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Darwin Correspondence Project

To J. D. Hooker   24 December [1856]1

Down Bromley Kent

Decr 24th

My dear Hooker

I am particularly glad of the reference about Leguminosæ, as I am at a dead lock with regard to them.2 Botanists seem to differ so much about Campanulaceæ, that I have given them up almost in despair, & cannot but think old C. C. Sprengel was right.—3

What a letter of Col. Portlock;4 it beats hollow all the many proofs which I have seen how little men, who are not naturalists, understand of Nat. History.—

I shall write to Harvey as it will cost him only a brief answer.—5

How I do wish I lived near you to discuss matters with.— I have just been comparing definitions of species, & stating briefly how systematic naturalists work out their subject:—Aquilegia in F. Indica was a capital example for me.—6 It is really laughable to see what different ideas are prominent in various naturalists minds, when they speak of “species” in some resemblance is everything & descent of little weight—in some resemblance seems to go for nothing & Creation the reigning idea—in some descent the key—in some sterility an unfailing test, with others not worth a farthing. It all comes, I believe, from trying to define the undefinable.

I suppose you have lost the odd black seed from Birds Dung, which germinated— anyhow it is not worth taking trouble over— I have now got about a dozen seeds out of small Birds dung.—7

Adios— | My dear Hooker | Ever yours | C. Darwin


Dated by CD’s interest in Leguminosae, which extended through the autumn and winter of 1856 (see letter to George Bentham, 26 November [1856]).
CD had tried to ascertain the probability of cross-fertilisation in the Leguminosae (see letter to George Bentham, 26 November [1856], and letter to George Bentham, 30 November [1856]). No reference is made to Hooker in the discussion of Leguminosae in Natural selection, pp. 68–71.
Christian Konrad Sprengel maintained that fertilisation of Campanulaceae takes place after the flower is opened (Sprengel 1793, p. 117). An annotated copy of Sprengel 1793 is in the Darwin Library–CUL.
Joseph Ellison Portlock was inspector of studies at Woolwich. It is not known to what letter CD refers.
J. D. Hooker and Thomson 1855, p. 44. CD had earlier discussed the case of Aquilegia with Hooker (see Correspondence vol. 5, letter to J. D. Hooker, 14 [August 1855]).
CD’s attempts to germinate seeds extracted from birds’ dung are recorded in his Experimental book, p. 15 (DAR 157a). Hooker had previously identified some of the seeds for him (see letter from J. D. Hooker, 22 November 1856).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.

Sprengel, Christian Konrad. 1793. Das entdeckte Geheimniss der Natur im Bau und in der Befruchtung der Blumen. Berlin: Friedrich Vieweg.


On the variety of species definitions prevalent among naturalists.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 114: 187
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 2022,” accessed on 23 April 2024,

Also published in The Correspondence of Charles Darwin, vol. 6