Page:Popular Science Monthly Volume 25.djvu/449

Rh to escape being observed and eaten. The reason for such a disposition on the part of the nut is easy enough to understand. In the true or succulent fruits—fruits, that is to say, according to the popular and strictly practical sense of the word—the part we eat is not the actual seed itself, the cherry-stone or plum-stone or raspberry-kernels (which even if we swallow we do not digest), but a soft, pulpy covering which has nothing essential to do with the young embryo or future plantlet. In nuts, on the other hand, the part we eat is the actual kernel or embryo itself, with all the starches, oils, and other food-stuffs laid up for its use by the mother-plant. In the simplest and earliest form of seeds, like those of mustard and cress, for example, there is hardly any store of nutriment put away by the mother for the benefit of its struggling seedling. These poorly endowed plantlets have to open their green leaves to the sunlight the moment they begin to sprout, and, unless they can assimilate fresh food from the air immediately under that genial influence, they must die forthwith of pure inanition. But at a very early period in the evolutionary history of plants, some seeds began to be stored at the outset with small quantities of starch or oil, which enabled their budding embryos to push their heads higher above the surrounding vegetation without depending entirely for support on the mere hand-to-mouth system of daily gains. They had, so to speak, a small reserve of capital to live upon. Of course, this gave all such plants a great advantage over their neighbors in the struggle for existence: they could live under conditions where poorer seedlings would starve and die; and so, from generation to generation, those kinds which laid by most material survived the best on the average, till at last in many cases the embryo came to be very richly endowed indeed with starches, oils, gluten, and other valuable collected food-stuffs. This is especially the case with such seeds as wheat, barley, rye, oats, Indian corn, rice, peas, beans, lentils, and buck-wheat.

Unfortunately for the plants, however, what will feed a seedling will feed an animal just as well: and so, exactly in proportion as the plants began to lay by food-stuffs for their own purposes in their embryos, did the animals begin to prey feloniously upon these convenient reservoirs of nutritious gums and starches. Not only does man eat the cereals and pulses, which are the richest in nutriment of almost all seeds, but many earlier and lower animals, such as harvest-mice, rats, chipmunks, deer, antelopes, horses, cow-kind, and even prairie-dogs commit great depredations upon them, both in the wild and cultivated states. Still more particularly have large numbers of animals, such as the squirrels, dormice, monkeys, parrots, nut-hatches, and even many grubs, taken to feeding off the fruits and seeds of forest-trees or woodland bushes. As a consequence, only those richly-stored seeds have for the most part survived which possessed some natural means of defense against their aggressive enemies; and in many instances