factors in the evolution-process, especially by his analysis of what occurs
in the case of domestic animals and cultivated plants, and by his
elaboration of the theory of Natural Selection, which Alfred Russel Wallace
independently stated at the same time, and of which there had been a few
previous suggestions of a more or less vague description. It was here that
Darwin's originality was greatest, for he revealed to naturalists the many
different forms--often very subtle--which natural selection takes, and with
the insight of a disciplined scientific imagination he realised what a
mighty engine of progress it has been and is.

(IV) As an epoch-marking contribution, not only to Aetiology but to
Natural History in the widest sense, we rank the picture which Darwin gave
to the world of the web of life, that is to say, of the inter-relations and
linkages in Nature. For the Biology of the individual--if that be not a
contradiction in terms--no idea is more fundamental than that of the
correlation of organs, but Darwin's most characteristic contribution was
not less fundamental,--it was the idea of the correlation of organisms.
This, again, was not novel; we find it in the works of naturalist like
Christian Conrad Sprengel, Gilbert White, and Alexander von Humboldt, but
the realisation of its full import was distinctively Darwinian.

AS REGARDS THE GENERAL IDEA OF ORGANIC EVOLUTION.

While it is true, as Prof. H.F. Osborn puts it, that "'Before and after
Darwin' will always be the ante et post urbem conditam of biological
history," it is also true that the general idea of organic evolution is
very ancient. In his admirable sketch "From the Greeks to Darwin"
("Columbia University Biological Series", Vol. I. New York and London,
1894. We must acknowledge our great indebtness to this fine piece of
work.), Prof. Osborn has shown that several of the ancient philosophers