that of the hog is marked with a few smooth lines. In other animals the stomach is less, not indeed much larger than the intestine, as the dog, lion, and man. In the forms of their bowels other animals are divided into two classes, resembling these types; for in some the stomach resembles a dog's, in others a hog's, both the greater and lesser animals in the same way; and the stomachs of various animals differ in size, form, thickness, thinness, and the position of the junction of the œsophagus.
[72] Felis onza, perhaps also canis aureus.
8. And the nature of the bowels differs in the before-named animals, those, namely, which have not, and those which have teeth in both jaws, in size, thickness, and folding. The intestines of the ruminants are all large, and so are the animals themselves; there are a few small animals of this class, and there is no horned animal which is very small. And some have appendages to the intestines, for none of the animals with teeth in both jaws have straight intestines. There are enlargements in the bowels of the elephant, which give it the appearance of having four stomachs; in these the food is detained, and apart from these there is no receptacle for the food. Its intestines are very like those of the hog, except that the liver is four times greater than that of the ox, and other parts also; the spleen is small in proportion to its size.
9. The stomach and intestines of oviparous quadrupeds bear a similar proportion to each other, as in the land and marine tortoise, the lizard, and both kinds of crocodiles,[73] and similar quadrupeds; for they have one simple stomach, in some it is like that of the hog, in others like that of the dog.
[73] Crocodilus niloticus and Lacerta stellio.
10. The class of serpents in almost every part of their body resemble the saurians, which have feet, and are oviparous, if we add to their length, and take away the feet; for snakes are covered with scales, and have their upper and lower parts like saurians, except that they have no testicles, but, like fish, two passages united in one, and a large and cloven uterus, but in other respects their intestines are so like those of saurians, except that from their elongated figure their intestines are long and narrow, that they might be mistaken for them, from their similarity.
11. For the trachea is very long, and the œsophagus still longer, and the commencement of the trachea is close to the mouth, so that the tongue appears to lie beneath it. The trachea appears to be above the tongue because this last can be retracted, and is not always in one position, as in other animals. Their tongue is long, thin, and black, and can be put forth for some distance. The tongue of serpents and saurians is distinct from that of all other animals, for the extremity of the tongue is cloven; this is most remarkable in serpents, for the extremities of their tongues are like hairs. The seal also has a forked tongue. The serpent has a stomach like a very wide entrail, like that of the dog, afterwards a very long and thin intestine, which is alike to its extremity.
12. Behind the pharynx is a small kidney-shaped heart, so that at times the apex does not appear to be directed towards the chest, next to this is a single lung, divided by a muscular passage, very long, and descending a long distance from the breast. The liver is long and simple, the spleen small and round, like that of the saurians. The gall resembles that of fish, in water serpents it is situated on the liver, in others generally upon the intestines. They all have pointed teeth, and as many ribs as there are days in the month, for they have thirty.
Some persons say that in one respect serpents resemble the young of the swallow, for if their eyes are pierced with a pointed instrument, they will grow again, and if the tails of serpents or lizards be cut off, they will be reproduced.
13. The same remarks will apply to the intestines and stomachs of fishes, for they have one simple stomach, but it differs in form, for in some fishes it is like a bowel, as in the one called scarus, and this is the only fish that appears to ruminate, and the size of the intestines is simple and folded together, for it can be resolved into one, by unfolding it. The appendages of the stomach appear to be peculiar to fishes and birds, for birds have them above the stomach, and few in number, but in fish they are above, and around the stomach. Some have many appendages, as the gobius,[74] galeus,[75] the cestreus has many on one side of the stomach, and only one on the other. Some have only a few, as the hepatus[80] and the glaucus,[81] and the chrysophrys[82] also has only a few, but some individuals differ from others, for one chrysophrys has many, another has only a few. There are some fish which have none of them, as most of the cartilaginous genera; others have a few, and some a great many, and all fish have these appendages very near the stomach itself.
[74] Gobio, gudgeon.
[75] Shark.
