SOME REASONS FOR PLANT MIGRATION 87 
them — it would be impossible to excel them — in the 
almost infinite variety of the problems they present to 
us, the ingenuity, the interest, and the charm of the beau- 
tiful contrivances which they offer for our study and our 
admiration.” 1 
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. The more we study in detail the 
methods of plant dispersion, the more we shall come to 
agree with a statement made by Darwin concerning the 
devices for securing cross-fertilization of flowers, that they 
“ transcend, in an incomparable degree, the contrivances 
and adaptations which the most fertile imagination of the 
most imaginative man could suggest with unlimited time 
at his disposal .” 2 
Let no reader think that the topics here taken up are 
treated exhaustively, for if he will go over any part of 
this work and verify any observation or experiment, he will 
be sure to find something new, and very likely something 
different from what is here stated. 
1 Flowers , Fruits , and Leaves , by Sir John Lubbock, p. 96. 
2 Fertilization of Orchids , p. 351. 
