[13] The words in brackets should probably be excluded from the text.
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.
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.
[14] Fibres and serum, as compared with veins and blood, refer to the circulation in animals without red blood.
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.