MIMICRY 57 



account of this work, the reader is referred to Professor 

 Poult on's recent ' Essays on Evolution, 5 and to Pro- 

 fessor R. C. Punnett's ' Mimicry in Butterflies.' 



Many students of evolution in its more recent develop- 

 ments are disposed to attach greater importance than 

 does Professor Poulton to the difficulties which beset 

 the theory of mimicry, in so far as the theory consists 

 in explaining these resemblances by natural selection 

 accumulating minute variations in the proper direction. 

 Indeed, the power of this evolutionary factor seems 

 here to be stretched to its utmost limits of tension. 

 The independent evolution of a similar external appear- 

 ance has certainly taken place in some cases in which 

 any suggestion of mimicry is excluded, and there is 

 nothing to prove that colour-patterns of the same type 

 may not have arisen from the same causes in widely 

 different groups. In cases where the environment to 

 which the different forms were exposed was similar 

 as would be the case especially in any single locality 

 such a process of parallel evolution might be thought 

 to be all the more likely. 



It is not to be supposed that we intend for a moment 

 to impugn the reality of these marvellous resem- 

 blances. The smallest acquaintance with the facts 

 must show the absurdity of any such suggestion, just 

 as the multiplicity of the cases described renders any 

 suggestion of coincidence ridiculous. It is only the 

 current explanation of these resemblances to which we 

 take exception, for the brain reels before the task of 

 picturing the gradual building up of such a resemblance 

 by the successive additions of small differences, each 

 one useful to the possessor of it. 



