206 VEGETABLE PHYSIOLOGY 



insect, attracted to the leaves by their glistening appearance, 

 is at once entangled in the viscid mucilage and is presently 

 suffocated. It is speedily digested by the secretion of the 

 sessile glands. 



Pinguicula, the butter-wort, has a mechanism of a 

 somewhat similar nature. It bears, resting on the ground, 

 large fleshy green leaves, the edges of which are slightly 

 curled over towards the upper surface, forming a kind of 

 open trough. All over the upper surface are distributed 

 glands which pour out a viscid mucilage. On contact with 

 any small mass of proteid, or with an insect or other small 

 animal, these glands also pour out an increased amount of 

 mucilage, mixed- now with a digestive fluid similar to that 

 of Drosopliyllum. If an insect alights upon the margin of 

 the leaf, not only is the secretion poured out, but the edge 

 slowly curls over more strongly, either covering the intruder, 

 or pressing it towards the centre of the trough. Here it is 

 suffocated and digested as in other cases. Pinguicula is 

 peculiar in that its secretion has the power of curdling 

 milk in the same way as the gastric juice of animals. 



In some cases a yet more elaborate mechanism is found 

 to effect the same purpose. We find associated with the 

 power of digesting and absorbing animal food, a mechanism 

 for the capture of the prey which involves a movement of 

 either the leaf-blade itself or of the glands which it pro- 

 duces. The former is exhibited by Dion&a, the Venus's 

 fly-trap ; the latter by the different species of Drosera (the 

 Sundews). 



Drosera is a small plant which is found growing upon a 

 substratum of bog-moss (Sphagnum). Its dimensions are 

 small, the plant not being more than a few inches in height. 

 It bears a rosette of leaves, from the middle of which rises a 

 single scape of flowers. The leaves are covered with stalked 

 glands (fig. 99), which stand out from the surface. Each 

 gland has a somewhat substantial stalk, containing a rudi- 

 mentary vascular bundle. At the top of the stalk is a 

 rounded head which is always covered by a viscid secretion 



