72 BTRUGOLE FOB EXI8TENGE. 



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 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 geo- 

 graphical 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 con- 

 fines 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 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 or- 

 ganic 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, the healthy and the happy survive and multiply. 



