THE SELF-FERTILIZATION OF PLANTS. 341 



self-impotence " vanish like a morning cloud " (as 

 Tyndall has it), "into the infinite azure of the past." 

 " Kolreuter, however," continues Darwin, " has de- 

 scribed some plants of Verbascurri, which varied in this 

 respect, even during the same season." If the plants 

 had suffered a change, from comparatively favorable, 

 to poor conditions, of light, heat, electricity, chemical 

 elements, &c, and this change had lessened the vigor 

 of the neglected parts of the plants, this variation 

 from fertility to sterility, during the same season, 

 would be explicable. Or, if the favorable conditions 

 were peculiarly propitious to the advanced develop- 

 ment of the special excellence of the plants, this 

 improvement in one character alone, would, through 

 affecting the proportion, induce self-impotence. In 

 corroboration of this last remark, is the following 

 from Darwin (p. 380, Vol. ii, Animals and Plants, &c): 



" In the Compositae, the so-called doubling of the 

 flowers consists in the greater development of the 

 corolla of the central florets, generally accompanied 

 with some degree of sterility." 



This sterility results, because the corolla alone, of 

 the central florets, and the central florets alone, have 

 been greatly developed, without the concurrent devel- 

 opment of the other florets, of the other parts of the 

 central florets, and of the several leaves, racemes, 

 stamens, branches, pistils, anthers, and other charac- 

 ters normally proper to the given species. As a 

 consequence, the true coordination has been im- 

 paired, — all the parts have not been brought into 

 harmony with each other. If the parts valued are 



