168 THE BEAUTIES OF NATURE 



INSECTIVOROUS PLANTS 



In the cases above mentioned the relation 

 between flowers and insects is one of mutual 

 advantage. But this is by no means an in- 

 variable rule. Many insects, as we all know, 

 live on plants, but it came upon botanists as a 

 surprise when our countryman Ellis first dis- 

 covered that some plants catch and devour in- 

 sects. This he observed in a North American 

 plant Dionsea, the leaves of which are formed 

 something like a rat-trap, with a hinge in the 

 middle, and a formidable row of spines round 

 the edge. On the surface are a few very sen- 

 sitive hairs, and the moment any small insect 

 alights on the leaf and touches one of these 

 hairs the two halves of the leaf close up 

 quickly and catch it. The surface then throws 

 out a glutinous secretion, by means of which 

 the leaf sucks up the nourishment contained 

 in the insect. 



Our common Sun-dews (Drosera) are also 

 insectivorous, the prey being in their case 



