(( vir ~) 
by Mr. Poulton in the course of a large number of experi- 
ments which he made upon larve during the period preparatory 
to pupation, which period he supposed to consist of three 
stages; and this discovery that the second and early part of 
the third stage of the ‘ Pre-pupational Period” (as Mr. 
White proposed to call it) is the time of chief susceptibility, 
had been applied to these experiments. The results of 
these recent experiments were entirely confirmatory of Mr. 
Poulton’s discovery, which is found to throw much lght 
upon the subject. Most of the colours employed affected 
the pups very materially, while some few, chiefly blue, 
produced only “normal” pupe. Black, green, and yellow 
were found to be the most potent influences; black sur- 
roundings producing much pigment, and completely covermg 
the surface of the pups in many cases; green produced in 
most cases pale green pup, while yellow was still more 
efficient in the production of an intense green colour without 
any pigment spots. 
The results of each group of experiments were separately 
considered in the paper according to Mr. Poulton’s Standard 
Grade of pupal colouration, and afterwards collectively 
tabulated for the purpose of comparative analyses of the 
different colour-factors, and again for comparison with the 
results of Mr. Poulton’s similar experiments. The various 
results were finally delineated* by means of a ‘ curve,” 
which followed the lines of that obtained by Mr. Poulton 
so closely as to add very strong testimony indeed to the 
efficiency of the causes as constant factors. 
The living pup experimented on were exhibited, together 
with a number of normal specimens for comparison with 
them, and also sample pieces of the coloured papers employed 
in the experiments. 
Mr. Poulton said that he was very much interested in the 
results of Mr. Griffith’s experiments. When he had himself 
experimented upon the colours of the pupe of the Pieridae, 
by means of papers of various colours, the results were so 
astonishing that it was in every way satisfactory to have 
them confirmed. Special interest attached to the colour- 
* A diagram was exhibited. 
