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.
Down Bromley Kent
My dear Huxley
I am extremely much obliged to you for having so fully entered on my point, 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.— It was meeting with Barneouds paper which made me think there might be truth in the doctrine. 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; 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, —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 embryonic 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 w
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, & I
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.”
- f1 2122.f1Dated by the relationship to the letter from T. H. Huxley, 7 July 1857.
- f2 2122.f2See letter from T. H. Huxley, 7 July 1857.
- f3 2122.f3CD's abstract of Brullé 1844 is in DAR 72: 123–4. See also letter to T. H. Huxley, 5 July  and n. 5.
- f4 2122.f4Barnéoud 1846.
- f5 2122.f5Because 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).
- f6 2122.f6Barnéoud 1846, pp. 287–8.
- f7 2122.f7In a draft of this letter preserved in DAR 11.1: 41a, this phrase reads: ‘which common embryonic [’plan‘ del; ’type‘ del] plan’.
- f8 2122.f8See letter to T. H. Huxley, 5 July , n. 4.
- f9 2122.f9CD 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 , 8 July , 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).