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Darwin Correspondence Project

From David Forbes   30 January 1869

11, York Place, | Portman Square, | London. W.

30 Jany. 1869.

My dear Mr Darwin

I have to thank you for Jenzsch’s book which I had previously read (after a trial of patience) and put down as consummate rubbish.1 Ideal wanderings of the brain and as I today have received a letter from Professor Zirkel of Kiel the most eminent of the Continental petrologists and observers (of the microscope in reference to rocks)—& in which he also mentions Jenzschs book I enclose you herewith a copy of his remarks in the original—2 It certainly would be a rather severe reflection on the microscopic powers of Sorby3 Zirkel and myself who have so many years worked on the subject if such a Flora and Fauna could exist—rocks which we have examined—and I know that Zirkel has carefully examined the Metaphysics alluded to by Jensch4—who undoubtedly is mad or something like it—

I am always thinking about writing a monograph on the Aymara Indian race of Bolivia, for the Ethnological but since Xmas I have been quite out of sorts with a very severe attack of Bronchitis which has also affected my head and made me very confused—5 Might I ask you when you purpose to bring out your book on man?—6 I really must endeavour to find some leisure for getting up some data for you—but I have been so thoroughly overwhelmed with work that I have not had an instants rest to sit down and collect my notes or thoughts on the subject.7

Wishing you a very happy new year and many of them believe me | My dear Mr Darwin | Yours most sincerely | David Forbes


Extract from a letter from Professor Zirkel of Kiel to DF.

Was sagt man denn in England zu der neuen Entdeckung von Jenzsch: eine mikroscopische fossile Flora und Fauna in den gemengtheilen von Eruptivgesteinen? Alle, mit denen ich mündlich oder brieflich darüber verhandelt habe, halten die Sache für Humbug— Das ist, bis ich eines bessern belehrt werde auch meine Ansicht. Ein neues heiteres Landschaftsbild: gegend Quarz im Melaphyr9 im Vorgrunde ein idyllisch weidendes ‘Infusorium’, welches mit ausgestrecktem Rüssel gemüthlich grüne Algenzellschichten benagt, daneben ein Räderthierchen in geburtswehen begriffen, in Hintergrund einige Fluidcavities mit beweglichen Bläschen. Ein Bild, würdig der Pinsels von Sir Edwin Landseer!10 Da uns eine solche Entdeckung entschlüpfen muste! Ich habe an Jenzsch geschrieben und ihn gebeten, mir für einen Tag einige Praeparate zu schicken und mir einige Melaphyr scherben zu schenken, damit ich mich selbst Praeparate machen könne; ich erhielt zur Antwort, er brauche seine Praeparate selbst und seine Melaphyrhandstücke seien so fest verpackt, das er selbst nicht mehr dazu kommen könne. “Sapienti sat.”11

Wenn Sie diese famose Schrift die natürlich allen Ultrametamorphiken und Dilettanten fabelhaft imponieren etwa noch nicht haben, so kann ich Sie Ihnen sc〈hic〉ken, ich besitze sie dreimal.


Forbes refers to Gustav Jenzsch and Jenzsch 1868, a copy of which CD evidently sent to Forbes.
Forbes refers to Ferdinand Zirkel. See enclosure.
Henry Clifton Sorby.
Forbes may refer to Jenzsch’s explanation of how volcanic rock was capable of supporting the microscopic flora and fauna he claimed to have discovered (see Jenzsch 1868, pp. 17–21).
Forbes’s paper ‘On the Aymara Indians of Bolivia and Peru’ was published in 1870 in the Journal of the Ethnological Society of London (D. Forbes 1870).
Forbes refers to Descent.
For more on Forbes’s work on the Aymara, see Correspondence vol. 16, letter from David Forbes, 26 March 1868.
For a translation of the enclosure, see Correspondence vol. 17, Appendix I.
Melaphyre: ‘any of various dark-coloured porphyritic (esp. basaltic) rocks. Later: (specifically) an altered basalt, esp. of Carboniferous or Permian age’ (OED).
Edwin Henry Landseer.
Sapienti sat.: abbreviation of ‘Verbum sapienti satis est’, a word to the wise is sufficient. (Latin.)


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Jenzsch, Gustav. 1868. Ueber eine mikroskopische Flora und Fauna krystallinischer Massengesteine (Eruptivgesteine). Leipzig: W. Engelmann.

OED: The Oxford English dictionary. Being a corrected re-issue with an introduction, supplement and bibliography of a new English dictionary. Edited by James A. H. Murray, et al. 12 vols. and supplement. Oxford: Clarendon Press. 1970. A supplement to the Oxford English dictionary. 4 vols. Edited by R. W. Burchfield. Oxford: Clarendon Press. 1972–86. The Oxford English dictionary. 2d edition. 20 vols. Prepared by J. A. Simpson and E. S. C. Weiner. Oxford: Clarendon Press. 1989. Oxford English dictionary additional series. 3 vols. Edited by John Simpson et al. Oxford: Clarendon Press. 1993–7.


DF’s opinion of Gustav Jenzsch’s book [Mikroskopische Flora und Fauna (1868)]. Encloses extract of a letter from Ferdinand Zirkel also mentioning Jenzsch’s work.

Letter details

Letter no.
David Forbes
Charles Robert Darwin
Sent from
London, York Place, 11
Source of text
DAR 164: 143–143/2
Physical description
2pp enc

Please cite as

Darwin Correspondence Project, “Letter no. 6584,” accessed on 14 April 2021,

Also published in The Correspondence of Charles Darwin, vol. 17