In butterflies, there is
undoubtedly a larger proportion of brilliant colour in the tropics; but
if we compare families which are almost equally developed over the
globe--as the Pieridae or whites and yellows, and the Satyridae or
ringlets--we shall find no great disproportion in colour between those
of temperate and tropical regions.
The various facts which have now briefly been noticed are sufficient to
indicate that the light and heat of the sun are not the direct causes of
the colours of animals, although they may favour the production of
colour when, as in tropical regions, the persistent high temperature
favours the development of the maximum of life. We will now consider the
next suggestion, that light reflected from surrounding coloured objects
tends to produce corresponding colours in the animal world.
This theory is founded on a number of very curious facts which prove,
that such a change does sometimes occur and is directly dependent on the
colours of surrounding objects; but these facts are comparatively rare
and exceptional in their nature, and the same theory will certainly not
apply to the infinitely varied colours of the higher animals, many of
which are exposed to a constantly varying amount of light and colour
during their active existence.
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