40 A TEXT-BOOk OF BOTANY 
one of the sticky drops, the hair begins to curve inward, and 
presently presses its victim down upon the surface of the 
blade. In the case of a larger insect, several of the mar- 
ginal hairs may join to- 
gether in holding it, or the 
whole blade may become 
more or less rolled inward. 
(6) Leaves of Dionea. 
—tThis is one of the most 
famous and remarkable of 
insect-trapping plants, be- 
ing found only in certain 
sandy swamps near Wil- 
mington, N.C. The leaf- 
blade is constructed so as 
to work like a steel trap, 
the two halves snapping 
together, and the marginal 
bristles interlocking like 
the teeth of a trap (Fig. 
Fic. 40.—Three leaves of Dionea: two with 40). A few sensitive hairs, 
Ene, Sane “ote ee wa Hep: shvh OP. Tiles feelers, ane developed 
on the leaf surface; and 
when one of these is touched by a small flying or hover- 
ing insect, the trap snaps shut and the insect is caught. 
Only after digestion, which is a slow process, does the trap 
open again. Dionea is popularly known as the “Venus 
fly-trap.”’ 
Sarracenia, Drosera, and Dionwa are conspicuous repre- 
sentatives of the so-called carnivorous or insectivorous 
plants, all of which capture insects and use them for food. 
They are green plants, so that they manufacture carbo- 
hydrates; but for some reason they supplement their food 
manufacture with a supply of food already manufactured, 
and obtained from the bodies of captured insects. 
KS 
