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Darwin Correspondence Project

From J. V. Carus   22 April 1871

My dear Sir,

The publisher prepares a second impression of the first volume, even before the second has come out.1 As you were so kind to send me proof-sheets of your second edition of the 2d. Volume, may I ask you, if there are any alterations to be made in the first.2

I should be obliged to you very much, if you would be so kind as to answer very soon, as I promised the publisher not to keep him waiting.

My friend Donders told me you were preparing your work on the expression of the various emotions, which you mention in the “Descent”.3 When will it come?

May I be allowed to send you a few remarks on a few points contained in the 1. Vol. of the Descent of Man.

p. 360. You say that the two Orders of the Neuroptera and Orthoptera are now generally ranked as quite distinct. Now since Erickson’s remarks both of these Orders are with us brought close together,4 indeed the Ephemeridae,5 Libellulidae6 Perlidae7 are ranked amongst the Orthoptera, and only the Phryganidae,8 Mantispa, Myrmadleon, Ascalaphus,9 Sialid,10 Embid11 are left by themselves as Neuroptera. Thus your instances of Ephemeridae, Libellulidae (p 261a) would come according to our generally accepted classification under “Orthoptera”.12

On p. 261 you mention the difference of colour between the two sexes of Oecanthus nivalis, an American form.13 The same difference, though not quite as great perhaps, is seen with our European Oecanthus pellucidus.14 Comp. Fischer Orthoptera Europaea. p 165, which statement I can confirm from observation.15

To page 416 I may state the fact, that I know some persons who instantly feel a nauseous incomfortable sensation about their stomach, as soon as they behold an “ugly coloured” toad or caterpillar, so that they are warned by instinct not to touch (or devour) them16

p. 314. With regard to the proportional numbers of the two sexes with Insects it struck me, that it is sometimes not only very difficult but indeed impossible to count the males and females, as with some of these, especially Cynipidae, Tenthrediridae, Psocus and some others Parthenogenesis takes place, so that there are entire generations consisting only of females without a trace of a male   The case is the same as with some of the lower Crustaceans.17 I fully appreciate your mentioning the asexual reproduction occurring with some of these forms. But I think in giving facts on the proportional numbers of the sexes you might perhaps lay a little more stress on the fact that in very many of these cases any numeration must be incorrect as long as the observer has not satisfied himself that in the case just under his notice Parthenogenesis has not taken place

Believe me, My dear Sir, | Yours most faithfully | Prof J. Victor Carus

Leipzig, 22. April | 1871.

CD annotations

1.1 The … come? 3.2] crossed blue crayon
4.1 May … observation. 6.4] crossed ink
8.1 p. 314.... place 8.11] crossed pencil; ‘Proportion of sexes.’ pencil
8.8 perhaps … place 8.11] scored blue crayon
Top of letter: ‘Proportion. Number of sexes’ pencil


Carus was translating Descent into German for E. Schweizerbart’sche Verlagshandlung (Carus trans. 1871).
The second printing of Descent came out in March and the third in April 1871 (Freeman 1977).
CD told Frans Cornelis Donders that he was at work on his ‘Essay on Expression’ (Expression, published in 1872) in his letter of 18 March 1871. He stated his intention to publish an essay on ‘the expression of the various emotions’ in Descent 1: 5.
The Linnaean order Neuroptera included most of the families that Wilhelm Ferdinand Erichson put into Orthoptera in Erichson 1838.
Ephemeridae are now in the order Ephemeroptera (mayflies).
Libellulidae (common skimmers) are now in the order Odonata (damselflies and dragonflies). Odonata and Ephemeroptera are now placed together in the infraclass Palaeoptera (ancient winged insects).
Perlidae (stoneflies) are in the modern order Plecoptera.
Phryganeidae (large caddisflies) are in the modern order Thichoptera (caddisflies).
Mantispidae (mantidflies), Myrmeleontidae (antlions), and Ascalaphidae (owlflies) are in the modern order Neuroptera (net-winged insects).
Sialidae (alderflies) are in the modern order Megaloptera (alderflies, dobsonflies, fishflies).
Embiidae are in the modern order Embiidina (webspinners).
CD removed the phrase ‘which are now generally ranked as quite distinct’ (Descent 1: 360) from Descent 2d ed. The page reference 261 is an error for 361.
The page reference 261 is an error for 361. Carus evidently refers to Oecanthus niveus, the narrow-winged tree cricket. CD referred to it as Oecanthus nivalis in Descent 1: 361.
Carus evidently refers to Oecanthus pellucens, the European tree cricket. CD added this observation to Descent 2d ed., p. 289 n. 47.
Carus refers to Fischer 1853.
In Descent 1: 416, CD discussed the bright colouring of caterpillars as a warning sign indicating ‘a nauseous taste’ to predators.
CD discussed the rarity of males in some insects and crustaceans in Descent 1: 314–15. He did not mention Carus’s observation in the second edition of Descent.


Descent 2d ed.: The descent of man, and selection in relation to sex. By Charles Darwin. 2d edition. London: John Murray. 1874.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Erichson, Wilhelm Ferdinand. 1838. Verhältnisse der Orthopteren und Neuropteren. Mittheilungen aus den Verhandlungen der Gesellschaft Naturforschender Freunde zu Berlin 3: 10–13.

Expression: The expression of the emotions in man and animals. By Charles Darwin. London: John Murray. 1872.

Fischer, Heinrich. 1853. Orthoptera europaea. Leipzig: G. Engelmann.

Freeman, Richard Broke. 1977. The works of Charles Darwin: an annotated bibliographical handlist. 2d edition. Folkestone, Kent: William Dawson & Sons. Hamden, Conn.: Archon Books, Shoe String Press.


On ratios of the sexes in insects, and other facts relating to sexual selection.

Letter details

Letter no.
Julius Victor Carus
Charles Robert Darwin
Sent from
Source of text
DAR 89: 98–9
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 7708,” accessed on 25 September 2020,

Also published in The Correspondence of Charles Darwin, vol. 19