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Darwin Correspondence Project


To Fritz Müller   1 December [1869]1

Down Beckenham | Kent

Dec 1st.

My dear Sir

I am much obliged for your letter of oct 18th, with the curious account of Abutilon & for the seeds.2 A friend of mine, Mr Farrer has lately been studying the fertilisation of Passiflora, & concluded from the curiously crooked passage into the nectary that it could not be fertilised by humming-birds; but that Tacsonia was thus fertilised.3 Therefore I sent him the passage from your letter, & I enclose a copy of his answer.4 If you are inclined to gratify him by making a few observations on this subject, I shall be much obliged & will send them on to him.

I enclose a copy of my rough notes, on your Escholtzias, as you might like to see them.

Somebody has sent me from Germany two papers by you, one with a most curious account of Alisma,5 & the other on Crustaceans. Your observations on the Bronchiæ & heart have interested me extremely.6

Alex. Agassiz has just paid me a visit with his wife. He has been in England two or three months, & is now going to tour over the continent to see all the zoologists.7 We liked him very much. He is a great admirer of yours, & he tells me that your correspondence & book first made him believe in Evolution.8 This must have been a great blow to his father, who, as he tells me, is very well & so vigorous that he can work twice as long as he, the son, can.9 I have been very sorry to hear from him that Dana is quite broken down in health.10 As I was sure that you would wish it, I gave him a copy of the English translation of your book.11 By the way Mr Murray takes stock of his books in November, & informs me that of the thousand published of your book, 537 are unsold; & this I think is a very fair sale for a purely scientific work.12

Dr Meyer has sent me his translation of Wallace’s Malay Archipelago, which is a valuable work;13 & as I have no use for the translation, I will this day forward it to you by post, but to save postage viâ England. With every good wish believe me, my dear Sir, | Yours very sincerely | Ch. Darwin


Escholtzia Californica 1869.14

Many plants were raised from crossed seed from self-sterile plants, from S. Brazil, sent by F. Müller.15 Two plants were covered with nets; & 8 flowers on the two were crossed with pollen from distinct plants, & all produced very fine pods; a medium one contained 80 seed & none contained much fewer seed.

8 flowers on the 2 plants were fertilized with pollen from same flower & produced 7 pods; the finest of these contained 25 seed, the next finest 16 seed, & several others from 4 to 7 or 8 seed; average about 12 seed.

Later in the season, though the uncovered plants still produced pods, 12 flowers were self-fertilized, & they produced only 2 pods, containing 3 & 6 seed; so the colder temperature checked self-fertilization.

There was this difference between the 2 covered plants, that one spontaneously produced only 1 pod with no seed, yet it produced some when artificially self-fertilized; whilst the other plant spontaneously produced 8 pods, the finest of which contained 30 seed, the next finest 12, & several others from 3 to 6 seed.— Hence these 2 plants differed a little in their self-sterility. It was most curious to observe the more sterile plant of the two after it had been uncovered for about a week & insects had access, how it became completely covered with young pods;—wonderfully good evidence of benefit of a cross. These Brazilian plants appear under our climate much more self-fertile than their parents in Brazil, & very much less self-fertile than our English plants— Effect partly inherited, partly the result of external conditions.16


The year is established by the relationship between this letter and the letter from Fritz Müller, 18 October 1869.
Müller evidently enclosed seeds with his letter of 18 October 1869 to replace those that had been damaged earlier (see letter to Fritz Müller, 18 July [1869] and n. 5).
For Thomas Henry Farrer’s observations, see Correspondence vol. 17, Appendix IV.
CD sent a copy of the extract from Müller’s letter of 18 October 1869 with his letter to T. H. Farrer, [27 November 1869]. For Farrer’s original reply, see the letter from T. H. Farrer, 28 November 1869. Both the enclosures to the letter to Müller are copies made by Emma Darwin.
The reference is evidently to a pre-publication copy of ‘Die Bewegung des Blüthenstieles von Alisma’ (The movement of the pedicle in Alisma; F. Müller 1870a); CD’s heavily annotated copy is in the Darwin Pamphlet Collection–CUL. See also Correspondence vol. 16, letter to Fritz Müller, 3 April [1868] and n. 3. The person in Germany who sent the papers has not been identified.
The second article sent was ‘Bemerkungen über Cypridina’ (F. Müller 1870c); an annotated copy is in the Darwin Pamphlet Collection–CUL. Müller observed that two species of Cypridina with branchiae had hearts, while a third species lacked both (F. Müller 1870d, p. 269).
The reference is to Alexander and Anna Russell Agassiz; for more on their European tour, see G. R. Agassiz ed. 1913, pp. 97–114.
CD refers to Für Darwin (F. Müller 1864a). For more on Agassiz’s correspondence with Fritz Müller, see Dobbs 2005, pp. 100–1; some of Agassiz’s letters to Müller are in G. R. Agassiz ed. 1913, pp. 48–52, 91–4.
Louis Agassiz had been an outspoken critic of CD’s theories; for his views on evolution in the late 1860s and early 1870s, see Lurie 1988, pp. 372–7, and Winsor 1991, pp. 150–1. See also letter from Louis Agassiz, 6 July 1869.
On the health problems of James Dwight Dana, see ANB.
The reference is to the translation of F. Müller 1864a (Dallas trans. 1869).
See letter from John Murray, 17 November 1869. Murray was the publisher of Dallas trans. 1869.
Adolf Bernhard Meyer had sent CD his German translation (Wallace 1869c) of Alfred Russel Wallace’s The Malay Archipelago: the land of the orang-utan, and the bird of paradise (Wallace 1869a). See letter from A. B. Meyer, 16 November 1869.
The enclosure, written in Emma Darwin’s hand, is a copy of notes written by CD that are now in DAR 76: B31–2.
Müller had sent CD seeds of Eschscholzia californica (the California poppy) earlier in the year, and CD had reported on their growth; see letter from Fritz Müller, 12 January 1869, and letter to Fritz Müller, 18 July [1869] and n. 6. CD included the information in Cross and self fertilisation, pp. 111–12.
For CD’s published discussion on the self-sterility of Eschscholzia californica in Brazil, and the effect of changed conditions on the plant’s reproductive system, see Cross and self fertilisation, pp. 343, 358, 444, and 449.

Letter details

Letter no.
Darwin, C. R.
Müller, J. F. T.
Sent from
Source of text
British Library (Loan 10: 31) (by kind permission of English Heritage)
Physical description
4pp, 4pp


Role of humming-birds in plant fertilisation.

Alexander Agassiz has visited Down.

Sales of Facts and arguments for Darwin.

Encloses copy of T. H. Farrer letter [7015] and observations on the self-sterility of Eschscholzia.

Please cite as

Darwin Correspondence Project, “Letter no. 7018,” accessed on 14 February 2016,