by Aristotle
The suckers are set in double line in all the Cephalopoda excepting in one kind of octopus where there is but a single row. The length and the slimness which is part of the nature of this kind of octopus explain the exception. For a narrow space cannot possibly admit of more than a single row. This exceptional character, then, belongs to them, not because it is the most advantageous arrangement, but because [15] it is the necessary consequence of the special nature of their substance.
In all these animals there is a fin, encircling the sac. In the octopus and the cuttlefish this fin is unbroken and continuous, as is also the case in the larger calamaries. But in the smaller kind, called Teuthides, the fin is not only broader than in the cuttlefish and the octopus where it is narrow, but, moreover, does not [20] encircle the entire sac, but only begins in the middle of the side. The use of this fin is to enable the animal to swim, and also to direct its course. It acts, that is, like the rump-feathers in birds, or the tail-fin in fishes. In none is it so small or so indistinct as in the octopus. For in these the body is of small bulk and can be steered by the [25] feet sufficiently well.
The Insects, the Crustacea, the Testacea, and the Cephalopoda, have now been dealt with in turn; and their parts have been described, whether internal or external.
[30] 10 · We must now go back to the vivipara that have blood, and consider such of their parts, already enumerated, as were before passed over. When we have done with these, we will pass on to the oviparous sanguinea, and treat of them in like manner.
[35] The parts that border on the head, and on what is known as the neck and throat, have already been taken into consideration. All animals that have blood [686a1] have a head; whereas in some bloodless animals, such as crabs, the part which represents a head is not clearly defined. As to the neck, it is present in all the Vivipara, but only in some of the Ovipara; for while those that have a lung also have [5] a neck those that do not inhale the outer air have none.
The head exists mainly for the sake of the brain. For every animal that has blood must of necessity have a brain; and must, moreover, for reasons already given, have it placed in an opposite region to the heart. But the head has also been chosen [10] by nature as the part in which to set some of the senses; because its blood is mixed in such suitable proportions as to ensure their tranquillity and precision, while at the same time it can supply the brain with such warmth as it requires. There is yet a third constituent superadded to the head, namely the part which ministers to the ingestion of food. This has been placed here by nature, because such a situation accords best with the general configuration of the body. For the stomach could not [15] possibly be placed above the heart, seeing that this is the sovereign organ; and if placed below, as in fact it is, then the mouth could not possibly be placed there also. For this would have necessitated a great increase in the length of the body; and the stomach, moreover, would have been removed too far from the source of motion and of concoction.
The head, then, exists for the sake of these three parts; while the neck, again, [20] exists for the sake of the windpipe. For it acts as a defence to this and to the oesophagus, encircling them and keeping them from injury. In all other animals this neck is flexible and contains several vertebrae; but in wolves and lions it contains only a single bone. For the object of nature was to give these animals an organ which should be serviceable in the way of strength, rather than for other purposes.
[25] Continuous with the head and neck is the trunk with the anterior limbs. In man the forelegs and forefeet are replaced by arms and by what we call hands. For of all animals man alone stands erect, in accordance with his god-like nature and substance. For it is the function of the god-like to think and to be wise; and no easy [30] task were this under the burden of a heavy body, pressing down from above and obstructing by its weight the motions of the intellect and of the general sense. When, moreover, the weight and corporeal substance become excessive, the body must of necessity incline towards the ground. In such cases therefore nature, in order to give support to the body, has replaced the arms and hands by forefeet, and has thus converted the animal into a quadruped. For, as every animal that walks [686b1] must of necessity have the two hinder feet, such an animal becomes a quadruped, its body inclining downwards in front from the weight which its soul cannot sustain. For all animals, man alone excepted, are dwarf-like in form. For the dwarf-like is that in which the upper part is large, while that which bears the weight and is used [5] in progression is small. This upper part is what we call the trunk, which reaches from the mouth to the vent. In man it is duly proportionate to the part below, and diminishes much in its comparative size as the man attains to full growth. But in his infancy the contrary obtains, and the upper parts are large, while the lower part is small, so that the infant can only crawl, and is unable to walk; and at first cannot [10] even crawl, but remains without motion. For all children are dwarfs in shape, but cease to be so as they become men, from the growth of their lower part; whereas in quadrupeds the reverse occurs, their lower parts being largest in youth, and advance of years bringing increased growth above, that is in the trunk, which extends from the rump to the head. Thus it is that foals are scarcely, if at all, below horses in [15] height; and that while still young they can touch their heads with the hind legs, though this is no longer possible when they are older. Such, then, is the form of animals that have either a solid or a cloven hoof. But such as are polydactylous and without horns, though they too are of dwarf-like shape, are so in a less degree; and therefore the greater growth of the lower parts as compared with the upper is also small, being proportionate to this smaller deficiency. [20]
Dwarf-like again is the race of birds and fishes; and so in fact, as already has been said, is every animal that has blood. This is the reason why no other animal is so intelligent as man. For even among men themselves if we compare children with adults, or such adults as are of dwarf-like shape with such as are not, we find that, whatever other superiority the former may possess, they are at any rate deficient as [25] compared with the latter in intelligence. The explanation, as already stated, is that in many their psychical principle is corporeal and impeded in its motions. Let now a further decrease occur in the elevating heat, and a further increase in the earthly matter, and the animals become smaller in bulk, and their feet more numerous, [30] until at a later stage they become footless and extended full length on the ground. Then, by further small successions of change, they come to have their principal organ below; and at last the part which answers to a head becomes motionless and destitute of sensation. Thus the animal becomes a plant, that has its upper parts downwards and its lower parts above. For in plants the roots are the equivalents of mouth and head, while the seed has an opposite significance, for it is produced [687a1] above at the extremities of the twigs.
