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Darwin Correspondence Project

From Fritz Müller   9 January 1881

Blumenau, St Catharina, Brazil

January 9. 1881.

My dear Sir

I do not know how to express you my deep heartfelt gratitude for the generous offer, which you made to my brother on hearing of the late dreadful flood of the Itajahy. From you, dear Sir, I should have accepted assistance without hesitation, if I had been in need of it; but fortunately, though we had to leave our house for more than a week and on returning found it badly damaged, my losses have not been very great.—1

I must thank you also for your wonderful book on the movements of plants, which arrived here on new year’s day.2 I think, nobody else will have been delighted more, than I did, with the results, which you have arrived at by so many admirably conducted experiments and observations; since I observed the spontaneous revolving movement of Alisma, I had seen similar movements in so many and so different plants, that I felt much inclined to consider spontaneous revolving movement or circumnutation as common to all plants and the movements of climbing plants as a special modification of that general phenomenon.3 And this you have now convincingly, nay, superabundantly, proved to be the case.

I was much struck with the fact, that with you Maranta did not sleep for two nights after having its leaves violently shaken by wind; for here we have very cold nights only after storms from the west or southwest and it would be very strange, if the leaves of our numerous species of Marantaceae would be prevented, by these storms, to assume their usual nocturnal position, just when nocturnal radiation was most to be feared.4 It is rather strange also that Phaseolus vulgaris should not sleep during the early part of the summer, when the leaves are most likely to be injured during cold nights.—5 On the contrary it would not do any harm to many subtropical plants, that their leaves must be well illuminated during the day in order that they may assume at night a vertical position; for, in our climate at least, cold nights are always preceded by sunny days.

Of nearly allied plants sleeping very differently I can give you some more instances. In the genus Olyra (at least in the one species observed by me) the leaves bend down vertically at night; now in Endlicher’s Genera plantarum this genus immediately precedes Strephium, the leaves of which you saw rising vertically.6

In one of two species of Phyllanthus growing as weeds near my house, the leaves of the erect branches bend upwards at night, while in the second species, with horizontal branches, they sleep like those of Phyllanthus Niruri or of Cassia.7 In this second species the tips of the branches also are curled downwards at night, by which movement the youngest leaves are yet better protected. From their vertical nyctitropic position the leaves of this Phyllanthus might return to horizontality, traversing 90o, in two ways, either to their own or to the opposite side of the branch; on the latter way no rotation would be required, while on the former each leaf must rotate on its own axis in order that its upper surface may be turned upwards. Thus the way to the wrong side appears to be even less troublesome. And indeed in some rare cases I have seen three, four or even almost all the leaves of one side of a branch horizontally expanded on the opposite side, with their upper surfaces closely appressed to the lower surfaces of the leaves of that side.


This Phyllanthus agrees with Cassia not only in its manner of sleeping, but also by its leaves being paraheliotropic.8 Like those of some Cassiæ its leaves take on almost perfectly vertical position, when at noon, on a summer day, the sun is nearly in the zenith; but I doubt, whether this paraheliotropism will be observable in England. To day, though continuing to be fully exposed to the sun, at 3 P.M. the leaves had already returned to a nearly horizontal position. As soon as there are ripe seeds, I will send you some; of our other species of Phyllanthus, I enclose a few seeds in this letter.9

In several species of Hedychium the lateral hal⁠⟨⁠ves⁠⟩⁠ of the leaves, when exposed to bright sunshine, bend downwards so that the lateral margins meet. It is curious, that a hybrid Hedychium in my garden shows scarcely any trace of this paraheliotropism, while both the parent species are very paraheliotropic.10

Might not the irregularity of the cotyledons of Citrus and of Pachira be attributed to the pression, which the several embryons enclosed in the same seed exert upon each other? I do not know Pachira aquatica, but in a species, of which I have a tree in my garden, all the seeds are polyembryonic, and so were also almost all the seeds of Citrus, which I examined. With Coffea arabica also seeds including two embryons, are not very rare; but I have not yet observed, whether in this case the cotyledons be inequal.11

I repeated to day Duval-Jouve’s measurements on Bryophyllum calycinum; but mine did not agree with his; they are as follows.12

Distance between the tips of the upper pairs of leaves.

