DISTRIBUTE INSECT VARIETY. 285 



varieties in unstable genera of moths sucli as the Annulets and 

 others. The Common Swift Moth I have taken at Guildford, in 

 Surrey, with its pale brown fore-wings rendered almost entirely 

 white from an enlargement of the streaks. Other moths, as 

 some of the Tortrieina, would appear inherently variable, and 

 species in the same hedgerow exhibit endless wing patterns. 

 This may be aseribable to atavism, or reverting to a former type, 

 or may be doubtless due to the variety of food the caterpillars 

 there consume. 



Mr. C. S. Gregson, of Liverpool, has published a small 

 pamphlet on the effects manufacturing towns of this country 

 induce on the circumambient lepidopterous 

 fauna. " The mere variation in shade of 

 colour,'''' he considers, is there always 

 unreal " when it tends lightwards, or to »,,• , ,. . ., n 



s> } ^ Albmo n Derratmn of the Com- 



buff or ochrey yellow, or yellowish, or ^IL^^^^il^ilfSfoWiil 

 to ashy drabs, from cold dark browns. iSi,j£'/,':.ri:riSinS 

 It does not follow, however, that the llTcrllseTtLtl^LtT. 

 wonderful changes in colour have always 



been intentionally caused. Often it appears as the insect emerges 

 from the pupa, and here the breeder jjoints proudly to the fact 

 that his friend the d^er or bleacher bred it for him whilst he 

 was away collecting. Such was a ' Forcellus ' case ; and the 

 word ' dyer ' set me thinking that the fumes from his clothes had 

 made the change, and it took me ten minutes to make one like it 

 on my return home again, I am told that this light buff and 

 this dark brown variety were taken in coj). on a tree-bole, and 

 as certain streams of gas are escaping from chemical works not 

 far away, shortly afterwards I have artificial varieties of a 

 ^ Betularia ' being manufactured in my little laboratory of all 

 shades of buffs. When we consider what a great difference in 

 colour a slight chemical action will make in many species of 

 Lepidoptera, and the great amount of free acid (chloric) gas is 

 ever escaping from our immense chemical works, the wonder is 

 we have not more aberrant coloured insects amongst us, especially 

 so when we know that a little chlorine in or near chrysalis boxes 

 will remove any of the more fugitive colours as the insects 

 appear. ^^ 



Mr. Gregson proceeds to notice certain chemical changes that 



