CHAPTER X 



MIMICRY AND VARIATION 



It is clear from the last few chapters that the 

 theory of mimicry in butterflies with its interpretation 

 of the building up of these likenesses by means of 

 natural selection in the form of predaceous birds and 

 other foes is open to destructive criticism from several 

 points of view. The evidence from mimicry rings 

 makes it almost certain that in some cases the resem- 

 blance must be founded on an initial variation of such 

 magnitude that the mimic could straightway be con- 

 fused with the model. Till the mimic can be mistaken 

 for the model natural selection plays no part. The 

 evidence from breeding suggests strongly that in certain 

 cases (e.g. Papilio polytes) the likeness arose in the 

 form in which we know it to-day. In such cases there 

 is no reason for supposing that natural selection has 

 had anything to do with the formation of the finished 

 mimic. Considerations of this nature may be said to 

 have destroyed the view, current until quite recently, 

 that in the formation of a mimetic resemblance the 

 exclusive agent was natural selection. During the past 

 few years it has come to be admitted by the staunchest 

 upholders of the theory of mimicry that natural 



