The other, we will say, served that same season a reasonable number, perhaps four to six in a week, or one every day, not more. Few came a second time and those for no fault of his. The calves bear a striking resemblance to the sire. Some from the better cows look even better in some points, than himself and few much worse. There is a remarkable uniformity among them; as they grow up they thrive better than those by the low priced one. They prove better adapted to the use intended. On the whole they are quite satisfactory and each pays annually in its growth, labor or milk a profit over the cost of food and attendance of five or ten dollars or more. If worked enough to furnish the exercise needful to insure vigorous health, he may be as serviceable and as manageable at eight or ten years old, as at two; meantime he has got, perhaps, five hundred calves, which in due time become worth ten or twenty dollars each more than those from the other. Which now seems the wiser purchase? Was the higher estimate placed on the well bred animal based upon fancy or upon intrinsic value? The conviction that a better knowledge of the principles of breeding would render our system of agriculture more profitable, and the hope of contributing somewhat to this end, have induced the attempt to set forth some of the physiological principles involved in the reproduction of domestic animals, or in other words, the laws which govern hereditary transmission. FOOTNOTES: [1] Local names for _lyery_, or black fleshed cattle. CHAPTER II. THE LAW OF SIMILARITY. The first and most important of the laws to be considered in this connection is that of SIMILARITY. It is by virtue of this law that the peculiar characters, qualities and properties of the parents, whether external or internal, good or bad, healthy or diseased, are transmitted to their offspring. This is one of the plainest and most certain of the laws of nature. Children resemble their parents, and they do so because these are hereditary. The law is constant. Within certain limits progeny always and every where resemble their parents. If this were not so, there would be no constancy of species, and a horse might beget a calf or a sow have a litter of puppies, which is never the case,--for in all time we find repeated in the offspring the structure, the instincts and all the general characteristics of the parents, and never those of another species. Such is the law of nature and hence the axiom that "like produces like." But while experience teaches the constancy of hereditary transmission, it teaches just as plainly that the constancy is not absolute and perfect, and this introduces us to another law, viz: that of variation, which will be considered by and by; our present concern is to ascertain what we can of the law of similarity.