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Letter 4438

Scott, John to Darwin, C. R.

28 Mar 1864

    Summary Add

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    Surprised at CD's account of Bryanthus.

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    H. Crüger's approach to Gongora fertilisation is beset with difficulties.

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    Reports his work on self-sterility of Oncidium.

Transcription

Denholm

28th. Mar. 1864.

Sir.

I am surprised with the account you give of Bryanthus! I regret having noticed it at all in my case paper—but it is now too late to correct as the Journal containing it will be out in the beginning of April… Strangely enough, however, Mr. I. Ander<son> Henry has lately—in the `Scottish Farmer' if I recollect rightly— stated, that he has actually raised the <Bryan>thus by crossing the Rhod. Chamaecistus and Menzesia empetrifolia. I have made several unsuccessful attempts to cross inter se the presumed parents, & the latter with the Bryanthus. It was <    > to have made the latter—when I had time— a <    > the following out your suggestions on the relative changes in the structure of hybrids & parents. From my examinations of the plants in the Botanic Gardens, I may state that its reproductive organs are clearly in an abnormal condition.

As Dr Crüger discusses the fertilisation of Gongora, I will not proceed further with Acropera until I have an opportunity of reading it. His idea as to the mode in which effected is curious—indeed from the point of view which I have been accustomed to take beset with difficulties.

As to the after-secretion of nectar on column of Acropera, I was inclined to regard it as somewhat different from the Vanilla case; inasmuch as in the former it only occurs after fertilisation has been perfectly effected— unfertilised flowers never in my observations secreting a single drop. I suppose in the Vanilla there are no such relations.

Your health I daresay will never have permitted your undertaking—as you intended—the work of estimating the number of seed <in a> capsule of Acropera. I have spent sometime at the <ta>sk. My results are truly astounding. In <    > measuring 212 in. long by 34 of an inch in diameter, full of the minute seed—my calculations give the prodigious number of 371,250! This is the mean result of the following modes. 1. I carefully measured of one-eight of an inch of the capsule: cutting this off I arranged the contained seed as equably as possible in line carefully measured, & counted the number contained in the 12th. of an inch. 2. I carefully arranged the seeds in spaces accurately measured off at 3 lines sq. counting the number contained in one space. I then similarly arranged all the seeds contained in the capsule.—— I have been struck with the prodigal fertility of our own humble orchids—as shown by your calculations—but how incomparably more so have I been when considering the results of my own computation on Acropera: These would indeed; have been surprising enough, had the product of the single capsule—given above—been the sum-total of its annual flowering; but when we consider the number of racemes annually produced <from a> single raceme of Gong. atropurpurea I have fert<ilised> above 20 flowers) we can only look in silent wonderment at Nature's prodigality. I should like much to hear if you have yet <    > on the productiveness of the larger e<    > orchids.

I have now the pleasure to communicate to you the most interesting—as I am inclined to think—of all my illustrations of the self-sterility of Orchids. The following were the subjects—Oncidium microchilum, O. divaricatum var. cupreum and O. ornithorynchum; all the plants belonging the Botanic Gardens Edinburgh. First on two plants of the O. michrochilum I made numerous attempts to fertilise either with own-pollen, yet in no case did I succeed though the flowers exhibited the usual symptoms of affection with pollen-tubes—in their shrivelling up & closing of stigmatic chamber. I then reciprocally fertilised the two plants, and had the following results. From plant No. 1: 6 flowers fertilised by pollen of No. 2, 4 flowers yielded good capsules. Again plant No. 2. 6 flowers fertilised by pollen of No. 1, did not yield a single capsule. A repetition of the latter experiment gave the self same result. I next tried O. microchilum No. 1 by pollen of O. divaricatum, cupreum—6 fl. fertilised produced 2 good capsules; 6 fl. of the latter fertilised by the former gave 4 capsules.— O. michrochilum no. 2. 6 fl. fertilised by pollen of O. divaricatum, cupreum produced two capsules but both dropped early. A repetition of this experiment gave no better re<sult.> From 6 fl. of O. divaricatum cupreum fertilised by pollen <of> michrochilum No. 2, 3 capsules were produced. Again <    > plants of O. michrochilum ultimately proved sterile to pollen <of O. ornith>orhynchum: though by applying the pollinia of the for<mer to th>e latter, I had in the one case from <8> fl. <5> cap. <    > the other, from 8 fl. 3 cap. . . The enclosed table will best show the complex relations of the above.

