riticism from Mr. Darwin upon
the presidential address which Mr. Bentham delivered to the Linnean
Society on May 24th, 1869. This letter, I think, has been overlooked and
not published previously. In it Mr. Darwin expresses himself with regard
to the multiple origin of races and some other points in very explicit
language. Prof. Meldola, to whom I mentioned in conversation the
existence of the letter, urged me strongly to print it. This, therefore,
I now do, with the addition of a few explanatory notes.

LETTER 290. TO G. BENTHAM. Down, November 25th, 1869.

(290/1. The notes to this letter are by Sir W. Thiselton-Dyer, and
appeared in "Nature," loc. cit.)

I was greatly interested by your address, which I have now read thrice,
and which I believe will have much influence on all who read it. But you
are mistaken in thinking that I ever said you were wrong on any point.
All that I meant was that on certain points, and these very doubtful
points, I was inclined to differ from you. And now, on further
considering the point on which some two or three months ago I felt most
inclined to differ--viz., on isolation--I find I differ very little.
What I have to say is really not worth saying, but as I should be very
sorry not to do whatever you asked, I will scribble down the slightly
dissentient thoughts which have occurred to me. It would be an endless
job to specify the points in which you have interested me; but I may
just mention the relation of the extreme western flora of Europe (some
such very vague thoughts have crossed my mind, relating to the Glacial
period) with South Africa, and your remarks on the contrast of passive
and active distribution.

Page lxx.--I think the contingency of a rising island, not as yet fully
stocked with plants, ought always to be kept in mind when speaking of
colonisation.

Page lxxiv.--I have met with nothing which makes me in the least doubt
that large genera present a greater number of varieties relatively to
their size than do small genera. (290/2. Bentham thought "degree of
variability... like other constitutional characters, in the first place
an individual one, which...may become more or less hereditary, and
therefore specific; and thence, but in a very faint degree, generic."
He seems to mean to argue against the conclusion which Sir Joseph
Hooker had quoted from Mr. Darwin that "species of large genera are
more variable than those of small." [On large genera varying, see Letter