[76] Cottus scorpius.
[77] Probably Pleuronectes rhombus.
[78] Mullus surmulentus.
[79] Sparus maina.
[80] Theutis hepatus.
[81] Probably Gobio gozo.
[82] Sparus aurata.
14. Birds have their internal parts different from each other and from other animals; for some have before the stomach a crop, as the domestic fowl, pigeon, dove, and partridge. The crop is a large and hollow skin, into which the food is received before it is digested. Hence from the œsophagus it is narrower, then wider, and where it descends into the stomach it is smaller.
15. In most birds the stomach is fleshy and thick, and on the outside there is a strong skin, which is separated from the fleshy part. Some birds have no crop, but instead of it a wide œsophagus, either wholly so, or in the part extending to the stomach, as in the colœus,[83] raven, and crow. The quail has the lower part of the œsophagus broad, the ægocephalus has it small but wider, and so has the owl. But the duck, goose, gull, diver, and bustard, have a wide and broad œsophagus, and so have many other birds.
[83] Three kinds of birds are called by this name. Corvus graculus, C.
monedula, and Pelicanus graculus.
16. And some have a part of the stomach itself like a crop, as the cenchreis;[84] and there are some which have neither œsophagus nor a wide crop, but a large stomach; these are small birds like the swallow, and the sparrow. A few have neither a crop, nor a wide œsophagus, but a very long one; these are birds with a long neck, as the porphyrion.[85] Almost all these emit a moister excrement than other birds.
[84] Falco tinnunculus.
[85] Fulica porphyrion.
17. The quail has these peculiarities, for it has a crop, and before the stomach a wide and broad œsophagus. And the crop is at a great distance from the part of the œsophagus before the belly, considering the size of the bird. Birds have generally a small intestine, which is single when unfolded, and birds have appendages, a few, as I have said, and not placed above, as in fish, but below, near the end of the intestine. Some birds have not these appendages, though they generally have them, as the domestic fowl, partridge, duck, night-raven,[86] localus,[87] ascalaphus,[88] goose, bustard, owl. Some of the small birds have them, but they are very minute, as the sparrow.
[86] Ardea nycticorax.
[87] Some kind of heron.
[88] Some kind of owl.
BOOK THE THIRD.
CHAPTER I.
1. We have treated of the other internal parts of animals, their number, their nature and varieties. It now remains for us to speak of the organs of generation. In females these are always internal; but there is much difference in males, for some sanguineous animals have no testicles at all, in others they are internal; and in some animals with internal testicles, they are placed near the kidneys, in others near the abdomen; in other animals they are external. The penis of these last is sometimes united to the abdomen, in others it is loose as well as the testicles; but in promingent and retromingent animals it is suspended from the abdomen in a different manner. Neither fish nor any other animal with gills, nor the whole class of serpents, have testicles; neither has any apodal animal which is not internally viviparous.
2. Birds have testicles, but they are internal and near the loins, and so have oviparous quadrupeds, as the lizard, tortoise, and crocodile, and among viviparous animals, the hedgehog. In some viviparous animals they are situated internally upon the abdomen, as the dolphin among apodal creatures, and the elephant among quadrupeds. In other animals the testicles are external. It has been previously observed, that the manner and position of their junction with the abdomen is various, for in some they are joined on and do not hang down, as in swine, in others they hang down as in man.
3. It has also been observed that neither fishes nor serpents have testicles, but they have two passages hanging down on each side of the spine from the diaphragm, and these unite in one passage above the anus, by above, we mean nearer the spinal column. At the season of coition these passages are full of semen, which exudes on pressure; the differences among these may be seen by dissection, and in another place they will each be considered more particularly.
4. All oviparous animals, whether bipeds or quadrupeds, have their testicles placed in the loins below the diaphragm, some of a white colour, others ochreous, but in all surrounded with small veins; from each of these a passage is produced, which afterwards become united in one, and, as in fish, open near the anus. This is the penis, which is inconspicuous in small animals; but in the larger, as the goose and such like, it becomes more conspicuous immediately after coition.
