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 in some cases starch, in others inulin, in others 

 various sugars which are not immediately available for 





