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Letter 4382

Scott, John to Darwin, C. R.

7 Jan [1864]

    Summary Add

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    Has finished correcting Primula paper [see 4332].

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    Has presented paper on monoecious spikes of maize [Edinburgh New Philos. J. 2d ser. 19 (1864): 213–20].

Transcription

Botanic Gardens [Edinburgh]

7th. Jany.

Sir.

I have at last finished—and sent off by todays mail—, in so far as I am able my paper on Primulas. It has proved much too heavy a subject for my pen; and I feel deeply that, after all my endeavours together with the assistance of your excellent suggestions, I should still be so miserably short of even satisfying myself. I should have sent it up to you sometime ago, but I have always been trying to improve it and so give you less trouble, for I feel quite ashamed to draw so much upon your kindness, knowing well how fully your time is engaged with your own works. Pray excuse me.

When you time to look it over you will find that in re-writing it I have been greatly benefited by your criticisms. On page 52. you will observe that I have excluded discussion on relations of Primroses & Cowslips. A few private remarks are attached. Perhaps you will favour me by writing and appending the absent foot-note.

I mentioned to you in a previous letter that the non-dimorphic Cowslips had lately produced an umbel in which the different flowers presented a curious series of differences in the relative lengths of stamens and pistils. I have added descriptions of these, along with three rude sketches of the more marked. I am sorry that I had not the measurements of the pollen-grains also; but unfortunately I have had no practice in the use of the micrometer; and Dr. Dickson who promised to do them for me was so long in coming that the flowers were nearly all past. The one figured with stamens & pistils of an equal length—both shorter than corolla-tube—was the only one of which he would venture to give me the exact measurement. These varied from the 4--6/4000 of an inch but those under 54000 seemed badly developed. I am sorry that I had not the exact measurements of all, and more particularly of the long-styled flower, which plainly—from comparison—approximated to those characteristic of the normal long-styled.

I have also made few crude remarks on the bearings of this variable umbel on the question of the original sexual characteristics of the Primulas. It especially, together with the summary will I fear prove troublesome to you, as I have not at all wrought it out as I ought to do. Nor indeed can I.

From an apparent scarcity of papers for the last Bot. Meet. here, I was asked to contribute something. I gave them a paper on the occurrence of the Monoicous spikes of Maize; concluding it with a few remarks on their theoretical bearings. I enclose the brief notice of it from the Courant. I will be glad to hear, whether I did rightly in openly expressing my convictions on these teachings. Prof. Balfour stated that he did not agree with me in my deductions.

I sincerely trust that your health—long ere this—is sufficiently strong to permit of your resuming study.

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



[Enclosure: 1]

Page 52.

I have entirely withdrawn discussion of relations of Primroses & Cowslips. Thanks to your caution, I had no evidence as to self-fertility of Oxlips; and after careful enquiry, I cannot hear of any person having raised them from seed. I was misled with the fertility of some of those less marked forms which one so frequently finds connecting Primroses with Oxlips & the latter with Cowslips. On your view, however, we can partly understand this by regarding them as the offspring of the hybrid of respective parents. I intended as you will observe to insert a foot-note on page 25. & noticing as you suggested the bearing of the high fertility of certain unions of the Primroses & Cowslips on the frequent production of natural hybrids or Common Oxlips, as affording an analogy with the Verbascums: in doing so however, it would be necessary to adduce facts in support of this view—as I doubt not, it will be keenly disputed. As I have no evidence of my own to adduce; I could only use that which you had communicated; not feeling at liberty to do this, I beg to leave it entirely in your hands, and I will be glad indeed if you insert a note as communicated by you. The only difficulty that occurs to me is that we frequently find many intermediate forms less or more closely allied to Primroses & Cowslips, without what would be regarded as a true Oxlip. If these are not then natural variations of their respective species—an opinion to which I can scarcely subscribe, from the general constancy of offspring when either species is growing in distinct localities—we certainly ought to have the Oxlip to explain the occurrence of these.



[Enclosure: 2]

III. Remarks on the Sexual Change in the Inflorescence of Zea Mays. By Mr John Scott.

After noticing the unisexual characteristics of the inflorescence of the maize, the author, by a series of specimens, illustrated several changes from the normal sexual characteristics of the florets. The male panicles, for example, were shown to produce, along with their own kind of florets, perfect female florets, imperfect and intermediate male and female florets, as well as structurally hermaphrodite florets. Similar changes were also illustrated in the female spikes. A few speculations were offered on the probable cause of these changes, in which the author, in accordance with that principle of reversion to type so much insisted upon by the opponents of Mr Darwin's hypothesis, considered himself justified in regarding such changes as indicative of the successively graduated modifications of the now unisexual Zea Mays from a hermaphrodite progenitor.