5. And these passages, both in fish and other animals, are joined to the loins below the stomach and between the entrails and the great vein, from which passages proceed to each of the kidneys; and, as in fish, the semen may be seen entering them at the period of coition, when these passages become very conspicuous, but when this season is passed the passages again become invisible. So also the testicles of birds are either small or entirely invisible when not excited, but when urged by desire they become very large; this is so remarkable in pigeons and partridges, that some persons have supposed that they had no testicles during winter.
6. In some of those animals in which the testicles are placed forwards, they are internal and upon the abdomen, as in the dolphin; in others they are externally conspicuous upon the extremity of the abdomen.
These animals are similar in other respects, but differ in this, for in some the testicles are uncovered, and others that have external testes they are placed in a scrotum.
7. This is the nature of the testicles of all viviparous animals with feet: from the aorta, passages like veins proceed to the head of each testicle, and two others from the kidneys, these last are full of blood, but those from the aorta contain no blood. From the head of each testicle to the testicle itself, there proceeds a thicker and more muscular passage, which is in each testicle reflected back to the head of the testicle, and from this point they again unite upon the penis towards the fore-part of it.
8. And both these passages which are reflected back upon themselves, and those which are seated upon the testicles, are covered with the same membrane as the testes themselves, so that unless this membrane is taken away, they all appear to be one passage. These last passages, which are seated upon the testicle, contain sanguineous fluid, but less than those above from the aorta; but in the reflected passages of the duct which is upon the penis, the fluid is white. A passage also leads from the bladder, and is united to the upper part of this duct, which is enclosed in the part called the penis as in a husk. The accompanying diagram will illustrate the position of these parts.
9. The origin of the passage from the trachea, _a_; the head of the testes and the descending passages, _b b_; the passages which proceed from these, and are seated upon the testicle, _c c_; the reflexed passages which contain the white fluid, _d d_; the penis, _e_; the bladder _f_; the testicles, _g g_. But when the testicles are cut out or otherwise destroyed, the upper passages are retracted; in young animals castration is performed by bruising the testicles, in older animals by excision. And it has happened that a bull has begotten young if admitted to the female immediately after castration. This is the nature of the testicles of animals.
10. The uterus of the females that possess this organ is not of the same nature, nor alike in all, but they differ from each other both in viviparous and oviparous animals. The uterus is double in all those animals in which it is situated near the external organ of generation, one part lying on the right side, the other on the left, but the origin is one, and there is but one os uteri, which is like a very fleshy tube, and in most animals, especially those of a large size, it is cartilaginous. One part of this organ is called the uterus and delphys (whence the word adelphi, brothers), and the vagina and os uteri are called metra.
11. In all viviparous animals, whether bipeds or quadrupeds, the uterus is placed below the diaphragm, as in the human female, the bitch, sow, mare, and cow, and it is the same in all horned animals.
At the extremity of the uterus most animals have a convoluted part called the horns; these are not distinct in all oviparous animals; but in some birds they are placed near the diaphragm, and in some fishes below, as in the viviparous bipeds and quadrupeds. But they are thin, membranaceous, and long, so that in very small fish each part of the roe appears as one ovum, as if the fish which are said to have a crumbling roe had but two ova, for it is not one ovum but many, and therefore it may be resolved into many.
12. In the uterus of birds the vagina is below, fleshy and tough, but the part near the diaphragm membranaceous and very thin, so that the eggs appear to be outside the uterus. In large birds the membrane is more conspicuous, and if inflated through the vagina, it swells and enlarges at places; in small birds these parts are not conspicuous. The uterus of oviparous quadrupeds, as the tortoise, lizard, frog, and such like, is of the same nature, for the vagina below is one and fleshy, but the division and the ova are higher up and near the diaphragm.
