=Dispersal of Seeds.=--Having described in the Plant World some of the provisions of Nature for the dispersal of seeds, Prof. W. J. Beal adds that these various devices, besides serving to extend and multiply the species and promote its plantation on favorable soil, enable plants to flee from too great crowding of their own kind and from their plant rivals and parasites. "The adventurers among plants often meet with the best success, not because the seeds are larger or stronger or better, but because they find for a time more congenial surroundings. Our weeds, for instance, are carried for long distances by man and by him are planted in new ground that has been well prepared. Every horticulturist knows that apples grown in a new country, if suitable for apples, are fair and healthy, but the scab and codling moth and bitter rot and bark louse sooner or later arrive, each to begin its peculiar mode of warfare." So with peach trees and plums and their enemies. The surest way to grow a few cabbages, radishes, squashes, cucumbers, and potatoes is to plant them here and there in good soil at considerable distances from where any have heretofore been grown. "For a time enemies do not find them." Pear trees planted scatteringly are more likely to remain healthy than in orchards. "Perhaps one reason why plants have become extinct or nearly so is their lack of means of migration. As animals starve out in certain seasons when food is scarce, or more likely migrate to regions which can afford food, so plants desert worn-out land and seek fresh fields. As animals retreat to secluded and isolated spots to escape their enemies, so many plants accomplish the same thing by finding the best places with some of their seeds sown in many regions. Frequent rotations seem to be the rule for many plants when left to themselves in a state of nature. Confining to a permanent spot invites parasites and other enemies and a depleted soil, while health and vigor are secured by frequent migrations."