HOW PLANTS DRINK. 55 



They are all root, all leaf, all flower, all fruit. 

 But higher plants tend to produce different or- 

 gans, which have become specially adapted by 

 natural selection for special purposes. If you 

 sow a pea or bean you will find at once that the 

 young seedling begins from the very first to dis- 

 tinguish carefully between two main parts of its 

 body. In one direction, it pushes downward, 

 forming a tiny root, which insinuates itself with 

 care among the stones and soil ; in the other 

 direction, it pushes upward, forming a baby stem, 

 which gradually clothes itself with leaves and 

 flowers. 



The tip of the root is the part of the plant 

 which exercises the greatest discrimination and 

 ingenuity, so much so that Darwin likened it to 

 the brain of animals. For it goes feeling its way 

 underground, touching here, recoiling there, in- 

 sinuating little fingers among pebbles and cran- 

 nies, and trying its best by endless offshoots to 

 fix the plant with perfect security. Large trees, 

 in particular, need very firm roots, to moor them 

 in their places, and withstand the force of the 

 winds to which they are often subject. After 

 every great storm, as we know, big oaks and 

 pines may be seen uprooted by the power of this 

 invisible but very dangerous enemy. 



The root, however, does not serve merely to 

 anchor the plant to one spot, and secure it a 

 place in which to grow and feed ; it also drinks 

 water. The hairs . and tips of the root absorb 

 moisture from the soil ; and this water circulates 

 freely as sap through the entire plant, dissolving 

 and carrying with it the starches and other ma- 

 terials which each part requires for its growth and 



