h butterflies and moths. Mr.
Fraser, in explanation of the letters, writes: "As an altogether unknown
and far from experienced naturalist, I feared to send my letters
for publication without, in the first place, obtaining Mr. Darwin's
approval." The information was published in "Nature," Volume III., April
20th, 1871, page 489. The article was referred to in the second edition
of the "Descent of Man" (1874), pages 312, 316, 319. Mr. Fraser
adds: "This is only another illustration of Mr. Darwin's great
conscientiousness in acknowledging suggestions received by him from the
most humble sources." (Letter from Mr. Fraser to F. Darwin, March 21,
1888.)

Down, April 14th [1871].

I am very much obliged for your letter and the interesting facts which
it contains, and which are new to me. But I am at present so much
engaged with other subjects that I cannot fully consider them; and, even
if I had time, I do not suppose that I should have anything to say worth
printing in a scientific journal. It would obviously be absurd in me to
allow a mere note of thanks from me to be printed. Whenever I have
to bring out a corrected edition of my book I will well consider
your remarks (which I hope that you will send to "Nature"), but
the difficulty will be that my friends tell me that I have already
introduced too many facts, and that I ought to prune rather than to
introduce more.

LETTER 460. TO E.S. MORSE. Down, December 3rd, 1871.

I am much obliged to you for having sent me your two interesting papers,
and for the kind writing on the cover. I am very glad to have my error
corrected about the protective colouring of shells. (460/1. "On Adaptive
Coloration of the Mollusca," "Boston Society of Natural History Proc."
Volume XIV., April 5th, 1871. Mr. Morse quotes from the "Descent of
Man," I., page 316, a passage to the effect that the colours of the
mollusca do not in general appear to be protective. Mr. Morse goes on to
give instances of protective coloration.) It is no excuse for my broad
statement, but I had in my mind the species which are brightly or
beautifully coloured, and I can as yet hardly think that the colouring
in such cases is protective.

LETTER 461. TO AUG. WEISMANN. Down, February 29th, 1872.

I am rejoiced to hear that your eyesight is somewhat better; but I fear
that work with the microscope is still out of your power. I have often
thought with sincere sympathy how much you must have suffered from your
gra