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Darwin Correspondence Project


From B. D. Walsh   12 November 1865

Rock Island. Illinois U.S. Nov. 12, 1865 Chas. Darwin Esq. Dear Sir,

I have not answered sooner your letter of July 9 because, as your health was so poor, I was afraid of worrying you by frequent scribbling.1

I received your Paper on Climbing Plants & was very much interested in it.2 I had always supposed that Climbers had some unknown means of perceiving where there was a twig, or other support suitable for them to grasp, & went straight to their mark as a wolf goes straight at a deer. But this discovery of their sweeping circles & groping in the dark for support, like a blind Cyclops, is very astonishing. And yet, when we consider that plants have no eyes, it is evidently the only possible way, & like the other ways of Nature so beautifully simple. The gradations too that you trace between the different kinds of Climbers are of high philosophical interest. Don’t be afraid that I shall ever find anything which you publish “not worth reading”.3 How you manage to get through such an amount of work is a mystery to me. If I did not know that you had been my Contemporary at college, I should suppose that you must be at least a hundred years old.4 An ordinary life-time seems too brief for what you have accomplished.

I conclude that you are aware that there was a long notice of your Paper in Silliman’s Journal by Asa Gray—the July number if I recollect right.5 He speaks of it in very high terms.

The extract I sent you as from a work by Gen. Paez was, I find, from a work by a son of Gen. Paez. 6 My memory played me false.

I don’t see—with my entomological ideas—how it can be possible for the males of Daphnia or any other genus to produce eggs. There may be dimorphous female forms in the genus, both of which produce eggs, but to call a form which oviposits a male seems to me simply an abuse of language. According to Dr. Minor, quoting from Wagner, both male & female Daphnia oviposit “without sexual influence”, i.e. as I understand it without copulation or any other mode of impregnation.7 Why then call one form a male & the other a female? If there is no impregnation, I don’t see how there can exist any male sexual organs; for, if they had primordial existence, they would have long ago been obliterated by disuse. But probably this may be all very plain to you, though to me, who know but little of Natural History out of my own special department, it is unintelligible. Please, if not too much trouble, lighten my darkness. Perhaps the supposed males are really hermaphrodites.

I sent you a few days ago a Paper of mine on “the new Potato Bug”, out of which you may possibly glean a useful fact or two.8 I have another Paper just ready for the Press “On Phytophagic Species & Unity of Coloration”, which will perhaps be of more interest to you. As soon as printed, I shall of course do myself the pleasure to forward you a copy.9 By the way I was vexed at finding out some months ago, that your Post-office is so rigidly stringent, that they do not allow simple errors of the press to be corrected in MS. in the margin without charging letter postage;10 & that I had in this way, through my thoughtless ignorance, put Mr. Bates to some trouble.11 I shall know better for the future. Here every body does it, & everybody puts as many Pamphlets as they please under a single stamp, provided they don’t exceed the just weight. Whereas I find your Post office requires a separate package & separate stamp for every Pamphlet, even if they each contain but four pages.12

I have been continuing this year my investigations into the Dimorphism of Cynipidæ, & though there are many mysteries still to solve, yet I think I have thrown some additional light upon the question.13 I find that (unless I am mistaken) the agamous dimorphous ♀ form aciculata o.s. produced galls out of which came many specimens of the same agamous female form, (A single ♀ of course out of a single gall, this gall being monothalamous,) & also one ♀ specimen of the copulative ♀ form spongifica. Assuming the truth of the above—and to be quite certain of the truth I have been repeating my experiments this autumn—two consequences follow:—1st. that aciculata & spongifica are necessarily the same species, (as I had concluded from other evidence,) since one gives birth to the other, & 2nd. that an agamous ♀ form may generate the same agamous ♀ form for at least two successive generations & probably for more. My present idea is, that the supposed agamous Cynipidæ generate only agamous ♀ ♀ for an indefinite series of years, say 4 or 5 or 8 or 10, & that then comes forth a brood ♂ ♀ of the copulative dimorphous form. There is an analogy to this in Aphis, some species of which produce a long series of agamous apterous ♀ generations all through the summer & then in the autumn the winged copulative ♂ ♂ ♀ ♀, while others produce the copulative & the agamous forms promiscuously all through the season.

You may perhaps like to know the rationale of my experiments. They proceed upon a postulation, which I have ascertained by long observation & which you must take my word for, viz. that Cynips scarcely ever fly at all but breed from year to year on the same tree. A tree that is infested by a particular species one year, will always have more or less galls of the same species on it the following year; & in the case of those particular kinds of gall (such as spongifica, ficus & poda) which hang on the tree more than 12 months, the particular boughs which bear the old galls are very generally, as I have repeatedly noticed, those which bear the new galls.

First, then, I select Black Oak Trees, which are isolated from others, & which I know have borne no spongifica galls the preceding year. Then in the autumn I place upon each of these trees 8 or 10 lively aciculata, sometimes as high up as I can reach on the trunk, sometimes on the overhanging boughs, taking notes in my Journal of the particular trees & where I placed the insects. Of three trees experimented on thus last autumn, one bore no galls at all, one, a rather small tree, where I had put the insects on the trunk, was covered all over with the galls this spring, so that I had to climb to get them, & the third—a very large tree with overhanging boughs, where I had put all the Cynips on certain particular boughs—had about a dozen galls on these particular boughs, which formed perhaps 120 part of the whole tree, & none whatever on any of the other boughs. Of course, if these galls had been made, not by my bred Cynips, but by wandering individuals, the chances are some 19 to 1 against their selecting the same particular boughs as I did.

