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Darwin Correspondence Project

From G. J. Romanes   [after 8 January 1877]1

By this post I return you Häckel’s essay on Perigenesis.2 Although I have kept it so long, I have only just read it, as you said there was no need to return it at any particular time.

To me it seems that whatever merit Häckel’s views may have in this matter, they certainly have no claim to be regarded as original; for I cannot see that his ‘Plastidules’ differ in anything but in name from Spencer’s ‘Physiological Units.’3 Why he does not acknowledge this, it is difficult to understand. Anyhow, the theories being the same, the same objections apply; and to me it has always seemed that this theory is unsatisfactory because so general. As you observe in your letter, everyone believes in molecular movements of some kind; but to offer this as a full explanation of heredity seems to me like saying that the cause, say, of an obscure disease like diabetes, is the persistence of force. No doubt this is the ultimate cause, but the pathologist requires some more proximate causes if his science is to be of any value. Similarly, I do not see that biology gains anything by a theory which is really but little better than a restatement of the mystery of heredity in terms of the highest abstraction. Pangenesis at least has the merit of supplying us with some conceivable carriers, so to speak, of the modified protoplasm from the various organs or parts of the parent to the corresponding organs or parts of the offspring, and the multiplication of gemmules seems to me to avoid a difficulty with which Perigenesis (as stated by Häckel) is beset, viz. that atavism sometimes occurs over too large a gap to be reasonably attributed to what remains of the original ‘stem-vibrations’ after their characters have been successively modified at each ‘bifurcation.’4 But it would be tedious to enter into details. Perigenesis, in my opinion, is ‘more simple’ than Pangenesis, only because its terms are so much more general.

P.S.— I forgot to tell you, when we were at lunch, that the seed of the grafted beets is ready for sowing; also that the vine is now four feet high, and so, I should think, might be grafted next spring.5


The date is established by the relationship between this letter, the letter from G. J. Romanes, [after 23 September 1876] (Correspondence vol. 24), and the letter to G. J. Romanes, 4 January 1877, in which CD invited Romanes to lunch the following Monday. The Monday following 4 January 1877 was 8 January. This was CD’s first visit to London since September 1876 (see CD’s ‘Journal’ (Appendix II)).
CD had sent his copy of Ernst Haeckel’s Die Perigenesis der Plastidule, oder die Wellenzeugung der Lebenstheilchen (Perigenesis of the plastidule, or the wave generation of vital particles; Haeckel 1876b) to Romanes (see Correspondence vol. 24, letter from Ernst Haeckel, 9 May 1876, and letter to G. J. Romanes, 29 May [1876]). Romanes later apologised for having kept the work so long (see Correspondence vol. 24, letter from G. J. Romanes, [after 23 September 1876]).
Herbert Spencer presented his theory of heredity in Principles of biology (Spencer 1864–7, 1: 182–3; 238–56); CD compared his notion of gemmules to Spencer’s physiological units in Variation 2: 375–6 n. 29 (see also Correspondence vol. 16, letter from Herbert Spencer, 8 February 1868).
In his letter to Romanes of 29 May [1876] (Correspondence vol. 24), CD had queried how Haeckel’s theory could explain atavism. Haeckel discussed reversion and atavism in Haeckel 1876b, pp. 57–9.
As part of a research programme to test CD’s hypothesis of pangenesis, Romanes was carrying out experiments on graft hybrids at Dunskaith House, Nigg, Scotland; he had informed CD in the autumn that because they were so far north, his seeds were not yet ripe (see Correspondence vol. 24, letter from G. J. Romanes, [after 23 September 1876]).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Spencer, Herbert. 1864–7. The principles of biology. 2 vols. London: Williams & Norgate.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Returns E. Haeckel’s Perigenesis [der Plastidule (1876)]. EH’s "plastidules" do not differ from Spencer’s "physiological units". Does not see that biology gains anything from EH’s theory.

Letter details

Letter no.
George John Romanes
Charles Robert Darwin
Sent from
Source of text
E. D. Romanes 1896, p. 93

Please cite as

Darwin Correspondence Project, “Letter no. 10554,” accessed on 3 March 2021,