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Darwin Correspondence Project

From B. D. Walsh   7 November 1864

Rock Island, Illinois, U.S. Nov. 7. 1864 Chas. Darwin Esq. Dear Sir,

Your welcome letter of Oct. 21 was received two days ago.1 I transmit you by this Mail a Paper of mine on “Certain Entomological Speculations of the New England Naturalists”, in which I have taken occasion to show the absurdity of Agassiz’s refutation of the “Origin of Species”.2 Since it was published, I have received a long letter of seven pages of letter-paper from Alex. Agassiz, criticizing in a friendly way sundry passages in it.3 Amongst other things, he observes in regard to my charge that Prof. Agassiz had misstated your theory, that “Darwin in a recent letter to father thanks him for the manner in which he has conducted his opposition to his theory.4 So you see that opinions may differ on the misstatement of Darwin’s Theory”. In reply, I suggested that that fact merely showed that having been abused as an atheist, deist, infidel &c by other writers, you probably felt grateful to any writer who was willing to allow you “a spirit quite as reverential as his own”. (Meth. Study Pref. p. iv.)5

I cannot resist the temptation of quoting the sentiments of a botanical friend of mine,6 to whom I had written that I was about to enter a plea in the great case of Agassiz. vs. Darwin,—“I hope you will give Agassiz a thorough blowing up. It may do some young naturalists good; but as for your penetrating the sublime self-complacency of the great I Am & disturbing his infallible theories, that is another matter. I cannot be so lenient as you are even—to attribute his course of argument to a mind so illogical that he cannot educe a correct conclusion. It is wilful, mean pettifogging—taking hold of every trivial thing that can be twisted into a fancied support of his position—& knowingly ignoring the most patent truths (that of themselves need but be stated to grind his deductions to powder) in a way that is insulting to a person of decent intelligence”.

I do not know what the European Scientific World thinks of Agassiz, but here he is popularly considered as the incarnation of Science & as infallible as the Bible.7 He strikes me as a very much overrated man, who perpetually allows his imagination to get the better of his judgement, & who not unfrequently argues for victory instead of for truth. I have heard him myself in a Public Lecture8 assert in the most unqualified manner as a notorious truth that all the animals of every Geological Epoch were specifically distinct from those of the Epochs preceding & following it & that in the Eocene, Miocene &c periods there merely began to be some approximation to the present order of things. I am told by a New England correspondent,9 who belongs to his School, that he positively denies the truth of the facts upon which the very names Eocene &c are based. Do any European authorities uphold him in these views? I am told Pictet does.10

You ask, “What can be the meaning or use of the great diversity of the external generative organs” in many groups of Insects?11 I don’t know that I can completely explain this matter, which has long occupied my attention, but I can quote you a few facts which throw some little light on it.

1st. In all the Agrionidæ & Libellulidæ, as you are doubtless aware, after the ♂ has embraced the neck of the ♀ with his caudal forceps, no copulation can possibly take place unless the ♀ voluntarily curves her abdomen downwards & forwards so as to meet the ♂ penis. 12 I conceive that the various thorns, tubercles, incurvings & excurvings which we find on the ♂ caudal forceps are so many different appliances for enciting the amorous passions of the ♀ & inducing her to curve her abdomen in the manner necessary to accomplish the coitus. In both sexes of many species, when they are roughly handled after capture, the abdomen is frequently curved downwards in a similar manner, which I suppose originated the English name of “Horse-stingers”. I conceive that a puncture from one of the sharp thorns found on the caudal ♂ forceps of many species would operate in the same manner, & that the first individual that had such a thorn gained an advantage in his amours over his thornless compeers. I have often watched the united sexes careering backwards & forwards for a long time without the ♀ consenting to the coitus.—

2nd. You must often have noticed how repeatedly the ♂ butterfly in many species strikes in the air at the ♀ without effectuating a connection. A very slight change in the shape or armature of his forceps might enable him to sieze the ♀ genitals more readily, & gain an advantage over other ♂ ♂.—

