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Darwin Correspondence Project

To Ernst Haeckel   30 December [1863] – 3 January [1864]1

Down. | Bromley. | Kent. S.E.

Dec 30

My dear Sir

Your letters are always most kind.2 I shall be proud to receive your monograph on the Radiolariæ which I saw & much admired in London;3 but I know so little of the group that in truth I am not worthy of your present. I sent off a few days since to Jena a copy of a paper by me, which if you have time I think is worth your reading.4

My health continues very weak & I have no strength to spare, so I am sure you will excuse the brevity of this note.

With very sincere respect believe me my dear Sir | Yours truly obliged | Charles Darwin

P S. Jan 3.

By a mistake this letter was put in a wrong envelope & you will have have received another note addressed to a friend which I fear will have surprized you.5

Please to tear it up. As there has been so much delay owing to my unfortunate mistake, I have directed this to Jena instead of to Berlin6


The years are established by the relationship between this letter and the letter from Ernst Haeckel, 2 January 1864 (Correspondence vol. 12).
The letter from Ernst Haeckel has not been found.
Haeckel 1862. CD visited London several times in 1863 (see ‘Journal’ (Correspondence vol. 11, Appendix II)), and may have seen Thomas Henry Huxley’s copy of Haeckel’s book, which Huxley had obtained in October 1862 (see L. Huxley ed. 1900, 1: 237).
CD may have sent Haeckel a copy of ‘Two forms in species of Linum.
CD had mistakenly sent the letter for Ernst Haeckel to Hugh Falconer, and vice versa. See following letter, and Correspondence vol. 12, letter from Ernst Haeckel, 2 January 1864. The letter intended for Falconer has not been found.
Haeckel must have told CD in a missing letter of his plans to move from Berlin to Jena in January 1864; Haeckel was professor extraordinarius of zoology at the University of Jena (DSB, NDB). See also Correspondence vol. 12, letter from Ernst Haeckel, 2 January 1864.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

DSB: Dictionary of scientific biography. Edited by Charles Coulston Gillispie and Frederic L. Holmes. 18 vols. including index and supplements. New York: Charles Scribner’s Sons. 1970–90.

Haeckel, Ernst. 1862. Die Radiolarien. (Rhizopoda Radiaria.) Eine Monographie. 2 vols. Berlin: Georg Reimer.

NDB: Neue deutsche Biographie. Under the auspices of the Historical Commission of the Bavarian Academy of Sciences. 26 vols. (A–Vocke) to date. Berlin: Duncker & Humblot. 1953–.

‘Two forms in species of Linum’: On the existence of two forms, and on their reciprocal sexual relation, in several species of the genus Linum. By Charles Darwin. [Read 5 February 1863.] Journal of the Proceedings of the Linnean Society (Botany) 7 (1864): 69–83. [Collected papers 2: 93–105.]


Will be proud to receive EH’s Die Radiolarien [1862].

Health continues very weak.

[P.S. 3 Jan] Has sent EH another letter by mistake.

Letter details

Letter no.
Charles Robert Darwin
Ernst Philipp August (Ernst) Haeckel
Sent from
Source of text
Ernst-Haeckel-Haus (Bestand A/ Abt. 1: 1026/1)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 4361,” accessed on 22 October 2021,

Also published in The Correspondence of Charles Darwin, vol. 11