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Letter 4175

Scott, John to Darwin, C. R.

[26 July – 2 Aug 1863]

    Summary Add

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    His orchid paper limited because he does not give illustrations from distinct genera.

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    Discusses the self- and cross-fertility of coloured primrose varieties. Thanks CD for tables of unpublished Primula work.

Transcription

[Royal Botanic Garden, Edinburgh] -- of individual sterility in Orchids. I have unfortunately failed in giving illustrations from genera distinct from those mentioned in my paper. This would have enhanced their interest; my experiments are so much limited here from want of subjects; our orchid collection being exceedingly poor.

I can give you no information whatever as to origin of our Red & White Primroses. I have asked several old and experienced growers as to this: I find that all agree in regarding them as varieties of the common yellow; but, none can affirm that he has raised either from a perfectly pure yellow primrose. It is possible they may have such an origin as you suspect. If I be permitted, however, to lay any stress upon my experiments, they appear to me somewhat opposed to this. Thus though both varieties manifest curious idiosyncrasies in the production of seed when fertilised with own-pollen, individuals of both, nevertheless do as I have proved, occasionally produce seed. Hence if we admit them to be crosses; or hybrids between cowslips & primroses; ought we not naturally to look for an increased fertility from conjunctions with either of their presumed parents? This not being the case I had concluded before you had suggested the above that they were truly & simply modified descendants of the common yellow primrose. Since I have procured seeds from them, however, there are hopes for enlightenments on this. Perhaps you would like to try results. I therefore enclose a few seeds from both. I am sorry that I had no more by me, having sown all as I gathered them to economise time in the elicitation of evidence. One of the packets of Red you will observe queried; this may chance to be from the White variety; having neglected to name when I gathered contents: you may rely on their being from one or other of same however. I have only a single capsule left—certainly—sowed from the White variety likewise enclosed: I will send young plants, however, if I succeed in raising them.

I enclose also a few self-fertilised seeds of my equal stamened & styled Cowslip: perhaps you will like to see their results likewise. The great self-fertility of this plant conjoined with the high degree of sterility from unions with the other forms has surprised me much.

I am greatly obliged for your interesting tables on crosses between Cowslips & primroses. I was much struck with results of the crosses between long-styled Cowslips & Primroses. These eight flowers heteromorphicaly crossed produced no seeds, while from the same number of homomorphic crosses I had three capsules, containing respectively 17, 10 & 6 seeds: they—the seeds—were all—seeds— smaller than usual. I have sown them, however & we will see how they germinate. Is it not singular how the homomorphic should so exceed the heteromorphic? In your reciprocal cross—Primrose female—I see the heteromorphic cross is again abortive! Again how singularly productive your short-styled crosses are! The average production per capsule of my heteromorphic unions with White Primroses is about 21 seeds: the homomorphic about 13. I here refer to unions with own-pollen—

I really do not think that there is any fear from imperfect castration when insects are guarded against. I have at least always found as you say when these plants were so protected that no seed was produced even when the anthers were all allowed to remain.

The plants of Linum Lewisii, with us have all turned out L. Libericum which has provoked me much. But, I have now got one plant which I am satisfied from description in Bot. Mag. is really L. Lewisii. But though I have watched every flower, there is no variation, all are short-styled. I have just had a note from a friend, however to call and see a plant of it which he informs me is producing in general short-styled flower, with others—occasionally sta. & sty. equal. This I will call and see. I trust it may prove so. I have looked over the specimens in the Herbaria here but they contain few specimens of it: they exhibit no traces however, of Planchon's trimorphic characteristics   Have you had any confirmatory evidence? Have you seen the Linum Mongynum, a dimorphic species? I find a long-styled plant of this singularly productive, and there is no short-styled plant near, indeed I have only seen dried specimens of the latter. The majority of the capsules produced by the former contained 10 apparently good seed—& this is the full number that it can possibly produce.

I am kept very busy at present; so pray excuse my hurried scrawl.

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

    Footnotes Add

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    f1 4175.f1
    The date range is established by the relationship between this letter and the letters to John Scott, 25 [July 1863], and 1 and 3 August [1863].
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    f2 4175.f2
    In his letter to CD of 23 July [1863], Scott had offered to send CD details of examples of self-sterility in orchids, additional to those to be published in Scott 1863a. See also letters to John Scott, 25 [July 1863], and 1 and 3 August [1863]. The genera mentioned in Scott 1863a are Oncidium and Maxillaria.
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    f3 4175.f3
    Scott was foreman of the propagating department at the Royal Botanic Garden, Edinburgh (R. Desmond 1994).
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    f4 4175.f4
    See letter to John Scott, 25 [July 1863] and n. 12.
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    f5 4175.f5
    In his paper, Scott noted: `The pure descent of the red and white Primrose from the common yellow has been questioned, and a hybrid origin from the Cowslip and Primrose (P. veris and P. vulgaris) ascribed to them' (Scott 1864a, p. 98 n.). He argued that his experimental results `negatived' such a view, and expanded the argument given here.
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    f6 4175.f6
    See letter to John Scott, 25 [July 1863] and n. 5.
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    f7 4175.f7
    See letter to John Scott, 20 [June 1863] and n. 8. Scott described his experiments with this plant in Scott 1864a, pp. 105--10. CD raised plants from the seeds sent him by Scott, repeating Scott's experiments in 1865 and 1866 with contradictory results (see DAR 108: 99--124 and `Illegitimate offspring of dimorphic and trimorphic plants', pp. 426--30). See also DAR 78: 4 v and 65--8, and Cross and self fertilisation, pp. 222--5.
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    f8 4175.f8
    See letter to John Scott, 25 [July 1863] and n. 6.
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    f9 4175.f9
    Scott refers to the results of crosses between a long-styled cowslip (Primula veris) and long- and short-styled primroses (P. vulgaris). His other experimental plants were accidentally damaged (see Scott 1864a, p. 103, and letter from John Scott, 23 July [1863]).
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    f10 4175.f10
    CD's results are reported in Scott 1864a, p. 103.
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    f11 4175.f11
    See letter to John Scott, 25 [July 1863].
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    f12 4175.f12
    See letter from John Scott, [3 June 1863], and letter to John Scott, 6 June [1863].
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    f13 4175.f13
    The reference has not been identified; neither Linum lewisii nor L. liburnicum were mentioned in the Botanical Magazine (see Chittenden 1956).
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    f14 4175.f14
    This individual has not been identified.
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    f15 4175.f15
    Scott refers to the statement by Jules Emile Planchon, reported by CD in `Two forms in species of Linum', pp. 82--3 (Collected papers 2: 104--5), that Linum lewisii was trimorphic (Planchon 1847--8, p. 175).
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