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Darwin Correspondence Project

To Fritz Müller   23 May 1866

Down Bromley Kent

May 23. 1866

My dear Sir

I thank you sincerely for your two letters of Mar. 6 & Ap. 3rd.1 Your account of the Orchis with affinities toward Cephalanthera, Vanilla, & Glossodia is extremely curious.2 I am much surprized at the course of the vessels; but Dr Crüger partly convinced me (as well as some observations which I have made on some other plants) that vessels often fail to give true homologies: at present I feel quite in the dark on the subject.3 As I am not likely to take up Orchids again, I did not like to retain your really beautiful drawings as they might be of use to yourself.4

I am very much obliged for all the facts which you give me in your former letter on the changes in the flora & fauna in your ditches & especially on the sea coast.5 If ever I have strength to publish my larger work these facts will come in very useful.6 The only analogous facts which I have met with refer to frequent changes in the Fuci growing on the same part on our shores.7

That is a singular fact of which you tell me about the male Orchestia externally like a female.8

I have recd your little pamphlet about poor old Gray’s absurd blunders.9 Such men do much harm in Nat. History; but he has done wonderfully well in accumulating materials for the Brit. Museum.10 You must have read carefully my book on the Lepadidæ to have picked out Gray’s method of classifying Scalpellum11   As you attend to plants, will you be so kind as to observe whether Oxalis with you exhibits different forms; for Dr Hildebrand of Bonn writes to me that the C of Good Hope species are trimorphic like Lythrum, as indeed I was aware as I have been experimenting on some for the last two years.12 I suspect that aquatic & marsh-plants are apt to be dimorphic so if you see any with a pistil much longer or shorter than the stamens pray look at the flowers of 3 or 4 other plants.13 I have almost finished correcting the new Ed. of the Origin14 & I am pleased to hear that my labour will be so much the more advantageous as a 3rd German Ed. is immediately to be printed revised by Prof. Leonhard.15 As you feel interested on the subject, I may mention that I have lately read two pamphlets in our favour, by good men, one by Oscar Schmidt & the other by Carl Nägeli.16 I think Rutimeyer, for whom I feel much respect is also with us; by the way he quoted in one of his last works your account of the metamorphoses of the “Garneelen”.17

With sincere thanks for all your kindness pray believe me | yours very truly | Ch. Darwin

P.S. I will keep safely your note on the curious Orchis & can return it to you if you shd desire it18