    Footnotes Add

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    f1 4382.f1
    The year is established by the relationship between this letter and the letter to John Scott, 7 November [1863] (Correspondence vol. 11), and by the reference to Scott 1863b (see n. 12, below).
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    f2 4382.f2
    Scott refers to a manuscript of Scott 1864a; CD had offered to communicate the paper to the Linnean Society for publication in the Journal of the Linnean Society (Botany) (see Correspondence vol. 11, letter to John Scott, 25 and 28 May [1863]).
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    f3 4382.f3
    CD had first encouraged Scott to publish a paper on the Primulaceae in December 1862 (see Correspondence vol. 10, letter to John Scott, 3 December [1862]). Scott and CD corresponded frequently throughout 1863 on their respective crossing experiments. In September 1863 Scott sent CD a draft of the paper, which CD returned with suggestions for minor alterations, praising it as an `excellent memoir' (see Correspondence vol. 11, letter from John Scott, 21 September [1863], letter to John Scott, 7 November [1863], and letter from Emma Darwin to John Scott, 19 November [1863]). There are annotated copies of the published paper (Scott 1864a) in the Darwin Pamphlet Collection--CUL and among CD's unbound journals in the Darwin Library--CUL; see the back page of CD's unbound journal for CD's comments on Scott 1864a.
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    f4 4382.f4
    Scott 1864a, pp. 103--4, included CD's experimental results of crossing primroses (Primula vulgaris) and cowslips (P. veris). Scott's own attempts at crossing primroses and cowslips had failed, but CD had sent him his own results (see Correspondence vol. 11, letter from John Scott, 23 July [1863], and letter to John Scott 25 [July 1863]). For Scott's `excluded discussion', see n. 15, below.
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    f5 4382.f5
    Scott refers to enclosure 1. CD evidently did not write the footnote for Scott 1864a (see n. 17, below); as a result of illness and his conviction that the paper was ready for publication, he urged Scott to allow him to send it to the Linnean Society as it was (see letter from Emma Darwin to John Scott, 9 January 1864).
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    f6 4382.f6
    Scott began experimenting with a non-dimorphic cowslip in May 1863 (see Correspondence vol. 11, letter from John Scott, 21 May [1863]). The letter in which Scott mentioned the variable cowslip umbel has not been found; however, see n. 7, below.
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    f7 4382.f7
    Scott discussed and illustrated the variable umbel in Scott 1864a, pp. 108--10. His illustration depicted three forms: a short-styled flower with stamens reaching the top of the corolla-tube, a long-styled flower with stamens reaching above the middle of the corolla-tube, and a flower with the stamen and pistil nearly equal in length, both slightly shorter than the corolla-tube (Scott 1864a, p. 109).
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    f8 4382.f8
    Scott refers to Alexander Dickson, lecturer on botany at Aberdeen University (DNB).
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    f9 4382.f9
    In the published paper, Scott included comparative descriptions of the pollen-grain sizes for each of the three different cowslip forms he had illustrated (see Scott 1864a, p. 109). CD believed that the precise sizes of pollen-grains were a factor in determining the different forms of a dimorphic plant species (see, for example, `Dimorphic condition in Primula', pp. 78--9 (Collected papers 2: 45--7).
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    f10 4382.f10
    Scott argued that the non-dimorphic flowers in the variable umbel were a reversion to the cowslip's original sexual condition, during the `period in its genealogy when non-dimorphism or perfect hermaphrodism was the genital characteristic of its line' (Scott 1864a, pp. 109--10).
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    f11 4382.f11
    When CD reviewed Scott's first draft of Scott 1864a, he asked him to conjecture in the summary what the `typical or parental form i.e. equal long or short-styled' of Primula had been (see Correspondence vol. 11, letter to John Scott, 7 November [1863], and letter from Emma Darwin to John Scott, 19 November [1863] and n. 4). In the last two paragraphs of the summary, Scott reiterated his argument that the existing non-dimorphic forms represented a reversion to the `original non-dimorphic progenitor' (see n. 10 above, and Scott 1864a, p. 126). CD marked the last two sentences of the summary in his copy of the paper (Darwin Pamphlet Collection--CUL); when recommending Scott's letter to Asa Gray, he noted `There is good Summary to Paper.—' (see letter to Asa Gray, 13 September [1864]). See also n. 3, above. CD later developed this notion of reversion in `Illegitimate offspring of dimorphic and trimorphic plants', pp. 434--5, and Forms of flowers, pp. 272--5. For CD's experimental notes on reversion, see DAR 108: 31 and 43.
