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Darwin Correspondence Project

From John Goodsir   28 August [1863]1

South Cottage— Wardie. [Edinburgh]

Augt. 28.

My dear Sir,

I enclose a slip of Litmus paper, from which you will observe that the fluid contained in the phial you have sent to me, is acid—2

A great part of the tenacious mass contained in the phial consists of bundles of that filamentous structure, to which I alluded in my account of your slide; but which I could 〈not〉 define or account 〈for the〉 putrifactive chang〈es that〉 had taken place. These bundles of minute filaments, appear to me to be referable to some form of Leptothrix; probably L buccalis, which is an Alga found on the mucous membrane of the Tongue and mouth, but accumulating occasionally in the stomach and bowels.3

I see these bundles of filaments on my slides 〈along〉 with numerous epi〈theliu〉m scales from the 〈mouth〉— These scales are seen enve〈loped by〉 molecular ma〈tter and〉 debris from w〈hich〉 bundles of filaments 〈    〉cied

I enclose a rough sketch of a bundle attached to molecular matter investing an epithelium scale; a〈nd〉 of a group of Torula cell〈s,〉 two buccal or saliva cells, and the minute cells, probably the spores of Leptothrix.4

As I have already stated—medical opinion 〈2 words〉 to any 〈2 words〉 as to the 〈    〉 of decreasing those parasites—5

Believe me— | my dear Sir— | sincerely yours | John Goodsir.

Charles Darwin Esq.


The year is established by the relationship between this letter and the letter from John Goodsir, 21 August [1863].
See letters from John Goodsir, 21 August [1863] and 27 August [1863]. CD had consulted Goodsir for a diagnosis of the cause of his persistent vomiting. No letter to Goodsir accompanying the phial of vomit has been found.
Leptothrix buccalis (now named Leptotrichia buccalis) is a bacterium (Bergey’s manual of systematic bacteriology).
These sketches have not been found.
Probably a reference to Goodsir’s letter to CD of 21 August [1863], paragraph 6.


Bergey’s manual of systematic bacteriology: Bergey’s manual of systematic bacteriology. Edited by Noel R. Krieg et al. 4 vols. Baltimore, Md., and London: Williams & Wilkins. 1984–9.


The phial of fluid sent by CD is acid. Sends his microscopical examination.

Letter details

Letter no.
John Goodsir
Charles Robert Darwin
Sent from
Source of text
DAR 165: 75
Physical description
4pp damaged

Please cite as

Darwin Correspondence Project, “Letter no. 4281,” accessed on 21 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 11