THE SELF-FERTILIZATION OF PLANTS. 401 



fertilize themselves is due to the anther-cells lack- 

 ing the power to open naturally, and to the conse- 

 quent inability of the pollen-mass to release itself and 

 fall to the level of the stigmatic surface. The modifi- 

 cation is very slight. It is simply a case of slightly ar- 

 rested development of the pollen-mass, and of the 

 anther-cells where they cohere. And, as to the possi- 

 bility of the modification's having been induced; Dar- 

 win shows (chap. ■ vii) that, many great modifications 

 have occurred, in almost every individual of this genus, 

 in many and important characters. 



Robert Brown, who "first observed that the struc- 

 ture of the Bee Ophrys is adapted for self-fertilization," 

 "believed" (though "erroneously," as Darwin con- 

 tends), "that this peculiarity (of self-fertilization) was 

 common to the genus." Darwin's only answer to this 

 induction of Mr. Brown, is, that " this one alone of the 

 four species" of British Orchids, shows this capacity. 

 But, this is no objection, as the assumption is, that the 

 other species originally fertilized themselves, and sub- 

 sequently becoming modified, thus lost, the power so 

 to do. 



The test, by which to ascertain, whether they have 

 so become modified, and by which to ascertain whether 

 the process of fertilization, per se, is injurious, is to be 

 found in a comparison of the fertility of the self-fertil- 

 ized plants, with the fertility of those which depend, for 

 their reproduction, upon the crossing which is effected 

 by insect agency. The test is the fairest possible; for, 

 Darwin's principal criterion, by which to judge of the 

 injurious effects wrought by self-fertilization, or by 



