It is interesting to note, that the colours produced were in all
cases such only as assimilated with the surroundings usually occupied by
the species, and also, that colours which did not occur in such
surroundings, as dark red or blue, only produced the same effects as
dusky or black.
Careful experiments were made to ascertain whether the effect was
produced through the sight of the caterpillar. The ocelli were covered
with black varnish, but neither this, nor cutting off the spines of the
tortoise-shell larva to ascertain whether they might be sense-organs,
produced any effect on the resulting colour. Mr. Poulton concludes,
therefore, that the colour-action probably occurs over the whole surface
of the body, setting up physiological processes which result in the
corresponding colour-change of the pupa. Such changes are, however, by
no means universal, or even common, in protectively coloured pupae,
since in Papilio machaon and some others which have been experimented
on, both in this country and abroad, no change can be produced on the
pupa by any amount of exposure to differently coloured surroundings.
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