ON THE ORIGIN AND TRANSITIONS OF ORGANIC BEINGS WITH PECULIAR HABITS
AND STRUCTURE.
It has been asked by the opponents of such views as I hold, how, for
instance, a land carnivorous animal could have been converted into one
with aquatic habits; for how could the animal in its transitional
state have subsisted? It would be easy to show that within the same
group carnivorous animals exist having every intermediate grade
between truly aquatic and strictly terrestrial habits; and as each
exists by a struggle for life, it is clear that each is well adapted
in its habits to its place in nature. Look at the Mustela vison of
North America, which has webbed feet and which resembles an otter in
its fur, short legs, and form of tail; during summer this animal dives
for and preys on fish, but during the long winter it leaves the frozen
waters, and preys like other polecats on mice and land animals. If a
different case had been taken, and it had been asked how an
insectivorous quadruped could possibly have been converted into a
flying bat, the question would have been far more difficult, and I
could have given no answer. Yet I think such difficulties have very
little weight.
Here, as on other occasions, I lie under a heavy disadvantage, for out
of the many striking cases which I have collected, I can give only one
or two instances of transitional habits and structures in closely
allied species of the same genus; and of diversified habits, either
constant or occasional, in the same species.
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