106 THE ENTOMOLOGIST. 



brightening of the wings by an increased paleness of the brown 

 ground colour, and by a multiplication of yellow scales between 

 the black spots of the costal margin of the fore wing and on the 

 outer border of the black spot at the root of the hind wing. 



The under side of both wings was rendered more uniform in 

 colour by the fact that, while the outer portion became darker, 

 the basal portion remained of almost the same colour. 



b. Cold. 



(1) After a 14-days' sojourn of the pupae on ice, the butter- 

 flies appeared in the room in 7—10 days longer. 



The brown ground colour becomes darker, the blue marginal 

 spots of the hind wing larger and brighter, the dark outer border 

 of the fore wing broader ; three ill-defined blue spots appear in 

 the middle of the outer border. 



On the under side the contrast between the basal and external 

 portions of the wing is enhanced by the increased lightness of 

 the latter. 



(2) After 28 days of exposure to cold the butterflies emerged 

 at the ordinary temperature of the room in 9 — 12 days more. 



These showed all the divergent characters above described in 

 increased measure — the much broader and darker outer border of 

 the fore wing, with its distinct blue spots, making this a far more 

 showy insect than the normal form. 



Besides this, the spot lying nearest to the root of the wing on 

 the dorsal margin of the fore wing in these specimens often dis- 

 appears, as also, in rare cases, the spot lying nearer to the outer 

 margin ; moreover, there are sometimes indications of the dis- 

 integration of the double spot in the middle of the fore wing. 



On the under side the tint of the outer portion of the wings 

 mostly becomes lighter ; in one specimen it may even be called 

 a dingy sulphur-yellow. 



(3) After 42 days' exposure upon ice only 20 per cent, of the 

 pupae, 13 — 16 days afterwards, yielded well-developed butterflies. 

 These are for the most part normal in the fore wings ; in two 

 cases, however, the four spots lying nearest to the dorsal margin 

 are more or less wanting, whilst on the hind wing the black basal 

 patch is markedly or entirely deficient ; and in the same way 

 the blue marginal spots have more or less comi^letely vanished, 

 their places being taken by very small sharply defined black 

 triangles. On the under side of both wings the well-marked 

 lightening of the colour of the outer portion disappears, being 

 replaced in almost all instances by a very peculiar tinge of 

 reddish brown. 



4. V. vrticcs, L. 

 a. Warmth. 

 Pupffi kept for 60 hours at 37° C. (98°— 99° F.) yielded butter- 

 flies at the temperature of the room in 80 — 100 hours after. 



