led to a rather wide generalisation, viz. that the great and
important classes of movements, excited by light, the attraction
of gravity, etc., are all modified forms of the fundamental
movement of circumnutation. It has always pleased me to exalt
plants in the scale of organised beings; and I therefore felt an
especial pleasure in showing how many and what admirably well
adapted movements the tip of a root possesses.

I have now (May 1, 1881) sent to the printers the MS. of a little
book on 'The Formation of Vegetable Mould, through the Action of
Worms.' This is a subject of but small importance; and I know
not whether it will interest any readers (Between November 1881
and February 1884, 8500 copies have been sold.), but it has
interested me. It is the completion of a short paper read before
the Geological Society more than forty years ago, and has revived
old geological thoughts.

I have now mentioned all the books which I have published, and
these have been the milestones in my life, so that little remains
to be said. I am not conscious of any change in my mind during
the last thirty years, excepting in one point presently to be
mentioned; nor, indeed, could any change have been expected
unless one of general deterioration. But my father lived to his
eighty-third year with his mind as lively as ever it was, and all
his faculties undimmed; and I hope that I may die before my mind
fails to a sensible extent. I think that I have become a little
more skilful in guessing right explanations and in devising
experimental tests; but this may probably be the result of mere
practice, and of a larger store of knowledge. I have as much
difficulty as ever in expressing myself clearly and concisely;