ation theory which had up to that time
appeared--that of Lamarck. In subsequent chapters he discusses the
questions of the modification and variability of species, of hybridity,
and of the geographical distribution of plants and animals. He then
gives vivid pictures of the struggle for existence, ever going
on between various species, and of the causes which lead to their
extinction--not by overwhelming catastrophes, but by the silent and
almost unobserved action of natural causes. This leads him to consider
theories with regard to the introduction of new species, and, rejecting
the fanciful notions of "centres or foci of creation," he argues
strongly in favour of the view, as most reconcileable with observed
facts, that "each species may have had its origin in a single pair, or
individual, where an individual was sufficient, and species may have
been created in succession at such times and in such places as to enable
them to multiply and endure for an appointed period, and occupy an
appointed space on the globe." ("Principles of Geology", Vol. II. (1st
edition 1832), page 124. We now know, as has been so well pointed out
by Huxley, that Lyell, as early as 1827, was prepared to accept the
doctrine of the transmutation of species. In that year he wrote to
Mantell, "What changes species may really undergo! How impossible will
it be to distinguish and lay down a line, beyond which some of the
so-called extinct species may have never passed into recent ones"
(Lyell's "Life and Letters" Vol. I. page 168). To Sir John Herschel in
1836, he wrote, "In regard to the origination of new species, I am
very glad to find that you think it probable that it may be carried on
through the intervention of intermediate causes. I left this rather to
be inferred, not thinking it worth while to offend a certain class of
persons by embodying in words what would only be a speculation" (Ibid.
page 467). He expressed the same views to Whewell in 1837 (Ibid. Vol.
II. page 5.), and to Sedgwick (Ibid. Vol. II. page 36) to whom he says,
of "the theory, that the creation of new species is going on at the
present day"--"I really entertain it," but "I have studiously avoided
laying the doctrine down dogmatically as capable of proof" (see Huxley
in "L.L." II. pages 190-195.))

After pointing out how impossible it would be for a naturalist to prove
that a newly DISCOVERED species was really newly CREATED (Mr F. Darwin
has pointed out that his father (like