2. If any of the pigs are injured or deteriorated during pregnancy, it is called metachæron. This may take place in any part of the uterus. In parturition the sow gives the first teat to the first pig. It is not necessary that she should go to the boar as soon as the sexual appetite is felt, or before her ears begin to hang down; for otherwise she desires to go again. If she goes to the boar when she is desirous of it, the impregnation is complete in a single act of intercourse. Barley is a proper food for the boar at the period of coition. It should be cooked for the female after parturition. Some sows produce excellent pigs from the first; others do not produce good offspring and pigs till they are grown up. Some persons say that if one of the eyes of a sow is put out, she generally speaking dies very soon. Most of them live fifteen. Some die in less than twenty years. CHAPTER XIX. 1. Sheep become pregnant after three or four acts of sexual intercourse. If rain falls after the act of intercourse, it must be repeated. The nature of goats is the same. They generally produce two, and sometimes three. Cases have occurred of their producing four. The period of gestation in the sheep and goat is five months; and in some places, where the weather is warm and fine, and food is abundant, they have young twice a-year. The goat will live eight years. The sheep lives ten years, or generally rather less; but the leaders of the flock live fifteen years; for in every flock they select one of the males as a leader, who, when called by the shepherd, places himself at the head of the flock. They are accustomed to this duty even when young. In Ethiopia the sheep live twelve or thirteen years, and the goats ten or eleven. 2. Both the sheep and goat enjoy sexual intercourse as long as they live. Sheep and goats produce twins, if either the pasture is good, or the ram or he-goat, or the ewe belongs to a race producing twins. They produce females or males both from the nature of the water (for there are some waters that cause them to produce males and others females) and from their manner of sexual intercourse; and if the wind is northward during copulation they produce males; and if it is southward, females; and one which naturally produces females will change its nature and produce males; so that it is necessary to see that they stand to the north during the act of sexual intercourse. If any are accustomed to copulate early, and the ram is introduced to them late, they will not endure it.