REMARKS ON NATURAL SELECTION. 353 



with any condition of life to which difficulty is attached 

 to be part of " the struggle " for life, and this we 

 should certainly do. 



The words " conditions of existence " may, then, be 

 used instead of the " struggle for existence with conse- 

 quent survival of the fittest," for as they cannot imply 

 any less than the " struggle, &c.," when they are set 

 out in full, and without suppression, so neither do they 

 imply more ; for nothing is a condition of existence, in 

 so far as its power of effecting the modification of any 

 animal is concerned, which does not also involve more 

 or less difficulty or struggle ; for if there is no difficulty 

 or struggle there will be nothing to bring about change 

 of habit, and hence of structure. This identity of 

 meaning may be also seen if we call to mind that the 

 conditions of existence can be only a synonym for " the 

 conditions of continuing to live," and " the conditions of 

 continuing to live " a synonym for " the conditions of 

 continuing to live a longer time," and " the conditions 

 of continuing to live a longer time," for " the conditions 

 of survival," and " the conditions of survival," for " the 

 survival of the fittest," inasmuch as the being fittest is 

 the condition of being the longest survivor. 



But we have already seen that "the survival of the 

 fittest," is, according to Mr. Darwin, a synonym for 

 " natural selection " ; hence it follows that " the con- 

 ditions of existence " imply neither more nor less than 

 what is implied by " natural selection " when this ex- 

 pression is properly explained, and may be used instead 

 of it; so that when Mr. Darwin says that "natural 

 selection" is the main but not exclusive means of modi- 



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