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Darwin Correspondence Project

From T. H. Huxley   8 December 1874

4 Marlborough Place | NW

Dec. 8th 1874

My dear Darwin

Best thanks for Semper1   It is an interesting but monstrous illnatured article (he doesn’t attack me) and it serves him right that he has not only been completely anticipated by Balfour— but that Balfour’s must 〈foot of page excised〉 shew that he has altogether blundered in his interpretation of the fact. Indeed the only value of the paper is that it confirms Balfours statement as to fact2

I will return the paper to you as soon as I have made some excerpts

It did us good on Sunday to see how well &3foot of page excised

P.S. | I forgot to say that I have been making out wonderful things about Amphioxus   His skull & brain are bigger in proportion (or at any rate longer) to his body than yours— and the theory of the vertebrate skull that I have been grinding at these seventeen years,4 is I believe just as clear proving at last the great break between Amphioxus & other fishes supposed to exist by us all up to this time—is pretty well bridged over & the relations of Amphioxus with the Lampreys are as clear as mud in a wine glass—5 The skull consists of above 14 segments all trace of which is lost even in the embryo of the higher vertebrates

Three cheers for our great ancestor!— Prot. Adam (Haekels)6



Huxley was preparing a paper on Amphioxus lanceolatus (the lancelet; now Branchiostoma lanceolatum) for the Royal Society of London (T. H. Huxley 1874b). CD may have sent him Carl Gottfried Semper’s note on the relationship between vertebrates and annelids (Semper 1874), a copy of which is in the Darwin Pamphlet Collection–CUL.
Francis Maitland Balfour’s paper on the embryogenesis of elasmobranch fishes (fishes with cartilaginous skeletons and plate-like gills, e.g. sharks, skates, and dogfish) was read at the meeting of the British Association for the Advancement of Science in September 1874 and published in the Quarterly Journal of Microscopical Science (Balfour 1874). Both Semper and Balfour described the segmented tubules of the kidney in the shark embryo (Balfour 1874, p. 358, Semper 1874).
Huxley had met CD on Sunday 6 December 1874 (see letter to H. A. Huxley, 5 December 1874).
Huxley’s first publication on the vertebrate skull was T. H. Huxley 1858. Huxley attempted to establish homologies between Amphioxus and the jawless fishes (Agnatha) using the larval lamprey for comparison, and argued that Amphioxus had equivalents of cranium and brain (T. H. Huxley 1874b, pp. 129–30).
Balfour identified meroblastic ova as a new development in the evolution of fishes and therefore recognised a closer relationship between Amphioxus and lampreys, which retained holoblastic ova (Balfour 1874, p. 337).
Ernst Haeckel had maintained that Amphioxus ought to form a distinct class, Acrania, among the vertebrates because it lacked a cranium, brain, and vertebral column (Haeckel 1868c, pp. 436–8), and CD suspected that it might offer a clue to the ancestor of vertebrates (Descent 1: 204–6). CD had cited Haeckel on this in Descent 1: 204–5.


Balfour, Francis Maitland. 1874. A preliminary account of the development of the elasmobranch fishes. Quarterly Journal of Microscopical Science n.s. 14: 323–64.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.


K. G. Semper’s article ["On the relationship of the Vertebrata and Annelida", Ann. & Mag. Nat. Hist. 15 (1875): 94–5] is ill-natured. Misinterprets facts already discovered by F. M. Balfour.

Has been working on Amphioxus. Puts his theory of vertebrate skulls on firm footing at last.

Letter details

Letter no.
Thomas Henry Huxley
Charles Robert Darwin
Sent from
London, Marlborough Place, 4
Source of text
DAR 103: 234–5

Please cite as

Darwin Correspondence Project, “Letter no. 9748,” accessed on 27 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 22