STRUGGLE FOR EXISTENCE 61 



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 de- 

 stroyed 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 ex- 

 tremely 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 num- 

 bers 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 neces- 

 sary, 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 be- 

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

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

 and the happy survive and multiply, 



