144 



Introduction to Botany. 



the pitcher and under surface of the pennant lure both 

 creeping and flying insects to the mouth of the pitcher, 

 and after they have passed beyond the incurved border, 



which they are likely to do, they 

 meet with a smooth surface 

 to which it is impossible for 

 them to cling, and are precipi- 

 tated to the bottom of 

 the pitcher, where a di- 

 gestive secretion awaits 

 them. The attempts of creeping 

 insects to crawl out of the 

 pitchers are frustrated by stiff, 

 downward-pointing hairs. 

 Winged insects can fly upward, 

 but instead of finding the open- 

 ing they are attracted by the 

 transparent spots in the over- 

 arching helmet, against which 

 they vainly beat until they be- 

 come exhausted and fall to the 

 bottom, where they become im- 



Dariwgtonia Caiifornica. After mcrsed in the digestive fluid. 

 Geddes. ° 



The pitcher plant known as 



Sarracenia variolaris, which is common in the southern 

 states, although not so elaborate, has essentially the same 

 devices as Darlingtonia, for alluring and entrapping in- 

 sects. 



Investigations thus far leave us in doubt whether the 

 main function of these pitchers is the capture of insects 

 for the food of the plant, or whether they are primarily 

 water, reservoirs to hold water that has been exuded from 

 the plant itself, or caught from the rain in those cases 



Fig. 



72. 



