SOME REASONS FOR PLANT MIGRATION. 85 
buried, a few in a place. By a slow process, which, how- 
ever, covers a considerable space, in a few years many 
plants send forth roots, rootstalks, stolons, and runners, 
and thus increase their possessions or find new homes. 
54. Plants migrate to improve their condition. — The 
various devices by which plants are shifted from place to 
place are not merely to extend and multiply the species, 
and reach a fertile soil, but to enable them to flee from 
the great number of their own kind, and from their ene- 
mies among animals and parasitic plants. The adven- 
turers 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 surround- 
ings. We must not overlook the fact, so well established, 
that one of the greatest points to be gained by plant migra- 
tion is to enable different stocks of a species to be cross fer- 
tilized, and thereby improved in vigor and productiveness. 
55. Fruit grown in a new country is often fair. — Every 
horticulturist knows that apples grown in a new country, 
that is suited to them, are healthy and fair; but, sooner 
or later, the scab, and codling moth, and bitter rot, and 
bark louse arrive, each to begin its particular mode of 
attack. Peach trees in new places, remote from others, 
are often easily grown and free from dangers; but soon 
will arrive the yellows, borers, leaf curl, rot, and other 
enemies. For a few years plums may be grown, in cer- 
tain new localities, without danger from curculio, or rot, 
or shot-hole fungus. It has long been known that the 
