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transmutation by means of Natural Selection which belong
alike to colours which conceal, to colours which act as
warnings, and to insects which mimic the coloration of
insects of different genera and species.
In the first place, after what has been said, it becomes a
mere truism to assert that the efficacy of Natural Selection
will be in inverse ratio to the amount of accidental death.
We have seen that it is a logical demand of the theory,
when dealt with from an abstract point of view', that we
must get rid of the idea of accidental death. Here, then,
is a good test to apply. The theory of defensive colouring,
if it be so admirable an illustration of the action of Natural
Selection, ought to introduce us to a sphere where acci
dental death is reduced to a minimum ; or, at the very
least, is not so common as in other spheres.
We shall be justified in applying this test especially to
the insect w'orld, for Mr. Wallace gives several conclusive
reasons for the fact that the phenomena of mimicry
abound among insects more than in other departments of
the animal kingdom.* What evidence, then, can be
adduced from the observation of naturalists to show that
the insect world is less free than other spheres of nature
from accidental death ? I have not been able to find any
such evidence adduced by the scientific theorist, but a very
different testimony is given by the practical naturalist.
Mr. Samuel H. Scudder says:—
“ The great sources of destruction here, as in all groups of animals,
are in early life. How large a proportion of the eggs that are laid
by butterflies ever finally produce imagines ? Let those answer
who have attempted to follow their history in their native haunts.
My experience leads me to believe that, at the very least, nine-tenths
—perhaps ninety-nine hundredths—never reach maturity. Hymen-
opterous and dipterous parasites beset them at every step ; the eggs,
although so small and often heavily ridged, cannot escape the
Contributions, pp. gg-ioo.