Müller’s letter of 6 March 1866 is incomplete (see letter from Fritz Müller, 6 March 1866 and n. 1); the letter of 3 April 1866 has not been found.
Müller’s account of the orchid was contained in his letter of 3 April 1866 (see n. 1, above; see also letter from Fritz Müller, 2 August 1866). He also discussed the orchid in letters to Max Johann Sigismund Schultze, 2 June 1866, and Hermann Müller, 1 July 1866; the letters are reproduced in Möller ed. 1915–21, 2: 83–4, 86–9. Müller described the orchid as similar to Cephalanthera in form and foliage but with flowers closely resembling Vanilla. He thought the flower was noteworthy in that the two stamens of the outer whorl were not merged with the labellum as CD had described (see Orchids, p. 294), but were clearly present in rudimentary form, though infertile (see Möller ed. 1915–21, 2: 84, 87). Müller did not mention Glossodia in the letters to Schultze and Hermann Müller.
Hermann Crüger had argued that the ‘production and multiplication of vascular cords and their distribution’ was related to ‘physiologic activity’ (Crüger 1864, p. 132), and cast doubt on CD’s claim in Orchids, p. 290, that tracing the spiral vessels of orchids could help determine the homologies of the parts relative to other flowers. CD added a reference to Crüger 1864 to Orchids 2d ed., p. 235, while maintaining his former claim.
The drawings have not been found.
The ‘larger work’ was presumably the ‘second work’ referred to in Variation 1: 4, in which CD planned to ‘discuss the variability of organic beings in a state of nature’. This work was never written.
Fucus is a genus of seaweed with species known to occur in all three intertidal zones. CD had written about the geographical range of F. giganteus in Journal of researches, p. 304. In his ‘big book’ on species (Natural selection, p. 284), CD quoted William Henry Harvey on environmentally induced changes in F. vesiculosus.
The information on the external similarity of the male and female forms of this amphipod must have been contained either in the missing portion of Müller’s letter of 6 March 1866 or in his missing letter of 3 April 1866 (see n. 1, above). Müller had earlier discussed dimorphism in males within the genus (see F. Müller 1864c, pp. 16–17).
Müller’s paper (F. Müller 1864b) was a critique of the generic diagnosis of a type of sea-pen (Pennatulacea) in the family Renilla (now Renillidae), given by John Edward Gray. Gray had proposed that the species Renilla edwardsii should be put into a new genus, which he called Herklotsia (see J. E. Gray 1860). Müller argued that Gray’s diagnosis was severely flawed, partly because of the disparity between live and preserved specimens of the organism, but also because of Gray’s use of inaccurate terminology (see F. Müller 1864b, p. 353). Herklotsia is now considered to be an invalid genus, and is placed in synonymy with Renilla (see Williams 1995, p. 101). Müller’s paper is not in the Darwin Pamphlet Collection–CUL.
Gray was keeper of the zoological collections at the British Museum. He had facilitated CD’s classificatory work on barnacles by arranging access to the museum’s specimens, providing CD with his own collection, and advising him on procuring other collections (see Correspondence vol. 4, Appendix II).
Müller had prefaced his paper with a quotation from Living Cirripedia (1851), p. 216, in which CD claimed that the ‘inordinate multiplication of genera’ destroyed ‘the main advantages of classification’. The statement was made in the context of a critique of Gray’s adoption of generic names for four species that CD included in a single genus, Scalpellum.
Friedrich Hildebrand had written a paper on trimorphism in Oxalis that he had promised to send to CD when it was published (Hildebrand 1866c). See letter from Friedrich Hildebrand, 11 May 1866 and nn. 2 and 3, and letter to Friedrich Hildebrand, 16 May [1866] and n. 10.
CD had earlier speculated whether there might be an unusual proportion of aquatic plants with separate sexes (see Correspondence vol. 11, letter to Daniel Oliver, 20 [January 1863]). See also Forms of flowers, p. 257 n.
CD had begun preparing the fourth edition of Origin on 1 March 1866 (see CD’s ‘Journal’, Appendix II).
CD’s German publisher had recently informed CD that he had asked Gustav von Leonhard to undertake the translation of the third German edition of Origin (see letter from E. Schweizerbart’sche Verlagsbuchhandlung, 10 May 1866 and nn. 6 and 7).
CD refers to Oskar Schmidt and Carl Wilhelm von Nägeli, and to Schmidt and Unger 1866, pp. 3–36, and Nägeli 1865, both of which are in the Darwin Pamphlet Collection–CUL. CD’s copy of Nägeli 1865 is heavily annotated and there is a partial manuscript translation, beginning on page 15, of the German text, along with a page of notes by CD, in the Darwin Pamphlet Collection–CUL. For more on Schmidt and Unger 1866, see the letter from Rudolf Suchsland, 16 April 1866 and n. 4.
CD refers to Ludwig Rütimeyer and to Müller’s paper on prawns, F. Müller 1863 (translated into English as F. Müller 1864a; the modern German spelling is ‘Garnelen’). No reference to F. Müller 1863 has been found in any of Rütimeyer’s publications.
Müller’s note on the orchid was contained in the letter of 3 April 1866 (see nn. 1 and 2, above). It has not been found.


Thanks for information on orchids

and facts on coastal flora and fauna.

Asks FM to look out for dimorphic aquatic and marsh plants.

Has read pamphlets "in our favour" by Carl v. Nägeli and Oscar Schmidt.

Letter details

Letter no.
Charles Robert Darwin
Johann Friedrich Theodor (Fritz) Müller
Sent from
Source of text
British Library (Loan 10: 7)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5097,” accessed on 19 January 2018,

Also published in The Correspondence of Charles Darwin, vol. 14