or from the surface on which they live. There
are many biologists who seriously question whether protective
coloration, as Darwin called it, is as effective as he believed it. In
some quarters it is the present fashion to doubt protective coloration
entirely. No one has yet shown any principles which will better
explain the great color scheme of the animal world, and until such
explanation is forthcoming I believe it will not be wise for us to
discard the idea of protective coloration. No doubt it has been
overworked by enthusiastic believers in its efficiency. At the same
time, to overlook it completely, is, I believe, to make a greater
error. I have little doubt that when the broader explanation comes,
which will satisfactorily explain the color scheme of the animal
world, the idea of protective coloration will be found, not so much to
have been wrong, as to have been but partial. It will be included
under the broader principle which takes its place and will not be
supplanted by it.

The idea of protective coloration is that very many animals have
ordinarily come to be colored like the background on which they live.
The process has taken many generations, and is very slow, but is none
the less sure in the end. In most cases the animal is probably
entirely unconscious of this point in its favor, and usually it does
nothing to assist the deception. The result is none the less effective
because the animals themselves are unconscious of the process. The
cabbage worm is green in color like the cabbage. This does not mean
that it got green by eating cabbage or by longing for greennesses.
Through long years the enemies of the cabbage worm have been picking
it off the plants on which it fed. This does not imply that cabbages
as we know them are very old, but cabbage worms doubtless ate the
leaves of the sea-kale long before man had cultivated it into cabbage.
During all these years the enemies of the caterpillars, generally in
the shape of birds, have been assiduously gathering them up.

When we see how much the various members of the same human family may
differ in complexion, how much the various pigs in the same litter may
differ in size and in coloration, it is easy to understand that among
these caterpillars which have eaten the cabbage there must have been
considerable color variations. I do not imagine for a moment that the
birds had any preference for any particular color in their cabbage
worms. They took every cate