Dear Sir.

I thank you sincerely for your very obliging letter, and the present of your two Essays—It is highly gratifying to me to hear of the great success of your lectures (on Darwinianism) though I must attribute this to your powers as a lecturer— Unfortunately I am a very poor German Scholar and I have not yet had time (but assuredly will soon find time) to read your essay excepting the two notes— Had I known of the “Mammæ Erraticæ” I should not have hazarded the speculation on Reversion— About the term “Struggle for Existence” I have always felt some doubts but was unable to draw any distinct line between the two ideas therein included, I suspect that the German term Kampf &c. does not give quite the same idea.—¹ The words “Struggle for Existence” express I think exactly what concurrency does— It is correct to say in English that two men struggle for existence who may be hunting for the same food during a famine, and likewise when a single man is hunting for food; or again it may be said that a man struggles for existence against the waves of the sea when shipwrecked. I have never hitherto made a list of all my works, but your letter has led me to do so. I now send a copy, though it gives fuller details than you can possibly want.²

It is the custom in our scientific societies to publish abstracts before the papers appear in full; but I have not thought it worth while to hunt these up. Your N^o. 12 is probably a translation of one such abstract, or perhaps of extracts of some of my letters. Your N^o. 18 I presume is an extract from my Journal of Travels.³

Whilst searching for the paper which you require I found one or two other trifling articles, which I send to you by this post.

I congratulate you on your election to your Professorship,⁴ and with very sincere thanks for your kind interest about me, | I remain, Dear Sir | Yours very faithfully | Charles Darwin.