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    f12 4382.f12
    Scott read `Remarks on the sexual changes in the inflorescence of Zea Mays' to the Botanical Society of Edinburgh on 10 December 1863 (Scott 1863b). After describing the transformation of sexual characteristics in maize florets, Scott suggested that the causes of such changes were `no longer enigmatical, but clearly the results of definite and well-known laws', owing to Darwin's theory of modified descent (ibid., p. 220).
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    f13 4382.f13
    The enclosure has not been found; however, the notice from the Edinburgh Evening Courant, 19 December 1863, p. 8, is reproduced as enclosure 2.
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    f14 4382.f14
    As regius keeper of the Royal Botanic Garden, Edinburgh, John Hutton Balfour was Scott's supervisor (DNB). Scott had earlier mentioned to CD that the reception of his papers in Edinburgh was not entirely favourable: `here of course anything that savours of the ``Origin'' is not at all palatable!' (see Correspondence vol. 11, letters from John Scott, [3 June 1863] and 16 June [1863]).
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    f15 4382.f15
    CD evidently expressed uncertainty whether oxlips were self-fertile or the hybrid offspring of cowslips and primroses in notes written on the first draft of Scott's paper (see Correspondence vol. 11, letter to John Scott, 7 November [1863]); in `Dimorphic condition in Primula', pp. 93--4 (Collected papers 2: 60--1), he had written that further experiments were `absolutely necessary' to determine the relationships of cowslips, primroses, and oxlips. See n. 16, below.
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    f16 4382.f16
    As part of his effort to determine whether sterility between two related plant forms indicated that they were two different species, CD had long been interested in whether oxlips were the hybrid offspring of primroses and cowslips (see Origin, pp. 49--50, Natural selection, pp. 128--33, and Correspondence vol. 10, letter to J. D. Hooker, 14 [October 1862] and n. 14). Beginning in 1862, he carried out experiments to answer this question (see n. 4, above, Correspondence vol. 10, letter to John Scott, 3 December [1862], and Correspondence vol. 11, letter to John Scott, 25 [July 1863]). In his letter to John Scott of 25 and 28 May [1863] (Correspondence vol. 11), he wrote that his experiments were leading him to believe that the common oxlip was a hybrid of the primrose and cowslip (see CD's experimental notes in DAR 108 and DAR 157a). CD eventually published his conclusions in 1869 in `Specific difference in Primula'; see also Forms of flowers, pp. 63--71.
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    f17 4382.f17
    The published form of the footnote Scott refers to is on p. 97, Scott 1864a. CD may have noted an analogy between cowslips and primroses and Verbascum species in his comments written on the manuscript of Scott 1864a (see Correspondence vol. 11, letter to John Scott, 7 November [1863]). He had briefly compared the two genera, though not particular species of Primula, in `Dimorphic condition in Primula', p. 91 (Collected papers 2: 59), referring to Karl Friedrich von Gärtner's measurements of fertility and sterility when crossing several distinct species of Verbascum (see Gärtner 1849); CD then concluded that `the homomorphic unions relatively to the heteromorphic unions in Primula are more sterile than the crosses between several distinct species relatively to the pure union of those species'. CD had discussed Gärtner's work (Gärtner 1844 and 1849) with Scott (see Correspondence vol. 10, letters to John Scott, 19 November [1862] and 11 December [1862], and Correspondence vol. 11, letter to John Scott, 25 [July 1863] and n. 4).
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    f18 4382.f18
    CD evidently did not add to the footnote (see n. 5, above). The published footnote on p. 97 of Scott 1864a quoted portions of CD's discussion of Gärtner's experiments with differently coloured varieties and species of Verbascum (see Origin 3d ed., p. 293, and n. 17, above). Scott concluded: `We thus see that the functional relations of varieties of a species MAY extend to, and similarly correlate the varieties of DISTINCT species!' (Scott 1864a, p. 97 n.). Although Scott had started experimenting with Verbascum at CD's suggestion in 1863, his work was evidently at too early a stage to be of use (see, for example, Correspondence vol. 10, letter to John Scott, 19 November [1862], and Correspondence vol. 11, letter from John Scott, 21 September [1863]).
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