412 
MR. E. B. POULTON OX THE COLOUR-RELATION BETWEEN EXPOSED 
4 living pupse of P. rupee were similarly compared. 
1 was with the group of 5 P. brassicce described 
above, and it was a. light (3), with a yellowish-grey ground-colour and a 
rather small amount of grey dusting. 
3 were scattered over the side with the 3 P. 
brassicce , and of these.2 were (3), typical, and of the usual light-grey colour 
caused by the abundant sprinkling of 
minute dots over the light ground-colour, 
w r hich is apparently very pale pinkish in 
this case, but very hard to determine. 
1 was (4), with very little pigment and a dim yellowish 
ground- colour. 
The effect of the dark surroundings is thus much more manifest in the pupse of 
P. brassicce than in P. rupee; nevertheless, the latter are very different from those 
produced in white surroundings. It is very strange that the results of a deep black 
surface exposed to daylight should be darker than those produced by the same 
surface in darkness, and yet this appears to be the case, for the pupal colours on the 
tarred fences are much darker than those described above. At the same time, the 
pupse on the fence were generally shaded in cracks and corners, and the fence itself 
was in a shady lane, but the amount of light must have been in all cases far larger 
than in the cylinder. Such results are the reverse of those obtained in the case of 
Vanessa urticce. 
B. 
September 11, at 7.30 P.M., 10 nearly mature larvae of P. rapes , found on migno¬ 
nette at Seaview, were placed in a cylinder (6 ~7 centimetres in internal diameter and 
2‘24 decimetres in height) lined for rather more than half of its internal circumference 
with opaque blackened paper, and with a roof and floor of the same material. Some 
of the food-plant was also included. No notes were taken as to the times of 
pupation, &c. 
Results. —10 pupse were obtained, of which—• 
5 were on the black roof, and of these. . . . 1 was (2), a little lighter than usual; yellowish-pink. 
4 were (3), 1 considerably lighter than normal and 
greenish; 3 normal and pinkish. 
4 were on the clear side of the cylinder, but so 
high up that they came against the inflected 
edge of the roof, and of these.3 ,, (1), not very black for this stage; 1 distinctly 
pinkish, the others chiefly grey. 
1 was (3), rather lighter than normal, and yellowisli- 
pink ground-colour. 
1 was fixed on to the background near to the 
roof, and it was a. 
(1), typical pinkish ground-colour as far as it 
could be seen. 
