Chapter XXXVII.

1. Animals not only change their forms and dispositions at particular ages and seasons, but also when castrated. All animals that have testicles may be castrated. Birds and oviparous quadrupeds have internal testicles near their loins. In viviparous animals with feet, they are generally external, though sometimes internal; in all they are situated at the extremity of the abdomen. Birds are castrated near the rump, the part with which they touch the female in copulation, for if they are burnt in that part two or three times with irons after they are full grown, the comb turns yellow, and they cease to crow, and no longer desire sexual intercourse. If they are not full grown, these parts never reach perfection.

2. The same is the case with the human subject, for if a boy is castrated, the hair that is produced after birth never appears, nor does his voice change, but continues sharp; but if a full grown man is castrated, all the hair produced after birth falls off except that on the pubes, this becomes weaker, but still remains. The hair produced at birth does not fall off, for the eunuch never becomes bald. The voice also of castrated animals changes to that of the female. Other animals, if not castrated when young, are destroyed by the operation; with the boar it makes no difference. All animals, if castrated when young, become larger and more graceful than those not castrated; but if already grown, they never become any larger.

8. If stags are castrated before they are old enough to have horns, these never appear; but if castrated after they have horns, their size never varies, nor are they subject to their annual change. Calves are castrated at a year old, if not they become bad and inferior. The steer is castrated in this manner: they lay down the animal and cut the scrotum, and press out the testicles; they next contract the root of the testicle as much as possible, and fill up the wound with hair in order that the discharge may escape, and if it inflames, they cauterize and sprinkle the scrotum. If adult bulls are castrated, they are still apparently capable of sexual intercourse.

4. The capria of the sow is also cut out, so that they should not desire coition, but fatten rapidly. They are cut after fasting two days. They hang them up by the hind legs and make an incision in the lower part of the belly, where the testicles of the male are generally found; the capria is there formed upon the matrix, from which they cut off a portion, and sew up the wound again.

5. The female camels also are cut when they wish to take them to war, that they may not become pregnant. Some of those in the upper parts of Asia possess as many as three thousand. Such camels, when they run, are far more swift than the Nisæan horses, from the length of their stretch. And on the whole, castrated animals are longer-bodied than those not castrated.

6. All animals that ruminate, derive as much use and pleasure from rumination as from eating. Animals that have not cutting-teeth in both jaws ruminate, as the ox, sheep, and goat. No observations have been made on wild animals except those which occasionally associate with men, as the stag, though this animal ruminates. They all lie down to ruminate, and do so most in the winter; those which are brought up in shelter ruminate for nearly seven months. Those that live in herds, ruminate for a shorter period, for they live out of doors. Some animals with cutting teeth in both jaws, ruminate, as the Pontic mice and the fish, which, from this process, is called meryx. Animals with long legs have loose bellies, and those with broad chests vomit more easily than others, in quadrupeds, birds, and the generality of mankind.