422 
MR. E. B. POULTON ON THE COLOUR-RELATION BETWEEN EXPOSED 
Y. Yellow. 
A. 
On September 14 four mature larvae of P. brassicce and four of P. rapes were 
placed in a cylinder 6 centimetres in internal diameter and 10 centimetres in height, 
lined internally with light-yellow opaque paper for about three-fourths of its circum¬ 
ference, and with a roof and floor of the same colour. Periodical inspection gave the 
following results :—- 
Sept. 14, 10.25 a.m. 
Experiment began. 
„ 15, 10.25 p.m. 
2 P. B. girdled for at least 12 hrs., as they were 
so in the morning when inspected. 
,, 16, 6.30 p.m. 
2 P. B. pupated lately, and 1 girdled, and also 
1 P. R. 
Whole period less than 56 hrs. 
if it began when they were 
placed in the cylinder. 
,, 17, 7.40 p.m. 
3 P. B. pupated and 1 P. R. girdled. 
,, 18, 8.30 p.m. 
3 P. B. and 1 P. R. pupated, and 2 P. R. and 
1 P. B. girdled. 
,, 19, 9.13 p.m. 
4 P. B. pupated and 2 P. R. pupated; 1 P. R. 
girdled. 
Results. —Three pupae of P. brassicce were alive when all were examined and 
compared :— 
1 on tlie roof was.(1), 7, typical; yellowish, with the faint greyish 
tinge and small black patches. 
2 were scattered over the side, and of these 1 was (2), typical. 
1 „ (3) 
Two living pupae of P. rapes were similarly compared, 
1 being on the roof; it was a.(5), with a distinct, but dull-green, ground-colour, 
much dusted with grey dots, and an amount of 
pigment on ridges, rosti’um, &c., which would 
be typical of (3). 
The other pupa was isolated on the clear side of 
the cylinder, and it was a.(3), with a rather distinct yellowish ground-colour, 
and rather less grey than usual in this degree. 
Thus the effects of yellow appear to be in the same direction as those of orange, 
although, as far as the evidence goes, the influence does not appear to be equally 
strong. 
YI. Green. 
A. 
September 14.—Four larvae of P. brassicce and one of P. rapee, and later four more 
of the former and four of the latter, were placed in a small glass cylinder (6 centi¬ 
metres in internal diameter and 8 5 centimetres in height) completely covered exter¬ 
nally with one layer of green tissue-paper, and with a roof and floor of the same 
material. Notes were taken at the following dates :— 
