5. The male copulates at all seasons, and as long as he lives; the female also as long as she lives; and at all seasons, unless they have on a fastening or some other hindrance, no peculiar time is appropriated for copulation in either sex, for there is no period of coition when they cannot also bring up their young. In Opus there was a horse in a herd which engendered when he was forty years old; but it was necessary to lift up his fore legs for him. Mares begin to desire sexual intercourse in the spring; and when the mare has foaled, she does not become pregnant again immediately, but waits for a time, and produces better foals at the end of four or five years. It is quite necessary that she should wait one year, and should pass through a fallow, as it were.
6. The horse, then, bears young at intervals, as I have observed; but the ass is not subject to intervals. Some mares are quite barren, and others, though they conceive, yet do not produce their young; and they give as a reason for this, that upon dissection the fœtus was found to contain other reniform bodies round the kidneys, so that it appeared to have four kidneys. As soon as the mare has foaled, she eats the chorion, and bites from the head of her foal the substance called hippomanes. In size this substance is somewhat less than a dry fig. Its form is flat and round, and its colour black. If any person is at hand to take it before the mare, and she smells it, the scent renders her wild and mad. For this reason it is sought after and collected by poisoners. If an ass copulates with a pregnant mare, the pre-existing fœtus is destroyed. Those who keep herds of horses do not place a leader over them, as they do over oxen, for they are not naturally stationary, but active and wandering.
Chapter XXIII.
1. The male and female ass begin to copulate at thirty months old, and shed their first teeth at the same period. They lose their second pair of teeth six months afterwards, and their third and fourth in the same way. These fourth teeth are called the marking teeth. Sometimes the ass has become pregnant and brought up its young at a year old. The she ass parts with the semen after coition, if she is not prevented; and therefore, immediately after coition, they beat her and drive her about. She foals in the twelfth month, and generally produces one foal, for this is their nature, though cases of twin births have occurred. If an ass mounts upon a mare, he destroys her fœtus, as I observed before. But the horse does not destroy the fœtus of the ass, if the mare has been impregnated by a he ass.
2. The pregnant female has milk at the end of ten months. After parturition, she will admit the male on the seventh day, and is very easily impregnated at that period. She will also receive it afterwards. If she does not produce young before losing her marking teeth, she can never be impregnated all the rest of her life. She does not like men to be witnesses of her parturition, nor will she produce her young in the day time; but when it is dark she retires, and so produces her young. She continues to procreate during her whole life, if she has begun before losing her marking teeth. The ass lives more than thirty years, and the female longer than the male. When a horse copulates with an ass, or a he ass with a mare, abortion is more frequent than between congeners, a horse with a mare, or two asses together. When the horse and ass are mixed together, the period of gestation follows from the male parent. I mean to say that it takes the same time as if the parents had been congeners; but in size, form, and strength the produce of their union generally resembles the female parent.
3. If the union takes place frequently, and sufficient time is not allowed to intervene, the female soon becomes barren. For which reason those who attend to this business do not permit them to have continual intercourse, but interpose a proper interval. The mare will not admit the he ass, nor the she ass the horse, unless the he ass has been suckled by a mare. They are careful, therefore, to admit only those asses which they call hippothelæ, i.e. asses which have been suckled by a mare. These copulate by force in the pastures, like horses.
Chapter XXIV.
1. The oreus (mule) mounts and copulates after shedding the first teeth, and when seven years old is able to engender; and the ginnus is produced when he mounts upon a mare. After this he no longer continues to copulate. The female oreus also has been impregnated, but the fœtus has never been known to come to maturity. The hemioni (female mules) of Syria, near Phœnicia, admit the male and procreate. The kind, however, though similar, is not the same. Those which are called ginni are produced from a mare, when the fœtus has received some injury in the uterus, like dwarfs among men and metachœra among swine; and the ginnus, like the dwarf, has a large genital organ.
2. The hemionus has a long life; for they have been known to live for eighty years, as in Athens, when they built the temple, this individual, though failing with age, helped in drawing, and went beside them, and encouraged the yoke mules to their work, so that an edict was made, commanding the corn-dealers not to drive it away from the vessels filled with corn. The female mule (oreus) grows old sooner than the male. Some persons say that she is purified when making water, but the male ages more rapidly from smelling the urine.
3. This is the manner of the reproduction of these animals. Those who are employed in bringing up these animals recognize the young from the old in this way. If the skin, when drawn back from the cheek, soon recovers its shape, the animal is young; if the skin continues wrinkled for a long while, the creature is aged.