The Making of Species 



" It follows not as a theory but as a fact that 

 whenever an advantageous variation is needed, 

 it can only consist in an increase or decrease of 

 some power or faculty already existing." Now, 

 in order for an increase or decrease to occur, 

 there must be something in existence to be 

 increased or diminished. Wallace, it is true, 

 speaks here only of powers and faculties ; but 

 it can scarcely be supposed that he believes that 

 variations as to structure are intrinsically different 

 from those relating to powers and faculties. 



4. Herbert Spencer urges, as an objection to 

 the theory of natural selection, that favourable 

 variations in one organ are likely to be counter- 

 balanced by unfavourable variations in some 

 other organ. He maintains that the chances are 

 enormous against the occurrence of the " many 

 coincident and co-ordinated variations " that are 

 necessary to create a life or death determining 

 advantage. 



This objection was urged by a writer in the 

 Edinburgh Review in January 1909, and even 

 by Wallace himself in the Fortnightly Review 

 last March against the mutation theory. This 

 objection, strong though it appears on paper, 

 exists only in the imagination of the objector. 



Those who urge it display a misunderstanding 

 of the manner in which natural selection acts, and 

 ignorance of the phenomenon of the correlation 

 of organs. 



38 



