POLL EN A 7 'ION : HE TEROSPOR Y. 



367 



the finger, and touch the upper surface of the labellum by thrusting it 

 between the latter and the style. The labellum curves quickly downward. 



671. Sometimes the bumblebees, after sipping the nectar, will crawl up 

 over the style in a blundering manner. In this way the flower may be pol- 



Fig. 468. 

 Pollenation of the canna flower by bumblebee. 



Canna flower. Pollen on style, sta- 

 men at left. 



lenated with its own pollen, which is equivalent to self pollenation. Un- 

 doubtedly self pollenation does take place often in flowers which are adapted, 

 to a greater or less degree, for cross pollenation by insects. 