I have elicited an analogous case to the above in my experiments on the Passiflora cærulea. As I have now got my experiments on the Passiflora tabulated, I will if you like send you up copies. Would it not be necessary in drawing up a paper on these to notice the results of former experimenters? If so I really could not undertake it at present: as I have here no books for reference.

I will be glad to hear from you—when your health permits—on any of the points worth noticing in the above.

I remain | Sir | Yours most respectfully | J. Scott

P.S. | I am sorry to trouble you—in your present weak state of health—with anything concerning my future plans; but as you have so kindly desired me, I will do so as briefly as possible.

In respect to future plans, I regret to state that I have no definite plans whatever to look to.— I left the Bot. Gard. Edinburgh completely chagrined with my masters behaviour to me.— Though there have been several young men sent out to India by Prof. Balfour & Mr. Mc. Nab since I refused to accept the situation they offered me at Darjeeling—respecting which perhaps you may remember I consulted you—they have never given me another offer. (And I know there has been one or two really good places at their disposal). I felt this repeated overlooking very deeply, as I had been led to hope that they would do what they could to get me some foreign situation.

Seeing, however, the utter hopelessness of entertaining this further, I with the completion of the experiment, in which I was immediately engaged intimated to Mr. Mc.Nab my intention to leave, which I did at the conclusion of my 5th. year in his service.

I would be glad indeed, if I might yet be permitted to entertain the hope that Dr. Hooker will `remember me when any place likely to suit, comes under his notice'—as he was once induced to write by the kind interest you were pleased to honour me with.

Sincerely regretting that I should have had any occasion for troubling you—more especially at present—with these merely personal details | I remain | Sir | J. Scott

