Mimicry 291 



mimicry did not also record that the characteristics which distinguish 

 the northern from the southern individuals of the African species 

 correspond with the presence, in the north but not in the south, 

 of certain entirely different butterflies. That this additional informa- 

 tion should so greatly weaken, in certain minds, the appeal of a 

 favourite study, is a psychological problem of no little interest. 

 This curious antagonism is I believe confined to a few students of 

 insects. Those naturalists who, standing rather farther off, are able 

 to see the bearings of the subject more clearly, will usually admit the 

 general support yielded by an ever-growing mass of observations 

 to the theories of Mimicry propounded by H. W. Bates and Fritz 

 Miiller. In like manner natural selection itself was in the early days 

 often best understood and most readily accepted by those who were 

 not naturalists. Thus Darwin wrote to D. T. Ansted, Oct. 27, 1860: 

 "I am often in despair in making the generality of naturalists even 

 comprehend me. Intelligent men who are not naturalists and have 

 not a bigoted idea of the term species, show more clearness of 

 mind 1 ." 



Even before the Origin appeared Darwin anticipated the first 

 results upon the mind of naturalists. He wrote to Asa Gray, Dec. 21, 

 1859: "I have made up my mind to be well abused; but I think it of 

 importance that my notions should be read by intelligent men, 

 accustomed to scientific argument, though not naturalists. It may 

 seem absurd, but I think such men will drag after them those 

 naturalists who have too firmly fixed in their heads that a species 

 is an entity 2 ." 



Mimicry was not only one of the first great departments of zoo- 

 logical knowledge to be studied under the inspiration of Natural 

 Selection, it is still and will always remain one of the most interesting 

 and important of subjects in relation to this theory as well as to 

 evolution. In mimicry we investigate the effect of environment in its 

 simplest form : we trace the effects of the pattern of a single species 

 upon that of another far removed from it in the scale of classification. 

 When there is reason to believe that the model is an invader from 

 another region and has only recently become an element in the 

 environment of the species native to its second home, the problem 

 gains a special interest and fascination. Although we are chiefly 

 dealing with the fleeting and changeable element of colour we expect 

 to find and we do find evidence of a comparatively rapid evolution. 

 The invasion of a fresh model is for certain species an unusually 

 sudden change in the forces of the environment and in some instances 

 we have grounds for the belief that the mimetic response has not 

 been long delayed. 



1 More Letters, i. p. 175. * Life and Letters, n. p. 245. 



192 



