200 VEGETABLE PHYSIOLOGY 
by a sort of joint. The lamina is roundish and is divided 
into two almost exactly similar halves, which are separated 
by the midrib (fig. 96). The edge of each half is furnished 
with a number of rigid teeth, and when the two halves are 
folded together on a hinge which the midrib forms, the 
teeth interlock with each other and a closed cavity is pre- 
pared. On the upper surface of each half of the leaf, about 
in the centre, are three short spines which project out- 
wards and upwards. When either of these is touched twice 
in rapid succession, the two lobes of the lamina become 
slightly concave and fold over quickly, the teeth interlock, 
and the cavity is closed. If the contact has been made by 
an insect, it is captured and imprisoned between the lobes. 
The closing is fairly rapid, taking only about a second. All 
over the upper surface of the lamina secreting glands are 
found, whose secretion is similar to that of Drosera. If 
the leaf encloses nitrogenous digestible matter, such as the 
body of an insect, the prison remains closed for some con- 
siderable time, and the glands surround the prey with 
the digestive fluid, the products of its decomposition being 
absorbed by the gland-cells. 
These mechanisms for the digestion and absorption of 
protein substances are seen to be extremely complex. Evi- 
dence of such digestion and absorption is shown also by far 
humbler plants without any differentiated structure. Many 
Fungi and Bacteria, when cultivated in solutions containing 
native proteins, such as albumin or globulin, are able to 
effect their digestion by the secretion of a similar enzyme to 
those of the plants already described. They subsequently 
absorb the peptone or the amino-acids which result from 
such action. Nor is protein material alone affected in this 
way by these humbler plants. They derive their carbo- 
hydrate supplies from their environment in the same way 
as their protein ones. Many of the filamentous fungi 
possess the property of forming digestive enzymes, which 
attack m some cases starch, in others inulin, in others 
various sugars which are not immediately available for 
