Chap. III.] STRUGGLE 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 im- 

 agination 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 cf 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 exclusively 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 



