Chap. III. STRUGGLE FOE EXISTENCE. 77 



A corollary of the highest importance may be deduced 

 from the foregoing remarks, namely, that the structure 

 of every organic being is related, in the most essential 

 yet often hidden manner, to that of all other organic 

 beings, with which it comes into competition for food or 

 residence, or from which it has to escape, or on which it 

 preys. Tin's is obvious in the structure of the teeth and 

 talons of the tiger ; and in that of the legs and claws of 

 the parasite which clings to the hair on the tiger's body. 

 But in the beautifully plumed seed of the dandelion, 

 and in the flattened and fringed legs of the water-beetle, 

 the relation seems at first confined to the elements of 

 air and water. Yet the advantage of plumed seeds no 

 doubt stands in the closest relation to the land being 

 already thickly clothed by other plants ; so that the 

 seeds may be widely distributed and fall on unoc- 

 cupied ground. In the water-beetle, the structure of 

 its legs, so well adapted for diving, allows it to 

 compete with other aquatic insects, to hunt for 

 its own prey, and to escape serving as prey to other 

 animals. 



The store of nutriment laid up within the seeds of 

 many plants seems at first sight to have no sort of 

 relation to other plants. But from the strong growth 

 of young plants produced from such seeds (as peas 

 and beans), when sown in the midst of long grass, 

 I suspect that the chief use of the nutriment in the 

 seed is to favour the growth of the young seedling, 

 whilst struggling with other plants growing vigorously 

 all around. 



Look at a plant in the midst of its range, why does 

 it not double or quadruple its numbers? We know 

 that it can perfectly well withstand a little more heat 

 or cold, dampness or dryness, for elsewhere it ranges 



