For during many successive
generations each individual beetle which flew least, either from its
wings having been ever so little less perfectly developed or from
indolent habit, will have had the best chance of surviving, from not
being blown out to sea; and, on the other hand, those beetles which
most readily took to flight would oftenest have been blown to sea,
and thus destroyed." {27}
We should like to know, first, somewhere about how much disuse was
able to do after all, and moreover why, if it can do anything at
all, it should not be able to do all. Mr. Darwin says: "Any change
in structure and function which can be effected by small stages is
within the power of natural selection." "And why not," we ask,
"within the power of use and disuse?" Moreover, on a later page we
find Mr. Darwin saying:-
"IT APPEARS PROBABLE THAT DISUSE HAS BEEN THE MAIN AGENT IN
RENDERING ORGANS RUDIMENTARY [italics mine]. It would at first lead
by slow steps to the more and more complete reduction of a part,
until at last it has become rudimentary--as in the case of the eyes
of animals inhabiting dark caverns, and of the wings of birds
inhabiting oceanic islands, which have seldom been forced by beasts
of prey to take flight, and have ultimately lost the power of
flying. Again, an organ, useful under certain conditions, might
become injurious under others, AS WITH THE WINGS OF BEETLES LIVING
ON SMALL AND EXPOSED ISLANDS; and in this case natural selection
will have aided in reducing the organ, until it was rendered
harmless and rudimentary [italics mine].
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