on the colouring of Preris napi, de. 63 
fused with dusky scales; an example of this is figured 
in Weismann’s work before quoted. 
By the kindness of friends, Mr. Fletcher and Mr. Nicholson, I 
was last spring supplied with some living specimens of the butterfly, 
which laid eggs on dock and sorrel, and from them I had more 
than 70 pup, which proved exceedingly healthy. Ten of these 
were forced at 85° and 10 at 80°, all emerging in from 6 to 73 days. 
There is little difference between these two lots, which are remark- 
able for the large size of the spots, and the comparative dul- 
ness of the colouring, the black parts being less intense, and the 
coppery parts especially having a slightly brassy appearance, and 
being in most cases more or less suffused with dusky scales, 
especially towards the bases of the fore wings, and often on the 
nervures; the coppery band on the hind wings is also narrow 
and broadly serrated. Six were brought out at the temperature 
of the room, averaging about 70°,—fairly representing an English 
summer temperature,—emerging in 11 to 15 days. These are 
noticeably different—the colours are more intense, the dark parts 
blacker, the coppery parts more vivid, and the spots smaller. 
Another lot of 6 was placed in a cool and shady place out of 
doors, the temperature averaging about 58°, 7.e., about the mean 
shade temperature of the latter part of May, and emerged in from 
22 to 80 days; these show a slight further increase in the bright- 
ness of the coppery parts, especially towards the bases of the 
fore wings, the spots are, I think, still smaller, and the coppery 
band on the hind wings is broader. Another lot, of 10, was 
placed in a cellar at a uniform temperature of about 56°, emerging 
in from 29 to 33 days; these are very similar to those last men- 
tioned. Six more were placed in the refrigerator at about 47°, 
representing the shade temperature of the earlier part of an English 
April, from which they evidently suffered, for only 3 emerged, in 
from 57 to 59 days, and one of these is unsymmetrical, one wing 
having a rather silvery hue; these 3 show a still further advance 
in the lightness (but not in the brightness) of the coppery parts, 
and certainly in the breadth of the coppery band on the hinder 
wing. 
More were kept at a temperature of 33° for about 10 weeks, 
and then brought into a temperature averaging about 55°, thus 
representing winter conditions followed by spring, and emerging 
in from 34 to 36 days more—i.e., in all about 15 weeks. About 
half died or were crippled. In those which emerged all the effects 
of the low temperature are seen in their extreme—the light colour 
of the coppery parts, the reduced size of the spots, one or two of 
