364 MR. E. B. POULTON ON THE COLOUR-RELATION BETWEEN EXPOSED 
from all the others that it was very hard to classify them according to the same 
standard, but I am quite sure that there has been no error in the direction of making 
them appear too dark ; if there has been any mistake, it has been in the other direction. 
Thus 15 pupse were obtained in this series. 
XII.—A large company of nearly mature larvae was found August 31 on a nettle- 
bed near South Hincksey, different from that on which the other series had been found. 
Id a few days the larvse became mature, almost simultaneously, and the following 
experiments were made :— 
A. The object of this experiment was to ascertain whether a black surface in a 
powerful light has a different effect from that of complete darkness. 
(a) 13 larvse were placed in a cylinder covered with two layers of black tissue- 
paper, and a similar roof; a black floor was added, and the whole was placed in 
shadow. The experiment and its results are given below :— 
Sept. 3, 10.15 A.M.-1.48 p.m. 
,, 11.10 p.m. . . . 
Sept. 4, 1.15 p.m. 
„ 6.30 p.m. 
„ 9 p.m. 
,, 12, MIDNIGHT 
Sept. 5, 10 a.m. . . . 
Results of comparison, 
Sept. 7 (with all others 
mentioned as compared 
on this day). 
The 13 larvae were introduced into the cylinder at these hours, and at 
various times between them. 
5 suspended; all the others except 1 are resting on roof. 
All suspended except 1, and it is in Stage III. on the floor, unfixed. 
2 pupated some little time. (If pupation be estimated at 5 p.m. and 
suspension at 11 p.m., Sept. 3, Stage III. would be 18 hours; hut it 
was probably longer.) 
2 pupated. (If pupation be estimated at 7.45 p.m. and suspension at 
11 p.m., Sept. 8, Stage III. would be 20| horn’s; but it was probably 
longer.) 
3 pupated. (If pupation be estimated at 10.30 p.m. and suspension at 
11 p.m. for 1 of the larvae, Stage III. would be 23J hours; but it was 
probably longer.) 
All have pupated some hours. (If pupation took place at 5 a.m. and 
suspension at 6 A.M., Sept. 4, Stage III. would be 23 hours; but the 
estimate is very rough.) 
1 pupa on floor was (3), lightish, but not a light (3). 
1 ,, on side was iight (3), with little gold, but 
other of the 13. 
Of the 11 pupae scattered over the roof, but not crowded 
2 were (1), very black indeed. 
( 2 ). 
dark (3). 
(3). 
was light (3). 
2 
4 
2 
1 
13 
more than any 
(/3) 14 larvse were placed in a similar shallow black cylinder, which was then 
made to rest on its side with the open end covered with a clear glass plate, directed 
towards a strong east light, and close to the window. Hence the roof of the cylinder 
was a segment of the side (in the other position), and the ordinary roof of black tissue- 
paper formed the back. The experiment and its results are given below:— 
