154 INSECT VISITORS. [CH. XI 



with the keel, the weight of the insect is brought to bear 

 on the keel and forces it downwards so that the anthers 

 and the style emerge and touch the under side of the bee's 

 body. The union of the wings and keel is effected in 

 the pea-flower by an interlocking of protuberances and 

 depressions which can hardly be understood without 

 examining the flower. In the bean the adhesion of the 

 wings to the keel has a similar use. The bee not only 

 carries away pollen from the flower visited, but also 

 brings to it pollen which had adhered to its hairy coat 

 during previous visits. In this way the insect will smear 

 the stigma with pollen and at the same time carry off a 

 fresh supply for future fertilisations. When the bee, after 

 having sucked the nectar, flies away, the keel, relieved 

 from its weight, springs up into its former position and 

 once more covers up the androecium and gynoecium in its 

 hood. In a wet climate like that of England this 

 arrangement must be of service to the plant in protecting 

 the anthers from wet, for it is a matter of experience 

 that pollen is injured by rain: the nectar too is tho- 

 roughly sheltered and cannot be diluted or washed away 

 by a shower. 



In books 1 especially devoted to this subject many 

 other details are given as to the adaptation of papi- 

 lionaceous flowers to the visits of insects. What is here 

 given must suffice for our present purpose. 



i See The Fertilisation of Flowers, by H. Miiller, 1883. 