13. In those apodal creatures which are outwardly viviparous and inwardly oviparous, as the sharks and selachea--[The selachea are apodal, furnished with gills, and viviparous]--the uterus is divided, and as in birds, it commences below and extends towards the diaphragm.
The ova are situated between the division, and above near the diaphragm; and the animal is produced from the ovum after this has descended into the open space.
14. The difference between the uteri of these fish and others may be studied more accurately in drawings of dissections. Serpents also differ much both among themselves and from other animals, for all serpents except the viper are oviparous; this one is viviparous, though at first internally oviparous, wherefore, in many respects, its uterus resembles that of the cartilaginous fishes. The uterus of the serpent is long, like the body, and descends downwards, beginning from one duct and continuing on either side of the spine as far as the diaphragm, as if each were a passage, in which the ova are placed in order; these ova are not extruded singly, but connected together like a chain.
15. In all animals that are either internally or externally viviparous, the uterus is situated above the abdomen; in all oviparous creatures it is placed below, near the loins. Those that are externally viviparous, but internally oviparous, partake of both characters, for the lower part in which the ova are situated is near the loins, the other part whence the ova are extruded above the intestines. And there is also this difference in the uteri of animals: those which have horns and not teeth in both jaws have cotyledons in the pregnant uterus, and some of those also with teeth in both jaws, as the hare, the mouse, and the bat. But other viviparous animals with teeth in both jaws, and with feet, have a smooth uterus. The embryo is not united to the cotyledon, but to the womb. This is the manner of the internal and external heterogeneous parts of animals.
CHAPTER II.
1. Of the homogeneous parts of animals, the blood is common to sanguineous animals; and so is the part in which it is contained, which is called a vein; analogous to these, in exsanguineous animals are the serum and the fibre. That which especially constitutes the body is flesh or its analogue: the bone and its analogue; the spine and the cartilage. Next to this we place the skin, membranes, sinews, hair, nails, and their analogue; after these, adeps, fat, and excrementitious matters; then are fæces, phlegm, and bile, both the yellow and the black.
2. But inasmuch as the blood and the veins seem to occupy the chief place, we will first of all speak of these, both for other reasons, and because former writers do not appear to have described them rightly.
The difficulty of understanding them is the reason of their errors, for in dead animals, the nature of the principal veins is obscure, for they collapse as soon as the blood has escaped, and it pours out of them as from a vessel. No part of the body, except the veins, contains any blood, except the heart, which has a little; but it is all in the veins. In living creatures their nature cannot be distinguished, for they are internal, and out of sight; so that those who consider them only in dead and dissected animals, cannot see their principal origins.
But some, by the examination of emaciated persons, have distinguished the origin of the veins, from the appearance of those which are external.
3. For Syennesis,[89] a Cyprian physician, speaks thus: "The larger veins are thus constituted. From the navel around the loins, through the back to the lungs, under the breasts; that from the right to the left, and that from the left to the right. That from the left, through the liver to the kidney and the testicle; that from the right to the spleen, the kidney, and the testicle, and from thence to the penis."
[89] Syennesis, a physician of Cyprus. Very little is known of him; he must have lived in or before the fourth century B.C.
4. Diogenes[90] of Apollonia writes thus: "The veins are thus placed in man. There are two very large ones, which extend through the stomach by the spine of the back, one to the right and the other to the left, each to the leg nearest itself, and upwards to the head by the collar-bone, and through the neck. From these great veins others extend through the whole of the body, from the right to the right side, and from the left to the left side. The largest are two from the heart, surrounding the spine of the back; and others, a little higher up, through the breasts under the arm-pits, each to the hand nearest itself; and the one is called the splenetic, the other the hepatic vein.
[90] Diogenes of Apollonia was an eminent natural philosopher of Crete, in the fifth century B.C. He wrote a work, περὶ φύσεως, in which he treated of natural philosophy in the widest sense of the words: a few fragments are still extant, of which this quoted by Aristotle is the longest.
