Modern
Science_. Cambridge, 1909.

{3} Obituary Notice of C. Darwin, _Proc. R. Soc._ vol. 44.
Reprinted in Huxley's _Collected Essays_. See also _Life and
Letters of C. Darwin_, ii. p. 179.

{4} See the extracts in the _Life and Letters_, ii. p. 5.

These quotations show that he was struggling to see in the origin of
species a process just as scientifically comprehensible as the birth of
individuals. They show, I think, that he recognised the two things not
merely as similar but as identical.

It is impossible to know how soon the ferment of uniformitarianism began
to work, but it is fair to suspect that in 1832 he had already begun to
see that mutability was the logical conclusion of Lyell's doctrine,
though this was not acknowledged by Lyell himself.

There were however other factors of change. In his Autobiography{5} he
wrote:--"During the voyage of the _Beagle_ I had been deeply impressed
by discovering in the Pampean formation great fossil animals covered
with armour like that on the existing armadillos; secondly, by the
manner in which closely allied animals replace one another in proceeding
southward over the Continent; and thirdly, by the South American
character of most of the productions of the Galapagos archipelago, and
more especially by the manner in which they differ slightly on each
island of the group; none of the islands appearing to be very ancient in
a geological sense. It was evident that such facts as these, as well as
many others, could only be explained on the supposition that species
gradually become modified; and the subject haunted me."

{5} _Life and Letters_, i. p. 82.

Again we have to ask: how soon did any of these influences produce an
effect on Darwin's mind? Different answers have been attempted.
Huxley{6} held that these facts could not have produced their essential
effect until the voyage had come to an end, and the "relations of the
existing with the extinct species and of the species of the different
geographical areas with one another were determined with some
exactness." He does not therefore allow that any appreciable advance
towards evolution was made during the actual voyage of the _Beagle_.

{6} _Obituary Notice_, _loc. cit._

Professor Judd{7} takes a very different view. He holds that November
1832 may be given with some confidence as the "date at which Darwin
commenced that long series of observations and reasonings which
eventua