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THE " MELANISM " CONTKOVERSY. 

 By W. F. de VisMES Kane, M.A., F.E.S. 



In the August number of the 'British Naturalist' there 

 appeared an article by Mr. W. E. Sharp, which seems to be ver}^ 

 opportune; and calculated to arrest temporarily the tide of specu- 

 lative theories by which the subject seems likely ere long to be 

 obscured. His criticism deals chiefly with the essays published 

 by Mr. Tutt, but applies equally to various contributions of other 

 writers from time to time. Now, Mr. Tutt has done yeoman 

 service in attracting more general attention to the scientific 

 aspect of Entomology, and eliciting the opinions of many 

 observers; but it seems full time that some weak points in 

 the chains of argument by which various theories have been 

 supported should be pointed out. Besides the objections urged 

 by Mr. Sharp, namely, a confusion of ideas as to the biological 

 problems involved, I am of opinion that a good deal of the 

 speculative discussion is somewhat " previous " and premature, 

 by reason of the premises being as yet insufficiently ascertained 

 and enunciated ; so that there is some danger of the question 

 being prejudiced in at least some of its aspects. Mr. Sharp, who 

 disclaims any special knowledge of the order of Lepidoptera, 

 takes for granted, or at least does not specially challenge, the 

 premises on the ground of definiteness and precision. Now, this 

 is the point I desire to draw attention to. No doubt Mr. Tutt 

 and many others have amassed large and interesting collections 

 of varietal forms, and many valuable contributions to our know- 

 ledge have appeared in the ' Record ' and elsewhere. Never- 

 theless the subject is so complex, when carefully examined, that 

 it would seem to me most advisable to have the facts sifted and 

 correlated much more carefully than has hitherto been done, so 

 that we may know much more precisely the phenomena we have 

 to analyse. Among the matters that should, in limine, be ascer- 

 tained, I may instance the following. Are the Rhopalocera and 

 Heterocera, whose life-habits are for the most part so distinct in 

 the imago stage, affected similarly by similar environments ? I 

 have a strong conviction to the contrary, though writers on 

 melanism seem usually to take for granted that they are. Then 

 as to Geometridse and Noctuidse in smoky districts, it would be 

 interesting (bearing in mind the larger area of wing surface 

 exposed by the former when at rest, and habits of diui-nal 

 concealment of species of the latter) to know the numerical 

 proportion of species of each affected by melanochroism. Again, 

 certain species of Lepidoptera we know present archaic or 

 congenital constant varieties, in districts widely separated 

 geographically and differing greatly in climatal and physical 

 characters. The vars, luneburgensis and sedi of E. lutulenta, and 



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