The conflicting interests in Nature sooner or later adjust themselves; her checks and balances bring about her equilibrium. In vegetation rivalries and antagonisms bring about adaptations. The mosses and the ferns and the tender wood plants grow beneath the oaks and the pines and are favored by the shade and protection which the latter afford them. The farmer’s seeding of grass and clover takes better under the shade of the oats than it would upon the naked ground. In Africa some species of flesh-eaters live upon the leavings of larger and stronger species, and in the tropics certain birds become benefactors of the cattle by preying upon the insects that pester them. Fabre tells of certain insect hosts that blindly favor the parasites that destroy them. The scheme has worked itself out that way and Nature is satisfied. Victim or victor, host or parasite, it is all one to her. Life goes on, and all forms of it are hers. It is easy to see why the wild plants run out the cultivated ones--the latter are the result of artificial selection. No favor has been shown the wild ones, and hence only the most vigorous have survived. The cultivated plants always have a greater burden to bear than the wild ones, and man helps them to bear it, or, rather, he saddles it upon them. The cultivated races of man have burdens to bear also, much greater than the savage tribes, but this is more than made up to them by their superior brain power, which brain power again has come about in the struggle for existence. Wild tribes have also been under the discipline of natural selection, but by reason of some obscure factors of race or climate or geography they have not profited as have the European and Asiatic races. Their moral natures are more rudimentary. Doubtless some obscure or unknown factors in the original germ-cells, far back in biological times, caused the divergence and splitting-up of animal forms, and gave to one an impulse that carried it higher in the scale of development than its fellows, just as the same thing happens in human families in our own times. Why some creatures are higher and some are lower, why some eventuated in the bird and some in toad and frog and snake and lizard, is one of the mysteries. In seeking the explanation of these things on natural grounds we are compelled to resort to the fertile expedient of conjecture, and pack the germ with many possibilities, each one depending for its development upon chance occurrence or conditions.