202 THE STORY OF THE PLANTS. 



rootlets are clustered thickest about the exact 

 spots where the leaves habitually drop the water 

 down upon them. Every plant is thus to some 

 extent a catchment-basin which utilises its own 

 rainfall : it collects rain for itself, and conducts 

 it by a definite system of pipes and channels to 

 the precise spots in the soil where it can best be 

 sucked up for the plant's own purposes. 



On the other hand, while every part of every 

 plant is thus minutely arranged for the common 

 advantage, every species of plant and animal 

 fights only for its own hand against all comers. 

 Nature is therefore one vast theatre of plot and 

 counterplot. The parasites prey on the vegeta- 

 tive kinds; the vegetative kinds respond in turn 

 by developing checks to counteract the parasites. 

 The squirrels produce sharper and ever sharper 

 teeth to gnaw through the nutshells; the nut- 

 trees retaliate by producing for their part thicker 

 and ever thicker shells to baffle the squirrels. 

 And this play and by-play goes on unceasingly 

 from generation to generation ; because only the 

 cleverest squirrels can ever get enough nuts to 

 live upon ; and only the hardest-shelled and 

 bitterest-rinded nuts can escape the continual 

 assaults of the squirrels. In order, therefore, 

 really to understand the structure and life of any 

 one species, we should have to know in the mi- 

 nutest detail all about its native conditions, its 

 soil, its surroundings, its allies, its hired friends, 

 its blackmailing foes, its exterminating enemies. 

 Such exhaustive knowledge of the tiniest weed is 

 clearly impossible; but even the little episodes 

 we can pick out piecemeal are full of romance, of 

 charm, and of novelty. 



