ECOLOGY OF LEAVES 



121 



petiole. On the inner surface and round the margin of the 

 blade (Fig. 85) are borne a considerable number of short 

 bristles, each terminating in a knob which is covered with 

 a clear, sticky liquid. When a smAlL insect touches one 

 of the sticky knobs, he is 

 held fast and the hairs at 

 once begin to close over 

 him, as shown in Fig. 86. 

 Here he soon dies and 

 then usually remains for 

 many days, while the leaf 

 pours out a juice by which 

 the soluble parts of the 

 insect are digested. The 

 liquid containing the 

 digested portions is then 

 absorbed by the leaf and 

 contributes an important 

 part of the nourishment 

 of the plant, while the un- 

 digested fragments, such 

 as legs, wing-cases, and so 

 on, remain on the surface 

 of the leaf or may drop 

 off after the hairs let go their hold on the captive insect. 



In the Venus' flytrap, which grows in the sandy regions 

 of eastern North Carolina, the mechanism for catching 

 insects is still more remarkable. The leaves, as shown in 

 Fig. 87, terminate in a hinged portion which is surrounded 

 by a fringe of stiff bristles. On the inside of each half of 

 the trap grow three short hairs. The trap is so sensitive 

 that when these hairs are touched it closes rather rapidly 



Fig. 87. Venus' Flytrap. 



