LEPIDOPTEROUS PUPU1 AND THEIR SURROUNDING SURFACES. 
421 
The five living pupse of P. rapce were also compared at the same time, and— 
Of these, 2 were fixed horizontally on the clear 
glass side, but high up, so that they 
came against the orange background 
formed by the margin of the paper 
roof (as above). 
The two pup® were both . . . 
1 was fixed to the roof with the 8 
P. brassicce described above. It was a 
1 was fixed vertically to the clear glass 
about g- from the roof, and it was a 
1 was fixed on the orange background 
close to the roof, and it was a . . . 
(5), with a pale transparent yellowish- 
green ground-colour; very little 
pigment on 1 pupa, and perhaps 
rather more than usual on the 
other. 
(4), typical, with a distinct, but very pale, 
yellowish-green ground-colour. 
(4) , typical; very faintly yellowish ground¬ 
colour. 
(5) , a beautiful bright-yellow green, with 
hardly any pigment. 
Tlie strong effects of the orange background in the prevention of pigment 
formation and in the production of a green ground-colour are very interesting and 
remarkable, for the results, although so well-marked, are certainly not especially 
protective. It is also most interesting that P. brassicce and P. rapce should have 
been influenced so uniformly. The bright green variety of P. brassicce chiefly formed 
by the use of this background is represented in Plate 26, figs. 29 and 30, X 2. 
B. 
About October 13 a few larvte of P. brassicce, which, I believe, were found upon 
Tropceolum ; and a few P. rapce, were placed in a cylinder lined with orange paper 
of the same size and arrangement as that already described. No notes were taken as 
to the dates of pupation. 
Results .— Two pupae of P. brassicce were obtained : 
Of these, 1 was isolated on the clear glass front, 
and was.(1), /3, normal; somewhat pale ochreous ground-colour. 
1 was isolated on the background, very 
low down; it was ..... (1), y, rather unusually greyish for this degree, but 
deep - green anteriorly and opaque - looking 
whitish - green posteriorly; the usual small 
black patches. 
1 pupa of P. rapce was isolated upon the clear glass side, and it was a (4), rather 
dark for this degree, and possessing a dull-yellowish ground-colour. 
The same results of the orange background are seen in these pupte, but they are 
not equal to those described in Division A. 
