opment of the idea of evolution. On the other hand, Lyell,
although he strongly opposed the ideas of Lamarck and some curious
notions of progressional creation due to the great Agassiz, had
prepared the way for Darwin by his advocacy of natural causes and slow
changes in opposition to the catastrophic and miraculous views in
vogue. Above all, Herbert Spencer had argued most strenuously in
favour of evolution. Thus, in an important passage quoted by Mr. Clodd
from the _Leader_ of March 20, 1852, Spencer had written as follows:

"Those who cavalierly reject the theory of evolution, as not
adequately supported by facts, seem quite to forget that their
own theory is not supported by facts at all. Like the majority of
men who are born to a given belief, they demand the most rigorous
proof of any adverse belief, but assume that their own needs
none. Here we find, scattered over the globe, vegetable and
animal organisms numbering, of the one kind (according to
Humboldt) some 320,000 species, and of the other, some 2,000,000
species (see Carpenter); and if to these we add the numbers of
animal and vegetable species that have become extinct, we may
safely estimate the number of species that have existed, and are
existing, on the earth, at no less than ten millions. Well, which
is the most rational theory about these ten millions of species?
Is it most likely that there have been ten millions of special
creations; or is it most likely that by continual modifications,
due to change of circumstances, ten millions of varieties have
been produced, as varieties are being produced still?... Even
could the supporters of the development hypothesis merely shew
that the origination of species by the process of modification is
conceivable, they would be in a better position than their
opponents. But they can do much more than this. They can shew
that the process of modification has effected, and is effecting,
decided changes in all organisms subject to modifying
influences.... They can shew that in successive generations these
changes continue, until ultimately the new conditions become the
natural ones. They can shew that in cultivated plants,
domesticated animals, and in the several races of men, such
alterations have taken place. They can show that the degrees of
difference so produced are often