5. "The extremity of these veins is divided, one branch goes to the thumb, and another to the wrist, and from these many small branches are extended upon each hand, and the fingers; and others, smaller still, branch off from these first veins, from the right side to the liver, from the left to the spleen and kidneys. The veins, which go to the legs, are divided near the junction, and extend through the whole thigh; but the largest of these extends to the back of the thigh, and appears thick; another, less thick, passes through the inside of the thigh, and afterwards veins extend by the knee to the leg and foot. As on the hands, they are distributed upon the tarsus of the foot, and from thence to the toes.
6. "A number of small veins are distributed on the stomach and the lungs. Those that extend to the head, through the jugular region, appear large in the neck. From the extremity of each of these many veins are distributed upon the head, some on the right side to the left, others on the left side to the right, they all end near the ear.
And there is a second vein upon the neck on each side, somewhat less than the other, to which the principal veins of the neck are united.
These pass inwards, through the neck, and from each of them veins pass beneath the shoulder-blade and to the hands; and near the splenetic and hepatic veins there appear others a little less, which they divide when any disease attacks the skin; but the hepatic and splenetic veins are divided for any disease in the neighbourhood of the stomach.
7. "Other veins pass from these, beneath the breasts; and there are other small ones, which proceed from each of these through the spinal marrow to the testicles, and others beneath the skin, through the flesh, reach the kidneys; in men they terminate upon the testicles, in women on the uterus. The first veins from the stomach are wider, and afterwards become smaller, until they pass over from the right to the left, and from the left to the right; these are called the spermatic veins. The thickest blood is beneath the flesh, but that which is in excess in these places becomes thin, and warm, and frothy." These are the opinions of Syennesis and Diogenes.
8. Polybus[91] writes thus: "There are four pair of veins, one from the back of the head through the neck, on the outside, near the spine on either side, as far as the thighs and the legs, afterwards through the legs to the ancles, on the outside, and to the feet. Wherefore, in complaints of the back and thigh, they divide the veins upon the poplitic region, or ancles, on the outside. Another pair of veins pass from the head, by the ears, through the neck, these are called the jugular veins; and others within, near the spine, lead by the loins to the testicles and the thighs, and through the poplitic region on the inside, and through the leg to the inner part of the ancle, and the feet; wherefore, in complaints of the loins and testicles, they bleed in the poplitic region and ancles.
[91] Polybus, a pupil of Hippocrates, a native of the island of Cos; he lived in the fourth century B.C. Many treatises on medical subjects are attributed to him.
9. "The third pair of veins, from the temple through the neck, and beneath the scapula, reach the lungs; those from the right to the left, under the breast, to the spleen and kidneys; and those from the left to the right side, from the lungs, under the breast, and liver, and kidney; and both end beneath the testicles. The fourth pair from the forepart of the head and the eyes, under the neck and collar-bones; from thence they extend through the humerus to the elbow, and through the cubitus to the wrist and the fingers, and through the lower part of the arm to the arm-pits, and the upper part of the lungs. The one reaches as far as the spleen, the other to the liver; afterwards they both pass over the abdomen to the pudendum."
CHAPTER III.
1. The opinions of other persons are nearly these; and there are other physiologists, but they have not treated so accurately of the veins.
But all agree in placing their origin in the head and brain, in which they are incorrect. But, as I have remarked before, it is difficult to discern the course of the veins; indeed, it is impossible to understand them unless a person will examine animals which, after emaciation, have been killed by strangulation. The following is the nature of the veins: There are two veins in the interior of the chest, near the spine; the larger of these is placed forward, the smaller is behind; the larger is inclined to the right side, the smaller to the left; and this by some persons is called the aorta, from the sinewy portion which is seen in dead animals.
2. These veins have their origin in the heart, for they pass completely through the other intestines, and always preserve the character of veins. The heart is, as it were, a part of them, and especially of the more forward and larger one, for these veins are above and below, and the heart is in the middle of them. The heart of all animals contains cavities, but in the heart of very small animals the largest cavity is scarcely perceptible, in moderately sized animals the second cavity is scarcely visible, but in large animals they are all three distinct enough. And when the apex of the heart is turned forwards, as I have observed, the principal cavity is on the right side, and above it the least is on the left side, and the middle-sized one is between them; the two smaller are far less than the greater.
