13 
a separate cage, and feeding them differently. One lot was 
fed on willow', another on butter bur, (Petasites vulgaris,) 
another on hawthorn, another on plum, one on dock, and 
one on nettle, grass, bramble, and various other kinds of 
food. A considerable proportion of each became perfect 
insects, and I could detect no difference whatever in the 
colours, from the food they had lived upon. That is to say, 
the variations in colour and marking, were not to be traced 
in any case to the food. I kept several batches of eggs, 
and reared the larvae carefully through the winter, and 
then again divided them, giving each lot a different kind of 
food. Again the same result. I found that one year the 
larvae I had brought from the coast had usually the inferior 
wings more or less of a yellow shade, instead of the bright 
scarlet of the Cheshire specimens. 
Having for many years continued these experiments 
without obtaining any marked results, I this year tried 
another of a different nature. 1 selected the tortoiseshell 
butterfly, as one of the least variable species we have, and I 
procured several broods of young larvae just emerged from 
the egg. These I kept in a dark box until I had all ready, 
and then I divided each brood into three lots, putting one- 
third into a box in my photographic room which is lighted 
with orange colored glass, one-third into a box lighted with 
blue glass, and the ventilators carefully shaded so that only 
light of a blue colour could reach the larvae, the remainder 
were put into an ordinary cage, in the natural light. 
The latter fed up and came out into butterflies in the 
usual time. 
Those in the blue light were not healthy, and though 
every care ■ was taken, at least fifty or sixty died before 
changing, and a considerable number changed into chrysa- 
lides, and then died, those that came out into perfect insects 
were very much smaller than usual. 
Those lighted by orange-coloured glass fed up very well, 
but many of the two first lots had come out before one 
of them changed into chrysalis; scarcely one of them died, 
and I examined each one before I allowed it to fly, to see 
