The selection of a mare, relatively larger than the horse, is an important rule in breeding, and it is believed that much of the success of Arabian and other Eastern horses as stock-getters, has resulted from the application of this principle. They possess valuable traits, but condensed within too small a compass. When such an animal is put to a well-bred, larger mare, the f[oe]tus has abundance of room and nourishment to develop and perfect the circumscribed outlines of the male parent, and acquire for itself increased volume and character. The horse ought not to be less than four or five, and the mare one year older, before being put to breeding. It would be still better to defer it for two or three years, or till the frame is fully matured. The Gestation of the Mare Sometimes varies from 44 to 56 weeks, but she usually goes with young from 47 to 50; and it is advisable she should take the horse at a time which will ensure the foaling when the weather is settled, and there is a fresh growth of grass. She will be the better for light working till near the time of foaling, if well, but not too abundantly fed. In a few days after this, she may resume moderate labor; and if not in the way or troublesome, the foal may run with her; but if she is exposed to heating, it should be confined till she cools, as suckling then is decidedly injurious to it. The mare is in danger of slinking her foal from blows and over-exertion, the use of smutty grain, foul hay, or offensive objects or smell; and when this has once occurred, which happens usually in the fourth or fifth month, she should afterwards be generously fed at that period, and only moderately worked, to prevent a recurrence of the casualty. When liable to slinking, the mare should be removed from others in foal, lest a peculiar sympathy should excite an epidemic. The Mare comes in Heat From nine to eleven days after foaling, when she should be put to the horse, if it be desirable to have a colt the following season. She comes round at intervals of about nine days. Management of the Colt. The colt may be weaned when five to seven months old; and preparatory to this, while with the mare, may be taught to feed on fine hay, meal, or oats. When taken away, he should be confined beyond a hearing distance of the dam, and plentifully supplied with rowen or aftermath hay, crushed oats, or wheat shorts. It is economy to provide a warm shelter through the inclement season for all animals, and especially for colts, which, with all other young, should have an abundance of nutritious food. They will thus grow evenly and rapidly, and attain a size and stamina at two years old, they would not otherwise have acquired at three. Castrating.