THE VEGETABLE KINGDOM. 



377 



In most of the Fuci the root merely represents a sort 

 of cramping-iron, serving just to anchor the plants at the 

 bottom of the sea, without drawing the least particle of 

 nourishment from the rock which it grasps. The myriads 

 of little claws by which the ivy attaches itself to the 



203. Adventitious Koots upon a Tnink. Duhamel's experiment. 



rugged stone of tombs and walls seem also designed solely 

 to fix it to its favourite site. 



On the contrary, the waterdentil, which spreads its 

 carpet of verdure on the surface of our pools, possesses 

 nothing but spongioles. The Pontederia, which floats on 

 the rivers of India, is only furnished with fine r'ootlets 

 scattered in their waves. 



But these are rare exceptions. Buried in the earth, 

 the root there performs its three functions in obscurity. 



For this purpose each of its capillary filaments is ter- 



