Many people, instead of conducting the stallion to the mare, let him loose in a park, where a number of mares are kept, and leave him at liberty to single out those which are in season: this method is good for the mares, and they will breed with more certainty; but the stallion is more hurt in six weeks than he would be well managed in as many years. As soon as the mares are with foal, and their bellies begin to grow heavy, they must be separated from those which are not so, lest they should be injured. They usually go with foal eleven months and some days; they bring forth standing upright, while almost all other quadrupeds lie down: in some cases, when the delivery is difficult they require assistance, and when the foal is dead, it is extracted with ropes. The foal generally presents its head first, as do all other animals; it breaks the membranes in the birth, and the waters flow out abundantly; at the same time there is voided several solid pieces of flesh formed by the liquor of the allantoides: these pieces, which the ancients have called the hippomanes, are not, as they say, pieces of flesh fastened to its head; but, on the contrary, separated by the amnios. The mare licks the foal after its birth, but she does not meddle with the hippomanes, notwithstanding the assertion of the ancients, that she devours it immediately. It is the usual custom to have the mare covered nine days after she has foaled: not to lose time, and to make all they can from the stud; yet it is certain, that the mare having a foal and foetus to provide for, her strength is divided, and she is not able to give them so much nourishment as if she had only one; it would, therefore, be better, in order to have excellent horses, to let the mares be covered but once in two years; they would last longer, and would not be so liable to drop their foals; for in common studs it is a great thing when, in the same year, half or two thirds produce foals. The mares, when with foal, can bear to be covered, though there is never any fresh conception: they usually breed till the age of 14 or 15 years, and the most vigorous not longer than 18. Stallions, when they have been taken care of, may engender till they are 20 years old, or upwards. The same remark has been made of these animals as of men, viz. that those who have begun too early are soonest incapacitated; for large horses, which sooner arrive at their growth than delicate ones, are frequently incapable before they are fifteen.