14. The elephant arrives at puberty, the earliest at ten years of age, the latest at fifteen, and the male at five or six years old. The season for the intercourse of the sexes is in the spring: and the male is ready again at the end of three years, but he never touches again a female whom he has once impregnated. Her period of gestation is two years, and then she produces one calf, for the elephant belongs to the class of animals which have but one young one at a time. The young one is as large as a calf of two or three months old. This, then, is the nature of the sexual intercourse of those animals which perform this function. CHAPTER XIII. 1. We must now treat of the mode of reproduction, both of those animals which use sexual intercourse, and those which do not; and, first of all, we will speak of the testacea, for this is the only entire class which is not reproduced by sexual intercourse. The purpuræ collect together in the spring, and produce what is called their nidamental capsules (melicera), for it is like honey-comb, though not so deeply cut, but, as it were, made up of the white pods of vetches. These capsules have neither opening nor perforation, nor are the purpuræ produced from them; but both these and other testacea are produced from mud and putrefaction. But this substance is an excrementitious matter both in the purpura and the ceryx, for these last also produce similar capsules. 2. The testacea which produce these capsules are generated in the same way as the rest of their class, but more readily when there are homogeneous particles pre-existing among them; for, when they deposit their nidamental capsules, they emit a clammy mucus, from which the scales of the capsules are formed. When all these have been deposited, they emit upon the ground a sort of chyle, and small purpuræ spring up upon the same spot and adhere to the larger purpuræ, though some of these can hardly be distinguished by their form. But if they are taken before the breeding season, they will sometimes breed in the baskets, not indeed anywhere, but they collect together like they do in the sea, and the narrow limits of their place of captivity make them hang together like bunches of fruit. 3. There are many kinds of purpuræ, some of which are large, as those which are found near Sigeum and Lectum; and others are small, as those in the Euripus and on the Carian coast. Those found in gulfs are large and rough. Most of them contain a black pigment; in others it is red, and the quantity of it small. Some of the largest weigh as much as a mina. Near the shore and on the coast they are small, and the pigment is red. Those which are natives of the north contain a black pigment; in those of the south it is red, generally speaking.