which were afterwards substantiated, thus the
geographer von Buch (1773-1853) detected the importance of the Isolation
factor on which Wagner, Romanes, Gulick and others have laid great
stress, but we must content ourselves with recalling one other pioneer,
the author of the "Vestiges of Creation" (1844), a work which passed
through ten editions in nine years and certainly helped to harrow the
soil for Darwin's sowing. As Darwin said, "it did excellent service in
this country in calling attention to the subject, in removing prejudice,
and in thus preparing the ground for the reception of analogous views."
("Origin of Species" (6th edition), page xvii.) Its author, Robert
Chambers (1802-1871) was in part a Buffonian--maintaining
that environment moulded organisms adaptively, and in part a
Goethian--believing in an inherent progressive impulse which lifted
organisms from one grade of organisation to another.

AS REGARDS NATURAL SELECTION.

The only thinker to whom Darwin was directly indebted, so far as the
theory of Natural Selection is concerned, was Malthus, and we may once
more quote the well-known passage in the Autobiography: "In October,
1838, that is, fifteen months after I had begun my systematic enquiry,
I happened to read for amusement 'Malthus on Population', and being well
prepared to appreciate the struggle for existence which everywhere goes
on from long-continued observation of the habits of animals and
plants, it at once struck me that under these circumstances favourable
variations would tend to be preserved, and unfavourable ones to be
destroyed. The result of this would be the formation of new species."
("The Life and Letters of Charles Darwin", Vol. 1. page 83. London,
1887.)

Although Malthus gives no adumbration of the idea of Natural Selection
in his exposition of the eliminative processes which go on in mankind,
the suggestive value of his essay is undeniable, as is strikingly
borne out by the fact that it gave to Alfred Russel Wallace also "the
long-sought clue to the effective agent in the evolution of organic
species." (A.R. Wallace, "My Life, A Record of Events and Opinions",
London, 1905, Vol. 1. page 232.) One day in Ternate when he was resting
between fits of fever, something brought to his recollection the work of
Malthus which he had read twelve years before. "I thought of his clear
exposition of 'the positive checks to increase'--disease, accidents,
war, and famine--which keep down th