16. Some animals are cunning and evil-disposed, as the fox; others, as the dog, are fierce, friendly, and fawning. Some are gentle and easily tamed, as the elephant; some are susceptible of shame, and watchful, as the goose. Some are jealous, and fond of ornament, as the peacock. But man is the only animal capable of reasoning, though many others possess the faculty of memory and instruction in common with him. No other animal but man has the power of recollection. In another place we will treat more accurately of the disposition and manner of life in each class.
Chapter II.
1. All animals possess in common those parts by which they take in food, and into which they receive it. But these parts agree or differ in the same way as all the other parts of bodies, that is, either in shape or size, or proportion or position; and besides these, almost all animals possess many other parts in common, such as those by which they reject their excrements, (and the part by which they take their food,)[13] though this does not exist in all. The part by which the food is taken in is called the mouth, that which receives the food from the mouth is called the stomach. The part by which they reject the excrement has many names.
2. The excrement being of two kinds, the animals which possess receptacles for the fluid excrement have also receptacles for the dry; but those which have the latter are not always furnished with the former. Wherefore all animals which have a bladder have a belly also, but not all that have a belly have a bladder; for the part appropriated to the reception of the liquid excrement is called the bladder, and that for the reception of the dry is called the belly.
3. Many animals possess both these parts, and that also by which the semen is emitted. Among animals that have the power of generation, some emit the semen into themselves, and some inject it into others. The former are called female, the latter male. In some animals there is neither male nor female, and there is a diversity in the form of the parts appropriated to this office. For some animals have a uterus, others have only something analogous to the uterus. These are the most essential organs; some of which exist in all animals, others in the majority only.
Chapter III.
1. There is only one sense, that of touch, which is common to all animals; so that no exact name can be given to the part in which this sense resides, for in some animals it is the same, in others only analogous.
2. Every living creature is furnished with moisture, and must die, if deprived of this moisture either in the course of nature or by force. But in what part of the body this moisture resides is another question. In some animals it is found in the blood and veins, in others the situation is only analogous, but these are imperfect, as fibres and serum.[14] The sense of touch resides in the simple parts, as in the flesh and in similar places, and generally in those parts which contain blood, at least in those animals which have blood; in others it resides in the analogous parts, but in all animals in the simple parts.
3. The capacity of action resides in the compound parts, as the preparation of food in the mouth, and the power of locomotion in the feet or wings, or the analogous parts. Again, some animals are sanguineous, as man, the horse, and all perfect animals, whether apodous, bipeds, or quadrupeds; and some animals are without blood, as the bee and the wasp, and such marine animals as the sepia and the carabus,[15] and all animals with more than four legs.