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Letter 3844

Darwin, C. R. to Scott, John

3 Dec [1862]

    Summary Add

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    JS's facts on Primula are new to CD.

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    In Linum CD has also found dimorphic and non-dimorphic species.

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    Plans to publish next autumn on successive homomorphic generations in Primula.

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    "Fluctuating forms" due to culture.

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    Urges JS to publish.

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    Lobelia functionally monoecious.

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    Where did JS publish on Clivia hybrids? Did he count parent and cross seeds, as Gärtner shows is necessary?

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    CD has done large experiments on artificially fertilised cowslips. They never resemble oxlips.

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    Would welcome detailed criticism of natural selection by a careful observer like JS. Most criticism worthless. Expects a great deal from Lyell's reaction.

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    Suggests JS do orchid experiment to see if rostellum can be penetrated by pollen.

Transcription

Down Bromley Kent

Dec. 3d

Dear Sir

What a capital observer you are! & how well you have worked the Primulas. All your facts are new to me. It is likely that I overrate the interest of the subject; but it seems to me that you ought to publish a paper on the subject.— It would, however, greatly add to value, if you were to cover up any of the forms having pistil & anthers of same height, & prove that they were fully self-fertile. The occurrence of dimorphic & non-dimorphic species in same genus is quite the same as I find in Linum.— Have any of the forms of Primula, which are non-dimorphic been propagated for some little time by seed in garden?— I suppose not: I ask because I find in P. Sinensis, a third, rather fluctuating form, apparently due to culture, with stigma & anthers of same height.— I have been working successive generations homorphically of this Primula & think I am getting curious results: I shall probably publish next autumn; & if you do not (but I hope you will) publish yourself previously, I shd. be glad to quote in abstract some of your facts.— But I repeat that I hope you will yourself publish—

Hottonia is dimorphic, with pollen of very different sizes in the two forms.—

I think you are mistaken about Siphocampylus; but I feel rather doubtful in saying this to so good an observer: In Lobelia the closed pistil grows rapidly & pushes out the pollen, & then the stigma expands; & the flower in function is monoicous; from appearance I believe this is case with your plant.— I hope it is so; for this plant can hardly require a cross, being in function monoicous; so that dimorphism in such a case would be a heavy blow to understanding its nature or good, in all other cases.—

I see few periodicals; where have you published on Clivia? I suppose that you did not actually count the seeds in the hybrids in comparison with those of the parent-forms; but this is almost necessary after Gärtner's observations—

I very much hope you will make a good series of comparative trials on the same plant of Tacsonia.—

I have raised 700--800 seedlings from cowslips, artificially fertilised with care; & they presented not a hairs-bredth approach to Oxlips.— I have now seed in pots from Cowslip fertilised by pollen of Primrose, & I hope they will grow; I have also got fine seedlings from seed of wild Oxlips; so I hope to make out this case.—

You speak of difficulties on Natural Selection; there are indeed plenty; if ever you have spare time (which is not likely, as I am sure you must be a hard worker) I shd. be very glad to hear difficulties from one who has observed so much as you have.— The majority of criticisms on the ``Origin'' are in my opinion not worth the paper they are printed on. Sir C. Lyell is coming out with what, I expect, will prove really good remarks.— Pray do not think me intrusive; but if you would like to have any Book I have published, such as my Journal of Researches or the Origin, I shd. esteem it a compliment to be allowed to send it.—

Will you permit me to suggest one experiment, which I shd. much like to see tried, & which I now wish the more from an extraordinary observation by Asa Gray (in number just out of Sillimans N. American Journal) on Gymnenadia tridentata.— Namely to split the labellum of a Cattleya, or of some allied orchis,—remove caudicle from pollen-mass (so that no lose grains are about) & put it carefully into the large tongue-like Rostellum, & see if pollen-tubes will penetrate, or better, see if capsule will swell— Similar pollen-mass ought to be put on true stigmas of 2 or 3 other flowers of same plant for comparison.— It is to discover whether Rostellum yet retains some of its primordial function of being penetrated by pollen-tubes.—

You will be sorry you ever entered into correspondence with me.— But do not answer till at leisure, & as briefly as you like.— My hand-writing, I know, is dreadfully bad—

Excuse this scribbling paper, as I can write faster on it, & I have a rather large correspondence to keep up.—

with sincere thanks for all your very interesting information— I remain | Dear Sir | Yours very faithfully | Ch. Darwin