3rdly Simple as the coitus of insects appears, there are four distinct modes in which it is effected. 1st. The normal mode, where the ♂ abdomen squarely surmounts the ♀ abdomen, the ♂ tip curving slightly downwards & the ♀ tip slightly upwards. 2nd. Where the ♂ surmounts the ♀ in the usual manner, but slips the tip of his abdomen sideways under that of the ♀, the penis being erected vertically—


Years ago in England I observed this was the method in the Nepidous genus Ranatra, & I observe it here in Perla & its allies. 3rd. Where the ♂ surmounts the ♀ in the usual manner but curves the tip of his abdomen downwards & forwards by the side of ♀ abdomen, so as to embrace the entire abdomen of the ♀ forward of the vulva, with the caudal forceps a, thus bringing ♂ ♀ genitals into contact,


I observe this method in the Phasmide genus Diapheromera. 4th The well-know coitus of Agrionidæ & Libellulidæ.— There may be other modes which I have not noticed, but these are sufficient to show that there is a great diversity in the mode in which the coitus of insects is effected, & in almost every case the structure of the parts is such that the ♀ can, if she chooses, refuse coition. Hence I conceive has arisen the great variation in the structure & armature of the ♂ organs.

You express a desire to know what my life in this new country is. I will, at the risk of boring you, give you the particulars. When I left England in 1838, I was possessed with an absurd notion that I would live a perfectly natural life, independent of the whole world—in meipso totus teres atque rotundus.13 So I bought several hundred acres of wild land in the wilderness, 20 miles from any settlement that you would call even a village, & with only a single neighbor. There I gradually opened a farm, working myself like a horse day after day, & raising great quantities of hogs & bullocks. Being far away from any mechanics, & having the natural gift of turning my hand to almost anything except blacksmithing, I did all kinds of jobs for myself, from mending a pair of boots to hooping a barrel or putting a new head into it, for the simple reason that it was less trouble to do such work myself than to hitch up my team & drive 10 or 20 miles to a mechanic’s. I suppose I should at this present moment be vegetating there like a cabbage, but there was a Swedish Colony that settled in the neighborhood & dammed up the river everywhere for mill-seats, so that a great deal of malaria was generated & I had some severe attacks of fever, one of which brought me almost to death’s door. So at the end of 12 years I sold out at a great sacrifice, & found that I was just $1000 poorer than when I began. I then moved to Rock Island14 & went into the Lumber business—“lumber” in America means all kinds of sawed boards & planks, “timber” being stuff that is hewed with the broad axe—& in seven years time had made a good many thousand dollars. I then, thinking I had been a slave about long enough, quitted that business, & invested most of my funds in building ten two-story brick houses for rent, upon the proceeds of which & a few of Uncle Sam’s Bonds, I manage to live & keep all the time out of debt. If the times were what they used to be, I should have my whole time to myself & as large an income as I care about. As it is, what with the depreciation of such property & what with the war-taxes &c,15 I have to devote about 14 of my time to executing sundry repairs on my tenements, & the remaining 34 I devote to Entomology. I suppose I have the largest collection of Insects in America, except one or two in the great Atlantic Cities.16

Will you favour me with your Photograph, & if convenient Prof. Westwood’s,17 for my Entomological Album? I enclose you my own.

Believe me, my dear Sir, | very sincerely yours | Benj. D. Walsh

CD annotations

1.1 Your welcome … intelligence”. 2.11] crossed ink; ‘Morphology? | Sexual Organs of | Insects—’ blue crayon over text
3.1 I do not … Pictet does. 3.12] crossed ink
8.1 You express … Atlantic Cities. 8.29] crossed ink
Top of page: ‘Sexual Organs of Insects’ ink, circled ink


