14 
what effect had been produced. I retained a few speci- 
mens of each lot to exhibit this evening, and now proceed 
to describe the difference. 
Those reared in the blue light differ from the ordinary form 
in being on an average much smaller ; the orange brown is 
lighter in shade, and the yellow and orange run into each 
other, instead of being distinct and separate. 
Those reared in the non-actinic, or yellow light, are also 
smaller, the orange brown is replaced by a salmon colour, 
the venation more strongly marked, and the blue dashes at the 
edge of the wings in the usual form, are in these of a dull 
slatey colour. A series of specimens of these side by side, 
with those reared in ordinary light, are here for exhibition. 
One evening I found about 60 butterflies out of chrysalis, 
of those in the photographic room, and taking each one care- 
fully I examined them all and allowed them to fly; shortly 
afterwards I found the whole of them had settled against 
the wall of the house, and presented a most remarkable 
appearance, they remained there more than half-an-hour, 
the western sun was shining against the wall, and it is not 
unlikely when being suddenly brought from the red light, 
where they had spent all their lives, to the bright daylight, 
they have been so dazzled as to act in this peculiar manner. 
The results of this experiment do not show any very 
startling change in colour, such as one would have expected 
from the known effects of light on plants and from the occa- 
sional occurrence of very much more strange varieties, one 
now and then meets with, which cannot have been subject 
to such severe treatment; still, when we consider that 
even this difference is caused in one generation, and in the 
course of a month, it is a very suggestive fact, and leads one 
to think that light has certainly as much or more effect on 
the colours of Lepidoptera, than the difference of food, and 
might in a long series of generations lead to very material 
changes in both form and colour, and perhaps considerably 
modify our ideas of what constitutes a species. 
