To C. G. Semper   30 April 1877

[Down.]

[…] I shall consider your dedication as a high & most gratifying honour.1 Your observation on the dorsal eyes of Onchidium are interesting & surprising in the highest degree.2 That the same animal should be provided with eyes of two widely different types is remarkable enough; but that you should have discovered gradations in the scale of their development on the same individual is most wonderful & shows us probably by what steps they were developed. On two occasions I have found gradations on the same individual but in structures of comparatively small importance, namely in the tendrils of the vine & in the ocelli on the feathers of the argus pheasant.3 Even theses cases interested me much though they are quite trifling compared with your case.

There is much truth in what you say about photographs in comparison with published memoirs or books; but the generous sympathy which I have received from so many men in Germany & Holland, some of them distinguished workers in science, has naturally given me much pleasure—4

Allow me to repeat that your intended dedication will always be considered by me as a very high honour, & I return you my most sincere thanks | Believe me, my dear Sir | Yours sincerely, | Charles Darwin

LS incomplete5

1
See letter from C. G. Semper, 26 April 1877. Semper had asked to dedicate his forthcoming work (Semper 1877b) to CD.
2
Semper had sent a copy of his preliminary report on the anatomy and development of the dorsal eyes found in many species of Onchidium, a genus of marine slugs (Semper 1877a).
3
CD had discussed gradations from tendril to flower in common grape vines in Climbing plants, pp. 81–2; his discussion of gradations in the ocelli of feathers in the Argus pheasant was in Descent 2: 141–50.
4
Semper had not provided a photograph of himself for the album of photographs of German and Austrian naturalists that was sent to CD to celebrate his birthday (see letter from C. G. Semper, 26 April 1877 and n. 1); CD had received a similar album from Dutch admirers (see letter from A. A. van Bemmelen and H. J. Veth, 6 February 1877). Semper argued that a more fitting tribute to CD would be a work with original research.
5
The letter is described in the dealer’s catalogue as complete and four pages long. The transcription is from the dealer’s catalogue and an image of the fourth page (from ‘which I have received’).

Please cite as “DCP-LETT-10945F,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10945F