60 SOME CRITICISMS [ch. v 



any rate little meaning can be attached to the state- 

 ment that the imitators differ from the bulk of 

 their alhes. 



The fifth of Wallace's conditions is clear and needs 

 no discussion. 



It is evident that at any rate a large proportion 

 of the instances of close resemblance do not fulfil 

 all of the conditions laid down by Wallace. Never- 

 theless we should expect them to do so if the resemblance 

 has been brought about by the cumulative effect of 

 natural selection on small favourable variations. Clearly 

 there is a 'prima facie case for doubting whether we 

 must of necessity ascribe all resemblance of the kind 

 to natural selection, and in the next few chapters 

 we shall discuss it in more detail from several points 

 of view. 



