368 ANIMAL BIOLOGY 



the insect and also for receiving the pollen, which the insect 

 has acquired in its previous visit to another flower of the 

 same species. This is very well illustrated by the flowers 

 of the sage Salvia pratensis. At the lower side of the 

 opening of the flower there is a sort of platform upon which 

 the insect alights. At the base of the flower is the nectar; 

 the anthers or pollen-bearing organs of the flower are at 

 the end of a movable lever which swings on a pivot. As 

 the insect goes toward the base of the flower in the pursuit 



FIG. 246. Flower of the sage (Salvia pratensis); I, lower lip of corolla; 

 p', pistil when immature; p", mature pistil; st', stamen when immature; 

 st", mature stamen. 



of honey it causes the anther to be pushed down and some 

 of the pollen becomes- dusted upon the insect's back. The 

 pollen and stigma mature at different periods so that a 

 flower is prevented from becoming fertilized by its own 

 pollen. When the stigma is ready to receive pollen it 

 becomes extended in the position shown in the figure. 

 When the insect visits a flower which is ready for fertili- 

 zation a part of the pollen upon its back becomes brushed 

 off upon the stigma whose position is now such as to be 

 brought into contact with it. This is but one of the very 



