114 



MORPHOLOGY OF LEAVES. 



tion of petiole and blade, and the stalked glands thickly beset 

 the whole upper surface of the latter. A small insect alighting 

 thereon is helpless, and is soon touched by all the glands within 

 reaching distance ; also the blade itself commonly incurves, 

 taking part in the general movement. It has recently been 

 demonstrated that the captured insect is fed upon, and that the 

 plant thereby receives nourishment. Here leaves which do the 

 normal assimilative work of vegetation, but somewhat feebly 

 (having a comparatively small amount of chlorophyll) , have 



also the power and the habit of obtaining ready-organized food 

 by capture, and are benefited by it. 



224. Species of Drosera inhabit most parts of the world, and 

 the genus is numerous in species. A near relative, Dionaea, is 

 of a single species, D. muscipula (Venus's Fly-trap), inhabiting 

 only a limited district in the sandy eastern border of North 

 Carolina. It is more strikingly sensitive and equally carnivo- 

 rous, but in a different way. It is destitute of stalked and viscid 

 glands. The apparatus for capture and digestion is the two- 

 valved body at the top of each leaf. (Fig. 230, 231.) If this 



FIG. 230. A plant of Dionaea muscipula, reduced in size. 231 Three of the leaves, 

 of almost the natural size ; one of them open, the others closed. Probably a fly is never 

 caught by the teeth, in the manner here represented. 



