84 



VARIATION IN EUROPEAN LEPIDOPTERA. 



Researches of the nature of those I refer to cannot be carried on 

 without the co-operation of a multitude of workers, and it is on this 

 account that I have ventured to suggest to you the necessity of a more 

 systematic collection of facts relating thereto. It is a great honour 

 to the Yorkshire Naturalists' Union that so widespread an interest 

 in such pursuits is shown by artisans, tradesmen, professional men, 

 and others whose occupations leave them but Httle time for such 

 matters; but at the same time I am impressed by a conviction that in 

 this country generally, very few even of those who have time and 

 leisure, devote themselves to the scientific aspect of the question. 

 The collections I have been allowed to inspect in England are 

 beautifully complete in arrangement and setting ; but with the excep- 

 tion of Mr. Bond's and a few others, rarely has anything more been 

 attempted. 



In countries which have a great diversity of climate, soil, and 

 elevation, especially such as have lofty mountains, the opportunities 

 and temptation to compare insects bred under different conditions 

 and in isolated regions is of course much greater. In Switzerland, 

 for instance, a butterfly will be found to range i,ooo or 1,500 feet 

 higher on the south side of an Alpine range than on the north ; and, 

 again, a variable species will be traced through every possible modifi- 

 cation of its characteristic, and present every link in the chain of its 

 divergence, within the limits of a cornps^ratively small district. 



But though the British Isles do not offer such extreme diversities 

 of local conditions, yet there exist quite sufficient to render the study 

 of this branch of science both interesting and productive, and I 

 therefore desire to urge the importance of carefully labelling each 

 specimen, even of common insects if prone to variation, with a 

 number or mark of reference, and of registering the date and the 

 locality of capture, and any other particulars known regarding its 

 life history. Of variable insects no limit ought to be put to the length 

 of series. It is very delightful to see a cabinet with an equal number 

 of every species, but I profess to you that my instincts rather rebel 

 against a rigid and purposeless uniformity. I am not greedy to 

 possess a long series of a rare insect, supposing the specimens to be 

 identical ; while on the other hand I consider any limit to be objec- 

 tionable as to the number of some changeable forms. But in any 

 case specimens without records are useless for scientific purposes. 

 These remarks are so obvious that I must apologise for making 

 them ; but I think their necessity would be understood on seeing 

 some Continental collections, with whole drawers given up to the 

 history of the variations of perhaps a single species. 



Naturalist, 



