FLOWERS 



35 



carried by the insect visitors from the anthers of the flower to its 

 stigma. 



Pollination. — It was not until the middle of the nineteenth cen- 

 tury, however, that an Englishman, Charles Darwin, discovered 

 the true relation of insects to flowers by his investigations upon 

 the cross-pollination of flowers. By pollination we mean the 

 transfer of pollen from an anther to the stigma of a flower. Self- 

 pollination is the transfer of pollen in one flower ; cross-pollination 

 is the transfer of pollen from the anthers of one flower to the stigma 

 of another flower of the same kind. It was found by Charles Darwin 

 — and it has since 

 been proved many 

 times — that flow- 

 ers which were 

 self-pollinated did 

 not produce so 

 many seeds, or 

 seeds with so 

 much vitality, as 

 those which were 

 cross - pollinated. 

 Microscopic ex- 

 amination of the 

 stigma at the time 

 of pollination also 

 shows that the pollen from another flower germinates before 

 the pollen which has fallen from the anthers of the same flower. 

 This latter fact alone in most cases renders it impossible for a 

 flower to produce seeds by its own pollen. Darwin worked for 

 many years on the pollination of many insect-visited flowers, and 

 discovered in almost every case that showy, sweet-scented, 

 or otherwise attractive flowers were adapted or fitted to be cross- 

 pollinated by insects. He also found, in the case of flowers that 

 were inconspicuous in appearance, often a compensation appeared 

 in the odor which rendered them attractive to certain insects. 

 The so-called carrion flowers, polUnated by flies, are examples, 

 the odor in this case being like decayed flesh. Other flowers open 



An orchid, a flower of the type from which Charles Darwin 

 worked out his theory of cross-poUination by insects. 



