This was shown by feeding two sets of larvae on the same plant but
exposed to differently coloured surroundings, obtained by sewing the
leaves together, so that in one case only the dark upper surface, in the
other the whitish under surface was exposed to view. The result in each
case was a corresponding change of colour in the larvae, confirming the
experiments on different individuals of the same batch of larvae which
had been supplied with different food-plants or exposed to a different
coloured light.
An even more interesting series of experiments was made on the colours
of pupae, which in many cases were known to be affected by the material
on which they underwent their transformations. The late Mr. T.W. Wood
proved, in 1867, that the pupae of the common cabbage butterflies
(Pieris brassicae and P. rapae) were either light, or dark, or green,
according to the coloured boxes they were kept in, or the colours of the
fences, walls, etc., against which they were suspended. Mrs. Barber in
South Africa found that the pupae of Papilio Nireus underwent a similar
change, being deep green when attached to orange leaves of the same
tint, pale yellowish-green when on a branch of the bottle-brush tree
whose half-dried leaves were of this colour, and yellowish when attached
to the wooden frame of a box.
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