68 STRUGGLE FOR EXISTENCE. 



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 dryer districts. In this case we 

 can clearly see that if we wish in imagination to give the 

 plant the power of increasing in numbers, we should have 

 to give it some advantage over its competitors, or over the 

 animals which prey on it. On the confines of its geographi- 

 cal 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 rigor 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, among 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 give it some advantage over a different set of 

 competitors or enemies. 



It is good thus to try in imagination to give any one species 

 an advantage over another. Probably in no single instance 

 should we know what to do. This ought to convince us of 

 our ignorance on the mutual relations of all organic beings ; 

 a conviction as necessary, as it is difficult to acquire. All 

 that we can do is to keep steadily in mind that each organic 

 being is striving to increase in a geometrical ratio ; that 

 each, at some period of its life, during some season of the 

 year, during each generation, or at intervals, has to struggle 

 for life and to suffer great destruction. When we reflect on 

 this struggle we may console ourselves with the full belief 

 that the war of nature is not incessant, that no fear is felt, 

 that death is generally prompt, and that the vigorous, tho 

 kealthy, and the happy survive and multiply. 