3. All these are perforated towards the lungs, but imperceptibly so from the minuteness of the passage, except in one place. The great vein is suspended from the upper portion of the principal cavity, and on the right side; afterwards through the cavity a vein extends again, as if the vein were a part of the cavity in which the blood stagnates. The aorta has its origin from the middle cavity, but in a different manner from the vein, for it communicates with the heart by a much narrower passage, and the vein is continued through the heart. But the aorta passes from the heart, and the great vein is membranous and like skin, but the aorta is narrow and very sinewy, and as it is continued towards the head and the lower parts of the body, it becomes narrow and quite sinewy.
4. A portion of the great vein is first of all extended upwards from the heart to the lung, and to the junction of the aorta, this vein being undivided and large; from this place it divides into two branches, the one towards the lung, and the other to the spine and the lowest vertebra of the neck. The branch which goes to the lungs is first divided into two branches, and afterwards it is continued upon every tube and passage of the lungs, greater to the greater, and less to the less, so as to leave no part in which there is not a passage and a small vein. These last are invisible from their minute size, so that the whole lung seems to be full of blood.
5. And the passages from the vein are above the tubes which extend from the trachea. And the vein which is continued upon the vertebra of the neck, and upon the spinal column, returns again to the spine, as Homer writes in his poems: "He cut off the whole vein which passes up the back and returns again to the neck;"[92] and from this vein branches extend to each rib and to each vertebra; but that which is upon the vertebra near the kidneys branches in two directions. These branches, then, of the great vein are subdivided in this manner.
[92] Iliad. xiii. 546.
6. And above these, from that part which is continued from the heart, the whole is again divided into two directions, for some reach to the sides and the clavicles, and afterwards through the armpits to the arms, in the human subject, but in quadrupeds to the fore-legs, to the wings in birds, and to the pectoral fins in fishes. The commencements of these veins, when they are first of all divided, are called jugular veins; and having branched off in the neck from the great vein, they are continued to the trachea of the lungs. And if these veins are held on the outside, men fall down dead with insensibility, with closed eyes, but without choking.
7. Extending in this manner, and receiving the trachea between them, they reach the place where the jaws unite with the head; and again from this point they are divided into four veins, one of which bends backwards and descends through the neck and shoulder, and meets the first division of the vein by the joint of the arm; the other portion terminates in the hand and fingers; and another branch extends from each part near the ear to the brain, where it is divided into many small branches upon the membrane which surrounds the brain.
8. The brain never contains blood in any animal, nor does any vein, small or great, terminate upon it; but some of the other branches that extend from this vein surround the brain in a circle, and others, end upon the organs of sense and the teeth in very small veins. In the same manner, also, the branches of the smaller vein, which is called the aorta, are divided: they are continued beside those of the great vein, but the tubes are smaller and the branches less than those of the great vein.
CHAPTER IV.
1. The veins, then, are thus distributed in the parts above the heart, but the part of the great vein which is below the heart passes through the middle of the diaphragm, and is united to the aorta and spinal column by membranous flaccid passages. From this a short and wide vein passes through the liver, from which many similar branches extend to the liver, and disappear upon it. There are two branches of the vein, one of which terminates upon the diaphragm, and what is called the præcordia, the other returns through the arm-pit to the right arm, and unites with the other veins near the interior part of the elbow.
For this reason physicians treat certain diseases of the liver by venesection in this vein.
2. From the left of this there is a short and wide vein, which reaches to the spleen, and the branches of this vein are lost upon this organ, and another portion branching off in the same way from the left the great vein passes up to the left arm, except that the last-mentioned pass through the liver, but this one through the spleen. Other branches also separate from the great vein, the one to the omentum, the other to the pancreas; and from this many veins extend through the mesenterium, and all end there in one great vein, which passes through the whole intestine and the stomach, as far as the œsophagus; and many veins branch off from them around these parts.
