a 
Hxperiments upon the colour-relation, &e. 249 
any known photographic chemical. No known substance 
retained permanently the colour reflected on it by 
adjacent objects.”* Such a statement leads us to infer 
that the varying colours of pupz are not directly due to 
any influence of an external photographic nature, as 
had previously been asserted by Mr. T. W. Wood,t but 
- rather emanate from within the organism itself upon 
the incidence of the appropriate stimulus, as Mr. Poulton 
has suggested. 
With regard to the question of consciousness of the 
process on the part of the insect, Mr. Poulton concludes 
that the production of appropriate results is probably 
automatic, and altogether beyond the control of the 
insect. 
The experiments made by Mr. E. B. Poulton included 
a vast number upon the pupe of the Vanesside, in 
which case the very remarkable effect upon those which 
were exposed to gilded surroundings constitutes the 
most striking result in the artificial production of a 
character that has ever been attained, the pup often 
appearing as if they had been covered with gold leaf. 
Although the results obtained in this family are very 
different from those caused in the genus Picris, the 
physiological nature of the susceptibility must be in 
many respects the same. Green, on tue other hand, 
which is so important a factor in the Pieride, produced 
absolutely no effect.t But, although Mr. Poulton shows 
that the Vanesside are affected differently by different 
colours, there are tints which do not produce any con- 
stant effect, or produce an effect which is not protective ; 
and the same colours often produce very different effects 
upon pup of different genera. Thus orange, which 
had no effect upon Vanessa, exercised the peculiarity of 
producing a more intense emerald-green colour in the 
pupe of Pieris than was produced by even green itself ; 
* Proc. Ent. Soc. Lond., 1874, p. xxiv. See also Prof. Meldola’s 
paper, communicated to the Zoological Society the previous year, 
‘*On a certain Class of Variable Protective Colouring in Insects ” 
(Proc. Zool. Soc., 1878, p. 153); also his important annotated 
translation of Prof. Weismann’s ‘ Studien zur Descendenz-Theorie’ 
(Leipzig, 1875), Part II., 1881, which contains many records 
bearing upon the general subject. 
+ Proc. Ent. Soc. Lond., 1867, pp. xcix—ci. 
{ Ibid., pp. 394, 395. 
