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Darwin Correspondence Project

To Christian Gottfried Ehrenberg   22 July [1866?]1

Down. | Bromley. | Kent. S.E.

July 22

Dear & honoured Sir

I beg leave to return you my sincere thanks for your two papers on the Tuff of Mexico & on the “Organisations-Präparate”, with its beautiful illustrations, shewing for what a wonderful length of time your method has preserved the specimens.2

I feel sincerely honoured by your kind remembrance of me & for the valuable assistance which many years ago you were so good as to afford me3

With the most sincere respect | I remain dear Sir | yours truly obliged | Ch. Darwin


The year is conjectured from the reference to Ehrenberg 1866 (see n. 2, below).
CD refers to ‘Über einen Phytolitharien-Tuff als Gebirgsart im Toluca-Thale von Mexico’ (‘On a phytolith-tuff as a kind of rock in the Toluca valley of Mexico’; Ehrenberg 1866), and ‘Über seit 27-Jahren noch wohl erhaltenen Organisations-Präparate des mikroskopischen Lebens’ (‘On a well-preserved 27-year-old specimen of microscopic life’; Ehrenberg 1862).
CD had corresponded with Ehrenberg between 1844 and 1846 (see Correspondence vol. 3). CD sent him material collected in South America and in the Subantarctic that he thought was likely to contain infusoria. Ehrenberg’s analysis and identifications helped CD to establish that dust falling on ships in the Atlantic Ocean had come from Africa (see ‘An account of the fine dust which often falls on vessels in the Atlantic Ocean’, Quarterly Journal of the Geological Society of London 2 (1846): pt 1, 26–30; Collected papers 1: 199–203), and that the pampas formations of Argentina had been deposited under brackish or estuarine conditions, rather than in cataclysmic deluges (see South America, p. 117).


Thanks CGE for two papers and for his assistance of many years ago.

Letter details

Letter no.
Charles Robert Darwin
Christian Gottfried Ehrenberg
Sent from
Source of text
Archiv der Berlin-Brandenburgischen Akademie der Wissenschaften, Nachlass C. G. Ehrenberg, Nr. 321
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5163,” accessed on 26 June 2017,

Also published in The Correspondence of Charles Darwin, vol. 14