23.)

Besides a general interest about the southern lands, I have been now
ever since my return engaged in a very presumptuous work, and I know
no one individual who would not say a very foolish one. I was so struck
with the distribution of the Galapagos organisms, etc., and with the
character of the American fossil mammifers, etc., that I determined to
collect blindly every sort of fact which could bear any way on what are
species. I have read heaps of agricultural and horticultural books, and
have never ceased collecting facts. At last gleams of light have come,
and I am almost convinced (quite contrary to the opinion I started with)
that species are not (it is like confessing a murder) immutable.
Heaven forfend me from Lamarck nonsense of a "tendency to progression,"
"adaptations from the slow willing of animals," etc.! But the
conclusions I am led to are not widely different from his; though
the means of change are wholly so. I think I have found out (here's
presumption!) the simple way by which species become exquisitely adapted
to various ends. You will now groan, and think to yourself, "on what a
man have I been wasting my time and writing to." I should, five years
ago, have thought so...(13/3. On the questions here dealt with see the
interesting letter to Jenyns in the "Life and Letters," II., page 34.)

LETTER 14. TO J.D. HOOKER. [November] 1844.

...What a curious, wonderful case is that of the Lycopodium! (14/1. Sir
J.D. Hooker wrote, November 8, 1844: "I am firmly convinced (but not
enough to print it) that L. Selago varies in Van Diemen's Land into L.
varium. Two more different SPECIES (as they have hitherto been thought),
per se cannot be conceived, but nowhere else do they vary into one
another, nor does Selago vary at all in England.")...I suppose you would
hardly have expected them to be more varying than a phanerogamic plant.
I trust you will work the case out, and, even if unsupported, publish
it, for you can surely do this with due caution. I have heard of some
analogous facts, though on the smallest scale, in certain insects being
more variable in one district than in another, and I think the same
holds with some land-shells. By a strange chance I had noted to ask you
in this letter an analogous question, with respect to genera, in lieu
of individual species,--that is, whether you know of any case of a genus
with most of its species being variable (say Rubus) in one continent,
having another se