acquired in botanical work to aid in the elucidation of many of the
difficulties that presented themselves. I well remember a visit which
I paid to Down at this period. At the side of the little study stood
flower-pots containing earth with worms, and, without interrupting
our conversation, Darwin would from time to time lift the glass plate
covering a pot to watch what was going on. Occasionally, with a humorous
smile, he would murmur something about a book in another room, and slip
away; returning shortly, without the book but with unmistakeable signs
of having visited the snuff-jar outside. After working about a year at
the worms, he was able at the end of 1881 to publish the charming little
book--"The Formation of Vegetable Mould through the Action of Worms,
with Observations on their Habits". This was the last of his books, and
its reception by reviewers and the public alike afforded the patient old
worker no little gratification. Darwin's scientific career, which had
begun with geological research, most appropriately ended with a return
to it.

It has been impossible to sketch the origin and influence of Darwin's
geological work without, at almost every step, referring to the part
played by Lyell and the "Principles of Geology". Haeckel, in the
chapters on Lyell and Darwin in his "History of Creation", and Huxley in
his striking essay "On the Reception of the Origin of Species" ("L.L."
II. pages 179-204.) have both strongly insisted on the fact that the
"Origin" of Darwin was a necessary corollary to the "Principles" of
Lyell.

It is true that, in an earlier essay, Huxley had spoken of the doctrine
of Uniformitarianism as being, in a certain sense, opposed to that of
Evolution (Huxley's Address to the Geological Society, 1869. "Collected
Essays", Vol. VIII. page 305, London, 1896.); but in his later years he
took up a very different and more logical position, and maintained
that "Consistent uniformitarianism postulates evolution as much in the
organic as in the inorganic world. The origin of a new species by other
than ordinary agencies would be a vastly greater 'catastrophe' than
any of those which Lyell success fully eliminated from sober geological
speculation." ("L.L." II. page 190.)

Huxley's admiration for the "Principles of Geology", and his conviction
of the greatness of the revolution of thought brought about by Lyell,
was almost as marked as in the case of Darwin himself. (See his Essay
on "Science an