The skillful gardener, looking over his flowers, finds a plant of more than ordinary beauty and thrift of growth. When it comes to maturity he keeps its seeds separate from those of the rest and next year plants them by themselves. As they come up he weeds out all unthrifty plants, only allowing the strongest to come to maturity. As they break into bloom he plucks away all whose flowers do not come up to the high standard he has set for himself. After a while he has but a few plants left, but these are the thriftiest and bear the most beautiful flowers. Again he allows these to mature and selects the seed of the very finest. Next year the process is repeated. After a few generations, usually three if the man is skillful enough, he has a definite strain of flowers that will thereafter come true. This is the process of artificial selection as carried on by man. Darwin saw that Nature is constantly carrying on a similar process. She produces seeds enough on almost any plant to clothe the world in a few years if all of them could fall into proper ground and thrive like their parents. A friend of mine found a mullein stalk that bore more than seven hundred seed pods and averaged more than nine hundred seeds to the pod, a total of more than six hundred and thirty thousand seeds. If each of these could find lodgment on a plot eighteen inches square, produce a similar number of seeds and plant them all, the result would be overwhelming. The fourth generation would cover land and sea, from pole to pole, one hundred layers deep. But there is no such danger. Year by year the mulleins hold their own and no more. Any particular field may have more or less, but in the long run the average for a district is about the same. Some of the seeds are poor and thin. These scarcely sprout. Others spring up into thin-skinned plants, and the first frost nips them. Still others lack the woolly coating in its finest abundance, and the browsing animals eat these. Others lack power to put out a wide-ranging root supply and the first drought kills these. Still others fail to send up a vigorous stem and the passing animal knocks them over and they die. Of the few that are still surviving, some produce such small and inconspicuous blossoms that the insects scarcely see them, and they go unfertilized. In the end only the aristocrats of the group are left, aristocrats in the best sense of the word. These are strong, thrifty, and beautiful, and are provided with every defense known to the mullein world. From these the mulleins of the next generation will spring. Again Nature will select the best of these, by a repetition of the same process. Thus year by year the stock is improved. Any new feature that is favorable helps its possessor to survive, and, if happily mated, will show itself after a while in the entire group. This, in brief, is the underlying idea of Natural Selection, as Darwin conceived it.