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Darwin Correspondence Project

To Nature   21 November [1877]1

The enclosed letter from that excellent observer, Fritz Müller, contains some miscellaneous observations on certain plants and insects of South Brazil, which are so new and curious that they will probably interest your naturalist readers.2 With respect to his case of bees getting their abdomen dusted with pollen while gnawing the glands on the calyx of one of the Malpighiaceæ, and thus effecting the cross-fertilisation of the flowers, I will remark that this case is closely analogous to that of Coronilla recorded by Mr. Farrer in your journal some years ago, in which parts of the flowers have been greatly modified, so that bees may act as fertilisers while sucking the secretion on the outside of the calyx.3 The case is interesting in another way. My son Francis has shown that the food-bodies of the Bull’s-horn Acacia, which are consumed by the ants that protect the tree from its enemies (as described by Mr. Belt), consist of modified glands; and he suggests that aboriginally the ants licked a secretion from the glands, but that at a subsequent period the glands were rendered more nutritious and attractive by the retention of the secretion and other changes, and that they were then devoured by the ants.4 But my son could advance no case of glands being thus gnawed or devoured by insects, and here we have an example.

With respect to Solanum palinacanthum, which bears two kinds of flowers on the same plant, one with a long style and large stigma, the other with a short style and small stigma, I think more evidence is requisite before this species can be considered as truly heterostyled, for I find that the pollen-grains from the two forms do not differ in diameter.5 Theoretically it would be a great anomaly if flowers on the same plant were functionally heterostyled, for this structure is evidently adapted to insure cross-fertilisation of distinct plants. Is it not more probable that the case is merely one of the same plant bearing male flowers through partial abortion, together with the original hermaphrodite flowers? Fritz Müller justly expresses surprise at Mr. Leggett’s suspicion that the difference in length of the pistil in the flowers of Pontederia cordata of the United States is due to difference of age; but since the publication of my book Mr. Leggett has fully admitted, in the Bulletin of the Torrey Botanical Club, that this species is truly heterostyled and trimorphic.6 The last point on which I wish to remark is the difference between the males and females of certain butterflies in the neuration of the wings, and in the presence of tufts of peculiarly-formed scales. An American naturalist has recently advanced this case as one that cannot possibly be accounted for by sexual selection.7 Consequently, Fritz Müller’s observations which have been published in full in a recent number of Kosmos, are to me highly interesting, and in themselves highly remarkable.8

Charles Darwin

Down, Beckenham, Kent, November 21


The year is established by the date of publication of the letter in Nature.
See letter from Fritz Müller, 19 October 1877. Thomas Henry Farrer had described the action of bees on the calyx of Coronilla varia (a synonym of Securigera varia, purple crown vetch) in an article on papilionaceous flowers published in Nature, 2 July 1874 (T. H. Farrer 1874, p. 169).
See F. Darwin 1876d, pp. 402–4. The food-bodies on Acacia sphaerocephala (a synonym of Vachellia sphaerocephala, bull’s-horn thorn) had first been described by Thomas Belt in The naturalist in Nicaragua (Belt 1874a, p. 218).
See letter from Fritz Müller, 19 October 1877 and n. 10. William Henry Leggett had confirmed tristyly in Pontederia cordata in Leggett 1877. In the preface to Forms of flowers 2d ed., p. viii, CD added a reference to Leggett 1877.
The American naturalist has not been identified.
See Fritz Müller 1877a.


Farrer, Thomas Henry. 1874. Fertilisation of papilionaceous flowers—Coronilla. Nature, 2 July 1874, pp. 169–70.

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.

Leggett, William Henry. 1877. Pontederia cordata. Bulletin of the Torrey Botanical Club 6 (1875–9): 170–1.


Sends letter from Fritz Müller [11191] containing observations on plants and insects of South Brazil, with prefatory comments.

Letter details

Letter no.
Charles Robert Darwin
Sent from
Source of text
Nature, 29 November 1877, p. 78

Please cite as

Darwin Correspondence Project, “Letter no. 11245,” accessed on 3 August 2021,