246 



THE LIFE OF THE PLANT 



time later the stamens ripen and split ; the insects 

 restlessly move about in their prison (71, upper section) 



and get covered with 

 pollen ; but this pol- 

 len on reaching the 

 stigma does not pro- 

 voke self-fertilisa- 

 tion, because the 

 stigma has already 

 withered. The hairs 

 of the corolla soon 

 afterwards wither 

 and fall off (7 1 , lower 

 section) , the door of 

 the prison is open, 

 and the insect, 

 covered with pollen, 

 flies out to be caught 

 again by a similar 

 trap in another 

 flower. Later on, the 

 upper lobe of the 

 corolla withers, and 

 bending over closes 

 the entrance into the 

 flower (7 1 , lower sec- 

 tion) ; and the whole 

 flower, until then erect, droops. In this way fertilised 

 flowers escape useless visits from insects. This adaptation 

 works as successfully as the mechanism for the fertilisa- 

 tion of the orchids, so that we can tell almost with 

 certainty' from the external appearance of the flower 

 whether we shall find insects inside it or not. The 

 number of insects thus temporarily imprisoned in a 

 flower is sometimes considerable. 



We may, then, assuredly see in the so-called unessential 

 parts of the flower, such as the bright colouring of the 



Fig. 71. 