    Footnotes Add

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    f1 4438.f1
    The letter giving CD's account of Bryanthus has not been found. Scott had referred to the `bigeneric hybrid' Bryanthus erectus in his letter of 19 March 1864. Bryanthus erectus is now known as Phyllothamnus erectus, an intergeneric hybrid.
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    f2 4438.f2
    In Scott 1864c, which Scott had evidently already sent to the Edinburgh New Philosophical Journal, a note on pp. 199--200 referred to Bryanthus erectus as a cross between Rhododendron chamaecistus and Menziesia empetrifolia. See also letter from John Scott, 19 March 1864 and n. 9.
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    f3 4438.f3
    The article by Isaac Anderson-Henry has not been found in the Scottish Farmer; however, see Anderson-Henry 1867, p. 2. An annotated copy of Anderson-Henry 1867 is in the Darwin Pamphlet Collection--CUL. In 1863, Anderson-Henry reported to CD his successful production of Bryanthus erectus from crossing the two genera Rhodothamnus and Menziesia (see Correspondence vol. 11, letter from Isaac Anderson-Henry, 24 April 1863 and nn. 5 and 6). See also Bean 1970--88, 3: 173.
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    f4 4438.f4
    Scott had mentioned his intention of crossing Bryanthus in his letter of 6 January 1863 (Correspondence vol. 11). He reported his failure to pollinate the plant in Scott 1864c, pp. 199--200 n.
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    f5 4438.f5
    For CD's suggestions for Scott's research, see, for example, Correspondence vol. 10, first enclosure to letter to John Scott, 19 December [1862], and Appendix VI.
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    f6 4438.f6
    Scott refers to Crüger 1864, which CD had communicated to the Linnean Society (see letter from John Scott, 19 March 1864 and nn. 7 and 20). Crüger discussed Gongora pollination in Crüger 1864, pp. 130--1. Scott had recently experimented with the related orchid, Acropera (see letter from John Scott, 19 March 1864 and nn. 12--18).
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    f7 4438.f7
    For Scott's discussion of nectar secretion in Acropera, see the letter from John Scott, 19 March 1864 and n. 15. The letter in which CD discussed Vanilla nectar is missing, but see Orchids, pp. 270 and 278. For CD's observations on Vanilla, see the letter to J. D. Hooker, 26[--7] March [1864] and n. 9.
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    f8 4438.f8
    See Correspondence vol. 10, letter to John Scott, 19 November [1862], and Correspondence vol. 11, letter to John Scott, 2 May [1863] and nn. 5 and 6; see also Correspondence vol. 10, letter to J. D. Hooker, 18 [November 1862].
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    f9 4438.f9
    CD reported Scott's figure for Acropera seeds per capsule in Variation 2: 379, `Fertilization of orchids', p. 158 (Collected papers 2: 155), and Orchids 2d ed., p. 278.
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    f10 4438.f10
    CD had devised a method similar to Scott's for counting large numbers of orchid seeds and had calculated the number per capsule for at least two British orchid species (see Orchids, pp. 343--5, and Variation 2: 379 n.).
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    f11 4438.f11
    CD included this information on Gongora atropurpurea in Variation 2: 379 n. For Scott's work with Gongora atropurpurea pollination, see Correspondence vol. 11, letters from John Scott, 6 January 1863 and 3 March 1863. See also letter from John Scott, 19 March 1864 and nn. 16--18.
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    f12 4438.f12
    CD added information on orchid seed production from his own calculations and from those of others to Orchids 2d ed., p. 278; these included Scott's estimate of the number of Acropera seeds. See also Variation 2: 379 n., and `Fertilization of orchids', p. 158 (Collected papers 2: 155).
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    f13 4438.f13
    Scott wrote a paper including the results of this work with the Oncidium species (see Scott 1864b, pp. 165--6). Scott had already published a paper on orchids (Scott 1863a), which included some earlier experiments on Oncidium (see Correspondence vol. 11, letter to John Scott, 1 and 3 August [1863] and nn. 2--6 and 10).
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    f14 4438.f14
    Some of this damaged portion of the letter has been reconstructed using the same data reported in Scott 1864b, p. 164.
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    f15 4438.f15
    The enclosure has not been found; however, the results of Scott's crosses are tabulated in Scott 1864b, p. 166.
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    f16 4438.f16
    For Scott's work on Passiflora, see the letter from John Scott, 19 March 1864 and n. 21. For CD's advice about working with P. caerulea in particular, see Correspondence vol. 11, letter to John Scott, 6 March 1863 and n. 15.
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    f17 4438.f17
    Scott sent his final results on Passiflora to CD on 9 June 1864 (see the first letter from John Scott, 10 June [1864]). The results of Scott's Passiflora experiments were published in Scott 1864d, `Notes on the sterility and hybridization of certain species of Passiflora, Disemma, and Tacsonia'; the paper did not include results of experiments other than Scott's. CD reported Scott's Passiflora results in Variation 2: 137 as examples of self-sterile plants; see also Cross and self fertilisation, p. 330.
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    f18 4438.f18
    CD evidently inquired in a missing letter about Scott's plans following his departure from his position at the Royal Botanic Garden, Edinburgh (see letter from John Scott, 10 March 1864, and letter to J. D. Hooker, 26[--7] March [1864] and n. 11).
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    f19 4438.f19
    Scott refers to his immediate supervisor, James McNab, curator of the Royal Botanic Garden, Edinburgh, where Scott had been foreman of the propagating department, and to John Hutton Balfour, keeper of the Royal Botanic Garden, Edinburgh (J. W. Kennedy 1908, R. Desmond 1994). For Scott's consultation of CD regarding the position at a Cinchona plantation in Darjeeling and his subsequent refusal of the position, see Correspondence vol. 11, letters from John Scott, 22 May 1863 and 26 May [1863]. See also ibid., letter from John Scott, [3 June 1863].
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    f20 4438.f20
    Hooker sent a note to CD with his letter of [23--7 May 1863] (Correspondence vol. 11), which CD then forwarded with his letter to Scott of 25 and 28 May [1863]. See also letter to John Scott, 11 June [1863].
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