Jauary 9. 1881. 8 A.M. 1 P.M. 6 P.M.

First plant: 54 mm. 43 mm. 36 mm.

2d – : 28 – 25 – 23.–

3d – : 28.– 27.– 27.–

4th – : 51.– 46.– 39.–

5th – : 61.– 52.– 45.–

222 193 170

Recently my attention has been called by Dr Paul Mayer to an extremely interesting subject, viz. the fertilisation of figs by various hymenoptera. Dr Paul Mayer is now investigating with Prof. Solms-Laubach the “caprifrication” of figs and they have found a great many quite novel and unexpected facts, which will probably be published in the course of this year.13 Dr Mayer bade me to examine for him our wild figs and I have been able to confirm most of the observations, made in Italy.14 Our figs appear to possess even a richer fauna of peculiar hymenopterous insects; you may meet with five or six different species in the figs of a single tree. I must of course refrain from communicating to you P. Mayer’s interesting discoveries; but I may at least give you a rough sketch of some of the odd fellows to be found in our Figs.


From what I know of it, I think, Dr Mayer’s paper will be one of the most interesting contributions to entomology ever published, and Prof. Solms-Laubach’s botanical researches on the figs will probably be equally important.15

Repeating my cordial thanks and wishing that the new year may be a very happy one for you and your family I am, dear Sir, with the highest respect | Yours very faithfully | Fritz Müller.



CD had heard about the flood that occurred near Müller’s home in September 1880 from Ernst Krause and immediately wrote to Müller’s brother Hermann Müller to offer financial assistance in replacing any scientific equipment that might have been lost (see Correspondence vol. 28, letter from Ernst Krause, 26 November 1880, and letter to Hermann Müller, 27 November 1880). The Itajahy river is now called Itajaí Açu.
Müller’s name is on CD’s presentation list for Movement in plants (see Correspondence vol. 28, Appendix IV).
Müller had written to CD in a now missing letter of 1868, describing the movements of the pedicel in Alisma macrophyllum (a synonym of Echinodorus macrophyllus); he later published a paper on these movements (F. Müller 1870; see also Correspondence vol. 16, letter to Fritz Müller, 3 April [1868]). In 1865, Müller had described the revolving motion of the stem of Linum usitatissimum (common flax; see Correspondence vol. 13, letter from Fritz Müller, 10 October 1865); CD cited Müller on this in Movement in plants, p. 203.
CD described the cessation of sleep in Maranta arundinacea (arrowroot) in Movement in plants, p. 319. CD had noted that sleep protected the upper surfaces of leaves from being chilled through radiation (ibid., pp. 3, 284).
See Movement in plants, p. 318; Phaseolus vulgaris is the common bean.
Olyra and Strephium are genera of bamboo; Stephan Ladislaus Endlicher had placed them next to each other in Endlicher 1836–42, 1: 82–3.
Phyllanthus niruri is gale of the wind; Cassia is a genus of the legume family (Fabaceae). CD described nyctitropic (sleep) movement in several species of Cassia in Movement in plants, pp. 369–73; he mentioned Wilhelm Pfeffer’s description of movements in P. niruri in ibid., pp. 388–9. Several species of Phyllanthus are native to the area where Müller lived, Santa Catarina, Brazil.
CD had coined the term ‘paraheliotropic’ to describe the movement of leaves during the day to reduce intense illumination (Movement in plants, p. 419).
Müller taped a branch of Phyllanthus with seed pods to the last page of the letter.
Hedychium is the genus of ginger lilies; most species are native to central and south-east Asia, but are invasive in Brazil and many other places with suitable conditions. Natural hybridisation among species is common.
In Movement in plants, p. 95 n., CD mentioned the disparity in size of the cotyledons of Pachira aquatica (Guiana-chestnut or provision tree; see also Correspondence vol. 26, letter to W. T. Thiselton-Dyer, 14 May 1878 and n. 5). Eduard Strasburger had described polyembryony in citrus species in Strasburger 1878b, pp. 654–9. Strasburger noted that the nucellar embryos (those that developed from the nucellus, or layer of cells in the ovule in which the embryo sac develops) were more vigorous than the fertilised one and germinated earlier.
In Movement in plants, p. 237, CD included Joseph Duval-Jouve’s measurements of the distance between the tips of the upper pair of leaves of Bryophyllum calycinum (a synonym of Kalanchoe pinnata, cathedral bells) at different times of day (Duval-Jouve 1868).
Caprification is the process of hanging clusters of wild fig (caprifig) flowers in edible fig trees in order to facilitate the transfer of pollen by fig wasps. Hermann Graf zu Solms-Laubach published his research in ‘Die Herkunft, Domestication und Verbreitung des gewöhnlichen Feigenbaums (Ficus Carica L.)’ (The origin, domestication and propagation of the common fig tree (Ficus carica L.); Solms-Laubach 1881).
Mayer had asked Müller to provide him with Brazilian figs for his research and to observe the local specimens. In his reply of 26 October 1880, Müller pointed out the difficulty in getting flowers because of the inaccessibility of the treetops, but promised to send specimens when he could (see Möller ed. 1915–21, 2: 400–1). Müller later sent Mayer numerous specimens of several local species (see Mayer 1882, pp. 572–6).
Mayer’s paper ‘Zur Naturgeschichte der Feigeninsecten’ (On the natural history of fig insects; Mayer 1882) appeared in September 1882. Müller summarised Mayer 1882 in a review in Kosmos, January 1883 (F. Müller 1883).


