temperature on fJte colouring of Lepidoptera . 37 



however, decided when the exposure had been of long 

 continuance. Twelve were forced, of which eleven, of 

 very uniform appearance, emerged in from 5 to 6 days. 

 I exhibit four of these, which are not extreme, but a fair 

 sample. From 42, which emerged after an exposure to 

 about 47° of from 2 to 58 days, and which, though 

 varying inter se in a moderate degree, are in general but 

 slightly darker than the forced ones, I have selected the 

 five darkest, each of which is darker than any of those 

 forced. Nine others, which emerged after an exposure 

 of from 60 to 67 days, present a very different appearance 

 from the rest, mostly darker. I exhibit four typical 

 specimens of these. 



The next family, which I call "L," were given to me 

 at the beginning of September. These were mostly 

 exposed within a few hours after pupation, eight of them 

 were forced, and of these I have selected four fair 

 samples. Of the remainder, placed at 47° for about 20 

 to 42 days, 17 emerged, and the great majority of these 

 present a peculiar appearance, mostly in the direction of 

 darkness. I exhibit the 10 most peculiar out of the 17. 



Another family, fine pupse not more than a few days 

 old, were given to me by Mr. Fletcher on the 22nd 

 September; a very late brood. These I call the "M" 

 family. Five were placed at 80°, emerging in from 6 to 

 7 days, and I exhibit them all; 13 emerged out of doors 

 in from 3 to 5 weeks at an average temperature of about 

 57°, and I exhibit the seven most strongly coloured and 

 marked of these. Others were exposed to a temperature 

 of about 47° for from about 3 to 7 weeks, and I exhibit 

 all of those which emerged, four in number ; they are 

 very different from the others, the general tendency 

 being to greater darkness. 



The general observations I have to make on the results 

 of the V. urtic(B experiments are as follows : The effect 

 of exposing this species to cold for a moderate period 

 seems to be generally, not universally, slightly to darken 

 the colouring, to lower the colour of the yellow parts (in 

 one individual this is almost gone), and to intensify the 

 contrasts of light and shade ; to spread the dark portions, 

 and especially the dark outer margins, and, above all, 

 the blue crescents contained in these. I have examined 

 some long series of V. urticte in other cabinets, selected 

 to represent all ordinary variations, and have scarcely, 



