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Darwin Correspondence Project

To Fritz Müller   4 January 1882

Down, | Beckenham, Kent. | (Railway Station | Orpington. S.E.R.)

Jan. 4th 1882.

My dear Sir

I must write a few lines to thank you for your letter of Dec. 2d, though I have nothing particular to say.1 Your appreciation of Balfour’s book has pleased me excessively, for though I could not properly judge of it, yet it seemed to me one of the most remarkable books which has been published for some considerable time.—2 He is quite a young man & if he keeps his health, will do splendid work. He is the younger brother of a Scotch man A. Balfour M.P. of immense fortune & nephew to a very grand gentleman, the Marquis of Salisbury.3 He has a fair fortune of his own, so that he can give up his whole time to Biology. He is very modest & very pleasant, & often visits here, & we like him very much.

Your Pontederia case is very curious: when writing the Origin, of Species what a fine instance it wd. have been of one species beating out another, & under the apparent disadvantage of the mid-styled form alone having been introduced.4

As you speak of the seedlings varying I suppose that you feel sure that a suspicion which crossed my mind, of hybrid origin is groundless.— It is also very odd about the seeding & the appearance of the long-styled form. I never saw such oddly-coloured petals which arrived quite brightly coloured.5

Your Janira seems a very curious & interesting case; & with what exquisite clearness, you have drawn all its exterior organs.6

I have been working at the effects of Carbonate of Ammonia on roots, the chief result being that with certain plants the cells of the roots, though not differing from one another at all in appearance in fresh thin slices, yet are found to differ greatly in the nature of their contents, if immersed for some hours in a weak solution of C. of Ammonia.7

My dear Sir | yours ever sincerely | Charles Darwin

I remember once suggesting to you to write ‘a Journal of a naturalist in Brazil’ or some such title, & give in it a resume of your endless & most interesting observations; I wish that my suggestion would bear fruit.8

P.S— I have just had to look to Bentham & Hookers Genera, & this has reminded me that I do not at all know whether I have completed your set. If you care to have any parts not sent, I beg you to let me hear.— Hooker tells me that they have nearly completed the Monocotyledons, & that the Palms, Grasses & Orchideæ were fearfully hard work. The Palms took 2 years.—9


Müller’s letter of 2 December 1881 has not been found.
CD had received two copies of A treatise on comparative embryology (Balfour 1880–1) and arranged with Francis Maitland Balfour to send the spare copy to Müller as a gift from Balfour (see Correspondence vol. 29, letter to F. M. Balfour, 6 July 1881, and letter from F. M. Balfour, 10 July 1881).
In Origin, pp. 60–79, CD discussed the natural checks to increase on species and varieties. In his now missing letter of 2 December 1881, Müller had evidently discussed a species of Pontederia (pickerel-weed) in which only one form had been introduced to an area (see letter from Fritz Müller, 1 January 1882 and n. 4). The species was probably P. crassipes (a synonym of Eichhornia crassipes, common water hyacinth); Müller later discussed it in a short paper, ‘Einige Eigenthümlichkeiten der Eichhornia crassipes’ (Some characteristics of Eichhornia crassipes; F. Müller 1883).
Müller had probably sent seeds of crosses between long- and mid-styled plants of Pontederia crassipes with his letter of 2 December 1881 (see letter from Fritz Müller, 1 January 1882).
Müller’s description of a species he identified as belonging to the isopod genus Janira was evidently in his now missing letter of 2 December 1881. Müller later described and figured the species in his paper ‘Descripção da Janira exul, crustaceo isopode do estado de Santa Catharina’ (Description of Janira exul, an isopod crustacean from the state of Santa Catharina; F. Müller 1892). Janira was a genus with only marine species, but Müller’s species was found in fresh water and was notable for its distinctive antennae.
The results of CD’s research were published in ‘Action of carbonate of ammonia on roots’.
In his letter of 22 April [1867] (Correspondence vol. 15), CD had suggested that Müller should write a book of ‘miscellaneous observations on all branches of natural history’, noting that such books were very popular in England. CD repeated the suggestion in a letter of [9 February 1876] (Correspondence vol. 24).
See Correspondence vol. 29, letter from J. D. Hooker, 27 October 1881. Genera plantarum (Bentham and Hooker 1862–83) was a systematic work undertaken by Joseph Dalton Hooker and George Bentham in 1860 (see Stearn 1956). Monocotyledones was the heading of the final part of Genera plantarum (Bentham and Hooker 1862–83, 3 (2): 448). The Orchideae (a synonym of Orchidaceae, orchids) was a large section completed by Bentham in August 1880, after which he worked on the Cyperaceae (sedges), finished in October 1880; the Gramineae (a synonym of Poaceae, grasses) formed the last section, which Bentham finished in late 1881 (Stearn 1956, p. 130; Bentham 1881). Hooker was working on palms (Palmae, a synonym of Arecaceae); see Bentham and Hooker 1862–83, 3 (2): 870–948. CD had sent earlier parts to Müller (see Correspondence vol. 14, letter to Fritz Müller, [late December 1866 and] 1 January 1867).


‘Action of carbonate of ammonia on roots’: The action of carbonate of ammonia on the roots of certain plants. By Charles Darwin. [Read 16 March 1882.] Journal of the Linnean Society of London (Botany) 19: 239–61.

Balfour, Francis Maitland. 1880–1. A treatise on comparative embryology. 2 vols. London: Macmillan & Co.

Bentham, George. 1881b. Notes on Gramineæ. [Read 3 November 1881.] Journal of the Linnean Society of London (Botany) 19: 14–134.

Bentham, George and Hooker, Joseph Dalton. 1862–83. Genera plantarum. Ad exemplaria imprimis in herbariis Kewensibus servata definita. 3 vols. in 7. London: A. Black [and others].

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Müller, Fritz. 1883b. Einige Eigenthümlichkeiten der Eichhornia crassipes. Kosmos 13: 297–300.

Müller, Fritz. 1892. Descripção da Janira exul, Crustaceo Isopode do estado de Santa Catharina). Archivos do Museu Nacional do Rio de Janeiro 8: 207–20.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.

Stearn, William T. 1956. Bentham and Hooker’s Genera plantarum: its history and dates of publication. Journal of the Society for the Bibliography of Natural History 3 (1953–60): 127–32.


On F. M. Balfour.

Effects of ammonium carbonate on roots.

FM’s Pontederia case is very curious.

Letter details

Letter no.
Charles Robert Darwin
Johann Friedrich Theodor (Fritz) Müller
Sent from
Source of text
The British Library (Loan MS 10: 58)
Physical description
ALS 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 13599,” accessed on 1 October 2023,