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Darwin Correspondence Project

To G. J. Romanes   29 May [1876]1

H. Wedgwoods E | Hopedene | Dorking

May 29th.

Dear Romanes

As you are interested in Pangenesis & will some day, I hope, convert an “airy nothing” into a substantial theory, therefore I send by this post an essay by Häckel, attacking Pan: & substituting a molecular hypothesis.2 If I understand his views rightly, he wd. say that with a bird which strengthened its wings by use, the formative protoplasm of the strengthened parts becomes changed, & its molecular vibrations consequently changed, & that these vibrations are transmitted throughout the whole frame of the bird & affect the sexual elements in such a manner that the wings of the offspring are developed in a like strengthened manner.— I imagine he wd say in cases like those of Ld. Moreton’s mare that the vibrations from the protoplasm or “plasson” of the seminal fluid of the Zebra set plasson vibrating in the mare & that these vibrations continued until the hair of her second colt was formed, & which consequently became barred like that of a Zebra.3 How he explains reversion to a remote ancestor I know not.— Perhaps I have misunderstood him, though I have skimmed the whole with some care. He lays much stress on inheritance being a form of unconscious Memory, but how far this is part of his molecular vibration I do not understand.

His views make nothing clear to me, but this may be my fault. No one I presume wd. doubt about molecular movements of some kind. His essay is clever & striking. If you read it (but you must not on my account) I shd. much like to hear your judgment. & you can return it at any time.— The blue lines are Häckel’s, to call my attention.—4

We have come here for rest for me, which I much needed, & shall remain here for about 10 days more, & then home to work which is my sole pleasure in life.5 I hope your splendid Medusa-work & yr experiments on Pang: are going on well.—6 I heard from my son Frank yesterday that he was feverish with a cold & could not dine with the Physiologists, which I am very sorry for as I shd. have heard what they think about the new bill.—7 I see that you are one of the Secs. to this young Socy. I was very much gratified by the wholly unexpected honour of being elected one of the Hony: Members.8 This mark of sympathy has pleased me to a very high degree.

Believe me | Yours very sincerely | Ch. Darwin

Häckel gives reference to a paper on Pang: of which I have never heard.9

I fear that you will have difficulty in reading my scrawl.—

Do you know who are the other Hon. members of your Socy.?


The year is established by the address. See n. 5, below.
Pangenesis was the hypothesis of heredity that CD first proposed in Variation 2: 357–404, and presented in revised form in Variation 2d ed. 2: 349–400. Romanes was carrying out experiments to test the hypothesis (see letter from G. J. Romanes, [c. 19 March 1876]). CD forwarded a copy of Die Perigenesis der Plastidule, oder die Wellenzeugung der Lebenstheilchen (Perigenesis of the plastidule, or the wave generation of vital particles; Haeckel 1876a) sent to him by Haeckel (see letter from Ernst Haeckel, 9 May 1876).
See letter from Ernst Haeckel, 9 May 1876 and n. 7. George Douglas, the earl of Moreton, had reported that a cross between a chestnut Arabian mare and a quagga (a type of zebra) had produced a hybrid foal that resembled the quagga, and that a subsequent mating of the mare with a black Arabian horse also produced offspring that resembled the quagga (Variation 2d ed. 1: 435). The influence of the first male on the progeny subsequently borne by the female to other males was a phenomenon known as telegony.
CD stayed at Hopedene in Surrey, the home of Hensleigh Wedgwood, from 24 May to 7 June 1876 (CD’s ‘Journal’ (Appendix II).
Romanes was working on the second part of his account of new species, varieties, and monstrous forms of medusae (G. J. Romanes 1876–7). For Romanes’s pangenesis experiments, see n. 2, above.
The Physiological Society had been formed in March 1876; at a meeting on 5 May 1876, it was decided that CD would be elected an honorary member of the society on 26 May 1876 (Sharpey-Schafer 1927, pp. 7 and 13).
CD made a pencil mark opposite a discussion of an article on the regeneration or preservation of organic molecules by Louis Elsberg (Elsberg 1874) in Haeckel 1876a, p. 73; at the end of Haeckel 1876a, CD wrote ‘P 73 This ought to be read’.


Elsberg, Louis. 1874. Regeneration, or the preservation of organic molecules: a contribution to the doctrine of evolution. Proceedings of the American Association for the Advancement of Science 23: 87–103.

Romanes, George John. 1876–7. An account of some new species, varieties, and monstrous forms of medusæ. [Read 6 April 1876 and 18 January 1877.] Journal of the Linnean Society (Zoology) 12 (1876): 524–31; 13 (1878): 190–4.

Sharpey-Schafer, Edward Albert. 1927. History of the Physiological Society during its first fifty years, 1876–1926. London: Cambridge University Press.

Variation 2d ed.: The variation of animals and plants under domestication. By Charles Darwin. 2d edition. 2 vols. London: John Murray. 1875.

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


Encloses essay by Haeckel criticising Pangenesis [Die Perigenesis der Plastidule (1876)]. Discusses Haeckel’s theory of inheritance.

Asks about the Physiological Society.

Letter details

Letter no.
Charles Robert Darwin
George John Romanes
Sent from
Source of text
American Philosophical Society (Mss.B.D25.493)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10516,” accessed on 21 June 2021,

Also published in The Correspondence of Charles Darwin, vol. 24