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. [15] Palinurus, Spiny Lobster. CHAPTER IV. 1. There are also viviparous, oviparous, and vermiparous animals. The viviparous, are such as man, and the horse, the seal, and others which have hair, and among marine animals the cetacea, as the dolphin and those which are called selache.[16] Some of these are furnished with a blow-hole, but have no gills, as the dolphin and the whale. The dolphin has its blow-hole on the back, the whale in its forehead; others have open gills, as the selache, the galeus,[17] and the batus.[18] That is called the egg of the perfect fœtus, from which the future animal is produced, from a part at first, while the remainder serves for its food. The worm is that from the whole of which the future animal is produced, and the fœtus afterwards acquires parts and increases in size. [16] Cartilaginous fishes. [17] Squalus galeus. [18] Raia batos. 2. Some viviparous animals are internally oviparous, as the selache; others are internally viviparous, as mankind and the horse. In different animals the fœtus assumes a different form, when first brought into the world, and is either a living creature, an egg, or a worm. The eggs of some animals, as birds, are hard-shelled, and are of two colours. Those of the selache and some other animals are soft-skinned, and have only one colour. Some species of the vermiform fœtus are capable of motion, others are not. But in another place, when we treat of generation, we will dwell more accurately on these subjects. CHAPTER V.