9. Fat goats are rarely productive, wherefore they compare barren vines with barren goats, but they are productive when they are lean. The rams copulate with the old sheep first, but they do not follow after the younger; and the younger, as I before observed, produce a smaller offspring than the older. 10. A wild boar will beget till he is three years old, but the progeny of older animals is inferior; for he has not the same power or strength. He generally goes to the female when full of food, and without having been to another female, or, if not, the act of coition is of shorter duration, and the progeny smaller. The sow produces the smallest number of pigs at her first litter, but at the second they are more flourishing. She also produces young when old, but the act of coition is longer. At fifteen years old, she no longer produces young, but becomes fierce. 11. If well-fed, she will be more ready for sexual intercourse, whether young or old; and, if rapidly fattened when pregnant, she has less milk after parturition. As regards the age of the parent, the young of those in the prime of their age are the best, and those that are born at the beginning of winter. The worst are those born in the summer, for they are small, and thin, and weak. If the male is well fed, he is ready for sexual intercourse at all seasons, by day as well as by night; but if not well fed, he is most ready in the morning, and as he grows old, he becomes less disposed for it, as was said before. And it frequently happens that those which are impotent, through age or weakness, and cannot copulate readily, will approach the female as she lies down tired with long standing. The sow generally becomes pregnant when she hangs down her ears in her heats; if she is not pregnant, she becomes heated again. 12. Bitches do not copulate during the whole of their life, but only to a certain period. Their coition and pregnancy generally takes place till they are twelve years old, but both males and females have been known to perform the act of coition at eighteen and even twenty years of age; but old age takes away from both sexes the power of reproduction, as in other animals. 13. The camel is retroningent, and performs the act of intercourse in the manner already described; the period of its coition in Arabia is in the month of September; the female goes with young twelve months, and produces one foal, for the animal is one of those which produce but one. Both the male and female arrive at puberty at the age of three years, and the female is ready for the male again at the end of a year after parturition.