360 
MR, E. B. POULTON ON THE COLOUR-RELATION BETWEEN EXPOSED 
The results of this 
Table will be most clearly expressed in the following analysis :— 
The degrees of colour from (1), darkest and least golden, 
to (5), lightest and most golden. 
(1) 
(2) 
Dark 
(3) 
(3) 
Light 
(3) 
(4) 
(5) 
II. In black for the whole period. 
1 
5 
1 
— y 
I. Transferred from gold into black, for Stage III. 
. . 
. . 
. . 
.. 
6 
9 
. . 
= ] 5 
III. „ „ black into gold ,, ,, 
. . 
• . 
• • 
i 
5 
3 
• • 
= 9 
IY. In gold for the whole period. 
* • 
• • 
5 
7 
8 
= 20 
51 
Such an analysis speaks for itself; it is quite clear that the pupae as a whole tend 
strongly towards the lighter forms, but it is equally clear that Numbers I. and III. 
are intermediate between the two extremes II. and IV. In the considerably lighter 
results of the former (I.) we probably see the proof that in the shorter stage, II., the 
influences are really more potent than in III., which is considerably longer. Similarly 
Stage II. was passed in black surroundings in the case of III., and its results are 
darker than those of I. In fact, in both I. and III. the colour in which Stao - e II. was 
passed predominates in the result, or rather it is more accurate to say that the gilt 
surroundings produce more effect in Stages I. and II. than in Stage III. alone. 
It is also probable that the earliest, most sensitive, part of Stage III. had already 
elapsed in most cases before transference took place. But further experiments will 
show the inferior susceptibility of Stage III. under the most favourable conditions, 
and indeed such a result might have been expected, for, although this stage is, as a 
rule, so much longer than any other, the larval sensory surfaces are probably only in a 
condition to be influenced in its most early part, for very rapid changes of pupal 
construction and shape are going on beneath the surface. These would seem to 
preclude the possibility of an external shell, shortly to be cast off, having any important 
physiological relation with the organism beneath. But in Stage II. the larva retains 
its shape, and the whole of its surface is in close relation with the colour into 
correspondence with which the pupal tints will afterwards deepen. On the other hand, 
the posterior part of the suspended larva is alone in close proximity with the surface 
to which it is fixed. But nevertheless the comparison of III. with IV., and I. with 
II., shows equally clearly that the larva is susceptible, and to a considerable extent, 
during Stage III., although the susceptibility is probably confined to the first part of 
it. Future experiments will supply the means for testing the sensitiveness of the 
different parts of this stage. This experiment showed that an investigation by the 
use of conflicting colours applied to Stage III. could be undertaken with, at. any rate, a 
fair prospect of success. After all the other experiments it is almost unnecessary to 
point out how entirely the former theory of pupal as opposed to larval sensitiveness is 
broken down by the analysis given above. 
