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Darwin Correspondence Project

From Hermann Müller   1 July 1873


July 1. 1873.

My dear Sir

I thank you very sincerely for your kindness in having sent me different papers which are of especial interest to me.1 I find notes which I think to be interesting to you, I will acquaint you with them. Today I found in “Botanische Zeitung 27 Juni 1873. Nr. 26” the following note:

Sitzungsberichte der Königlichen physikalischekonomischen Gesellschaft zu Koenigsberg. 1871. Caspary, über seine 3 Jahre hinter einander angestellten Untersuchungen in Betreff der Befruchtungsweise der einheimischen Arten von Corydalis. Bei Corydalis cava zeigte sich Selbstbestäubung in der Regel unwirksam (was auch Hildebrand, aber als ausschliessliche Regel angibt, während Caspary in seltenen Fällen erfolgreiche Selbstbestäubung beobachtete). Bei Corydalis Halleri war das Ergebniss der Selbstbestäubung schon weniger ungünstig, obwohl Bestäubung mit Pollen anderer Blüthen derselben Stockes und noch mehr von fremden Stöcken Bessere Resultate lieferte; Corydalis intermedia dagegen brachte ebenso reichliche Samen, wenn sie durch Glassglocken von Insecten-besuch abgesperrt wurde, als wenn sie demselben (den Caspary übrigens nie beobachtete) zugänglich blieb.”2

I have received now Kurr’s little book on the nectaria and I am very glad, that you have turned my attention to it.3

I have begun my trials with those flowers which exist in two forms, one more conspicuous and never selffertilizing itself, the other one less conspicuous and regularly selffertilising itself

Malva silvestris and rotundifolia, Viola tricolor arvensis and the large flowered form will give interesting results, but with Rhinanthus and Euphrasia, which are parasitic, I will not succeed with my trials.4

Believe me, my dear Sir | yours very faithfully | H. Müller.

CD annotations

2.6 Bei Corydalis … blieb.” 2.11] scored red crayon
Top of letter: ‘Corydalisred crayon
End of letter: ‘The only important thing here is that Corydalis [case] not always self-sterile; & another sp. in same state. & a third quite self-fertile.—’ ink; ‘(Self-sterile Plants)’5 blue crayon


The papers sent to Müller have not been identified, but H. Müller 1873 was praised in George Bentham’s anniversary address to the Linnean Society (see the letter to J. D. Hooker, 28 June 1873 and n. 6).
Müller quotes from a report by Paul Ascherson in Botanische Zeitung 31: 414. The German translates as: Meeting of the Royal Physical-Economical Society at Königsberg. 1871. Caspary, on his researches, carried out successively over 3 years, on the manner of fertilisation of native species of Corydalis. In Corydalis cava self-pollination was shown to be ineffective as a rule (which Hildebrand also stated but as an invariable rule, while Caspary in rare cases observed successful self-pollination). With Corydalis Halleri the result of self-pollination was even less favourable, although pollination with pollen of another flower of the same plant yielded better results and even more so with pollen from a different plant; Corydalis intermedia on the other hand had equally productive seed, whether insect visits were prevented by a glass bell, or permitted (which, moreover, Caspary never saw). CD summarised the observations of Robert Caspary and Friedrich Hildebrand on Corydalis in Cross and self fertilisation, p. 331.
CD had recommended Untersuchungen über die Bedeutung der Nektarien in den Blumen (Studies on the importance of nectaries in flowers) by Johann Gottlob von Kurr (Kurr 1833; see letter from Hermann Müller, 10 June 1873).
Malva sylvestris (‘silvestris’ is a misspelling) is the common mallow; M. rotundifolia is the low mallow. Viola tricolor arvensis is now V. arvensis (the field pansy); the ‘large flowered form’ is V. tricolor (heart’s-ease). Rhinanthus (rattles) and Euphrasia (eyebrights) are facultative parasites (meaning that, when they come into contact with neighbouring plants, they will derive some of their nutrition from them). Müller reported his observations on self-fertilisation on Viola tricolor in his letter of 10 June 1873.
CD discussed the self-sterility of varieties of Corydalis in Cross and self fertilisation, pp. 331 and 340–2.


Cross and self fertilisation: The effects of cross and self fertilisation in the vegetable kingdom. By Charles Darwin. London: John Murray. 1876.

Kurr, Johann Gottlob von. 1833. Untersuchungen über die Bedeutung der Nektarien in den Blumen: auf eigene Beobachtungen und Versuche gegründet. Stuttgart: Henneschen Buchhandlung.

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.


Sends a note on R. Caspary’s observations of Corydalis self-fertilisation [see Cross and self-fertilisation, p. 331].

Has begun his experiments on the self- and cross-fertilised flowers.

Letter details

Letter no.
Heinrich Ludwig Hermann (Hermann) Müller
Charles Robert Darwin
Sent from
Source of text
DAR 76: B184
Physical description
ALS 2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 8961,” accessed on 20 September 2023,

Also published in The Correspondence of Charles Darwin, vol. 21