2. Both the male and the female commence sexual intercourse, so as to produce young, at a year old, though not generally till they are a year and eight months old, or two years old according to general agreement. The female is pregnant nine months, and produces her young in the tenth month; some persons affirm that parturition takes place at ten months to a day; if any of them calve before the above mentioned time, the calf is abortive and does not live, and even if born a little before the proper time it cannot live, for the hoofs are imperfect. The female generally produces one at a time, sometimes two. She continues to bear and to have sexual intercourse as long as she lives. 3. The female usually lives fifteen years, and so does the male if he is not castrated; some live for more than twenty years if they have an active body. They usually place castrated oxen as leaders of the herd, as they do in sheep, and these live longer than the others, for they do no work, and feed in a superior pasture. They attain perfection at five years old, wherefore some say that Homer was right when he spoke of the male flourishing at five years old, and the cow at nine years old, for both expressions have the same meaning. 4. Oxen change their teeth at two years old, not all of them, however, but only like the horse; they do not cast their hoofs when they are lame, but only swell very much about the feet. The milk is good immediately after calving, but the cow has no milk beforehand. The milk which is first formed becomes hard like a stone when it is coagulated; this takes place if it is not mixed with water. They do not produce young before they are a year old, except in some remarkable cases, for some have been known to copulate at four months old. Most of them desire sexual intercourse in the months of April and May. Some, however, are not impregnated before the autumn. When many become pregnant and admit the male, it is a sign of cold and rainy weather. The usual discharges occur in cows as they do in mares, but the quantity is less. CHAPTER XXII.