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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).


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

Letter details

Letter no.
Darwin, C. R.
Oliver, Daniel
Sent from
Source of text
DAR 261.10: 64
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8068,” accessed on 25 October 2016,