242 REVIEWS. 



the larger part of Darwin's latest volume on "The Different 

 Forms of Flowers on Plants of the Same Species " is devoted. 

 In such flowers — and they are rather numerous and of many 

 families — the advantage of cross-breeding between different 

 individuals of the same species is unquestionable, for it is 

 essential to full fertility. The differences in structure, which 

 consist of relative and reciprocal length of stamens and style 

 in blossoms otherwise alike, have long been known ; the mean- 

 ing of it was one of Darwin's happy thoughts, and the con- 

 firmation is due to his labors. He demonstrated that the 

 structure was correlated to the transport by insects of the 

 pollen of the one sort to the stigma of the other, and that each 

 pollen was inert, or nearly so, upon the stigma of the flower 

 it belonged to, but potent upon the stigma of the other sort, 

 upon which, in passing from blossom to blossom among the 

 plants (of about equal number as to sort), the visiting insects 

 are pretty sure to deposit it. 



It is noteworthy that this significant dimorphism belongs to 

 certain species of a considerable number of natural families, 

 while others, sometimes even of the same genus, and in most 

 of their species, show no trace of it; as if certain favored 

 species had acquired a peculiarity in which their brethren have 

 not shared. We ourselves call to mind some species in which 

 this acquisition is either incipient or the correlations imperfect. 

 But in his earliest work of the present series, on " The Vari- 

 ous Contrivances by which Orchids are Fertilized by Insects," 

 — a fascinating volume, which has recently been brought out 

 in a second edition, — the " contrivances," as they may well be 

 termed, are the common property of the whole order, although 

 each genus seems to have patented a modification of its own. 

 Here there is no dimori)hism, but (with rare exceptions) all 

 the flowers are alike, and all agree in having the pollen placed 

 tantalizingly near the stigma, but prevented from reaching 

 it, as well as in having some arrangement for the pollen's 

 being transported by insects from one flower to another, ulti- 

 mately from one i)lant to another. Wonderful arrangements, 

 indeed, they are, which it requires a volume to describe, and 

 of which we can here offer no details. Suffice it to say that, 



