Ch. Darwin.
Another deeply interesting letter of Darwin's bearing upon protective
resemblance, has only recently been shown to me by my friend Professor
E.B. Wilson, the great American Cytologist. With his kind consent and
that of Mr Francis Darwin, this letter, written four months before
Darwin's death on April 19, 1882, is reproduced here (The letter is
addressed: "Edmund B. Wilson, Esq., Assistant in Biology, John Hopkins
University, Baltimore Md, U. States."):
December 21, 1881.
Dear Sir,
I thank you much for having taken so much trouble in describing fully
your interesting and curious case of mimickry.
I am in the habit of looking through many scientific Journals, and
though my memory is now not nearly so good as it was, I feel pretty sure
that no such case as yours has been described (amongst the nudibranch)
molluscs. You perhaps know the case of a fish allied to Hippocampus,
(described some years ago by Dr Gunther in "Proc. Zoolog. Socy.") which
clings by its tail to sea-weeds, and is covered with waving filaments
so as itself to look like a piece of the same sea-weed. The parallelism
between your and Dr Gunther's case makes both of them the more
interesting; considering how far a fish and a mollusc stand apart. It
would be difficult for anyone to explain such cases by the direct
action of the environment.--I am glad that you intend to make further
observations on this mollusc, and I hope that you will give a figure and
if possible a coloured figure.
With all good wishes from an old brother naturalist,