Many thanks about capsule of Orchis for comparison with that of Acropera—

    Footnotes Add

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    f1 3844.f1
    The year is established by the relationship to the letter from John Scott, 6 December [1862].
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    f2 3844.f2
    See letter from John Scott, [20 November -- 2 December 1862]; some of Scott's comments on the genus Primula were included in the missing portion of that letter. In a note dated 3 December 1862 (see Correspondence vol. 10, Appendix VI), CD referred to a list, provided by Scott, containing information about species of Primula; the list has not been found, but was apparently sent with Scott's letter of [20 November -- 2 December 1862] (see letter from John Scott, 6 December [1862] and n. 3).
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    f3 3844.f3
    After further research, Scott wrote a paper entitled `Observations on the functions and structure of the reproductive organs in the Primulaceæ' (Scott 1864c), which was communicated by CD to the Linnean Society of London in 1864.
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    f4 3844.f4
    See `Two forms in species of Linum', pp. 82--3 (Collected papers 2: 104--5). According to his Journal (Correspondence vol. 10, Appendix II), CD wrote this paper between 11 and 21 December 1862.
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    f5 3844.f5
    In `Illegitimate offspring of dimorphic and trimorphic plants', p. 414, CD recalled that his interest in the equal-styled variety of Primula sinensis first arose in 1862, following his observation of some anomalous flowers in a long-styled plant, descended from a self-pollinated long-styled parent. He reported that upon subsequent examination of the plants `in several small collections', he had discovered that the equal-styled variety was `not rare' (ibid., p. 415). CD's notes on these observations, dated 1--30 March and 24 April 1862, are in DAR 108: 56--66.
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    f6 3844.f6
    CD carried out crossing experiments with Primula sinensis in 1861 (see `Dimorphic condition in Primula', pp. 87--8; see also Collected papers 2: 54--6); he subsequently raised plants from the seeds resulting from those experiments in which plants were crossed with their own-form pollen (what CD called `homomorphic unions' and later renamed as `illegitimate unions'). With this second generation of plants CD carried out further homomorphic crosses in late January and February 1862, the results of which were published in `Illegitimate offspring of dimorphic and trimorphic plants', pp. 410--18 (see also the experimental notes in DAR 108: 15--18, 26--8, 34--9). The experiments were designed to investigate the phenomena of cross and hybrid sterility (see Correspondence vol. 10, Appendix VI and `Illegitimate offspring of dimorphic and trimorphic plants', pp. 431--7). `Illegitimate offspring of dimorphic and trimorphic plants' was read before the Linnean Society on 20 February 1868.
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    f7 3844.f7
    See letter from M. S. Wedgwood, [6 August 1862] and n. 2.
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    f8 3844.f8
    The letter from John Scott, [20 November -- 2 December 1862], is incomplete; Scott evidently commented on Siphocampylus in the portion that is now missing.
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    f9 3844.f9
    CD discussed this case in Origin, p. 98.
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    f10 3844.f10
    Scott mentioned some crossing experiments that he had carried out with species of Clivia in his letter to CD of [20 November -- 2 December 1862]; he had not, however, published an account of his experiments (see letter from John Scott, 6 December [1862]).
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    f11 3844.f11
    CD refers to Karl Friedrich von Gärtner's practice of assessing the degree of inter-sterility of two plants by the number of seeds produced from the hybrid cross, as compared with the number produced by pure-type parents (Gärtner 1849, pp. 207--15). CD's heavily annotated copy of Gärtner 1849 is in the Darwin Library--CUL (see Marginalia 1: 256--98). CD described Gärtner's practice in Origin, p. 247.
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    f12 3844.f12
    See letter from John Scott, [20 November -- 2 December 1862].
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    f13 3844.f13
    See letter from John Scott, [20 November -- 2 December 1862] and n. 2. CD was interested in the commonly held view that oxlips were the hybrid offspring of primroses and cowslips. He initially maintained that the various forms were varieties descended from a common parent (Natural selection, pp. 128--33, and Origin, pp. 49--50), but as a result of his work on dimorphism in Primula, he came to distrust the experimental evidence against the occurrence of hybridisation, stating that further experiments were `absolutely necessary' (`Dimorphic condition in Primula', pp. 93--4; see also Collected papers 2: 60--1). In a note in his Experiment book (DAR 157a, p. 75), dated 21 April 1862, CD reported that since 1859 he had grown several generations of artificially pollinated cowslips (amounting to 765 plants), in order to ascertain whether they would vary under changed conditions of culture, without a `vestige of a sign of modification'. These findings were reported in `Specific difference in Primula', p. 442.
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    f14 3844.f14
    CD began his crossing experiments with cowslips and primroses in April 1862 (see the dated notes in DAR 157a, pp. 76--7 and DAR 108: 70). He continued to carry out similar experiments between 1863 and 1867, the results of which are recorded in DAR 108 and in `Specific difference in Primula', pp. 438--40.
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    f15 3844.f15
    There are notes on these seedlings, dated 27 April 1862, in DAR 157a, pp. 75--7. CD's crossing experiments with oxlips, carried out over succeeding years, are detailed in DAR 108 and in `Specific difference in Primula', pp. 443--5. CD eventually concluded that the common cowslip, the primrose, and the Bardfield oxlip were distinct species, but that the common oxlip was a hybrid between the cowslip and the primrose.
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    f16 3844.f16
    See letter from John Scott, [20 November -- 2 December 1862].
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    f17 3844.f17
    CD refers to Charles Lyell's Antiquity of man (C. Lyell 1863a), which was published on 6 February 1863 (C. Lyell 1863b, p. vii).
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    f18 3844.f18
    In A. Gray 1862b, p. 426, Asa Gray reported that pollen falling onto certain viscid parts of the rostellum in the orchid Gymnadenia tridentata, readily sent pollen tubes into it, and that those parts of the rostellum appeared `to act as stigmas'. In the letter to Asa Gray, 26[--7] November [1862], CD mentioned that this observation anticipated an experiment he was intending to try with Cattleya. Gray's paper appeared in the November issue of the American Journal of Science and Arts, commonly known as `Silliman's journal' after its founding editor, Benjamin Silliman.
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    f19 3844.f19
    See letter from John Scott, [20 November -- 2 December 1862] and n. 8.
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