¢ shy) 
all the pupxe being brought indoors for all or the greater 
part of their existence as such. The forced ones, which he 
exhibited, were strikingly different in appearance from the 
others, being of a warmer, yellower tint and much less 
spotted and marked with dark. His experiments were by no 
means completed; so far as they had gone, they seemed to 
show that retardation in the earlier stages was a cause of 
darkness of hue in the perfect insect, a retardation that 
would be the result of cold; and perhaps this threw light on 
the tendency to melanism often noticed in North-country 
examples of generally-distributed moths. The experiments 
with alniaria seemed very strongly to indicate, that the tem- 
perature to which the growing larva is exposed influences the 
colouring of the moth either directly or, more probably, by 
producing retardation, since the temperature was not a very 
low one, and the gradual darkening of the colour in the 
illustraria moths emerging from the pup lent by Mr. Jenner, 
and all kept at a summer or forcing temperature, seemed 
some evidence that retardation without cooling will originate 
the dark hue. Mr. Merrifield said he had not had facilities 
for bringing up so many separate broods as he should have 
liked to do, and that he would gladly hand over eggs from 
varieties, to those likely to follow out the results of breeding 
in any particular lines; and he would also be glad to be 
himself supplied with living specimens (for breeding) of 
illustraria from any other parts than the east and south of the 
United Kingdom, from which his original stock had come. 
Lord Walsingham said he had observed the readiness with 
which a dark-coloured insect responded to a transient gleam 
of sunshine; and it was probably an advantage to a moth in 
a cold country to be of a colour which readily absorbed heat; 
and it would be interesting if it were established that the 
game cause, a cold climate, which made darkness of hue a 
valuable quality, was also a means of causing it. 
Mr. Poulton said he had noticed in some experiments 
which he had conducted some years since upon Selenia 
illunaria, the same tendency of a brood of larve to divide 
into various detachments feeding up at different rates. 
Although his experiments were on a much smaller scale 
PROC. ENT. SOC, LOND., V., 1888. H 
