SELECTION 155 



NATURAL SELECTION. How will this 

 struggle for existence act in regard to varia- 

 tion ? Can the principle of selection, so potent 

 in the hands of man, apply under Nature? 

 Most efficiently; for, when we bear in mind 

 the constant occurrence of variation, with 

 the strength of the hereditary tendency, also 

 how infinitely close and complex are the 

 mutual relations of organic beings to each 

 other and to their physical conditions of life, 

 and consequently what infinitely varied diver- 

 sities of structure might be of use to each 

 being under changing conditions of life, can it 

 be thought improbable, seeing that variations 

 useful to man have undoubtedly occurred, 

 that other variations, useful in some way to 

 each being in the great and complex battle 

 of life, should occur in the course of many 

 generations ? And if such do occur, can we 

 doubt (remembering that many more in- 

 dividuals are born than can possibly survive) 

 that individuals having any advantage, how- 

 ever slight, over their fellows would have the 

 best chance of surviving and of procreating 

 their kind ? On the other hand, we may feel 

 sure that any variation in the least degree 

 injurious would be inevitably destroyed. 



This preservation of favourable and this 

 destruction of injurious variations are called 



