JNSKcrrS AND KLOWKKS. I4f> 



sary to plants in which the stamens and pistils 

 were not in the same flower, that they were un- 

 necessary to those plants (which are by far the 

 greater number) in which these organs are in 

 the same flower. This however is not so. 

 The stamens and pistils of complete flowers 

 commonly ripen at different times, so that 

 when the stigmas are ready to receive pollen, 

 the stamens of that particular flower have 

 already shed their pollen. In other cases 

 various arrangements are found whereby the 

 pollen of a flower is prevented from reach- 

 ing the stigma of the same flower. The re- 

 sult is that crow-fertilization, the fertilixation 

 of a flower by the pollen of another flower, is 

 the general rule and self-fertilization that is, 

 by the pollen of the same flower is compara- 

 tively rare even in plants which have both 

 stamens and pistils in one flower. 



4 Many flowers can be pollinated by almost 

 any insect. Others have very complicated 

 arrangements and are specially adapted to 

 particular insects. This is well illustrated 

 by the vanilla, which is so elaborately made 

 that it must be visited by certain insects be- 

 fore it can be pollinated naturally, and, as these 

 particular insects are not found in the 

 West Indies, the cultivator of vanilla, in or- 



