on the colouring of Pieris napi, ce. De 
English May ; of these all but 4, which have ‘“ gone over’’ to the 
spring, emerged in from about 36 to 40 days (with one exception, 
which was a few days more). The residue of 11 that had been 
iced, were placed at about 80°, and all but 3, which have ‘“ gone 
over,’ emerged in from 6 to 10 days. None were in any way 
crippled. 
We thus have for comparison, individuals of the summer 
brood of three classes, viz.—(1) placed throughout at a high 
summer temperature; (2) first exposed to a severe artificial 
winter of 3 or 4 months, and then exposed to an artificial spring 
of 5 or 6 weeks; (3) first exposed to the artificial winter, and 
then to a high summer temperature for a week or ten days, with- 
out any intermediate spring. Class 1 was of course of the usual 
form of the summer emergence. A comparison of it with Class 2 
shows that the effect of the artificial winter and spring on these 
pupx, belonging naturally to the summer form, was to bring out 
most, but not all, of the characteristics of the spring form, thus— 
on the upper surface the greater suffusion, but less intensity of 
dusky colouring, especially along the nervures, and particularly in 
the females, and the characteristic colouring of the dark parts, viz., 
grey instead of dark brown; on the under surface, faintness of the 
spots on the forewings, the strong marking of the nervures of 
all the wings, and the stronger colouring of the yellow tinted 
parts. 
In Class 3, 2.e., those exposed to a hot summer temperature 
immediately after a winter one, all these characteristics are notice- 
ably less, especially the faintness of the spots on the under surface 
of the fore wings, but with one remarkable exception—that the 
nervures, especially on the hind wings, are more strongly marked 
than in either of the two other classes, the greater strength of the 
marking, however, being attributable more to the darkness of it 
than to an extension of its area. 
The only general remark I will make on these results 
is that I think the experiments prove that some, but not 
all, of the characteristic colouring of this species de- 
pends, not on the particular emergence, i.e., summer or 
spring, to which the insect when entering on the pupal 
stage belongs, but on the temperature to which the indi- 
vidual pupa is exposed. I have nearly 90 pupe naturally 
belonging to the spring emergence on which I shall 
experiment during the approaching winter and spring, 
and may then perhaps have some more definite conclu- 
sions to bring forward. 