The reasons have now been stated why some animals have many feet, some only two, and others none; why, also, some living things are plants and others animals; and, lastly, why man alone of all animals stands erect. Standing thus erect, [5] man has no need of legs in front, and in their stead has been endowed by nature with arms and hands. Now it is the opinion of Anaxagoras that the possession of these hands is the cause of man being of all animals the most intelligent. But it is more rational to suppose that man has hands because of his superior intelligence. For the [10] hands are instruments, and the invariable plan of nature in distributing the organs is to give each to such animal as can make use of it; nature acting in this matter as any prudent man would do. For it is a better plan to take a person who is already a flute-player and give him a flute, than to take one who possesses a flute and teach him the art of flute-playing. For nature adds that which is less to that which is [15] greater and more important, and not that which is more valuable and greater to that which is less. Seeing then that such is the better course, and seeing also that of what is possible nature invariably brings about the best, we must conclude that man does not owe his superior intelligence to his hands, but h
is hands to his superior intelligence. For the most intelligent of animals is the one who would put the most [20] organs to good use; and the hand is not to be looked on as one organ but as many; for it is, as it were, an instrument for further instruments. This instrument, therefore,—the hand—of all instruments the most variously serviceable, has been given by nature to man, the animal of all animals the most capable of acquiring the most varied arts.
Much in error, then, are they who say that the construction of man is not only [25] faulty, but inferior to that of all other animals; seeing that he is, as they point out, barefooted, naked, and without weapon of which to avail himself. For other animals have each but one mode of defence, and this they can never change; so that they must perform all the offices of life and even, so to speak, sleep with sandals on, never laying aside whatever serves as a protection to their bodies, nor changing such single weapon as they may chance to possess. But to man numerous modes of defence are [687b1] open, and these, moreover, he may change at will; as also he may adopt such weapon as he pleases, and at such places as suit him. For the hand is talon, hoof, and horn, at will. So too it is spear, and sword, and whatsoever other weapon or instrument you [5] please; for all these can it be from its power of grasping and holding them all. In harmony with this varied office is the form which nature has contrived for it. For it is split into several divisions, and whereas being compounded is contained in being divided, the reverse is not the case. The divisions also may be used singly or two [10] together and in various combinations. The joints, moreover, of the fingers are well constructed for prehension and for pressure. One of these also, short and thick but not long, is placed laterally. For were it not so placed all prehension would be as impossible, as were there no hand at all. For the pressure of this digit is applied from [15] below upwards, while the rest act from above downwards; an arrangement which is essential, if the grasp is to be firm and hold like a tight clamp. As for the shortness of this digit, the object is to increase its strength, so that it may be able, though but one, to counterbalance the other four.19 Moreover, were it long it would be of no use. (The finger which stands at the end is small, while the central one of all is long, like a centre oar in a ship. This is rightly so; for it is mainly by the central part of the [20] encircling grasp that a tool must be held when put to use.) And for this reason it is called the great finger, though it is small, because the others are pretty well useless without it.
No less skilfully contrived are the nails. For, while in man these serve simply as [25] coverings to protect the tips of the fingers, in other animals they are also used for active purposes.
