OTHEE METHODS OF OBTAINING FOOD 201 



apex. This orifice is guarded by a number of stiff tapering 

 bristles, and is closed by a sort of trapdoor which opens 

 inwards and shuts again with a kind of spring. A small 

 animal such as an aquatic insect can easily open it by press- 

 ing against it, and thus can enter the bladder. The trapdoor 

 immediately closes by virtue of its own elasticity, and 

 cannot be opened by pressure from within. The insect 

 accordingly finds egress, impossible, and after a short 



FIG. 94. TRAPS OF Utricularia neglecta. (After Kerner.) 



a, a bladder magnified ( x 4) ; 6, section of a bladder ; c, absorption-cells 

 on the internal surface of the bladder ( x 250). 



time, usually ranging from one to three days, it perishes 

 and its body decays, yielding to the plant the products 

 of its decomposition, which are absorbed by particular 

 cells growing from the internal wall of the bladder (fig. 94). 

 Some of the ascidia-bearing or pitcher-plants show a 

 somewhat similar mechanism and utilise corresponding 

 organic substances. The Sarracenias afford good examples. 



