The Politics of Aristotle

by Aristotle

  In the Cephalopoda there are two teeth, enclosing what is called the mouth; and inside this mouth is a flesh-like substance which represents a tongue and serves for the discrimination of pleasant and unpleasant food. The Crustacea have front [10] teeth in the same way, and also have the fleshy representative of a tongue. This latter part is found, moreover, in all Testacea for the same reason as in sanguineous animals, viz. to perceive their food. Similarly provided also are the Insects. For [15] some of these, such as the bees and the flies, have, as already described, their proboscis protruding from the mouth; while those others that have no such instrument in front have a similar part inside the mouth. Such, for instance, is the case in the ants and the like. As for teeth, some insects have them, the bees and the flies for instance, though in a somewhat modified form, while others that live on [20] fluid nutriment are without them. For in many insects the teeth are not meant to deal with the food, but to serve as weapons.

  In some Testacea, as was said in the first treatise, the organ which is called the tongue is of considerable strength; and in sea-snails there are also two teeth, just as [25] in the Crustacea. The mouth in the Cephalopoda is succeeded by a long gullet. This leads to a crop, like that of a bird, and directly continuous with this is the stomach, from which a gut runs without windings to the vent. The cuttlefish and the octopus resemble each other completely, so far as regards the shape and consistency of these [30] parts. In the calamaries, as in the other groups, there are the two stomach-like receptacles; but the first of these cavities has less resemblance to a crop, and in neither is the form the same as in the other kinds, the whole body indeed being made of a softer kind of flesh.

  The object of this arrangement of the parts in question is the same as in Birds; [35] for these also are all unable to masticate their food; and therefore it is that a crop precedes their stomach.

  For purposes of defence, and to enable them to escape from their foes, the [679a1] Cephalopoda have what is called their ink. This is contained in a membranous pouch, which is attached to the body and provided with a terminal outlet just at the point where what is termed the funnel gives issue to the residua of the stomach. This [5] funnel is placed on the under surface of the animal. All Cephalopoda alike have this characteristic ink, but chief of all the cuttlefish, where it is more abundant than in the rest. When the animal is disturbed and frightened it uses this ink to make the surrounding water black and turbid, and so, as it were, puts a shield in front of its body.

  In the Calamaries and the octopus the ink-bag is placed in the upper part of the body, in close proximity to the mytis, whereas in the cuttlefish it is lower down, against the stomach. For the cuttlefish has a more plentiful supply of ink than the [10] rest, inasmuch as it makes more use of it. The reasons for this are that it lives near the shore, and that it has no other means of protection; whereas the octopus has its tentacles to use in its defence, and is, moreover, endowed with the power of changing colour. This changing of colour, like the discharge of ink, occurs as the result of fright. As to the calamary, it lives far out at sea, being the only one of the [15] Cephalopoda that does so. Thus the ink is more abundant in the cuttlefish, and this greater abundance explains the lower position; for it allows the ink to be ejected with ease even from a distance. The ink itself is of an earthy character, in this resembling the white deposit on the surface of a bird’s excrement, and the explanation in both cases is the same, namely, the absence of a bladder. For it is the ink that serves for the excretion of the earthiest matter. And this is more especially [20] the case in the cuttlefish, because there is a greater proportion of earth in its composition. The earthy character of its bone is a clear indication of this. For in the octopus there is no bone at all, and in the calamary it is thin and cartilaginous. (Why this bone should be present in some Cephalopoda, and wanting in others, and how its character varies in those that have it, has been explained.)

  These animals, having no blood, are in consequence cold and of a timid [25] character. Now, in some animals, fear causes a disturbance of the bowels, and, in others, a flow of urine from the bladder. Similarly in these it produces a discharge of ink, and, though the ejection is the result of necessity, like the discharge of urine, yet at the same time nature makes use of this residue for the protection and safety of the [30] animal.

  The Crustacea also, both the crayfish and the crabs, are provided with two anterior teeth and between these the tongue-like piece of flesh, as has indeed been already mentioned. Directly after their mouth comes a gullet, which is small in proportion to the body; and then a stomach, which in the crayfish and some of the [35] crabs is furnished with a second set of teeth, the anterior teeth being insufficient for adequate mastication. From the stomach a uniform gut runs in a direct line to the [679b1] excremental vent.

