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Darwin Correspondence Project

To T. H. Huxley   23 April [1853]1

Down Farnborough Kent

Ap. 23d.

My dear Sir

I have got out all the specimens, which I have thought could by any possibility be of any use to you;2 but I have not looked at them, & know not what state they are in, but shd. be much pleased if they are of the smallest use to you. I enclose a catalogue of Habitats: I thought my notes wd. have turned out of more use: I have copied out such few points as perhaps wd. not be apparent in preserved specimens.— The Bottle shall go to Mr. Gray3 on Thursday next by our weekly carrier.—

I am very much obliged for your Paper on the mollusca;4 I have read it all with much interest; but it wd. be ridiculous in me to make any remarks on a subject on which I am so utterly ignorant; but I can see its high importance. The discovery of the type or “idea” (in your sense, for I detest the word as used by Owen, Agassiz & Co) of each great class, I cannot doubt is one of the very highest ends of Natural History:5 & certainly most interesting to the worker out. Several of your remarks have interested me; I am, however, surprised at what you say versus “anamorphism”: I shd. have thought that the archetype in imagination was always in some degree embryonic, & therefore capable & generally undergoing further development.—6

Is it not an extraordinary fact, the great difference in position of the heart in different species of Cleodora?7 I am a believer that when any part usually constant differs considerably in different allied species; that it will be found in some degree variable, within the limits of the same species:—8 Thus, I shd. expect that if great numbers of specimens of some of the species of Cleodora had been examined with this object in view, the position of the heart in some of the species, wd. have been found variable.— Can you aid me with any analogous facts?

I am very much pleased to hear that you have not given up the idea of noticing my Cirripedia volume.9 All that I have seen since confirms everything of any importance stated in that volume. More especially I have been able rigorously to confirm, in an anomalous species, by the clearest evidence, that the actual cellular contents of the ovarian tubes, by the gland-like action of a modified portion of the continuous tube, passes into the cementing stuff:10 in fact cirripedes make glue out of their own unformed eggs!.11

Pray believe me | Yours sincerely | C. Darwin

I told the above case to Milne Edwards & I saw he did not place the smallest belief in it.—12


The date is established by the relationship to the letter to T. H. Huxley, 11 April [1853].
CD’s collection of ascidians from the Beagle voyage (see letter to T. H. Huxley, 11 April [1853]). He also enclosed notes extracted from his zoological diary of the voyage (DAR 30.2: 167–73).
John Edward Gray, keeper of the zoological department, British Museum.
T. H. Huxley 1853b.
T. H. Huxley 1853b was primarily concerned with establishing an archetype for the cephalous Mollusca. Huxley, although using the term ‘archetype’ coined by Richard Owen, expressly distanced his particular usage from any idealistic connotations, stating (ibid., p. 50): I make no reference to any real or imaginary ‘ideas’ upon which animal forms are modelled. All that I mean is the conception of a form embodying the most general propositions that be affirmed respecting the Cephalous Mollusca, standing in the same relation to them as the diagram to a geometrical theorem, and like it at once imaginary and true. For both Huxley and CD, the archetype of a class was suggested by comparative embryology and was a hypothetical structure representing general anatomical uniformities (see Correspondence vol. 4, Appendix II and di Gregorio 1984, pp. 22–35). Richard Owen and Louis Agassiz, on the other hand, believed in a Platonic archetype (see A. Desmond 1982, pp. 42–4).
Huxley denied the existence of transitional forms between archetypes. ‘Anamorphism’, as he used the term, denoted a progression from a lower to a higher type, which he doubted ever occurred: ‘It may indeed be a matter of very grave consideration whether true anamorphosis ever occurs in the whole animal kingdom. If it do, then the doctrine that every natural group is organized after a definite archetype, a doctrine which seems to me as important for zoology as the theory of definite proportions for chemistry, must be given up.’ (T. H. Huxley 1853b, p. 63). See di Gregorio 1984, p. 33.
See T. H. Huxley 1853, p. 42 and Plate IV.
CD repeated this rule in Natural selection, p. 307, where he attributed it to George Robert Waterhouse (Waterhouse 1846–8, 2: 452 n. 1).
See letter to T. H. Huxley, 11 April [1853], and n. 9.
Proteolepas bivincta, which CD classified as the sole species of a new order, Apoda. Proteolepas is now known not to be a cirripede. The observations on the cementing apparatus and process mentioned in this letter are described in Living Cirripedia (1854): 599–600. In T. H. Huxley 1857, Huxley stated that while he had not been able to trace the connection between the peduncular tubes and the cement gland, he nonetheless rather favoured ‘the conclusion that they are thus connected.’ (p. 239).
See letter to J. D. Dana, 8 May [1852], n. 5. In Living Cirripedia (1851): 38 n. and in Living Cirripedia (1854): 151 n., CD cited cases from the Crustacea of genera in which organs of the ovaria secrete a substance which served to attach the eggs to the parent’s body, but he pointed out that these were only analogous to the situation he described in cirripedes.
CD is referring to the 1849 meeting of the British Association for the Advancement of Science at which he commented on Albany Hancock’s paper and which Henri Milne-Edwards also attended. In his report on Hancock’s paper, published in the Athenæum (Collected papers 1: 250–1), CD remarked that the cementing substance of Cirripedia was ‘certainly secreted from glands which are actually continuous portions of the branching ovarian tubes or caeca’. To this Milne-Edwards ‘suggested that the secretion … was produced by a gland at the base of the antennae, similar to that which occurs in some species of macrourous Crustacea.’ CD ‘in reply stated that the gland in the cirripedes was truly ovarial.’ (Collected papers 1: 251).


On THH’s paper on cephalous Mollusca [Philos. Trans. R. Soc. Lond. 143 (1853) pt 1: 29–66]. Discovery of the type or "idea" (in THH’s sense, not Owen’s or Agassiz’s) is one of the highest ends of natural history.

Discusses anamorphism;

position of heart in Cleodora.

Variability within species;

cementing process in cirripedes.

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: 4)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 1480,” accessed on 26 April 2017,

Also published in The Correspondence of Charles Darwin, vol. 5