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Darwin Correspondence Project

To Ernst Haeckel   3 October [1869]1

Down. | Beckenham | Kent. S.E.

Oct. 3d

My dear Häckel

I received this morning your letter of the 29th. & am heartily glad that you have had so successful an expedition.2 You give a very pleasant account of all your doings. It is, also, very satisfactory to hear from you of so many naturalists who believe in our views. I am particularly glad to hear about Sars,3 for whom I have always felt an unbounded respect.

I received some time ago your Siphonophoren, & have admired the exquisite Plates; but I have not yet had time to read any as yet, though it now stands as the top book of a pile next to be read. I am very much obliged to you for telling me of the pages, in the work & in your memoir on Sponges, for, as you know, I am a very poor German scholar, & alas shall never improve.4

Do not work yourself to death or sickness.

Let your wife5 sing that into your ears night & day.— I have forwarded your letter & papers to Mr. Norman.—6

My dear Häckel | Yours most truly | C. Darwin


The year is established by the relationship between this letter and the letter from Ernst Haeckel, 29 September 1869.
Michael Sars.
CD refers to Zur Entwicklungsgeschichte der Siphonophoren (On the developmental history of siphonophores; Haeckel 1869a) and ‘Ueber den Organismus der Schwamme und ihre Verwandtschaft mit den Corallen’ (Haeckel 1869b), which was later translated as ‘On the organisation of sponges, and their relationship to the corals’ (Haeckel 1870a). See letter from Ernst Haeckel, 29 September 1869 and nn. 7 and 9.
Agnes Haeckel.
Alfred Merle Norman. See letter from Ernst Haeckel, 29 September 1869 and n. 4.


Mentions views of Sars on species.

EH’s work on Siphonophora.

Letter details

Letter no.
Charles Robert Darwin
Ernst Philipp August (Ernst) Haeckel
Sent from
Source of text
Ernst-Haeckel-Haus (Bestand A-Abt. 1: 1–52/23)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 6924,” accessed on 25 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 17