It is worthy of note that “natural” selection has many advantages over “artificial” selection. The breeder may be mistaken; he may select the wrong puppy and drown its superior. The horse that won the great race may have had a fleeter-footed companion in the same stable had the trainer known how to develop his possibilities. The gardener may have passed the best root or stem through carelessness. But nature makes no such mistakes, or if she does she eventually redeems them. Her method, while it is wholly fortuitous and unintelligent, is practically infallible. The condition of survival is, adaptation to environment. The very process of selection is, in itself, a sure test of fitness. True, moral considerations are eliminated--at least in the non-social world--yet nature offers something like a fair field and no favors. When we speak of nature’s favorites, we simply mean those who are best fitted to meet her hard conditions. Take a row of celery plants, from which future seedlings are to be “selected.” In this instance, let us suppose, the quality desired is ability to resist frost. How is the gardener to know which of fifty plants are the “best” in this respect. He has no method of finding out with any degree of certainty. But nature comes along some night with a sharp frost and “selects” ten by killing forty. And the very act of this “natural” selection proves that these ten are better able to withstand the frost than their fellows. Breeders of white sheep who supply the white wool market have a very tangible guide--they kill every lamb that shows the least tinge of black. But even here, nature is not to be out-done. In Virginia there is--or at least was in Darwin’s day--a wild hog of pure black. One of its staple foods was known as the “paint-root.” Any hog with the least speck of white on its body was poisoned by this root while its all-black brothers found it a health-sustaining and succulent food. In an environment which remained constant and where a species of animals had reached a population which strained the limits of subsistence--food supply--those offspring which most closely resemble their parents, who had won out in that environment, would again succeed and be selected. While if the environment changed--became warmer or colder for example--those descendants which happened to vary in a direction making them better able to cope with the new conditions would be selected for survival as against those who resembled their parents, which parents had survived in their day because they were adapted to the prior environment.