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Darwin Correspondence Project

To Daniel Oliver   15 November 1871

Down, | Beckenham, Kent.

Nov 15 1871

Dear Professor Oliver

Will you have the kindness to give me a small piece of information. Is it now believed that the spungeoles at the extremity of the rootlets secrete carbonic acid or any other element in a nascent state, which acts on bones & rocks so as to obtain the necessary phosphates & alkalis?1

I remember years ago having seen a statement to this effect, & I am anxious to know whether it is now thought true.2

Pray excuse my troubling you & believe me | yours sincerely | Ch. Darwin


CD’s query related to his study of earthworms, and the power of the digestive acids of worms to dissolve rocks and eventually cause the denudation of land (see Earthworms, pp. 240–6). A ‘spongiole’ is the ‘tender extremity of the radicle [root] of a plant, characterized by loose sponge-like cellular tissue’ (OED).
CD later referred to Julius Sachs on the secretion of carbonic acid by plant rootlets (see Earthworms, p. 243).


Earthworms: The formation of vegetable mould through the action of worms: with observations on their habits. By Charles Darwin. London: John Murray. 1881.

OED: The Oxford English dictionary. Being a corrected re-issue with an introduction, supplement and bibliography of a new English dictionary. Edited by James A. H. Murray, et al. 12 vols. and supplement. Oxford: Clarendon Press. 1970. A supplement to the Oxford English dictionary. 4 vols. Edited by R. W. Burchfield. Oxford: Clarendon Press. 1972–86. The Oxford English dictionary. 2d edition. 20 vols. Prepared by J. A. Simpson and E. S. C. Weiner. Oxford: Clarendon Press. 1989. Oxford English dictionary additional series. 3 vols. Edited by John Simpson et al. Oxford: Clarendon Press. 1993–7.


Is it now thought that the spongioles of rootlets secrete carbonic acid which acts on bones and rocks?

Letter details

Letter no.
Charles Robert Darwin
Daniel Oliver
Sent from
Source of text
DAR 261.10: 64 (EH 88206047)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8068,” accessed on 22 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 19