Now, in the bull, the arteries which correspond to the mammary or lacteal arteries of the cow are not so fully developed; and the escutcheons are smaller, shorter, and narrower. Guénon applied the same name, milk-mirror, to these marks in the bull; and the natural inference was, that there should exist a correspondence or similarity in the mirror of the bull and the cow which are coupled for the purpose of producing an offspring fit for the dairy,--that the mirror in the bull should be of the same class, or of a better class than that of the cow. It is confidently asserted by the advocates of Guénon’s method, and with much show of reason, that the very large proportion of cows of bad or indifferent milking qualities, compared with the good, is owing to the mistakes in selecting bulls without reference to the proper marks or points. As to the transmission of the milk-mirror, it has been found in many cases that bulls sprung from cows with good mirrors had smaller and more heart-shaped mirrors, spreading out pretty broad upon the thighs. Pabst, a successful German breeder, says that he has used such bulls for three years, and that the milk-mirrors were transmitted in the majority of the male progeny, and in nearly every case very large and beautiful mirrors were given to the heifer-calves. A son of the bull with which he began was serving at the time of which he speaks, having a mirror more highly developed than his sire, and the first calves of his get had also very large milk-mirrors. The female offspring of the first bull of good milk-mirror promised first rate, though they had not then come in. His inference is, that in breeding from cows noted as milkers regard should be had to the form of the mirror on the bull, and the chance of his transmitting it. If any credit is due to this ingenious method, it may be laid down, as a principle in the selection of a bull to get dairy stock, that the one possessing the largest and best-developed milk-mirror is the best for the purpose, and will be most likely to get milkers of large quantity and continued flow. This method will be more fully developed in the chapter on the Selection of Milch Cows.