To Ernst Haeckel   9 March 1864

Haeckel 1864a, an article on marine zooplankton. There is an annotated copy in the Darwin Pamphlet Collection–CUL.

Haeckel sent an article from the Neue Stettiner Zeitung, 20 September 1863, entitled ‘38 Versammlung deutscher Naturforscher und Aerzte’ (Thirty-eighth assembly of German scientists and physicians). The article included a report of a speech of Haeckel’s that presented CD’s theory for a general audience; the speech was published later in 1863 (see Haeckel 1863 and letter to Ernst Haeckel, 21 November [1864]). CD’s annotated copy of the Stettin newspaper article is in DAR 226.1: 273; his copy of Haeckel 1863 is in the Darwin Pamphlet Collection–CUL.

The article in Neue Stettiner Zeitung, 20 September 1863 (see n. 2, above), reported that, in his lecture, Haeckel discussed CD’s theory of descent; CD triple-scored a passage that noted CD’s appropriation of Georges Cuvier’s empirical method, and his 1859 explanation in Origin of natural selection and the struggle for survival. The triple-scored passage also included Haeckel’s discussion of the significance of both heredity and variation to CD’s theory. See Nyhart 1995, pp. 129–30. See also n. 4, below.

In his article on marine zooplankton, Haeckel discussed the genus Sapphirina, and included the following statement (Haeckel 1864a, p. 101), which CD triple-scored and annotated with the comment ‘good’: Gerade diejenigen Charaktere, welche man hauptsächlich zur Unterscheidung der verschiedenen Sapphirinen–Arten mit Recht benutzt, … haben mir bei Vergleichung zahlreicher Individuen gezeigt, dass sie keineswegs unabänderlich sind, sondern zahlreiche feine individuelle Abänderungen erkennen lassen. [Especially those characters that are chiefly and quite rightly used to distinguish between the different species of Sapphirina … have shown me, when comparing numerous individuals, that they are by no means constant, but exhibit numerous subtle individual variations.] This statement followed a lengthy endorsement of CD’s theory of natural selection, including the notion that varieties could be viewed as incipient species; Haeckel argued that crustaceans (the class to which Sapphirina belong) were particularly suited to provide proof of the theory of descent owing to the striking variation of their hard shells. Although a specific reference to Haeckel’s statement has not been found in CD’s publications, see CD’s more general reference to Haeckel’s work on descent in the sixth edition of Origin, p. 381.