he were appealing to superior
authority for information in all his conversations. It was only when a
question was fully discussed with him that one became conscious of the
fund of information he could bring to its elucidation, and the breadth
of thought with which he had grasped it. Of his gentle, loving nature,
of which I had so many proofs, I need not write; no one could be with
him, even for a few minutes, without being deeply impressed by his
grateful kindliness and goodness.")

LETTER 287. TO COUNT SAPORTA. Down, August 15th, 1878.

I thank you very sincerely for your kind and interesting letter. It
would be false in me to pretend that I care very much about my election
to the Institute, but the sympathy of some few of my friends has
gratified me deeply.

I am extremely glad to hear that you are going to publish a work on the
more ancient fossil plants; and I thank you beforehand for the volume
which you kindly say that you will send me. I earnestly hope that you
will give, at least incidentally, the results at which you have arrived
with respect to the more recent Tertiary plants; for the close gradation
of such forms seems to me a fact of paramount importance for the
principle of evolution. Your cases are like those on the gradation in
the genus Equus, recently discovered by Marsh in North America.

LETTER 288. TO THE DUKE OF ARGYLL.

(288/1. The following letter was published in "Nature," March 5th, 1891,
Volume XLIII., page 415, together with a note from the late Duke of
Argyll, in which he stated that the letter had been written to him by
Mr. Darwin in reply to the question, "why it was that he did assume the
unity of mankind as descended from a single pair." The Duke added that
in the reply Mr. Darwin "does not repudiate this interpretation of his
theory, but simply proceeds to explain and to defend the doctrine." On
a former occasion the Duke of Argyll had "alluded as a fact to the
circumstance that Charles Darwin assumed mankind to have arisen at
one place, and therefore in a single pair." The letter from Darwin was
published in answer to some scientific friends, who doubted the fact and
asked for the reference on which the statement was based.)

Down, September 23rd, 1878.

The problem which you state so clearly is a very interesting one, on
which I have often speculated. As far as I can judge, the improbability
is extreme that the same well-characterised species should be produced
in two dist