CHAPTER III. — THE LEAF. 



39 



akin to gastric juice, which the secreting glands of the tentacles 

 pour out freely upon the doomed animal, the nutritive portions 

 of his body are dissolved and gradually absorbed by the plant 

 as food. , 



Fig. 132 represents one of the rosette of radical leaves of 

 the Venus' Fly-trap, a plant belonging to the same family as the 

 Sundew. The blade of the leaf consists of two spiny-margined 

 valves, which are movable upon the mid-rib as upon a hinge. 

 The face of each valve is also provided with three sensitive 

 spines, and when an insect, attracted by the glandular secretions 

 on the surface of the lobes, alights on one of them and touches 

 one of the sensitive spines, the lobes instantly come together 

 like the jaws of a steel-trap, almost invariably securing the 



Fig. 131. 



Fig. 132. 



Fig. 133. 



Fig. 134. 



Fig. 131.— Leaf of the Sundew serving the purpose of an insect trap. 



Fig. 132. — Leaf of Venus' Fly-trap. 



Fig. 133. — Leaf of the Northern Pitcher-plant. 



Fig. 134. — Leaf of the California Pitcher-plant (Darlingtonia). 



intruder, which becomes the food of the plant, and is digested 

 in much the same way as is done by the Sundew. 



The leaves of the Pitcher-plant of our northern bogs, Sarra- 

 cenia purpurea, Fig. 133, also entraps insects, though in a-quite 

 different way, and uses them for food. The pitchers are usually 

 found from half to two-thirds filled with water, which is mainly 

 secreted by the plant ; the lip of the pitcher has its inner surface 

 clothed with stiff and sharp-pointed bristles, which point down- 

 ward, and a secretion, enticing to insects, is poured out on the 

 inner surface, particularly about the throat. Insects are thus 

 enticed into the pitchers in great numbers, and owing partly to 

 the difficulty of escaping past the sharp-pointed hairs, and partly, 



