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.

It is a curious point that, with the small tortoise-shell larva, exposure to light from gilded surfaces produced pupae with a brilliant golden lustre; and the explanation is supposed to be that mica abounded in the original habitat of the species, and that the pupae thus obtained protection when suspended against micaceous rock.