^"^^ AND ^^^ 



JOURNAL OF VARIATION. 



No. 3. Vol. III. March 15th, 1892. 



Scientific notes. 



Effects of Temperature on the Colouring of Lepidoptera.— 

 The statement, in your " Current Notes," of my paper read at the 

 last meeting of the Entomological Society, conveys the impression that 

 where the temperature experiments described in it had caused darkening 

 this was generally associated with, more or less, crippling and disease. 

 This is not so. The crippling effect observed in some of the specimens 

 exhibited was the result of extreme condition, whether of heat or cold, 

 and as such, is probably what might have been expected, though some 

 of the peculiar appearances so caused (of which darkness is not always 

 one) are, I think, deserving of attention. What is remarkable is, that 

 some of the most conspicuous effects obtained in coloration, can be, 

 and are produced, with extreme regularity, by such moderately low 

 temperatures, as to not in any way effect the healthy appearance of the 

 perfect insect. This is proved by many examples of several different 

 species, and especially of Selenia illunaria and S. illustraria, in which 

 the full effect of intensification of darkness has been produced, the 

 insect being in all respects well developed and symmetrical, and not 

 exhibiting a trace of disease. I have some hundreds of these, belonging 

 to several different broods, those at the moderately low temperature 

 showing conspicuously darker colouring than those at the higher 

 temperatures. In some of the species which I exhibited, there was a 

 considerable proportion that were more or less crippled. But these, as 

 the labels attached showed, had in nearly all cases been subjected to 

 extreme conditions ; and, as in these cases much individual variation had 

 ensued, a rather large proportion of them was selected for exhibition. 

 In insects, the colouring of which is greatly affected by moderate 

 temperature, I have found no great variation in those treated alike, the 

 darkness caused by the lower temperature being in general extremely 

 uniform ; and accordingly, as stated in my paper, only typical examples 

 of these were shown. They are merely the representatives of large 

 numbers of equally healthy specimens in my possession, many of which 

 were exhibited to the Society at the meeting of March last. — F. Merri- 

 FfELD, Brighton. [I spoke, of course, only of those specimens which I 

 saw, and about which there could be no mistake. When I use the term 



