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:--
“DEAR SIR--I have some doubts whether Fritz Müller would like extracts from his letters being published after so long an interval,--that is if the letter relates to the origin of mimicry; for he published about a year ago an excellent paper on this subject. I believe it was in the Jenaische Zeitschrift, but the paper is out of its proper place in my library and I cannot find it. If you thought it worth while to send me your copy I could then judge about the publication of extracts.
“I fear it is not likely that I shall have anything to communicate to the Entomological Soc. I quite agree with you that it is a great pity that our Entomologists should confine themselves to describing species.
“Dear Sir, yours faithfully, “CH. DARWIN.”
“MY DEAR SIR--I am doubtful whether speculations in a letter ought to be published, especially after a long interval of time. Any fact which he states, I feel pretty sure he would not at all object being used by anyone.--Pray do the best you can.--I should grieve beyond measure to be accused of a breach of confidence.--He has lately, as I mentioned, thrown much light on the first steps in mimicry.
“With respect to dimorphic Butterflies, those about which I have read appear at different seasons, and have been the subject of an _admirable_ essay by Prof. Weismann. It is some little time since I read the essay and one subject drives another out of my head, but I think he explains all such cases by the direct inherited effects of temperature. He tried experiments. If you read German, I believe I could find Weismann’s essays and lend them to you. In your present interesting case I really do not know what to think: it seems rather bold to attribute the 2 coloured forms to nat. selection, before some advantage can be pointed out.--May not the female revert in some cases? I do not doubt that the intermediate form could be eliminated as you suggest.