72 ON THE PROPAGATION 



In the plants called " Cryptogamia," it is very evident 

 that the multiplication of the plants is perfectly secured, 

 since the spores, which occur in enormous numbers, fall 

 at once upon the ground, where they may become fully 

 developed. But the matter does not seem quite so certain 

 in the Phanerogamia. In many blossoms, it is true, the 

 germens and the stamens are so closely associated, that the 

 pollen apparently cannot miss the place, the stigma, on 

 on which its development is to begin. But this relative 

 position is not alone sufficient ; the two parts, the stamens 

 and the germen, or, more correctly, the pollen and the 

 stigma, must simultaneously stand in the same physiological 

 stage of development ; when the anther bursts, when the 

 pollen falls out, the stigma must also be ready to receive 

 it and call forth its power of development. Now, in a 

 great many blossoms, this does not take place ; the pollen 

 is probably lost to the stigma of the same flower much 

 oftener than perhaps is usually supposed, either because 

 the latter is not yet sufficiently perfect, or, on the other 

 hand, has begun to decay, at the moment when the 

 scattering of the pollen approaches. And much more 

 adverse are the circumstances in a not inconsiderable 

 number of plants, in which each blossom contains only 

 stamens or only germens, and where these two kinds of 

 blossoms are at some distance from each other, either in 

 the same plant or in different plants, such as those which 

 Linnaeus called single-housed (Monoecia,) and double- 

 housed (Dioecia.) In many groups of plants, as in the 

 Asclepiadaceee and Orchidacese, Nature appears to have 

 methodically taken pains, in the complicated and irregular 

 structure of the organs, to render impossible the natural 

 application of the pollen upon the stigma. Here totally 

 foreign powers come wonderfully to the aid of the 



