The Politics of Aristotle

by Aristotle

  [15] Each vein of the other pair stretches from the region of the ear to the brain, and branches off in a number of fine and delicate veins into the so-called meninx which surrounds the brain. The brain itself in all animals is destitute of blood, and no vein, [20] great or small terminates there. But of the remaining veins that branch off from the last-mentioned vein some encircle the head, others end their courses in the organs of sense and at the teeth in exceedingly fine small veins.

  4 · And in like manner the parts of the lesser vein, designated the aorta, [25] branch off, accompanying the branches from the big vein; only that, in regard to the aorta, the passages are less in size, and the branches very considerably less than are those of the great vein. So much for the veins as observed in the regions above the heart.

  [30] The part of the great vein that lies underneath the heart extends, freely suspended, right through the midriff, and is united both to the aorta and the backbone by slack membranous passages. From it one vein, short and wide, extends through the liver, and from it a number of minute veins branch off into the liver and [35] disappear. From the vein that passes through the liver two branches separate off, of which one terminates in the diaphragm or so-called midriff, and the other runs up [514b1] again through the armpit into the right arm and unites with the other veins at the inside of the bend of the arm; and that is why when the surgeon opens this vein, the patient is relieved of certain pains in the liver; and from the left-hand side of it there extends a short but thick vein to the spleen and the little veins branching off it [5] disappear in that organ. Another part branches off from the left-hand side of the great vein, and ascends in the same way into the left arm; only that in the one case it is the vein that traverses the liver, while in this case it is distinct from the vein that runs into the spleen.

  Again, other veins branch off from the big vein; one to the omentum, and [10] another to the pancreas, from which vein run a number of veins through the mesentery. All these veins terminate in a single large vein, which extends along the entire gut and stomach to the oesophagus; about these parts many veins branch off. [15]

  As far as the kidneys, each of the two remaining undivided, the aorta and the big vein extend; and here they get more closely attached to the backbone, and branch off, each of the two, into a Λ shape, and the big vein gets to the rear of the aorta. But the chief attachment of the aorta to the backbone takes place in the [20] region of the heart; and the attachment is effected by means of minute and sinewy vessels. The aorta, just as it draws off from the heart, is a tube of considerable volume, but, as it advances in its course, it gets narrower and more sinewy. And from the aorta there extend veins to the mesentery just like the veins from the big vein, only that they are considerably less in magnitude; they are, indeed, narrow and [25] fibrous, and they end in delicate and complex fibre-like veinlets.

  There is no vessel that runs from the aorta into the liver or the spleen.

  From each of the two great blood-vessels there extend branches to each of the two flanks, and both branches fasten on to the bone. Vessels also extend to the [30] kidneys from the big vein and the aorta; only that they do not open into the cavity but into the body of the kidney. From the aorta run two other ducts to the bladder, firm and continuous; and there are other ducts from the hollow of the kidneys, in no way communicating with the big vein. From the centre of each of the two kidneys [35] springs a hollow sinewy vein, running along the backbone right through the narrow parts; by and by each of the two veins first disappears in its own flank, and soon [515a1] afterwards reappears stretching in the direction of the flank.11 The extremities of these attach to the bladder,12 and also in the male to the penis and in the female to the womb. From the big vein no vein extends to the womb, but the organ is [5] connected with the aorta by veins numerous and closely packed.

  Furthermore, from the aorta and the great vein at the points of branching there come other veins. Some of these run first to the groins—large hollow veins—and then pass on down through the legs and terminate in the feet and toes. And, again, another set run through the groins and the thighs, from right to left and [10] from left to right, and unite in the hams with the other veins.

  In the above description we have thrown light upon the course of the veins and their points of departure.

  In all sanguineous animals the case stands as here set forth in regard to the points of departure and the chief veins. But the description does not hold equally [15] good for the entire vein-system in all these animals. For, in point of fact, the parts are not identically situated in them all, nor do all animals have the same parts. Furthermore, things are not equally clear in all cases—they are clearest in the case of animals of considerable magnitude and supplied abundantly with blood. For in [20] little animals and those scantily supplied with blood, either from natural causes or from a prevalence of fat in the body, it is less easy to discover the arrangement; for in the latter of these creatures the passages get clogged, like water-channels choked [25] with mud; and the others have a few minute fibres instead of veins. But in all cases the big vein is plainly discernible, even in creatures of insignificant size.

  5 · The sinews of animals are arranged as follows. For these also the point of origin is the heart; for the heart has sinews within itself in the largest of its three [30] chambers, and the aorta is a sinew-like vein; in fact, at its extremity it is actually a sinew, for it is there no longer hollow, and is stretched like the sinews where they terminate at the jointings of the bones. Nevertheless, the sinews do not proceed in unbroken sequence from one point of origin, as do the blood-vessels.

  For the veins have the shape of the entire body, like a sketch of a mannikin; in [515b1] such a way that the whole frame seems to be filled up with little veins in very attenuated subjects—for the space occupied by flesh in fat individuals is filled with little veins in thin ones—whereas the sinews are distributed about the joints and the [5] flexures of the bones. Now, if the sinews were continuous, this continuity would be discernible in attenuated specimens.

