322 
MR. E. B. BOULTON ON THE COLOUR-RELATION BETWEEN EXPOSED 
Of the 14 pupae, 13 were suspended from the green roof—7*0 centimetres in diameter— 
and. one from the food-plant, but the latter and seven of the former were dead and 
discoloured. On August 9, at 10.45 p.m., 11 individuals had already pupated on the 
roof, and two larvae were suspended before pupation. At this tune the roof was cut 
off and pinned in close proximity to a north window, so that the pupae, &c., still hung 
vertically. At 10.5 A.M., August 10, these two larvae had pupated, but evidently 
quite recently, for the surface of both was still greenish. Compared with the rest on 
August 19, these results were obtained : — 
Of the 4 living pupse which threw off the larval 
skin in the cylinder.4 were (3), 
Of the 2 living pupse which threw off the larval 
skin in the strong north light.1 was (3). 
1 „ (4). 
( 6 ) 
It might be supposed that the greater amount of light perhaps influenced the 
colour of the two larvae which pupated latest, and which were exposed in the window 
for 10-11 hours, but the evidence is insufficient, as the difference between the two 
sets of pupae is so small. 
D. Another lot of larvae were placed in a cylinder similar to the last. On August 9, 
at 10.30 P.M., the yellowish-green paper roof, 7'5 centimetres in diameter, was cut off 
and pinned in a north window as before. At that time four pupae were hanging from 
the paper, to which nine larvae were also suspended. By 10.5 a.m., August 10, four 
had pupated some hours, and two more quite recently, while the three remaining 
larvae pupated at some time (unknown) later than 10.5 a.m. All these were marked 
and compared on August 19, the following results being obtained :— 
Of the 4 which pupated in the cylinder.2 were (2). 
2 „ (3). 
,, 4 ,, „ after a short time in the north light 1 was (1). 
3were(3),2 of them approaching (2) very 
closely and really intermediate. 
„ 2 „ ,, „ longer „ ,, 1 was (2). 
1 „ (3), with rather more gold than usual. 
,, 3 „ ,, „ still longer ,, ,, 3 were (3), 2 of them tending towards (2). 
13 
In this case it is seen that practically no effect was produced by the light, a fact 
which I afterwards learnt was to be expected, for a strong light merely tends towards 
the special, coloration which follows from the illumination of the surroundings of the 
pupa, if such surroundings are coloured by any of the tints for which the organism is 
sensitive. In all the experiments with green cylinders I had in mind the green form 
2 of them with rather unusual gold, and 
tending in lightness also towards (4). 
