10th. Animals should never be allowed to breed either too early or too late in life. These periods cannot be arbitrarily laid down, but must depend on their time of maturity, the longevity of the breed, and the stamina of the individual. 11th. No violent cross, or mixing of distinct breeds, should ever be admitted for the purposes of perpetuation, as of cattle of diverse sizes; horses of unlike characters; the Merino and the long-wools, or even the long, or short, and the middle-wools. For carcass and constitution, these crosses are unexceptionable; and it is a practice very common in this country, and judicious enough where the whole produce is early destined for the shambles. But when the progeny are designed for breeders, the practice should be branded with unqualified reprehension. GENERAL FORM AND CHARACTERISTICS. Within certain limits, these may be reduced to a common standard. All animals should have a good head, well set up; a clean fine muzzle, and a blight, clear and full, yet perfectly placid eye. With the exception of the dog and cat, whose original nature is ferocity, and whose whole life, unless diverted from their natural instincts, is plunder and prey; and the jockey racehorse, which is required to take the purse, at any hazard of life or limb to the groom; a mild, quiet eye is indispensable to the profitable use of the domestic brute. The neck should be well formed, not too long, tapering to its junction with the head, and gradually enlarging to a firm, well-expanded attachment to the back, shoulders, and breast. The back or chine should be short, straight, and broad; the ribs springing out from the backbone nearly at right angles, giving a rounded appearance to the carcass, and reaching well behind to a close proximity to the hip; tail well set on, and full at its junction with the body, yet gradually tapering to fineness; thighs, fore-arms, and crops well developed; projecting breast or brisket; the fore-legs straight, and hind ones properly bent, strong and full where attached to the carcass, but small and tapering below; good and sound joints; dense, strong bones, but not large; plenty of fine muscle in the right places; and hair or wool, fine and soft. The chest in all animals should be full, for it will be invariably found, that only such will do the most work, or fatten easiest on the least food. The Lungs.