  In the ham, or the part which controls the act of jumping, is an important system of sinews; and another sinew, a double one, is that called the tendon, and others are those brought into play when a great effort of physical strength is required; that is to say, the epitonos and the shoulder-sinews. Other sinews, devoid [10] of specific designation, are situated in the region of the flexures of the bones; for all the bones that are attached to one another are bound together by sinews, and a great quantity of sinews are placed in the neighbourhood of all the bones. But in the head there is no sinew; but the head is held together by the sutures of the bones.

  [15] Sinew is fissile lengthwise, but crosswise it is not easily broken, but admits of a considerable amount of tension. Around the sinews a liquid mucus is developed, white and glutinous, and they are sustained by it and appear to be composed of it. Now, vein may be cauterized, but sinew, when cauterized, is completely destroyed; [20] and, if sinews be cut asunder, the severed parts will not again cohere. A feeling of numbness is incidental only to parts of the frame where sinew is situated.

  There is a very extensive system of sinews connected severally with the feet, the hands, the ribs, the shoulder-blades, the neck, and the arms.

  All animals supplied with blood are furnished with sinews; but in the case of animals that have no flexures to their limbs, but are destitute of feet and hands, the [25] sinews are fine and inconspicuous; and so the sinews in the fish are chiefly discernible.

  6 · Fibres are intermediate between sinew and vein. Some of them are supplied with fluid, the lymph; and they pass from sinew to vein and from vein to [30] sinew. There is another kind of fibre that is found in blood, but not in the blood of all animals alike. If this fibre be left in the blood, the blood will coagulate; if it be removed, the blood does not coagulate. While, however, this fibrous matter is found in the blood of the great majority of animals, it is not found in the blood of the deer, the roe, the antelope, and some oth
er animals; and so the blood of these animals does not coagulate to the extent observed in the blood of other animals. The blood of the [516a1] deer coagulates to about the same extent as that of the hare: that is to say, the blood in either case coagulates, but not into a stiff substance, like the blood of ordinary animals, but only into a flaccid consistency like that of milk which is not subjected to the action of rennet. The blood of the antelope admits of a firmer consistency in [5] coagulation; for in this respect it resembles, or only comes a little short of, the blood of sheep. Such are the properties of vein, sinew, and fibrous tissue.

  7 · The bones in animals are all connected with one single bone, and are continuous with one another, like the veins and there is no instance of a bone standing apart by itself.

  In all animals furnished with bones, the backbone is the point of origin. The [10] spine is composed of vertebrae, and it extends from the head down to the loins. The vertebrae are all perforated, and, above, the bony portion of the head is connected with the topmost vertebrae, and is designated the skull. And the serrated lines on the skull are termed sutures. [15]

  The skull is not formed alike in all animals. In some animals the skull consists of one single bone, as in the case of the dog; in others it is composite in structure, as in man; and in the human species the suture is circular in the female, while in the male it is made up of three separate sutures, uniting above in three-corner fashion; and instances have been known of a man’s skull being devoid of suture altogether. [20] The skull is composed not of four bones, but of six; two of these are in the region of the ears, small in comparison with the other four. From the skull extend the jaws, constituted of bone. [Animals in general move the lower jaw; the river-crocodile is [25] the only animal that moves the upper one.]13 In the jaws is the tooth-system; and the teeth are constituted of bone, and are partly perforated, partly not; and this is the only kind of bone which it is impossible to grave with a graving tool.

  On the upper part of the course of the backbone14 are the collar-bones and the ribs. The chest rests on ribs; and these ribs meet together, whereas the others do not; [30] for no animal has bone in the region of the stomach. Then come the shoulder-bones, or blade-bones, and the arm-bones connected with these, and the bones in the hands connected with the bones of the arms. With animals that have forelegs, the bones of the foreleg resemble those of the arm in man.

  At the lower end of the backbone, after the haunch-bone, comes the hip-socket; [35] then the leg-bones, those in the thighs and those in the shins, which are termed limb-bones, a part of which is the ankle, while a part of the same is the so-called [516b1] plectrum in those creatures that have an ankle;15 and connected with these bones are the bones in the feet.

  Now, with all animals that are supplied with blood and furnished with feet, and are at the same time viviparous, the bones do not differ greatly one from another, but only in the way of relative hardness, softness, or magnitude. Again, in [5] one and the same animal certain bones are supplied with marrow, while others are destitute of it. Some animals might appear to have no marrow whatsoever in their bones—e.g. the lion—since they have marrow only in small amount, poor and thin, and in very few bones; for marrow is found in the thigh and arm-bones. The bones of [10] the lion are exceptionally hard; so hard, in fact, that if they are rubbed against one another they emit sparks like flint-stones. The dolphin has bones, and not fish-spine.