  The parts described are to be found also in all the various Testacea. The degree of distinctness, however, with which they are formed varies in the different kinds, and the larger the size of the animal the more easily distinguishable are all these parts severally. In the sea-snails, for example, we find teeth, hard and sharp, as [5] before mentioned, and between them the flesh-like substance, just as in the Crustacea and Cephalopoda, and again the proboscis, which, as has been stated, is something between a sting and a tongue. Directly after the mouth comes a kind of bird-like crop, then a gullet, succeeded by a stomach, in which is the ‘poppy’, as it is [10] styled; and continuous with this is an intestine, starting directly from it. It is this residual substance which appears in all the Testacea to form the most palatable morsel. The purple murex, the trumpet-shell, and the other spiral-shells resemble [15] the sea-snail. The genera and species of Testacea are very numerous. For there are those with spiral shells, of which some have just been mentioned; and, besides these, there are bivalves and univalves. Those with spiral shells may, indeed, after a certain fashion be said to resemble bivalves. For they all from their very birth have an operculum over that part of their body which is exposed to view. This is the case [20] with the purple murex, the trumpet-shell, the nerites, and the like. Were it not for this, the part which is undefended by the shell would be very liable to injury by collision with external objects. The univalves also are not without protection. For on their upper surface they have a shell, and they attach themselves to the rocks, and so [25] after a manner become bivalved by virtue of this borrowed protection. Of these the animals known as limpets are an example. The bivalves, scallops and mussels, for instance, are protected by the power they have of closing their valves; and the spiral-shells by the operculum just mentioned, which transforms them, as it were, from univalves into bivalves. But of all there is none so perfectly protected as the sea-urchin. For here there is a shell which encloses the body completely, and which [30] is, moreover, set with sharp spines. This peculiarity distinguishes the sea-urchin from all other Testacea, as has already been mentioned.

  The structure of the Testacea and of the Crustacea is exactly the reverse of that of the Cephalopoda. For in the latter the fleshy substance is on the outside and the earthy substance within, whereas in the former the soft parts are inside and the hard part without. In the sea-urchin, however, there is no fleshy part whatsoever.

  [35] All the other Testacea also possess, as has been said, a mouth with the tongue-like body, a stomach, and a vent for excrement, but they differ from each [680a1] other in the positions and proportions of these parts. The details, however, of these differences must be looked for in the History of Animals and the Anatomies. For while there are some points which can be made clear by verbal description, there are others which are more suited for ocular demonstration.

  [5] Peculiar among the Testacea are the sea-urchins and the animals known as ascidians. The sea-urchins have five teeth, and in the centre of these the fleshy body which is common to all the animals we have been discussing. Immediately after this comes a gullet, and then the stomach, divided into a number of separate compartments, which look like so many distinct stomachs; for the c
avities are separate and [10] all contain abundant residual matter. They are all, however, connected with one and the same oesophagus, and they all end in one and the same excremental vent. There is nothing besides the stomach of a fleshy character, as has already been stated. All that can be seen are the so-called eggs, of which there are several, contained each in a separate membrane, and certain black bodies which have no name, and which, beginning at the animal’s mouth, are scattered round its body here and there. These [15] sea-urchins are not all of one species, but there are several different kinds, and in all of them the parts mentioned are to be found. It is not, however, in every kind that the so-called eggs are edible. Neither do these attain to any size in any other species than that with which we are all familiar. A similar distinction may be made [20] generally in the case of all Testacea. For there is a great difference in the edible qualities of the flesh of different kinds; and in some, moreover, the residual substance known as the poppy is good for food, while in others it is uneatable. This in the spiral kinds is lodged in the spiral part of the shell, while in univalves, such as limpets, it occupies the fundus, and in bivalves is placed near the hinge, the so-called egg lying on the right; while on the opposite side is the vent. The former is [25] incorrectly termed egg, for it merely corresponds to what in well-fed sanguineous animals is fat; and thus it is that it makes its appearance at those seasons of the year when they are in good condition, namely, spring and autumn. For no Testacea can abide extremes of temperature, and they are in evil plight in seasons of great cold or [30] heat. This is clearly shown by what occurs in the case of the sea-urchins. For though the eggs are to be found in these animals even directly they are born, yet they acquire a greater size than usual at the time of full moon; not, as some think, because sea-urchins eat more at that season, but because the nights are then warmer, owing to the moonlight. For these creatures are bloodless, and so are unable to stand cold and require warmth. That is why they are found in better condition in summer everywhere except in the Pyrrhean tidal strait. There the [680b1] sea-urchins flourish as well in winter as in summer. But the reason for this is that they have a greater abundance of food in the winter, because the fish desert the strait at that season.

