LEPIDOPTEROUS PUPiE AND THEIR SURROUNDING SURFACES. 
367 
The results are analysed in the following Table :—- 
(1) 
(2) 
Dark 
(3) 
(3) 
Light 
(3) 
(4) 
(5) 
6 pupae exposed to gilt surroundings for the whole 
1 
2 
3 
period 
2 pupae exposed to gilt surroundings for the whole 
2 
period of Stage III. 
1 pupa exposed to gilt surroundings for the last 
1 
part of Stage III. 
It is probable that the above results indicate, on the whole, the relative 
susceptibility of Stage III. to the whole period, although, at the same time, the single 
dark pupa in the first line shows that we must be prepared for exceptions, and that 
it is necessary to make use of large numbers of larvee in order to obtain a sufficiently 
accurate result. 
C. It seemed that interesting results might he obtained by exposing a few larvae 
during Stage III. to a very powerful direct light, and yet without any coloured 
background, at a distance which could affect them. If negative results were obtained, 
they would serve as a confirmation of conclusions rendered probable by other experi¬ 
ments, viz., that the effective influence is due to the presence or absence of reflected 
light, and its quality, if present, but seldom or never under natural conditions, to 
direct light falling upon the larvae. In the following experiments I proposed to place 
the larvae under conditions in which they could only be illuminated by direct light. 
This object was achieved by pinning the suspended larvae to the central vertical bar of 
a large east window, the pin being thrust through the boss of silk so far that the 
larvae hung suspended from the head of the pin which projected from the side of the 
bar, so that the whole length of the pin intervened between the larva and the bar 
(painted stone-colour). Very long pins were made use of in the experiment. The 
suspended larvae were taken from the main stock in the cylinders, where they were 
found fixed to the food-plant. The following Table explains the manner in which the 
experiment was conducted : — 
