Chap. III.] STKUGGLE FOR EXISTENCE. 95 



suspected that the chief use of the nutriment in the 

 seed is to favour the growth of the seedlings, 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 into slightly hotter or colder, damper or drier 

 districts. In this case we can clearly see that if we 

 wish in imagination to give the plant the power of 

 increasing in number, we should have to give it some 

 advantage over its competitors, or over the animals 

 which prey on it. On the confines of its geographical 

 range, a change of constitution with respect to climate 

 would clearly be an advantage to our plant; but we 

 have reason to believe that only a few plants or 

 animals range so far, that they are destroyed ex- 

 clusively by the rigour of the climate. Not until we 

 reach the extreme confines of life, in the Arctic regions 

 or on the borders of an utter desert, will competition 

 cease. The land may be extremely cold or dry, yet 

 there will be competition between some few species, or 

 between the individuals of the same species, for the 

 warmest or dampest spots. 



Hence we can see that when a plant or animal is 



placed in a new country amongst new competitors, the 



conditions of its life will generally be changed in an 



essential manner, although the climate may be exactly 



the same as in its former home. If its average numbers 



are to increase in its new home, we should have to 



modify it in a different way to what we should have 



had to do in its native country ; for we should have to 

 6 



