Ɛpsilon

To Alexander Agassiz   28 August [1871]1

Down, | Beckenham, Kent.

Aug. 28

My dear Mr. Agassiz

I cannot thank you enough for your letter of Aug 9th, which, even if I had not wished much to learn something about the pedicillariæ, would at any time have interested me beyond measure.2 It is a splendid case of gradation of structure. I wish extremely I could give the whole of the case, but this is impossible from want of space, even if I had the requisite knowledge to do it well; but I must give some of your conclusions & remarks.3 Over & over again I have come across some structure, & thought that here was an instance in which I shd. utterly fail to find any intermediate or graduated structure; but almost always by keeping a look out I have found more or less plain traces of the lines through which development has proceeded by short & easy & serviceable steps. Rarely, however, have I learnt so fine an instance as this of yours.— I have been very unwell for the last 5 weeks with giddiness & horrid head feelings & have done nothing: I was not able to read your letter at one time, but now I have just finished it, & it has served as a more splendid stimulus than any physic, & has enabled me to write myself this note.

Accept my cordial thanks, & believe me | yours very sincerely | Ch. Darwin

I am very much obliged for the beautiful book, “Sea-side Studies”, which I will read as soon as my odious head allows me to read anything.4

1
The year is established by the relationship between this letter, the letter from Alexander Agassiz, [before 1 June 1871], and the letter to Alexander Agassiz, 1 June [1871] (Correspondence vol. 19).
2
Agassiz’s letter has not been found. CD and Agassiz had discussed the development of pedicellariae (small pincer-like appendages in echinoderms; see Correspondence vol. 19, letter from Alexander Agassiz, [before 1 June 1871] and n. 11, and letter to Alexander Agassiz, 1 June [1871] and n. 3). Agassiz published on the subject in A. Agassiz 1873.
3
See Origin 6th ed., pp. 191–2 (published in 1872). Agassiz’s view that the pedicellariae were modified spines, and were of use to the animals throughout their process of development, was an argument against St George Jackson Mivart’s argument that since they were useless unless fully developed they could not have evolved by natural selection.
4
There is an annotated copy of the second edition of Seaside studies in natural history, by Elizabeth Agassiz and Alexander Agassiz (E. C. Agassiz and Agassiz 1871), in the Darwin Library–CUL. Elizabeth Agassiz was Alexander Agassiz’s mother.

Manuscript Alterations and Comments

1.5 to … well] interl
1.13 served as] interl
1.14 myself] interl

Please cite as “DCP-LETT-7918G,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-7918G