420 MR, E. B. BOULTON ON THE COLOUR-RELATION BETWEEN EXPOSED 
Since writing the above, I have had an experience which confirms my hesitation 
in accepting the above results as necessarily following from the red colour. I had 
long noticed a large number of pupae of P. rapce upon Keble College chapel, and when 
I removed them in order to describe the colours for this paper I carefully obseiwed 
and noted the places of pupation. After I had collected 20 or 30 pupae I found 
it useless to proceed, as they had almost without exception been attacked by 
Ichneumon flies and were dead and faded. I noticed, however, that not a single 
pupa was attached to the red brick wall of the chapel, but to the mortar immediately 
beneath the projecting stone-courses, or upon the overhanging surfaces or hollows of 
the stone itself. 
IV. Orange. 
A. 
On September 14, 12 mature larvae of P. brassicce and 10 of P. rctpce were placed 
in a cylinder 8 centimetres in internal diameter and 18 centimetres in height, and 
lined internally with deep-orange opaque paper for about two-thirds of the circum¬ 
ference, and with a roof and floor of the same material. Periodical examination 
produced the following results :— 
Sept. 14, 10 a.m. . 
Experiment began. 
,, 16, 6.5 p.m. . 
4 P. B. pupated, and 1 P. R.; 8 P. B. 
The whole period for the 5 pupated 
girdled, and 3 P. R. girdled 
must have been less than 56 hours if 
it began when they were placed in 
the cylinder. 
„ 17, 7.25 p.m. 
7 P. B. and 2 P. R. pupated; 5 P. B. 
1 
and 3 P. R. girdled. 
,, 18, 8.35 p.m. 
12 P. B. and4 P. R. pupated; 1 P. R. 
girdled. 
* 
,, 19, 9.15 p.m. 
12 P. B. and 5 P. R. pupated; 2 P. R. 
girdled. 
Results —All the 12 pupae of P. brassicce were alive when they were compared, aud 
of these einht were rather crowded on the roof. 
Of the 8 pupae. 
1 pupa was fixed in a horizontal position on 
the clear glass side, but so high up that 
it came against the orange background 
formed by the margin of the paper 
forming the roof. It was. 
1 pupa was fixed horizontally on the clear 
glass just below the last. It was 
1 pupa was fixed vertically on the clear 
glass about a from the roof. It was 
1 pupa was fixed vertically on the orange 
backgi’ound, but high up aud close to 
the roof. It was. 
2 were (1), (3, both yellowish, and not so grey as 
usual in this degree. 
6 ,, (3), very typical forms. 
(3), an unusually deep bluish-green on 
almost the whole of the dorsal 
surface. 
(3), typical. 
(2), with rather larger black spots than usual. 
(3), typical. 
