His observations and
experiments, so far as they have yet gone, confirm in _every instance_
my hypothetical explanation of the colours of caterpillars. He finds
that all nocturnal-feeding obscure-coloured caterpillars, all _green_
and _brown_ and _mimicking_ caterpillars, are greedily eaten by almost
every insectivorous bird. On the other hand, every gaily coloured,
spotted or banded species, which never conceal themselves, and all spiny
and hairy kinds, are _invariably rejected_, either without or after
trial. He has also come to the curious and rather unexpected conclusion,
that hairy and spiny caterpillars are not protected by their hairs, but
by their nauseous taste, the hairs being merely an external mark of
their uneatableness, like the gay colours of others. He deduces this
from two kinds of facts: (1) that very young caterpillars before the
hairs are developed are equally rejected, and (2) that in many cases the
smooth pupae and even the perfect insects of the same species are equally
rejected.
His facts, it is true, are at present not very numerous, but they all
point one way.
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