106 CLASS-BOOK OF BOTANY. 
heads towards it, and all the glands which can reach it pour: 
out a peculiar secretion upon it. This secretion contains a 
ferment which acts much as the digestive fluid of animals. 
Fig. 210. Leaf of Drosera binata. 
does, and in a longer or shorter time, according to the 
size of the insect, all its soft parts are dissolved away and 
apparently absorbed by the plant. Any readily-decom- 
posable nitrogenous substance, animal or vegetable (e.g., 
raw or cooked food, or bread), serves to similarly excite 
these glands. 
More specialised stillis the Venus’s Fly-trap (Dionwa mus- 
cipula), which is allied to Drosera, but in which the leaf-blades 
act as a trap. The midrib is strongly keeled, and the margin 
furnished with serrated processes. Hach side of the blade 
bears three stiff hairs, and if anything touches one of these 
the two sides close together and catch the intruder. The leaf- 
