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Letter 3934

Darwin, C. R. to Scott, John

21 Jan [1863]

    Summary Add

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    Urges JS to publish on orchid pollen-tubes.

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    Suggests comparing stigmatic tissue of sterile hybrids and fertile parent; he would expect hybrid plant's cell contents not to be coagulated after 24 hours in spirits of wine.

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    Suggests JS coat orchid stigmas with plaster of Paris for his work on rostellar germination.

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    Asks for list of "bud-variation" cases; CD has devoted a chapter to the subject.

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    Inquiries about I. Anderson-Henry's observational competence.

Transcription

Down Bromley Kent

Jan. 21st

Dear Sir

I thank you for your very interesting letter; I must answer as briefly as I can, for I have a heap of other letters to answer. I strongly advise you to follow up & publish your observations on the pollen-tubes of orchids; they promise to be very interesting. If you could prove what I only conjectured (from state of utriculi in Rostellum & in stigma of Catasetum & Acropera) that the utriculi somehow induce or are connected with penetration of pollen-tubes you will make an important physiological discovery. I will mention, as worth your attention (& what I have anxiously wished to observe, if time had permitted & still hope to do) viz the state of tissues or cells of stigma in an utterly sterile hybrid, in comparison with the same in fertile parent-species: to test these cells, immerse stigmas for 48 hours in spirits of wine; I shd. expect in hybrids that the cells would not show coagulated contents. It would be interesting discovery to show difference in female organs of hybrids & pure species. Anyhow it is worth trial & I recommend you to make it & publish if you do.—

The pollen-tubes directing themselves to stigma is also very curious; though not quite so new; but well worth investigation when you get Cattleya &c in flower.— I say not so new; for remember small flower of Viola & Oxalis; or better, see Bibliography of Nat. Hist. Review Part VIII. p. 419—(Oct 1862) for quotation from M. Baillon, on pollen tubes finding way from anthers to stigma in Helianthemum. I shd. doubt gum getting solid from continued secretion. Why not sprinkle fresh Plaister of Paris & make impenetrable crust? You might modify experiment by making little hole on one lower corner, & see if tubes find it out.— See in my future paper on Linum pollen & stigma recognising each other.— If you will tell me that pollen smells the stigma I will try & believe you; but I will not believe the Frenchman (I forget who) who says that Stigma of Vanilla actually attracts mechanically by some unknown force the solid pollen-masses to it!

Read Asa Gray in 2d Review of my Orchis Book on pollen of Gymnadenia penetrating rostellum; I can, if you like, lend you these Reviews; but they must be returned.— R. Brown, I remember, says pollen-tubes separate from grains before the lower ends of tubes reach ovules.— I saw, & was interested by, abstract of your Drosera paper: we have been at very much same work.—

With respect to bud-variation: perhaps it would give you the least trouble first to send me mere list. I have devoted whole Chapter to subject. Perhaps it will be best to specify cases which interest me most—variation by modified buds as bulbs or tubers—or underground as suckers—anything on inheritance from seed of the varying buds—, whether parents are crossed plants, & whether the variation is case of Reversion. Of course the more marked the variation is so much better. I do not care for mere zoned leaves, unless something unusual about them.

I have hitherto just alluded to every case of change in colour in flower, especially if accompanied by any other change. Mr Salter & Mr Rivers are aiding me.—

With respect to Ferns I am so ignorant that I hardly know what to do. Am I right in supposing (probably I am wrong) that a spore (whether spore be unfertilised ovule or bud) from a variagted branch produces a thallus, & this produces the two sexual individuals & from their union a variegated fern is produced; if so, the case would not come under variation independent of sexual union. Please briefly illuminate my ignorance.—

Mr. Bridgman sent me his paper.—

Asa Gray has sent me a few white & red seed of N. England Popping very small seeded maize; shall you experiment on this; if so these would be good to cross with some large kind of different colour.— Shall I send??

Yesterday I had very kind letter from Mr I. Anderson Henry, of Hay Lodge, Trinity offering to try any experiment for me. I have suggested peloric flowers & pollen of short stamens of Pelargonium.— Please tell me in strict confidence whether you think him a good observer; from his short papers, I say to you in confidence that I doubt it.— You will see that it is of paramount importance for me not to waste time in suggesting experiments &c & asking for information from an inaccurate observer.—

Excuse this hurried letter. | Dear Sir | Yours very faithfully | Chs. Darwin

I hardly know what to say on your view of male & female organs & variability.— I must think more over it. But I was amused by finding the other day in my Portfolio devoted to Bud-variation, a slip of paper dated June 1860, with some such words as these ``May not permanence of grafted buds be due to the two sexual elements, derived from different part not having come into play?'' I had utterly forgotten, when I read your paper, that any analogous notion had ever passed through my mind—nor can I now remember, but the slip shows me that it had.—

