 
 Nucleus, 2. 
 Nitrogen, 1, 9. 
 Nose, 16. 
 
 Odontoid process, 3. 
 Oesophagus, 9. 
 Omenta, 9. 
 Optic thalami, 14. 
 chiasms, 15. 
 Oxygen, 1, 8. 
 
 Pancreas, 11. 
 Papillae of skin, 13. 
 
 tongue, 16. 
 Pelvis, 13. 
 Pepsin, 10. 
 Pericardium, 5. 
 Peritoneum, 9. 
 Peripheries of nerves, 15. 
 Perspiration, 13. 
 Peyer's patches, 10. 
 Physiology, 1. 
 Plasma, 7. 
 Pleurae, 7. 
 Protoplasm, 1. 
 Pylorus, 10. 
 
 Rectum, 10. 
 
 Reissner's membrane, 17, 18. 
 
 Respiration, 8. 
 
 Retina, 19. 
 
 Rods and cones, 19. 
 
 ScALiE of cochlea, 17. 
 
 Sclerotic, 18. 
 
 Semicircular canals, 17. 
 
 Skeleton, 2. 
 
 Skin, 13. 
 
 Skull, 3. 
 
 Smell (sense of), 16. 
 
 Sound, 17. 
 
 Spleen, 13. 
 
 Spine, 2, 3. 
 
 Spinal cord, 13, 15. 
 
 Stimulus, 5. ■ 
 
 Stomach, 9. 
 
 Sympathetic nerves, 14. 
 
 Taste (sense of), 16. 
 Teeth, 9. 
 Tendons, 4. 
 
 Tissues (elementary), 2. 
 Trachea, 8. 
 Thoracic duct, 10. 
 Thymus, 13. 
 Thyroid gland, 13. 
 
 cartilage, 16. 
 
 Urea, 12. 
 Ureters, 13. 
 
 Valves of heart, 5, 7. 
 
 veins, 5. 
 Vascularity, 2. 
 Veins, 6, 11, 12. 
 Ventricles, 5, 7. 
 Vertebrae, 2, 15. 
 Villi, 10. 
 Vital force, 1. 
 Vitreous humour, 18. 
 Voice, 16. 
 
 Windpipe, 8. 
 
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