The Origin of Wheat. 



M5 



tage which the lilies thus gain is obvious enough. 

 Their bright petals, usually larger and more attrac- 

 tive than those of the alismas, allure a sufficient 

 number of insects to enable them to dispense with 

 the numerous stamens and ovaries of their primitive 

 ancestors. Moreover, this diminution in number is 

 accompanied by an increase in effectiveness and 



Fig. 33. — Flower of White Lily and section of ovary. 



specialisation : for the lilies have only three sensitive 

 surfaces to their pistil, combined on a single stalk : 

 and the honey is usually so placed at its base that the 

 insect cannot fail to brush off pollen at every visit 

 against all three surfaces at once. Again, while the 

 number of ovaries has been lessened, the number of 

 seeds in each has been generally increased, which also 



