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Darwin Correspondence Project

To Friedrich Hildebrand   9 February 1872

Down, | Beckenham, Kent.

Feb 9. 72

My dear Sir

Owing to other occupations I was able to read only yesterday yr paper on the Dispersal of the seeds of Compositæ. Some of the facts which you mention are extremely interesting.1

I write now to suggest, as worthy of yr examination, the curious adhesive filaments of mucus emitted by the Achenia of many Compositae, of which no doubt you are aware. My attention was first called to the subject by the Achenia of an Australian Pumilio, (P. argyrolepis) which I briefly described in the Gardener’s Chronicle 1861. p. 5.2

As the threads of mucus dry & contract they draw the seeds up into a vertical position on the ground. It subsequently occurred to me that if these seeds were to fall on the wet hairs of any quadruped they wd adhere firmly & might be carried to any distance. I was informed that Decaisne has written a paper on these adhesive threads.3 What is the meaning of the mucus so copiously emitted from the moistened seeds of Iberis & of, at least, some species of Linum?4 Does the mucus serve as a protection against their being devoured, or as a means of attachment?5

I have been prevented reading yr paper sooner by attempting to read Dr Askenasy’s pamphlet;6 but the German is too difficult for me to make it all out.

He seems to follow Nägeli completely.7 I cannot but think that both much under-rate the utility of various parts of plants; and that they greatly under-rate the unknown laws of correlated growth, which leads to all sorts of modifications, when some one structure, or the whole plant, is modified for some particular object.

With sincere esteem believe me | my dear Sir | yours very faithfully | Charles Darwin


See letter from Friedrich Hildebrand, 5 February 1872 and n. 4. The reference is to Hildebrand 1872a.
See Correspondence vol. 9, letter to Gardeners’ Chronicle, [before 5 January 1861]. Pumilio argyrolepis is a misspelling of Pumilo argyrolepis.
Joseph Decaisne, in a paper on the structure of the hairs covering the pericarp of some composites, noted that when exposed to water the hairs became sticky (Decaisne 1839, p. 252).
Iberis is the genus of candytufts; Linum is the genus of flax.
In ML 2: 387 n. 2, Francis Darwin noted some theories on the function of the mucus, namely that by anchoring the seed the entrance of the radicle into the soil was facilitated, or that the mucus acted as a temporary water-store.
CD’s annotated copy of Eugen Askenasy’s essay on criticisms of Darwinian theory (Askenasy 1872) is in the Darwin Library–CUL.
Carl Wilhelm Nägeli, in his essay on the origin and concept of the natural historical species (Nägeli 1865), claimed that ‘higher’ species evolved through the operation of a ‘perfectibility principle’ (‘Vervollkommnungsprincip’): a tendency within each organism to develop more complicated structures. CD had responded to Nägeli’s critique in Origin 5th ed., p. 151 (see also Correspondence vol. 14,letter to C. W. von Nägeli, 12 June [1866], and letter to J. V. Carus, 21 November 1866). Askenasy supported Nägeli’s view and countered CD’s response in Askenasy 1872, pp. 9–27.


Askenasy, Eugen. 1872. Beiträge zur Kritik der Darwin’schen Lehre. Leipzig: Wilhelm Engelmann.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Decaisne, Joseph. 1839. Sur la structure des poils qui couvrent le péricarpe de certaines Composées. Annales des sciences naturelles (botanique) 2d ser. 12: 251–4.

ML: More letters of Charles Darwin: a record of his work in a series of hitherto unpublished letters. Edited by Francis Darwin and Albert Charles Seward. 2 vols. London: John Murray. 1903.

Nägeli, Carl Wilhelm von. 1865. Entstehung und Begriff der naturhistorischen Art. 2d edition. Munich: Verlag der königl. Akademie.

Origin 5th ed.: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 5th edition, with additions and corrections. By Charles Darwin. London: John Murray. 1869.


Comments on FH’s paper ["Verbreitungsmittel der Compositenfrüchte", Bot. Ztg. 30 (1872): 1–14].

Discusses function of mucus filaments on seeds of Compositae and other plants.

Comments on Eugen Askenasy’s publication [Beiträge zur Kritik der Darwin’schen Lehre (1872)].

Comments on evolutionary views of Carl Nägeli.

Please cite as

Darwin Correspondence Project, “Letter no. 8206,” accessed on 26 February 2020,

Also published in The Correspondence of Charles Darwin, vol. 20