  The number of the eggs is the same in all sea-urchins, and is an odd one. For there are five ova, just as there are also five teeth and five stomachs; and the [5] explanation of this is to be found in the fact that the eggs are not really eggs, but merely, as was said before, the result of the animal’s well-fed condition. Oysters also have a so-called egg, corresponding in character to that of the sea-urchins, but existing only on one side of their body. Now inasmuch as the sea-urchin is of a spherical form, and not merely a single disk like the oyster, and in virtue of its [10] spherical shape is the same from whatever side it be examined, its egg must necessarily be of a corresponding symmetry. For the spherical shape has not the asymmetry of the disk-shaped body of the oysters. For in all these animals the head is central, but in the sea-urchin it is at the top. But even so the egg cannot be [15] continuous—for it is not so in the others—but is on one side of the disk only. Thus since this is a common property of them all and the sea-urchin is peculiar in being spherical, this animal cannot possibly have an even number of eggs. For were they an even number, they would have to be arranged exactly opposite to each other, so as to keep the necessary symmetry; and in that case there would be eggs on both [20] sides of the disk. But this is not the case in any of the other shell-fish. For both in the oysters and in the scallops we find the egg only on one side of the circumference. The number then must be uneven, three for instance, or five. But if there were only three they would be much too far apart; while, if there were more than five, they [25] would come to form a continuous mass. The former arrangement would not be for the animal’s good, the latter would not be possible. There can therefore be neither more nor less than five. For the same reason the stomach is divided into five parts, and there is a corresponding number of teeth. For seeing that the eggs represent each of them a kind of body for the animal, their disposition must conform to that of [30] the stomach, seeing that it is from this that they derive the material for their growth. Now if there were only one stomach, either the eggs would be too far off from it, or it would be so big as to fill up the whole cavity, and the sea-urchin would have great difficulty in moving about and finding due nourishment for its repletion. As then there are five intervals so are there of necessity five divisions of the stomach, one for each interval. So also, and on like grounds, there are five teeth. For [681a1] nature is thus enabled to allot one alike to each of the aforementioned parts. These, then, are the reasons why the number of eggs in the sea-urchin is an odd one, and why that odd number is five. In some sea-urchins the eggs are excessively small, in others of considerable size, the explanation being that the latter are of a warmer [5] constitution, and so are able to concoct their food more thoroughly; and that is why the inedible ones tend to be full of residue. Those of a warmer constitution are, moreover, in virtue of their warmth more given to motion, so that they make expeditions in search of food, instead of remaining stationary like the rest. As evidence of this, it will be found that they always have something or other sticking to their spines, as though they moved much about; for they use their spines as feet.

  [10] The ascidians differ but slightly from plants, and yet have more of an animal nature than the sponges, which are plants and nothing more. For nature passes from lifeless objects to animals in such unbroken sequence, interposing between them beings which live and yet are not animals, that scarcely any difference seems to [15] exist between two neighbouring groups owing to their close proximity.

  A sponge, then, as already said, in these respects completely resembles a plant, that throughout its life it is attached to a rock, and that when separated from this it dies. Slightly different from the sponges are the so-called Holothurias and the sea-lungs, as also sundry other sea-animals that resemble them. For these are free [20] and unattached. Yet they have no sensation, and their life is simply that of a plant separated from the ground. For even among landplants there are some that spring up and grow, either upon other plants, or even entirely free. Such, for example, is the plant which is found on Parnassus, and which some call the rockplant. This you may hang up on a peg and it will yet live for a considerable time. Sometimes [25] ascidians and the like so far resemble plants as that they never live free and unattached, but, on the other hand, inasmuch as they have a certain flesh-like substance, they must be supposed to possess some degree of sensibility—and it is unclear whether they are to be classed as plants or as animals.

  An ascidian has a body divided by a single septum and with two orifices, one [30] where it takes in the fluid matter that ministers to its nutrition, the other where it discharges the surplus juice, for it has no visible residual substance, such as have the other Testacea. This is itself a very strong justification for considering an ascidian, and anything else there may be among animals that resembles it, to be a plant; for plants also never have any residuum. Across the middle of the body of these there [35] runs a thin transverse partition, and here it is that we may reasonably suppose the part on which life depends to be situated.

  The sea-anemones or sea-nettles, as they are variously called, are not Testacea [681b1] at all, but lie outside the recognized groups. Their constitution approximates them on one side to plants, on the other to animals. For seeing that some of them can [5] detach themselves and can fasten upon their food, and that they are sensible of objects which come in contact with them, they must be considered to have an animal nature. The like conclusion follows from their using the asperity of their bodies as a protection against their enemies. But, on the other hand, they are closely allied to plants, firstly by the imperfection of their structure, secondly by their being able to attach themselves to the rocks, which they do with great rapidity, and lastly by their having no visible residuum notwithstanding that they possess a mouth.

  Very simila
r again are the Starfishes. For these also fasten on their prey, and suck out its juices, and thus destroy a vast number of oysters. At the same time they [10] present a certain resemblance to such of the animals we have described as the Cephalopoda and Crustacea, inasmuch as they are free and unattached. The same may also be said of the Testacea.

  Such, then, is the structure of the parts that minister to nutrition and which every animal must necessarily possess. But besides these organs it is quite plain that in every animal there must be some part or other which shall be analogous to what [15] in sanguineous animals is the presiding seat of sensation. In the Cephalopoda this part consists of a fluid substance contained in a membrane, through which runs the gullet on its way to the stomach. It is attached to the body rather towards its upper surface, and by some is called the mytis. Just such another organ is found also in the [20] Crustacea and there too is known by the same name. This part is at once fluid and corporeal and, as before said, is traversed by the gullet. For had the gullet been placed between the mytis and the upper surface of the animal, the hardness of the back would have interfered with its due dilatation as the food enters. On the outer [25] surface of the mytis runs the intestine; and in contact with this latter is placed the ink-bag, so that it may be removed as far as possible from the mouth and its obnoxious fluid be kept at a distance from the nobler and sovereign part. The position of the mytis shows that it corresponds to the heart of sanguineous animals; for it occupies the self-same place. The same is shown by the sweetness of its fluid, [30] which has the character of concocted matter and resembles blood.