Duval-Jouve, Joseph. 1868. Note sur les mouvements des feuilles du Bryophyllum calycinum Salisb. [Read 14 February 1868.] Bulletin de la Société botanique de France 15: 11–13.

Endlicher, Stephan Ladislaus. 1836–42. Genera plantarum secundum ordines naturales disposita. With 4 supplements; in 2 vols. Vienna: Friedrich Beck.

Mayer, Paul. 1882a. Zur Naturgeschichte der Feigeninsecten. Mittheilungen aus der Zoologischen Station zu Neapel 3 (1881–2): 551–90.

Möller, Alfred, ed. 1915–21. Fritz Müller. Werke, Briefe und Leben. 3 vols in 5. Jena: Gustav Fischer.

Movement in plants: The power of movement in plants. By Charles Darwin. Assisted by Francis Darwin. London: John Murray. 1880.

Müller, Fritz. 1870a. Die Bewegung des Blüthenstieles von Alisma. Jenaische Zeitschrift für Medizin und Naturwissenschaft 5: 133–7.

Müller, Fritz. 1883c. Dr. Paul Mayer, zur Naturgeschichte der Feigeninsecten. [Review of Mayer 1882.] Kosmos 12 (1882–3): 310–14.

Solms-Laubach, Hermann. 1881a. Die Herkunft, Domestication und Verbreitung des gewöhnlichen Feigenbaums (Ficus Carica L.). [Read 3 December 1881.] Abhandlungen der Königlichen Gesellschaft der Wissenschaften zu Göttingen 27: 1–106.

Strasburger, Eduard. 1878b. Ueber Polyembryonie. Jenaische Zeitschrift für Naturwissenschaft 12: 647–70.


Thanks for CD’s offer of assistance after flood damage.

Comments on Movement in plants. Discusses sleep movements and paraheliotropism of Maranta and other plants.

Describes the fertilisation of figs by Hymenoptera.

Letter details

Letter no.
Johann Friedrich Theodor (Fritz) Müller
Charles Robert Darwin
Sent from
Santa Catharina, Brazil
Source of text
DAR 99: 217–20
Physical description
ALS 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 12996,” accessed on 15 April 2024,