I carefully preserved alive the dimorphous ♀ agamous forms raised in each of these cases, & have placed them this autumn on isolated oaks again, so as to find out what they will produce next year. It is tedious having to wait so long for the fruits of one’s labor, but it seems to me the only possible way of solving the enigma. I have tried enclosing the insects on the trees in gauze bags, & the hateful boys will not let them alone.

But I shall tire you to death. Adieu, & may your health soon improve. | Yours ever very truly, | Benj. D. Walsh

P.S. Has Mr. Lubbock arrived at any conclusions on this subject?14


See letter to B. D. Walsh, 9 July [1865].
CD had sent Walsh his paper ‘Climbing plants’ earlier in the year (see letter to B. D. Walsh, 9 July [1865]). No presentation list for the paper has been found.
See letter to B. D. Walsh, 9 July [1865].
See letter from B. D. Walsh, 1 March 1865 and n. 2.
The first part of Asa Gray’s review of ‘Climbing plants’ appeared in the September 1865 issue of the American Journal of Science and Arts (A. Gray 1865–6). The journal was also known as ‘Silliman’s Journal’ after its founder, Benjamin Silliman. See letter from Asa Gray, 6 November 1865 and n. 3.
In his letter of 29 May 1865, Walsh had discussed a passage from Wild scenes in South America, or life in the llanos of Venezuela by Ramón Páez (Paez 1863).
Walsh refers to the review of Wagner 1865 by William Chester Minor (Minor 1865). See letter from B. D. Walsh, 29 May 1865 and n. 14.
Walsh 1865. Walsh’s article ‘The new potato bug, and its natural history’ described a beetle, Doryphora lineata, that had recently migrated from the Rocky Mountain region into the state of Illinois. Walsh suggested that the insect fed on wild species of Solanum, and had migrated eastward as cultivated varieties of Solanum, such as domestic potatoes, were introduced into the Plains region. For a discussion of Walsh’s research on the potato beetle, see Sorensen 1995, pp. 121–5.
The second part of Walsh’s article ‘On phytophagic varieties and phytophagic species’ was published in the December 1865 issue of Proceedings of the Entomological Society of Philadelphia (Walsh 1864–5). CD’s heavily annotated copy is in the Darwin Pamphlet Collection–CUL. Walsh had sent CD the first part of the paper earlier in 1865 (see letter from B. D. Walsh, 1 March 1865 and n. 14); for CD’s comments on it, see the letter to B. D. Walsh, 27 March [1865] and nn. 3 and 5. See also letter from B. D. Walsh, 29 May 1865.
For periodicals carrying the newspaper stamp, British postal regulations prohibited any writing or other marks on the publication, except for the name and address of the recipient; an additional postage of 2d. was charged for a breach of the rule. Each publication had to carry a separate stamp. Offprints of articles, and periodicals published at intervals greater than thirty days, would usually travel by book post. A book packet could contain any number of separate publications, but no letters or ‘communication of the nature of a letter’; packets containing such communications were charged additional postage (British postal guide, 1 July 1865, pp. 10–14).
Henry Walter Bates. Walsh had sent copies of some of his papers to Bates earlier in the year (see letter from H. W. Bates, 22 March 1865).
See n. 10, above.
Walsh had sent CD an article on dimorphism in Cynips in 1864 (see Correspondence vol. 12, letter from B. D. Walsh, 29 April – 19 May 1864, and letters to B. D. Walsh, 21 October [1864] and 4 December [1864]). Walsh argued that the gall insect Cynips quercus aciculata, hitherto regarded as a distinct species, was a dimorphic female form of C. q. spongifica (Walsh 1864a, pp. 447–8). See also letter from B. D. Walsh, 1 March 1865, and letter to B. D. Walsh, 27 March [1865]. No further article by Walsh on the subject has been found.
CD had forwarded Walsh 1864a to John Lubbock, who wrote a brief notice of the paper in the January 1865 issue of Natural History Review, pp. 138–41. Lubbock thought the evidence for dimorphism in Cynips was inconclusive (see Correspondence vol. 12, letter from John Lubbock, 3 November 1864, and Lubbock 1865, p. 141)


Acknowledges CD’s paper on "Climbing plants".

Mentions Asa Gray’s complimentary notice in Silliman’s Journal [Am. J. Sci. and Arts 2d ser. 40 (1865): 273–82].

His difficulty in understanding how males of Daphnia or any other genus can produce eggs. If there is no impregnation, how can there be sexual organs? Why call one form male and another female?

He has sent CD his paper on "the new Potato Bug".

Will soon send "On Phytophagi Species & Unity of Coloration". [phytophagic!?]

Complaints about practices of the English Post Office.

His current research and description of the rationale of his experiments.

Letter details

Letter no.
Walsh, B. D.
Darwin, C. R.
Sent from
Rock Island, Ill.
Source of text
Field Museum of Natural History, Chicago (Riley bequest of 1948)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 4934A,” accessed on 28 August 2016,