ON PLANT LIFE 



127 



less. In the other two the anthers or cells pro- 

 ducing the pollen, which in most flowers form 

 together a round knob or 

 head at the top of the 

 stamen, are separated by 

 a long arm, which plays 

 on the top of the stamen 

 as on a hinge. Of these 

 two arms one hangs down 

 into the tube, closing the 

 passage, while the other ^'s-^- 



lies under the arched upper lip. When the 

 Bee pushes its proboscis down the tube (Fig. 11) 



Fig. 10. 



Fig- 11. 



it presses the lower arm to one side, and the 

 upper arm consequently descends, tapping the 



