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Darwin Correspondence Project

From Richard Spruce   [before 1 April 1869]1

Welburn | Castle-Howard | York.

8 lines missing〉 plain of 〈    〉— I never again saw a plant of that fam〈ily〉 〈Had〉 I been able to travel I should have gone again in quest of them, not only to try to obtain the information you wanted, but to follow up some observations of my own touching the origin of curious bags on the leaves of some of the species inhabited by ants.2

A few years ago I drew up a memoir on certain modifications of the organs of plants which I consider entirely the work of insects, altho’ some of them take rank as specific and even generic characters. I have kept the Mst. by me hoping at least to go again to Kew and reexamine my specimens of those curious structures, but as the state of my health renders that an impossibility I have written out the memoir afresh, and send it to you by this day’s post, requesting to be kind enough to look through it carefully and then hand it over to the Linnean Society to be read at one of their meetings.3 I shall be thankful for a line to say how far you consider my inferences justified by the facts.

8 lines excised

It is a great defect of my relation that it contains no definite account of the ants infesting the plants, & I have no materials for supplying it. I have somewhere a small packet of ants that dropped out of my specimens of Amaioua saccifera,4 but I cannot just now lay my hand on it.

I have often wished to write to thank you for your admirable writings on philosophic biology, most of which I have read since I returned home invalided 4 years ago. The ‘Origin of Species’, especially, filled up a void of which I had long been sensible in my own speculations. When a very young botanist I came to some of the same conclusions as yourself, but very empirically, & not by any process of laborious and accurate observation such as you have gone through. When I read Linnæus’s definition of a species in the ‘Philosophia Botanica’, based on the supposed fact that no hybrid between true species could be fertile,5 I said to myself “We ought surely to experiment unceasingly on the interbreeding of so-called species, for we may go on describing animals & plants to the end of all time and we shall never attain to the correct delimitation of a single species”. Afterwards, when I tried to deduce some “law of species” from the writings of eminent botanists, I could find only this, running through the descriptions of every author: “My species are good species—those of other authors probably not”—the same as in any other orthodoxy & heterodoxy. I could then only resolve to examine everything for myself—to take names and descriptions as (at best) attempts to fix transitory aspects of things—and to try to trace what variation of form & structure was tending to. Your book makes it most clear that variation in plants and animals is not oscillation round fixed centres but progress in directions determined by surrounding influences.

But I am taking up too much of your precious time, so, wishing you still a long lease of life and energy to continue your most valuable labours, I subscribe myself | Yours very faithfully | Rich. Spruce.

Charles Darwin Esq.


The date is established by the relationship between this letter and the letter to Richard Spruce, 1 April 1869.
Spruce probably refers to the former family Melastomeae in the order Melastomaceae (now the family Melastomataceae in the order Myrtales). CD had sent Spruce queries about Melastomataceae at the end of 1863, when Spruce was ill and coming to the end of his stay in South America (see Correspondence vol. 12, letter from A. R. Wallace, 2 January 1864 and nn. 12 and 13); CD’s letter to Spruce has not been found. CD was interested in a possible new form of dimorphism in the Melastomaceae (see Correspondence vol. 10, letter to Asa Gray, 22 January [1862] and n. 13).
Spruce’s paper was read at the Linnean Society on 15 April 1869, but was not published in the society’s proceedings. The paper is printed in full in Spruce 1908, 2: 384–412, together with an account by Alfred Russel Wallace of events associated with its reading. Spruce also refers to the Royal Botanic Gardens, Kew.
Amaioua saccifera is a synonym of Duroia saccifera, a member of the family Rubiaceae. It has ‘ant-houses’ on its leaves (Willis 1973). A specimen of the wood of A. saccifera is in the Richard Spruce Collection, Royal Botanic Gardens, Kew.
Spruce refers to Carl von Linné and Linnaeus 1751: see especially sections 132 and 259. CD wrote on hybrid fertility in Origin, pp. 246–50; see Origin 4th ed., pp. 310–26, and Correspondence vol. 10, Appendix VI.


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

Linnaeus, Carolus (Carl von Linné). 1751. Philosophia botanica in qua explicantur fundamenta botanica cum definitionibus partium, exemplis terminorum, observationibus rariorum, adjectis figuris æneis. Stockholm: Godofr. Kiesewetter.

Origin 4th ed.: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 4th edition, with additions and corrections. By Charles Darwin. London: John Murray. 1866.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.

Spruce, Richard. 1908. Notes of a botanist on the Amazon & Andes, being records of travel … during the years 1849–1864. Edited by Alfred Russel Wallace. 2 vols. London: Macmillan and Co.

Willis, John Christopher. 1973. A dictionary of the flowering plants and ferns. 8th edition. Revised by H. K. Airy Shaw. Cambridge: Cambridge University Press.


Sends CD a paper ["Ant-agency in plant structure", published in Spruce Notes of a botanist on the Amazon and Andes, ed. A. R. Wallace (1908)] on plant structures he believes are the work of insects; asks him to forward it to the Linnean Society [read 15 Apr 1869].

Writes of his support for the Origin, before which he had been much concerned by the delimitation of so-called species.

Letter details

Letter no.
Richard Spruce
Charles Robert Darwin
Sent from
Welburn, Castle Howard
Source of text
DAR 177: 241
Physical description
3pp inc

Please cite as

Darwin Correspondence Project, “Letter no. 6690,” accessed on 18 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 17