1. We have hitherto treated of the external and internal parts of all animals, of their senses, voice, and sleep, with the distinctions between the males and females; it remains to treat of their generation, speaking first of those which come first in order, for they are many, and have numerous varieties, partly dissimilar, and partly like each other. And we will pursue the same order in considering them as we did before in their division into classes; we commenced our consideration by treating of the parts in man, but now he must be treated of last, because he is much more intricate.

2. We shall begin with the testacea, and after these treat of the malacostraca, and the others in the order of their succession. These are the malacia and insects, next to these fishes, both viviparous and oviparous; next to them birds, and afterwards we must treat of animals with feet, whether viviparous or oviparous; some viviparous creatures have four feet, man alone has two feet. The nature of animals and vegetables is similar, for some are produced from the seed of other plants, and others are of spontaneous growth, being derived from some origin of a similar nature. Some of them acquire their nourishment from the soil, others from different plants, as it was observed when treating of plants.

3. So also some animals are produced from animals of a similar form, the origin of others is spontaneous, and not from similar forms; from these and from plants are divided those which spring from putrid matter, this is the case with many insects; others originate in the animals themselves, and from the excrementitious matter in their parts; those which originate from similar animals, and have both the sexes are produced from coition, but of the class of fishes there are some neither male nor female, these belong to the same class among fishes, but to different genera, and some are quite peculiar. In some there are females but no males, by these the species is continued as in the hypenemia among birds.

4. All these among birds are barren, (for nature is able to complete them as far as the formation of an egg,) unless persons suppose that there is another method of communicating the male influence, concerning which we shall speak more plainly hereafter. In some fish, after the spontaneous production of the ovum, it happens that living creatures are produced, some by themselves, others by the aid of the male. The manner in which this is done will be made plain in a future place, for nearly the same things take place in the class of birds.

5. Whatever are produced spontaneously in living creatures, in the earth, or in plants, or in any part of them, have a distinction in the sexes, and by the union of the sexes something is produced, not the same in any respect, but an imperfect animal, as nits are produced from lice, and from flies and butterflies are produced egg-like worms, from which neither similar creatures are produced, nor any other creature, but such things only. First of all, then, we will treat of coition, and of the animals that copulate, and then of others, and successively of that which is peculiar to each, and that which is common to them all.

Chapter II.

1. Those animals in which there is a distinction of the sexes use sexual intercourse, but the mode of this intercourse is not the same in all, for all the males of sanguineous animals with feet have an appropriate organ, but they do not all approach the female in the same manner, but those which are retromingent, as the lion, the hare, and the lynx, unite backwards, and the female hare often mounts upon the male; in almost all the rest the mode is the same, for most animals perform the act of intercourse in the same way, the male mounting upon the female; and birds perform it in this way only.

2. There are, however, some variations even among birds; for the male sometimes unites with the female as she sits upon the ground, as the bustard and domestic fowl: in others, the female does not sit upon the ground, as the crane; for in these birds the male unites with the female standing up; and the act is performed very quickly, as in sparrows. Bears lie down during the act of intercourse, which is performed in the same manner as in those that stand on their feet, the abdomen of the male being placed upon the back of the female: in the hedgehogs, the abdomens of both sexes are in contact.

3. Among the large animals, the roe-deer seldom admits the stag, nor the cow the bull, on account of the hardness of the penis; but the female receives the male by submission. This has been observed to take place in tame deer. The male and female wolf copulate like dogs. Cats do not approach each other backwards, but the male stands erect, and the female places herself beneath him. The females are very lascivious, and invite the male, and make a noise during the intercourse.

4. Camels copulate as the female is lying down, and the male embraces and unites with her, not backwards, but like other animals. They remain in intercourse a whole day. They retire into a desert place, and suffer no one to approach them but their feeder. The penis of the camel is so strong, that bowstrings are made of it. Elephants also retire into desert places for intercourse, especially by the sides of rivers which they usually frequent. The female bends down and divides her legs, and the male mounts upon her. The seal copulates like retromingent animals, and is a long while about it, like dogs. The males have a large penis.