    Footnotes Add

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    f1 3934.f1
    The year is established by the relationship between this letter and the letter from John Scott, 16 January 1863.
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    f2 3934.f2
    Letter from John Scott, 16 January 1863.
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    f3 3934.f3
    In his letter of 16 January 1863, Scott provided CD with an account of some of his observations on the pollination of orchids and the paths of pollen tubes (see n. 4, below). These observations were undertaken at CD's suggestion to discover whether the rostellum retained any of its rudimentary stigmatic functions. In his letter to Scott of 3 December [1862] (Correspondence vol. 10), CD asked Scott to try to split the labellum of a Cattleya, or an allied orchid, and place a single pollen-mass `carefully into the large tongue-like Rostellum, & see if pollen-tubes will penetrate'. Scott published accounts of his work on orchid pollination in Scott 1863a and 1864b, copies of which are in the Darwin Pamphlet Collection--CUL.
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    f4 3934.f4
    For CD's discussion of the stigma and rostellum in Catasetum and Acropera, see Orchids, pp. 204--7 and 237--8. He discussed the possible derivation of the rostellum from the stigma on pp. 307--23. In his letter of 16 January 1863, Scott told CD that his observations tended to confirm the view that the absence of the coherent spindle-formed utriculi from the rostellum was related to the infertility of the organ, that is, that pollen tubes did not penetrate it. See letter from John Scott, 16 January 1863 and n. 6.
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    f5 3934.f5
    CD had previously used this method to examine stigmas, though not to compare those of a sterile hybrid and a fertile parent (see Orchids, pp. 206--7). See also Correspondence vol. 10, letter to Daniel Oliver, 8 June [1862], and this volume, letter to Isaac Anderson-Henry, 20 January [1863].
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    f6 3934.f6
    See letter from John Scott, 16 January 1863.
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    f7 3934.f7
    The references are to Daniel Oliver's bibliographic review of botanical literature in the Natural History Review ([Oliver] 1862a, p. 419), and to Baillon 1861, p. 56.
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    f8 3934.f8
    In his letter to CD of 16 January 1863, Scott suggested putting a `thickish solution of gum to stigma and allowing it to harden, before applying pollen-mass to rostellum', in order to test whether pollen tubes would penetrate the rostellum.
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    f9 3934.f9
    `Two forms in species of Linum', p. 75 (Collected papers 2: 98). CD's paper on Linum was read before the Linnean Society on 5 February 1863 (see letter from George Bentham, 16 January 1863).
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    f10 3934.f10
    The reference has not been identified. In his letter of 16 January 1863, Scott wrote: `A latent provisional force, an almost conscious sympathy … seems to exist between pollen and stigma, and is strikingly evoked, when these are not directly and normally applied to each other'.
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    f11 3934.f11
    A. Gray 1862a, p. 426.
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    f12 3934.f12
    Robert Brown 1831b, p. 705.
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    f13 3934.f13
    An abstract of Scott's paper, `On the propagation and irritability of Drosera and Dionæa', read at a meeting of the Botanical Society of Edinburgh on 11 December 1862, appeared in the Gardeners' Chronicle, 10 January 1863, p. 30. An abstract was also published in the Transactions of the Botanical Society [of Edinburgh] 7: 429--30 (Scott 1862b).
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    f14 3934.f14
    CD began writing chapter 11 of Variation, dealing with `bud-variation', on 21 December 1862 (Correspondence vol. 10, Appendix II); in his letter to Scott of 19 December [1862], CD asked Scott to provide him with any cases of `what Gardeners sometimes call sports, & which I shall call ``bud-variation'''. In his letter of 16 January 1863, Scott asked whether CD merely wanted lists of plants presenting variations or `the history of each'.
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    f15 3934.f15
    Scott had asked whether CD was interested in changes in colours of flowers (see letter from John Scott, 16 January 1863). CD refers to John Salter, proprietor of the Williams Street nursery in Hammersmith, London (R. Desmond 1994). Salter was cited several times in chapter 11 of Variation on bud-variations in pelargoniums, chrysanthemums, and Phlox (see Variation 1: 378--9); however, no correspondence on these points has been found. CD also refers to the Hertfordshire nurseryman, Thomas Rivers, whom he cited on bud-variation in roses (see Variation 1: 379--81). For their correspondence on bud-variation, see the letters to Thomas Rivers, 7 January [1863], 11 January [1863], and 15 January [1863].
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    f16 3934.f16
    In his letter of 16 January 1863, Scott asked CD whether he intended to discuss ferns. See also letter to John Scott, 16 February [1863] and nn. 7--8. Ferns were briefly discussed in Variation; the reader was referred to Bridgman 1861 and Scott 1862a (Variation 1: 383).
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    f17 3934.f17
    William Kencely Bridgman; see n. 16, above.
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    f18 3934.f18
    See Correspondence vol. 10, letter from Asa Gray, 29 December 1862. See also letter to Asa Gray, 19 January [1863] and n. 3.
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    f19 3934.f19
    Letter from Isaac Anderson-Henry, 17 January 1863.
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    f20 3934.f20
    See letter to Isaac Anderson-Henry, 20 January [1863].
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    f21 3934.f21
    CD may refer to Isaac Anderson-Henry's contributions to the discussions regarding variegation in plants in the Gardeners' Chronicle and the Journal of Horticulture in 1861 (Gardeners' Chronicle, 11 May 1861, pp. 432--3; Journal of Horticulture n.s. 2 (1861): 41--3). Scott's reply has not been found (see letter to John Scott, 16 February [1863]).
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    f22 3934.f22
    Scott enclosed a copy of his paper on fern spores (Scott 1862a) with his letter to CD of 6 December [1862] (Correspondence vol. 10). He argued that ferns, the product of a single organ, presented the most favourable opportunity for reproducing individual variations (see letter from John Scott, 16 January 1863 and n. 11). There is an annotated copy of Scott 1862a in the Darwin Pamphlet Collection--CUL.
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    f23 3934.f23
    CD's note has not been found. CD discussed bud-variation in chapter 11 of Variation (Variation 1: 373--411).
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