  Of the other animals supplied with blood, some differ but little, as is the case [15] with birds; others have systems analogous, as fishes; for viviparous fishes, such as the Selachia, are gristle-spined, while the ovipara have a spine which corresponds to the backbone in quadrupeds. This exceptional property has been observed in fishes, that in some of them there are found delicate spines scattered here and there throughout the fleshy parts. The serpent is similarly constructed to the fish; in other [20] words, his backbone is spinous. With oviparous quadrupeds, the skeleton of the larger ones is more osseous; of the smaller ones, more spinous. But all sanguineous animals have a backbone of either one kind or other: that is, composed either of bone or of spine.

  The other portions of the skeleton are found in some animals and not found in [25] others, but the presence or the absence of this and that part carries with it, as a matter of course, the presence or the absence of the bones. For animals that are destitute of arms and legs cannot be furnished with limb-bones; and in like manner with animals that have the same parts, but yet have them unlike in form; for in these animals the bones differ in the way of excess or defect, or in the way of analogy. So [30] much for the osseous systems in animals.

  8 · Gristle is of the same nature as bone, but differs from it in the way of excess or defect. And just like bone, cartilage also, if cut, does not grow again. In [35] terrestrial viviparous sanguinea the gristle formations are unperforated, and there is no marrow in them as there is in bones; in the selachia, however—for they are [517a1] gristle-spined—there is found16 in region of the backbone, a gristle-like substance analogous to bone, and in this there is a liquid resembling marrow. In viviparous animals furnished with feet, gristle formations are found in the region of the ears, in [5] the nostrils, and around certain extremities of the bones.

  9 · Furthermore, there are parts of other kinds, neither identical with, nor altogether diverse from, the parts above enumerated: such as nails, hooves, claws, and horns; and also, beaks, such as birds are furnished with—all in the several [10] animals that are furnished therewith. All these parts are flexible and fissile; but bone is neither flexible nor fissile, but frangible.

  And the colours of horns and nails and claw and hoof follow the colour of the skin and the hair. For according as the skin of an animal is black, or white, or of [15] medium hue, so are the horns, the claws, or the hooves, as the case may be, of hue to match. And it is the same with nails. The teeth, however, follow after the bones. Thus in black men, such as the Aethiopians and the like, the teeth and bones are white, but the nails are black, like the whole of the skin. [20]

  Horns in general are hollow at their point of attachment to the bone which juts out from the head inside the horn, but they have a solid portion at the tip, and they are simple in structure. In the case of the stag alone of all animals the horns are solid throughout, and ramify into branches. And, whereas no other animal is known to shed its horns, the deer sheds its horns annually, unless it has been castrated; and [25] with regard to the effects of castration in animals we shall speak hereafter. Horns attach rather to the skin than to the bone; which will account for the fact that there are found in Phrygia and elsewhere cattle that can move their horns as freely as their ears.

  Of animals furnished with nails—and all animals have nails that have toes, [30] and toes that have feet,17 except the elephant; and the elephant has toes undivided and slightly articulated, but has no nails whatsoever—of animals furnished with nails, some are straight-nailed, like man; others are crooked-nailed, as the lion [517b1] among animals that walk, and the eagle among animals that fly.

  10 · The following are the properties of hair and of parts analogous to hair, and of skin. All viviparous animals furnished with feet have hair; all oviparous animals furnished with feet have horn-like tessellates; fishes, and fishes only, have [5] scales—that is, such oviparous fishes as have the crumbling egg. For the lanky fishes, the conger has no such egg, nor the muraena, and the eel has no egg at all.

  The hair differs in the way of thickness and fineness, and of length, according to the locality of the part in which it is found, and according to the quality of skin on [10] which it grows. For, as a general rule, the thicker the hide, the harder and the thicker is the hair; and the hair is inclined to grow in abundance and to a great length in localities of the bodies hollow and moist, if the localities be fitted for the growth of hair at all. The facts are similar in the case of animals coated with scales or with tessellates. With soft-haired animals the hair gets harder with good feeding, [15] and with bristly animals it gets soft
er and scantier from the same cause. Hair differs in quality also according to the heat or coldness of the locality: just as the hair in man is hard in warm places and soft in cold ones. Again, straight hair is inclined to be soft, and curly hair to be bristly. [20]

  11 · Hair is naturally fissile, and in this respect it differs in degree in diverse animals. In some animals the hair goes on gradually hardening into bristle until it no longer resembles hair but spine, as in the case of the hedgehog. And in like manner with the nails; for in some animals the nail differs as regards hardness in no [25] way from bone.

  Of all animals man has the most delicate skin: that is, if we take into consideration his relative size. In the skin of all animals there is a mucous liquid, scanty in some animals and plentiful in others, as, for instance, in the hide of the ox; [30] for men manufacture glue out of it. (In some places glue is manufactured from fishes also.)18 The skin, when cut, is in itself devoid of sensation; and this is especially the case with the skin on the head, owing to there being no flesh between [518a1] it and the skull. And wherever the skin is quite by itself, if it be cut asunder, it does not grow together again, as is seen in the thin part of the jaw, in the prepuce, and the eyelid. In all animals the skin is one of the parts that extends continuous and unbroken, and it comes to a stop only where the natural ducts pour out their contents, and at the mouth and nails.