I believe I mentioned this to you before.
LETTER 331.

TO ASA GRAY.

Down, October 12th [1856].
I received yesterday your most kind letter of the 23rd and your "Statistics," and two days previously another copy.

I thank you cordially for them.

Botanists write, of course, for botanists; but, as far as the opinion of an "outsider" goes, I think your paper admirable.
I have read carefully a good many papers and works on geographical distribution, and I know of only one essay (viz.