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Darwin Correspondence Project

To J. D. Hooker   5 July [1857]1

Down Bromley Kent

July 5th

My dear Hooker

Am I right in supposing that in Linnean Journal p. 5. your words “some states of the Wahlenbergia saxicola” means a variation of this species; & does it mean that this variation alone presents “the unequal inclined anthers &c”.2

I ask because this wd be a valuable case to add to my list of variations of one species assuming the character of a distinct, but allied species or genus.—3

I am particularly interested on this point.—

The briefest answer will suffice. If you had been a stranger I shd have quoted the sentence, but it is far safer to ask.—

Ever yours | C. Darwin

P.S. I have just had a seed case which has surprised me: Fresh Nuts sink in sea-water; but old Spanish nuts float for between 75 & upwards of 90 days— after this prolonged bath, I opened one & it looked so fresh, that I planted 2 others & one has germinated well—4 I had fancied a seed with so much organized matter wd. have assuredly gone bad when after having been long dry, & then kept in water for 3 months.—

What a capital number of the Linnean Journal! Owen’s is a grand Paper; but I cannot swallow Man making a division as distinct from a Chimpanzee, as an ornithorhynchus from a Horse: I wonder what a Chimpanzee wd. say to this?5


The year is established by CD’s reference to experiments testing the viability of nuts, which were recorded in his Experimental book (see n. 4, below).
The passage referred to discusses the problem with using the anthers and corolla as characters for classifying the Lobeliaceae (J. D. Hooker and Thomson 1858, p. 5).
CD included this case in his chapter on ‘Laws of variation’ (Natural selection, p. 327).
Under the heading ‘1857 Dryed Seeds’ in CD’s Experimental book, pp. 12–13 (DAR 157a), there is a list of the various nuts that he floated in salt water. In the Experimental book, p. 12, an entry dated 16 May 1857 reads: ‘3d. nut still floating after 90 days’. On 2 July CD recorded: ‘one of these two germinated’.
In a paper on the classification of the Mammalia, Richard Owen proposed to use the brain to delimit the ‘most natural primary divisions’ of the class (Owen 1857b, p. 14). Applying this criterion to man, he concluded: ‘I am led to regard the genus Homo, as not merely a representative of a distinct order, but of a distinct subclass of the Mammalia’ (ibid., p. 20).


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.


Does JDH’s Wahlenbergia confirm CD’s law? Variations of one species assume the character of a distinct but allied species or genus.

Seed-salting: old ones float and germinate.

Owen’s "grand paper" [? J. Proc. Linn. Soc. Lond. (Zool.) 2 (1858): 1–37].

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 114: 203
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 2117,” accessed on 4 June 2023,

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