Comments on sheet of EH's Generelle Morphologie . In emphasising divergence of character EH shows his clear understanding of CD's views. It was years before CD saw necessity of divergence.
Interested in Carl Claus [Copepodenfauna von Nizza (1866)].
Down. | Bromley. | Kent. S.E.
My dear Sir
I received a few days ago a sheet of your new work, & have read it with great interest. You confer on my book, the ``Origin of Species'', the most magnificent eulogium which it has ever received, & I am most truly gratified, but I fear if this part of your work is ever criticized, your reviewer will say that you have spoken much too strongly. Your abstract seems to me wonderfully clear & good; & one little fact shews me how clearly you understand my views, namely your bringing prominently forward, which no one else has ever done, the fact & the cause of Divergence of Character. Oddly enough, as it now appears to me, it was many years before I clearly saw the necessity of admitting a tendency to divergence of character, & some more years until I could see the explanation.
I have read with much interest your discussion on Inheritance &c; & all the more so as I give in my next work, which will not be published for half a year, several chapters on this & other allied subjects. So that I shall feel very curious to read your remaining chapters when published; but it is a terrible evil to me that I cannot read more than one or two pages at a time of German, even when written as clearly as is your book.
I suppose you have seen Prof. Claus new work on Copepoda in which he discusses individual variability, & alludes to your work; I have been interested by it. I heartily congratulate you that your great undertaking is so nearly completed & with my cordial thanks for the great honour which you have done me & with a full belief that you will do excellent service in the cause which we have both at heart, I remain my dear sir | yours very sincerely Ch. Darwin
- f1 5193.f1The reference is to a proof-sheet of Haeckel's Generelle Morphologie (Haeckel 1866). CD's annotated copy of the book, which he later received, is in the Darwin Library--CUL (see letter from Ernst Haeckel, 19 October 1866 and n. 3; see also Marginalia 1: 355--7). For Haeckel's discussions of his work on the book, see Correspondence vols. 12 and 13.
- f2 5193.f2In a section about the history of the theory of descent, Haeckel wrote that Origin was the book through which CD founded a new era in general morphology and physiology and also in anthropology and the whole of science in general (Haeckel 1866, 2: 163).
- f3 5193.f3See Haeckel 1866, 2: 249--56, and Marginalia 1: 357. For CD's discussion of divergence, see Origin, pp. 111--26.
- f4 5193.f4CD's notes on divergence and classification are in DAR 205.5. See Correspondence vols. 3 and 6 for some early discussions of the principle of divergence.
- f5 5193.f5See Haeckel 1866, 2: 170--90. CD refers to Variation, which was published in January 1868 (Freeman 1977). In Variation 2: 397 n., CD cited Haeckel 1866, 2: 170, on the simplest form of inheritance.
- f6 5193.f6Carl Friedrich Claus's monograph on the copepods of Nice (Claus 1866) presented a classification scheme influenced by Darwinian transmutation theory; it focused particularly on the role of environmental factors in determining morphological features in the sub-class Copepoda. CD had earlier recommended it to Joseph Dalton Hooker (see letter to J. D. Hooker, 3 and 4 August  and n. 20). Claus referred to Haeckel's conclusions on variability within the copepod family, Corycaeidae, but did not cite a specific work (Claus 1866, p. 2).