3. Both the aorta and the great vein continue as far as the kidney each as a single duct; from this point they are more closely united to the spinal column, and are each divided into two parts, like the letter lambda (Λ), and the great vein is placed farther back than the aorta.
The aorta is more closely united to the spinal column, near the heart, and the junction is formed by small sinewy veins.
4. The aorta leaves the heart as a large hollow passage, but as it advances it becomes narrower and more sinewy. From the aorta, veins extend also to the mesenterium, like those from the great vein, but far inferior in size, for they are narrow and muscular. They terminate in small hollow muscular veins. No branch of the aorta extends to the liver and the spleen, but the branches of either vein extend to each hip, and both touch upon the bone. Branches reach the kidney both from the great vein and the aorta; they do not, however, enter the cavity, but are taken up in the substance of the kidney.
5. Two other strong and continuous passages reach from the aorta to the bladder, and others from the cavity of the kidney; but these do not communicate with the great vein. From the centre of each kidney a hollow sinewy vein passes through the other veins to the spinal column; first of all they disappear upon each hip, and then appear again in branches towards the hip; their extremities are distributed upon the bladder and penis in the male, and upon the uterus in the female; no branch of the great vein passes to the uterus, but many and thick ones reach it from the aorta.
6. From the aorta and great vein branches are distributed to the nates; at first they are large and hollow, afterwards they pass through the legs, ending upon the feet and toes; and others again pass through the nates and thighs, alternately from right to left, and they join with other veins below the knees.
7. The nature and origin of the veins are evident from this description. In all sanguineous animals, the nature and origin of the principal veins are the same, but the multitude of smaller veins is not alike in all, for neither are the parts of the same nature, nor do all possess the same parts. Nor are the veins equally apparent in all animals; but they are more manifest in those which have most blood, and in the largest creatures; but in those animals which are small, and have not much blood, either by nature or from excess in fat, they are not so easily investigated, for some of the passages are confused, like rivulets that are lost in beds of mud; and there are some animals which have but few, and these fibres instead of veins. The great vein is very conspicuous in all, even the smallest animals.
CHAPTER V.
1. The following is the nature of the sinews of animals. The origin of these, also, is in the breast, for there is a sinew in the principal cavity of the heart itself; and that which is called the aorta is a sinewy vein, for its terminations are always sinewy, for they are not hollow, and are extensible, like the sinews which end upon the bending of the bones: for it is not the nature of sinews to be continuous from one origin, like the veins, for the veins have the whole form of the body as in outline sketches, so that in emaciated subjects the whole mass appears full of veins, for the same place is occupied by veins in lean persons that in fat ones is flesh.
2. The sinews are drawn round the joints and flexures of the bones; but, if their nature were continuous, the continuation would be evident in emaciated persons. The principal parts of the sinews are around the part of the body appropriated to leaping, and this is called the poples. Another double sinew is the tendon of the neck, and the epitonus and the sinew of the shoulder, which aid in the support of the body. The sinews around the joints have not received any name, for all the bones where they are contiguous are bound together by the sinews.
3. And there are many sinews round all the bones; there are none in the head; but the sutures of the skull are adapted to each other. It is the nature of sinew to tear readily lengthwise, but across the fibre it is indivisible, and it is very extensible. The sinews are surrounded by a mucous, white, and gelatinous fluid, by which they are nourished, and from which they seem to derive their origin. The vein does not alter its form by combustion, but the sinew is entirely destroyed. Neither does it unite after division.
4. Numbness does not take place in those parts of the body which contain no sinews. The sinews are most abundant on the hands and feet, and on the ribs and shoulder-blades, and round the neck and arms. All sanguineous animals have sinews; but in those which have not jointed limbs, and are without feet and hands, the sinews are small and inconspicuous, so that in fishes they are most distinct near the fins.
CHAPTER VI.