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Darwin Correspondence Project

To T. H. Huxley   9 July [1857]1

Down Bromley Kent

July 9th

My dear Huxley

I am extremely much obliged to you for having so fully entered on my point,2 I knew I was on unsafe ground, but it proves far unsafer than I had thought. I had thought that Brulle had a wider basis for his generalisation; for I made the extract several years ago, & I presume (I state it as some excuse for myself) that I doubted it, for differently from my general habit, I have not extracted his grounds.—3 It was meeting with Barneouds paper which made me think there might be truth in the doctrine.4 Your instance of Heart & Brain of Fish seems to me very good.—

It was a very stupid blunder on my part, not thinking of the posterior part of the time of development. I shall, of course not allude to the subject, which I rather grieve about, as I wished it to be true;5 but alas a scientific man ought to have no wishes, no affections,—a mere heart of stone.—

There is only one point in your letter which at present I cannot quite follow you in: supposing that Barneoud’s (I do not say Brulle’s) remark were true & universal, ie that the petal which have to undergo the greatest amount of development & modification begins to change the soonest from the simple & common embryonic form of the petal,6 —if this were a true law, then I cannot but think that it would throw light on Milne Edwards’ proposition that the wider apart the classes of animals are, the sooner do they diverge from the common embryonic plan,—which common embryonic7 may be compared with the similar petals in the early bud—the several petals in one flower being compared to the distinct but similar embryos of the different classes.—

I much wish, that you wd. so far keep this in mind, that whenever we meet, I might hear how far you differ or concur in this.— I have always looked at Barneoud’s & Brulle’s proposition as only in some degree analogous.—

With hearty thanks for your very kind assistance. | Your’s most truly | C. Darwin

P.S. | I see in my abstract of M. Edwards paper he speaks of “the most perfect & important organs” as being first developed,8 & I shd. have thought that this was usually synononymous with the most developed or modified.—

P.S. | Allman’s account of the fertilisation of the ova in his F.W. Polyzoa seems dreadfully opposed to “Darwin not an eternal hermaphrodite.”9


Dated by the relationship to the letter from T. H. Huxley, 7 July 1857.
CD’s abstract of Brullé 1844 is in DAR 72: 123–4. See also letter to T. H. Huxley, 5 July [1857] and n. 5.
Because Huxley had refuted Gaspard Auguste Brullé’s ‘law’, CD decided to omit this discussion from his chapter on ‘Laws of variation’, renumbering folio 45 as ‘40 to 45’ (see DAR 11.1: 45 and Natural selection, p. 303 n. 1).
Barnéoud 1846, pp. 287–8.
In a draft of this letter preserved in DAR 11.1: 41a, this phrase reads: ‘which common embryonic [’plan‘ del; ’type‘ del] plan’.
CD had asked Huxley to provide him with cases that might oppose his view that all organic beings crossed, even if only occasionally (see letters to T. H. Huxley, 1 July [1856], 8 July [1856], and 13 [December 1856]). Such a case seemed to be presented by the freshwater Polyzoa described by George James Allman (Allman 1850). Allman stated his grounds for believing that the polyzoans he had dissected were hermaphrodites and that they must also, from lacking ‘some orifice through which ova may escape from the cells’, be perpetually self-fertilised (Allman 1850, p. 321–5).


Allman, George James. 1850. On the present state of our knowledge of the freshwater Polyzoa. Report of the 20th meeting of the British Association for the Advancement of Science held at Edinburgh, pp. 305–37.

Barnéoud, François Marius. 1846. Mémoire sur le développement de l’ovule, de l’embryon et des corolles anomales. Annales des Sciences Naturelles. Botanique 3d ser. 6: 268–96.

Brullé, Gaspard Auguste. 1844. Recherches sur les transformations des appendices dans les articulés. Annales des Sciences Naturelles. Zoologie 3d ser. 2: 271–374.

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.


Thanks THH for his cautionary response on Brullé, but departs from THH in thinking that Barnéoud, if true, would shed light on Milne-Edwards’ proposition that the wider apart classes of animals are the earlier they depart from common embryonic plan.

Letter details

Letter no.
Charles Robert Darwin
Thomas Henry Huxley
Sent from
Source of text
Imperial College of Science, Technology, and Medicine Archives (Huxley 5: 50)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 2122,” accessed on 29 November 2021,

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