Page:Popular Science Monthly Volume 33.djvu/757

Rh to upset the dormant condition—allows the failing growth to continue. The seed swells, the fruit ripens, and a new plant is shed forth upon the earth, the product of two distinct prior individuals.

But if the embryo is not thus quickened, growth in it ceases altogether. The seed shrivels up, the pod does not swell, and no new plant is produced at all. It does not contain within itself the needful energy for further development. Supposing all the flowers on a pea-plant were thus to fail—supposing no pollen were ever to be carried from blossom to blossom—then that particular plant would wither and die out altogether, leaving no offspring at all behind to represent it.

In the case we have supposed, however, the flower did get fertilized, and the pea before me—a dormant but still a living plant—is the irrefragable proof that it actually did so. Now, in some instances, perhaps in this one, a flower gets fertilized with its own pollen. In such cases, as a rule, the fruit nevertheless swells out properly and the seed produces a young plant. How, then, are we to reconcile this apparent discrepancy with the general principles of sexual growth laid down above? Well, we must recollect that in a certain sense each leaf is a distinct individual. Again, from the biological point of view the flower consists of modified leaves, some of them specialized to do duty as sepals, some as petals, some as stamens, and some as ovaries. Each of these is therefore in some sense an individual. In the entire community or compound organism, in other words, we may regard the stamens and ovaries as particular members, told off, like the queen-bees and drones in the hive, to fulfill the part of fathers and mothers, while the true leaves, like the workers, provide the food or material for growth. Thus, even in the same flower the stamens and ovaries are properly to be regarded as distinct individuals, capable of producing healthy offspring with one another, like the queen bees and drones of the same hive.

Nature, however, does not stop here. The fundamental fact at the bottom of all fertilization whatsoever seems to be this, that where individual formative power fails it can be supplemented and set on foot again by an access of fresh formative power from without. Union is strength: what one can not do, two can. But the fresh fillip seems to be most distinctly felt when it comes not from another member of the same original colony—that is to say, from a stamen of the same blossom or of another blossom on the same plant—but from a totally distinct and separate colony, or, in other words and in more familiar language, from the flower on another neighboring plant. Where the parents are too closely related, it would seem, both are apt to have the same weak points, which therefore reappear in the offspring and vitiate it. But