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Darwin Correspondence Project

From J. S. Burdon Sanderson   28 July [1873]1

49, Queen Anne Street. | W.

July 28

My dear Sir

I write a single line to acknowledge the receipt of your kind letter.2 I will not attempt to answer it by this post for it so happens that my time has been so occupied since I received it that I could do so properly.

I may however just mention that Dr Osler has made some comparative observations on the behaviour of colourless blood corpuscles in solutions of sodium and potassium salts of the same strength. He finds that in the latter the amœboid movements continue nearly as long as in the former.3

I am, my dear Sir | very faithfully yours | J S B Sanderson

CD annotations

1.1 I write … properly. 1.3] crossed pencil
Top of letter: ‘on Effects of Sodium & Potassium on Blood corpuscles’ pencil


The year is established by the relationship between this letter and the letter to J. S. Burdon Sanderson, 25 July 1873.
William Osler was a postgraduate student in Burdon Sanderson’s laboratory at University College, London; his experiments ultimately led to the description of platelet cells in human blood (Cooper 2005). For details of Osler’s experiments, see Osler and Schäfer 1873 and Osler 1874.


Cooper, Barry. 2005. Osler’s role in defining the third corpuscle, or ‘blood plates’. Proceedings of the Baylor University Medical Center 18: 376–8.

Osler, William. 1874. An account of certain organisms occurring in the liquor sanguinis. [Read 18 June 1874.] Proceedings of the Royal Society. 22: 391–8.


A hasty answer to CD’s letter [8987] of 25 July. Mentions Dr Osler’s observations on behaviour of colourless blood corpuscles in solutions of sodium and potassium salts of same strength.

Letter details

Letter no.
John Scott Burdon Sanderson, baronet
Charles Robert Darwin
Sent from
London, Queen Anne St, 49
Source of text
DAR 58.1: 28–9
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 8988,” accessed on 28 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 21