The arms in man and the fore limbs in quadrupeds bend in contrary directions, this difference having reference to the conveying of food and to the other offices which belong to these parts. For quadrupeds must of necessity bend their anterior limbs inwards that they may serve in locomotion; for they use them as feet. Not but what even among quadrupeds there is at any rate a tendency for such as are [30] polydactylous to use their forefeet not only for locomotion but as hands. And they are in fact so used, as any one may see. For these animals seize hold of objects, and also repel assailants with their anterior limbs; whereas quadrupeds with solid hoofs [688a1] use their hind legs for this latter purpose. For their fore limbs are not analogous to the elbows and hands of man.
It is this which explains why in some of the polydactylous quadrupeds, such as wolves, lions, dogs, and leopards, there are actually five digits on each forefoot, though there are only four on each hind one. For the fifth digit of the foot [5] corresponds to the fifth digit of the hand, and like it is called the big one. It is true that in the smaller polydactylous quadrupeds the hind feet also have each five toes. But this is because these animals are creepers; and the increased number of nails serves to give them a tighter grip, and so enables them to creep up steep places with [10] greater facility, or even to run head downwards.
In man between the arms, and in other animals between the forelegs, lies what is called the chest. This in man is broad, as one might expect; for as the arms are set laterally on the body, they offer no impediment to such expansion in this part. But in quadrupeds the chest is narrow, owing to the legs having to be extended in a forward [15] direction in progression and locomotion.
For this reason the breasts of quadrupeds are never placed on the chest. But in the human body there is ample space in this part; moreover, the heart and neighbouring organs require protection, and for these reasons this part is fleshy and [20] the breasts are placed upon it separately, being themselves of a fleshy substance in the male for the reason just stated; while in the female, nature, in accordance with what we say is her frequent practice, makes them minister to an additional function, employing them as a store-place of nutriment for the offspring. The human breasts [25] are two in number, in accordance with the division of the body into two halves, a right and a left. They are somewhat firmer and divided, because the ribs in this region are joined together and because their presence is not burdensome. In other animals it is impossible for the breasts to be placed on the chest between the [30] forelegs, for they would interfere with locomotion; they are therefore disposed of in a variety of ways. Thus in such animals as produce but few at a birth, whether horned quadrupeds or those with solid hoofs, the breasts are placed in the region of the thighs, and are two in number, while in such as produce litters, or such as are polydactylous, they are either numerous and placed laterally on the belly, as in pigs and dogs, or are only two in number, being set, however, in the centre of the [688b1] abdomen, as in the case in the lion. The explanation of this is not that the lion produces few at a birth, for sometimes it has more than two cubs at a time, but is to be found in the fact that this animal has no plentiful supply of milk. For, being a flesh-eater, it gets food at but rare intervals, and such nourishment as it obtains is all expended on the growth of its body.
In the elephant also there are but two breasts which are placed under the pits [5] of the forelimbs. The breasts are not more than two, because this animal has only a single young one at a birth; and they are not placed in the region of the thighs, because they never occupy that position in any polydactylous animal such as this. Lastly, they are placed above, close to the armpits, because this is the position of the [10] foremost breasts in all animals whose breasts are numerous, and they give the most milk. Evidence of this is furnished by the sow. For she always presents these foremost teats to the first-born of her litter. A single young one is of course a first-born, and so such animals as only produce a single young one must have these first breasts, and the first breasts are those under the armpits. This, then, is the [15] reason why the elephant has but two breasts, and why they are so placed. But, in such animals as have litters of young, the teats are disposed about the belly; the reason being that more teats are required by those that will have more young to nourish. Now it is impossible that these should be set transversely in rows of more than two, one, that is, for each side of the body, the right and the left; they must [20] therefore be placed lengthways, and the only place where there is sufficient length for this is the region between the front and hind legs. As to the animals that are not polydactylous but produce few at a birth, or have horns, their breasts are placed in the region of the thighs. The horse, the ass, the camel are examples; all of which bear but a single young one at a time, and of which the two former have solid hoofs, while in the last the hoof is cloven. As still further examples may be mentioned the [25] deer, the ox, the goat, and all other similar animals.
The explanation is that in these animals growth takes place in an upward direction; so that there must be an abundant collection of residual matter and of blood in the lower region, that is to say in the neighbourhood of the orifices for efflux, and here therefore nature has placed the breasts. For the place in which the [30] nutriment is set in motion must also be the place whence nutriment can be derived by them. In man there are breasts in the male as well as in the female; but some of the
males of other animals are without them. Such, for instance, is the case with horses, some stallions being destitute of these parts, while others that resemble their dams have them. Thus much then concerning the breasts.