Letter to B. D. Walsh, 21 October [1864].
The reference is to Walsh 1864b. Walsh claimed that Louis Agassiz’s Methods of study in natural history (Agassiz 1863b) contained an implicit attack on CD’s theory of species as presented in Origin (see Walsh 1864b, pp. 223–4). Walsh argued that Agassiz had misrepresented CD’s theory, ignoring natural selection and the struggle for existence (Walsh 1864b, pp. 223–31). An annotated copy of Walsh 1864b is in the Darwin Pamphlet Collection–CUL. See also Correspondence vol. 11, letters from Asa Gray, 26 May 1863 and n. 12, and 23 November 1863 and n. 18. For a discussion of Walsh’s public support of CD’s theory, see Sorensen 1995, pp. 199–200 and 211–12.
Walsh refers to Alexander Agassiz, son of Louis Agassiz.
In his letter of 12 April 1864, CD had thanked Agassiz for his presentation copy of Methods of study in natural history (Agassiz 1863b). A lightly annotated copy of Agassiz 1863b is in the Darwin Library–Down (see Marginalia 1: 13). See also letter to B. D. Walsh, 4 December [1864].
In the preface to Methods of study in natural history, Agassiz stated his opposition to ‘the transmutation theory’, allowing that others might hold contrary views ‘in a spirit quite as reverential’ as his own. He insisted, however, that the theory was ‘opposed to the processes of Nature, … contradicted by the facts of Embryology and Paleontology’, and that the experiments upon domesticated animals and cultivated plants, on which its adherents based their views, were ‘entirely foreign to the matter in hand’ (Agassiz 1863b, pp. iii–v). For a discussion of Agassiz’s book and its role in a public campaign against transmutation theory in America, see Lurie 1960, pp. 306–8.
Walsh’s botanical friend has not been identified.
Although Agassiz was highly regarded in American literary and intellectual circles in the 1860s, his reputation among professional naturalists was less secure (see Lurie 1960, pp. 309–11). Agassiz’s scientific reputation among his colleagues at Harvard may have been tainted by jealousy over his success in attracting patronage for his Museum of Comparative Zoology (see Dupree 1959, pp. 224–6, 313–23). On Agassiz’s controversial professional style and his deteriorating relationship with his students during this period, see Winsor 1991, pp. 27–42 and 44–65.
Walsh may have attended one of the public lectures given by Agassiz on his tour of the mid-western United States from December 1863 to March 1864 (see Marcou 1896, 2: 138–9).
Walsh’s New England correspondent has not been identified; however, for a list of Agassiz’s students at Harvard, see Winsor 1991, pp. 35–6.
Walsh refers to François Jules Pictet de la Rive. See letter to B. D. Walsh, 4 December [1864] and n. 7.
See letter to B. D. Walsh, 21 October [1864]. Walsh’s observations of male insects that were structurally adapted for the grasping of females were eventually published in the Practical Entomologist (Walsh 1867, p. 88). CD cited this article in Descent 1: 342.
In Descent 1: 361–4, CD discussed sexual selection in the order Neuroptera, which included Agrionidae, or damsel-flies, and Libellulidae, or dragonflies; on Walsh’s view of the variation of sexual organs, and natural selection, in Neuroptera, see Winsor 1991, pp. 99–100. CD cited Walsh 1862a on differences of coloration between the sexes (ibid., pp. 361–2).
In meipso totus teres atque rotundus: ‘in myself a whole, smoothed and rounded’. The phrase is adapted from Horace’s Satires, 2.7.86, in se ipso totus, teres atque rotundus: ‘in himself a whole, smoothed and rounded’ (Fairclough trans. 1978).
Rock Island is a town on the Mississippi River in north-western Illinois (Columbia gazetteer of the world).
For a discussion of taxes levied by the Union government and economic conditions during the American Civil War, see McPherson 1988, pp. 442–50.
Walsh’s collection was destroyed in the Chicago fire of 1871 (DAB).
The reference is to John Obadiah Westwood. Westwood enclosed a photograph for Walsh in his letter to CD, 2 December 1864. See also letters to B. D. Walsh, 4 December [1864] and [4 December 1864?].


Notes Louis Agassiz’s opinions on CD’s views.

Mating and sexual organs of insects.

Letter details

Letter no.
Benjamin Dann Walsh
Charles Robert Darwin
Sent from
Rock Island, Ill.
Source of text
DAR 181: 10
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 4663,” accessed on 21 November 2017,

Also published in The Correspondence of Charles Darwin, vol. 12