skip to content

Darwin Correspondence Project

From Joseph Fayrer   25 June 1874

16 Granville Place

25 June 1874

Dear Sir

Many thanks for your letter and the information it contains.1

I would venture to suggest that the virus2 was over diluted: Will you repeat the Expert. with a stronger solution, say gr 14 to [DRACHM]ss. (half a drachm of water) I return the little packet and if you require it can send you a little more;3 I need hardly say that I feel honored in furthering any scientific investigation that may interest you—.

The Question of its (cobra poison) action on ciliæ & on musculature, on topics generally apart from the nervous element shall be again investigated & the result communicated to you.—

I beg to send a copy of some investigations by Dr. Brunton & myself, since I returned to England—on the subject of Cobra poison.4 We are now engaged in an enquiry into the nature of the action of Crotalus poison.5

Have you seen my Indian book on venomous snakes?6 if not I should like to send you my copy.

Believe me | Yours very truly | J Fayrer

CD annotations

Margin of first page: ‘1 gr to 2 oz or 4 gr to 1 oz’ blue crayon


Fayrer uses ‘virus’ in the sense of venom or poison.
CD had used a quarter grain of poison diluted in two drams of water (see letter to Joseph Fayrer, [before 25 June 1874]).
CD’s lightly annotated copy of Fayrer and Thomas Lauder Brunton’s paper ‘On the nature and physiological action of the poison of Naja tripudians and other Indian venomous snakes’ (Brunton and Fayrer 1873–4) is in the Darwin Pamphlet Collection–CUL.
Fayrer and Brunton published the results of this research in 1875 (Brunton and Fayrer 1875). Crotalus is the genus of rattlesnakes.


Fayrer, Joseph. 1872. The Thanatophidia of India: being a description of the venomous snakes of the Indian Peninsula, with an account of the influence of their poison on life and a series of experiments. London: J. and A. Churchill.

Fayrer, Joseph. 1875. The royal tiger of Bengal, his life and death. London: J. & A. Churchill.


Action of cobra poison.

Letter details

Letter no.
Joseph Fayrer, 1st baronet
Charles Robert Darwin
Sent from
London, Granville Place, 16
Source of text
DAR 164: 109
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 9514,” accessed on 24 September 2020,

Also published in The Correspondence of Charles Darwin, vol. 22