4. It has already been observed that this purification is more abundant in women than in any other creature. In animals that are not viviparous no symptoms of anything of the kind occur, for this superfluous matter is returned into their own body, for in many the females are superior to the males in size, and in many it is turned to the formation of plates, or scales, or abundance of feathers. In viviparous animals with feet, it is turned to the formation of hair and bulk of body (for man is the only animal that is smooth), or of urine; for in almost all animals this secretion is thick and abundant. In women, on the contrary, all the superfluous matter of the body is directed to this purification. 5. The case of the male is the same, for in proportion to his size, man emits more semen than other animals; (wherefore, also, man is the smoothest of all animals,) and among men those which abound in humours, and are not very full fleshed, and fair men more than dark ones. So also among women. For in those that are full fleshed, the greater part of the secretion goes to the supply of the body, and in the act of sexual intercourse, fair women have naturally more seminal fluid than dark ones. Liquid and acid foods also increase this kind of intercourse. CHAPTER III. 1. It is a sign that women have conceived when the pudendum remains dry after coition. If the labia are smooth they will not conceive, for it slips out; nor will they if the labia are thick: but if there is a sensation of roughness and resistance when touched with the finger, and the labia are thin, they are then adapted for conception. In order that they may be able to conceive, such women must prepare the uterus, and the contrary that they may not conceive; for if the labia are smooth they do not conceive: so that some women, in order that the semen may fall outside the uterus, anoint themselves with oil of cedar, or with ceruse, or oil mixed with frankincense. 2. If it remain seven days, it is evident that conception has taken place, for in this period what are called the outpourings take place. The purification takes place in many women after conception. Thirty days afterwards in the case of conceiving a female child, and forty in the case of a male. After parturition, also, the purification lasts a similar number of days, though it is not exactly the same in all.