ssentially a field
naturalist, and his theory of natural selection would have been an empty
and abstract thing if his vast knowledge and understanding of the "web
of life" had not given it colour and form. He never lost touch with the
living thing in its living, breathing reality--even plants he rightly
regarded as active things, full of tricks and contrivances for making
their way in the world. No one ever realised more vividly than he the
delicacy and complexity of the adaptations to environment which are the
necessary condition of success in the struggle for existence. Almost his
greatest service to biology was that he made biologists realise as they
never did before the vast importance of environment. He took biology
into the open air, away from the museum and the dissecting-room.

Naturally this attitude was not without its drawbacks. It led him to
take only a lukewarm interest in the problems of morphology. It is true
he used the facts of morphology with great effect as powerful arguments
for evolution, but it was not from such facts that he deduced his theory
to account for evolution. It is questionable indeed whether the theory
of natural selection is properly applicable to the problems of form. It
was invented to account for the evolution of specific differences and of
ecological adaptations; it was not primarily intended as an explanation
of the more wonderful and more mysterious facts of the _convenance des
parties_ and the interaction of structure and function. Perhaps Darwin
did not realise this inner aspect of adaptation quite so vividly as he
did the more superficial adaptation of organisms to their environment.
It was, perhaps, his lack of morphological training and experience that
led him to disregard the problems of form, or at least to realise very
insufficiently their difficulty.

It is in any case very significant that only a small part of his _Origin
of Species_ is devoted to the discussion of morphological
questions--only one chapter out of the fourteen contained in the first
edition.

Though the theory of natural selection took little account of the
problems of form, Darwin's masterly vindication of the theory of
evolution was of immense service to morphology, and Darwin himself was
the first to point out what a great light evolution threw upon all
morphological problems. In a few pages of the _Origin_ he laid the
foundations of evolutionary morphology.

We have here to consider his interpret