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Darwin Correspondence Project

To Hermann Müller   1 January [1878]1


Jan. 1.

My dear Sir

I must write two or three lines to thank you cordially for your very handsome and very interesting Review of my last book in Kosmos, which I have this minute finished.2 It is wonderful how you have picked out everything important in it. I am especially glad that you have called attention to the parallelism between illegitimate offspring of heterostyled plants and hybrids. Your previous article in Kosmos seemed to me very important, but for some unknown reason the German was very difficult, and I was sadly over-worked at the time, so that I could not understand a good deal of it.3 But I have put it on one side and when I have to prepare a new Edit. of my book, I must make it out.—4 It seems that you attribute such cases as that of diœcious Rhamnus and your own of Valeriana to the existence of two forms with larger and smaller flowers.5 I cannot follow the steps by which such plants have been rendered diœcious, but when I read your article with more care I hope I shall understand. If you have succeeded in explaining this class of cases I shall heartily rejoice, for they utterly perplexed me and I could not conjecture what their meaning was. It is a grievous evil to have no faculty for new languages.

With the most sincere respect and hearty good wishes to you and all your family for the new year, believe me, | Yours very sincerely | Ch. Darwin

What interesting papers your wonderful brother6 has lately been writing.


The year is established by the reference to Müller’s review of Forms of flowers (see n. 2, below).
Müller reviewed Forms of flowers in the December 1877 issue of Kosmos (H. Müller 1877b). CD’s annotated copy is in the unbound journal collection in the Darwin Archive–CUL.
CD’s annotated copy of Müller’s article ‘Das Variiren der Größe gefärbter Blüthenhüllen und seine Wirkung auf die Naturzüchtung der Blumen’ (Variation in the size of coloured perianths and its effect on the natural selection of flowers; H. Müller 1877a) is in the unbound journal collection in the Darwin Archive–CUL.
CD cited H. Müller 1877a in Forms of flowers 2d ed., p. viii.
In an annotation to H. Müller 1877b, p. 290, CD wrote, ‘He accounts for one class of Dioicious plants by the flowers being of different sizes—see his former paper in Kosmos.’ In Forms of flowers 2d ed., p. viii, CD wrote that in H. Müller 1877a, p. 130, Müller showed that Valeriana dioica existed under four forms closely allied to the four presented by Rhamnus. (Valeriana dioica is marsh valerian; Rhamnus is the genus of buckthorns.) In H. Müller 1877a, pp. 131–2, Müller argued that homogamous flowers with large, colourful corollas became insect-pollinated while small inconspicuous ones became self-fertilised when insects did not visit the former first. However, if the large, colourful flowers were visited first, they eventually became staminate while the small ones become pistillate. In Valeriana dioica, he argued, the process was not complete so four forms were present. H. Müller 1877a discussed the development of insect-aided pollination from pollination by wind, and only secondarily mentioned the origins of gynodioecism. Müller also discussed the origins of gynodioecism in H. Müller 1873.
CD particularly admired Fritz Müller’s recent paper on butterflies (F. Müller 1877a). See also letter to Raphael Meldola, 1 January [1878].


Forms of flowers 2d ed.: The different forms of flowers on plants of the same species. 2d edition. By Charles Darwin. London: John Murray. 1880.

Forms of flowers: The different forms of flowers on plants of the same species. By Charles Darwin. London: John Murray. 1877.

Müller, Hermann. 1873. Die Befruchtung der Blumen durch Insekten und die gegenseitigen Anpassungen beider. Ein Beitrag zur Erkenntniss des ursächlichen Zusammenhanges in der organischen Natur. Leipzig: Wilhelm Engelmann.


Thanks HM for his review [of Forms of flowers, Kosmos 2 (1877–8): 286].

Thinks HM’s previous article was very important [Kosmos 2 (1877–8): 128–40]. CD will "heartily rejoice" if HM has explained the steps by which Rhamnus and Valeriana have been rendered dioecious.

Letter details

Letter no.
Charles Robert Darwin
Heinrich Ludwig Hermann (Hermann) Müller
Sent from
Source of text
DAR 146: 438
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 11307,” accessed on 29 July 2021,