“DEAR SIR--I thank you for your information on various subjects. The point to which you allude seems to me very obscure, and I hardly venture to express an opinion on it. My first impression is that the colour of an imitating form might be modified to any extent without any tendency being given to the retention of ancient structural peculiarities. The difficulty of the subject seems to me to follow from our complete ignorance of the causes which have led to the generic differences between the imitating and imitated forms. The subject however seems worth investigating. If the imitator habitually lives in company with the imitated, it would be apt to follow in some respects the same habits of life, and this perhaps would lead to the retention or acquirement of some of the same structural characters. “I wish you all success in your essay, and remain, dear Sir, yours very faithfully, “CH. DARWIN.” The next very brief letter, acknowledging the receipt of a note, was written from Down, March 26th, 1873. It contained some sympathetic remarks upon the progress of Meldola’s work upon Mimicry. In the succeeding letter, printed below, we find a very definite statement of opinion as to the _rôle_ of monstrosities in evolution:-- “_Aug. 13th_ [1873]. “Down. “DEAR SIR--I am much obliged for your present which no doubt I shall find at Down on my return home.... “I am sorry to say that I cannot answer your question; nor do I believe that you could find it anywhere even approximately answered. It is very difficult or impossible to define what is meant by a larger variation. Such graduate into monstrosities or generally injurious variations. I do not myself believe that these are often or ever taken advantage of under nature. It is a common occurrence that _abrupt_ and considerable variations are transmitted in an unaltered state, or not at all transmitted, to the offspring or to some of them. So it is with tailless or hornless animals, and with sudden and great changes of colour in flowers.--I wish I could have given you any answer. “Dear Sir, yours very faithfully, “CH. DARWIN.” The succeeding three letters show Darwin’s scrupulous care as regards the publication, although with every acknowledgment, of the results obtained by others. They refer to a letter from Fritz Müller which he had forwarded to Meldola. The latter had written to ask Darwin’s permission and advice as to the inclusion of some of F. Müller’s observations in his most interesting paper, “Entomological Notes bearing on Evolution” (_Ann. and Mag. Nat. Hist._, 1878, 5th series, Vol. I. p. 155), which he was then preparing:-- “_Sept. 14, 1877._