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Darwin Correspondence Project

To G. J. Romanes   24 June [1881]1

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R. [Glenridding House, Patterdale.]

June 24th

My dear Romanes

I have been thinking about Pompilius & its allies.—2 Please take the trouble to read on Perforation of the corolla by Bees p. 425 of my Cross Fertilisation to end of Chapter.3 Bees show so much intelligence in these acts, that it seems not improbable to me that the progenitors of Pompilius originally stung caterpillars & spiders &c in any part of their bodies, & then observed by their intelligence that if they stung them in one particular place, as between certain segments on the lower side, their prey was at once paralysed. It does not seem to me at all incredible that this action shd then become insttive i.e. memory transmitted from one generation to another. It does not seem necessary to suppose that when Pompilius stung its prey in the ganglion that it intended or knew that the prey would long keep alive. The development of the larvae may have been subsequently modified in relation to their half-dead, instead of wholly dead prey; supposing that the prey was at first quite killed which would have required much stinging. Turn this notion over in your mind, but do not trouble yourself by answering.—4

Yours very sincerely | Ch. Darwin

N.B. Once on a time a fool said to himself that at an ancient period small soft crabs or other creatures stuck to certain fishes; then struggled violently & in doing so discharged electricity, which annoyed the parasites; so that they often wriggled away. The fish was very glad, & some of its children gradually profited in a higher degree & in various way by discharging more electricity & by not struggling.— The fool who thought thus persuaded another fool to try an eel in Scotland, & lo & behold electricity was discharged when it struggled violently. He then placed in contact with the fish or near it a small medusa or other animal which he cleverly knew was sensitive to electricity, & when the eel struggled violently the little animals in contact showed by their movements that they felt a slight shock.—5 Ever afterwards men said that the two fools were not such big fools as they seemed to be.—



The year is established by the relationship between this letter, the letter to G. J. Romanes, 16 April 1881, and the letter from G. J. Romanes, 17 April 1881.
Pompilus is a genus of the family Pompilidae (spider wasps). In his previous letter to Romanes, CD had mentioned sand wasps and referred to Jean-Henri Fabre’s discussion of their habits (see letter to G. J. Romanes, 16 April 1881). Fabre had referred to the genus Bembex (a synonym of Bembix: sand wasps; see Fabre 1879, pp. 129–30). The taxonomy of these wasps has changed significantly since the nineteenth century, and many wasps formerly placed within Pompilus are now included in Bembix or other genera in the family Bembicidae. Thus, CD probably had a much broader idea of what would be considered ‘allies’ of Pompilus.
In Cross and self fertilisation, pp. 425–35, CD had discussed humble-bees (bumble-bees) biting holes in the corollas of flowers to obtain nectar.
Romanes quoted the entire paragraph from CD's letter in Mental evolution in animals, and compared the instincts of the wasps in stinging their prey to those of bees biting the corolla to suck nectar (see G. J. Romanes 1883a, pp. 301–2).
CD had discussed the origin of electrical organs in fish as one of the special difficulties of the theory of natural selection (see Origin 6th ed., pp. 150–1). Romanes had worked on the nervous system of medusae (G. J. Romanes 1876).
Stultus: fool (Latin).


Cross and self fertilisation: The effects of cross and self fertilisation in the vegetable kingdom. By Charles Darwin. London: John Murray. 1876.

Fabre, Jean-Henri. 1879. Souvenirs entomologiques: études sur l’instinct et les mœurs des insectes. Paris: Librairie Ch. Delagrave.

Origin 6th ed.: The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 6th edition, with additions and corrections. By Charles Darwin. London: John Murray. 1872.

Romanes, George John. 1876. The physiology of the nervous system of medusae. [Read 28 April 1876.] Proceedings of the Royal Institution of Great Britain 8 (1875–8): 166–77.

Romanes, George John. 1883a. Mental evolution in animals: with a posthumous essay on instinct by Charles Darwin. London: Kegan Paul, Trench & Co.


Discusses possible case of inherited memory involving Pompilus. Cites similar example of electric eel.

Letter details

Letter no.
Charles Robert Darwin
George John Romanes
Sent from
Source of text
American Philosophical Society (Mss.B.D25.530)
Physical description
ALS 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 10813,” accessed on 27 March 2023,