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 
Fie. 87. Venus’ Flytrap. 
