From John Scott 21 May 1
Botanic Gardens [Edinburgh]
I regret to find by your last that your health is still very weak.1 I sincerely trust you have derived more benefit by your short absence from home than you anticipated. I was glad to hear that Orchid pods arrived safe.2 I thank you for remittance of postage stamps; pray never mind anything of the kind in future; I am equally anxious with you that all should arrive safe, and it gratifies me much to have aught to send which is likely to interest you.
I thought you would be somewhat surprised when you heard the plan I had taken in certain cases to fertilise the Acroperas & Gongoras.3 In some of my late experiments on G. truncata, I cut off not only the clinandrum but an eighth of an inch from the extremity of the stigma, before inserting pollinia; these capsules are now swelling rapidly. These plants must certainly present less contracted stigmatic chambers in their native haunts or at least secrete, as I formerly suggested, more viscid matter. But even granting this, I am quite at a loss to understand how the pollinia are applied to stigma! If ever I am fortunate enough to be amongst them in their native haunts, I shall certainly embrace every opportunity to satisfy myself as to Nature’s modus operandi.
In respect to Drosera paper, I am sorry to say that it has not been published. Perhaps it might have found a place in the Proceedings of the Bot. Soc. here, if there had been no connection between the latter & the Edin. New. Phil. Jour.. But not being a paper adapted for the latter, it is consequently excluded from both—excepting the short notice you saw in Gard. Chron.—the one as respects this being simply a repetition of the other.4 I will thus, I fear, be unable to send you a printed copy of it, as I have no acquaintance with any Editors likely to receive such contributions; however, I will if you like send my manuscript, and you will then see if it contains aught worthy your notice.
I have read paper on Sterility of Orchids;5 it appeared to be pretty well received by the Society in general: in the remarks upon it by Professors, Balfour, & Maclagan, no reference whatever was made to the opinions occasionally deduced from experiments.6 I suppose this was due to the decided tendency I exhibited throughout to support your views.7 The Edin. Phil. Jour. will be published in the beginning of July, & I will then send you a copy:8 I will be impatient to have your opinion upon it. I have ventured in a a few preliminary remarks to refer to Prof. Huxley’s “absent link” mentioned in “Mans Place”;9 and have there attempted to show that such cases of sterility as those stated in paper & others which I referred to in your writings connected indirectly the broken chain, and seemed to leave no difficulties to those of us who like Prof. Huxley needed only the above link to render your theory “amply competent” &c &c.10
By the way I enclose a copy of note in my paper on closing of stigmatic orifice in Orchids 11 I have drawn attention to an observation of yours in ‘Orchid Fertilisation” which has always struck me as very remarkable Indeed I have often wondered how it has escaped the attention of your numerous reviewers.12 You will see that the phenomenon as presented by my experiments, is more strikingly adapted for the end in view, than in the Bolbophyllum case: fertilisation being dependent on external agents; Now it is evident that if stigmas close at definite periods, Nature’s design may be frequently frustrated; whereas, when this is dependent on the mutual action of the organs which accomplish the latter, it is a most beautiful provision. Have you ever observed the phenomenon in any other Orchid yet? It seems most anomalous & exceptional; If you have not 〈several pages missing〉
am glad to say it has now done. I must state—a slight though in a certain sense an unimportant—peculiarity it has now presented. This is in regard to the style which varies a little in length: in some flowers it is exactly the same length as stamens, the latter reaching or nearly the mouth of corolla-tube: these flowers produce nice plump capsules. Other flowers again, have stigma protruded beyond the corolla-tube, and are accordingly perfectly sterile when the flower is protected. Artificial fertilisation, however, shows that they are equally as fertile as the others: irrespective then of this peculiarity—certainly important as affording an opportunity for crossing—as already stated, the difference is unimportant. I am trying this species also with others presenting the two forms. In my observations on Primula, I have found five distinct plants of cultivated Auricula with stamens & pistils equal; but these as in case alluded to by you in Primula paper;13 have pollen-grains as small or even smaller than those from normal short-styled forms. It is different, however, with a cultivated cowslip, which I am at present experimenting upon, with stamens & pistils equal.14 In this the anthers approach corolla mouth, stigmas reaching the middle of anthers. It is also producing fine plump capsules. I have examined pollen-grains & stigmas The former are as large as any I have yet observed on short-styled plants; stigmas similar in form to those of long-styled plants; papillæ shorter and more like those of short-styled forms
I am likewise trying results of crosses between these & the long & short-styled forms. I will of course detail more particularly my Primula work at some future time: it is not sufficiently advanced yet.15 The Passifloras are now beginning to flower: so I will soon be able to commence work upon them.16
In conclusion allow me to present my most sincere thanks for the encouraging remarks you have been pleased to make on my occasional observations in your last.17 I cannot, indeed, thank you as I would like to do, for the honour you have done me. Pray, excuse my inability and rest assured that the stimulus you have thus given shall be truly excitative, and make me strive more & more to improve those faculties, and to overcome other mental defects, or rather deficiencies, which a stern and inflexible Nature has been so niggardly in her bestowment. I used to entertain foolish ideas in respect to this: I thought in fact that Nature had formed me as it were in very mockery, endowed me with an insatiable desire for knowledge, & yet so constituted my mental nature, that it seemed all but unattainable. Now, however, I look upon myself as the subject of general, not special laws, so banishing these hard thoughts of Nature, my earnest endeavour is now to constantly strive to make the most of all.
I remain | Sir | Yours very respectfully | John Scott
〈Mr. D〉arwin records the following very remarkable 〈observa〉tion on the closing of the stigmatic orifice in B. rhizopharæ;— “Orchid fertilisation” p. 170.18 “After the 〈fl〉ower has remained some time open, the sides of 〈the〉 oval orifice of the stigmatic chamber close in & shut it completely,—a fact which I have observed in no other Orchid, and which, I presume, is here related to the much exposed condition of 〈the who〉le flower.” This case then of Mr . Darwin’s 〈differs〉 from that above mentioned, and from all 〈ot〉hers which I have observed, in requiring no external stimulus for its excitation!19 After the application of pollen to the stigma, I have observed it in a number of species from different tribes; in absence of the pollen, however, it remained open to the last. There is thus in the closing as here manifested; an almost conscious sympathetic action—a case that the grand end of vegetal life is not too readily frustrated by an oversensitiveness of the stigmatic chamber; inasmuch as I find, that, when pollen is applied from widely distinct genera〈, the〉 orifice 〈does not〉 move. As illustrating this〈, I〉 applied pollinia from species of Cypri〈pedium〉 and Asclepias to flowers of Tric〈hopilia tortilis;〉 nevertheless, though pollen tubes we〈re emitted,〉 the stigmatic orifice did not close, which 〈it〉 invariably does eighteen hours or so after the application of its own pollen. In respect 〈to the〉 suggestion of Mr. Darwin as to the special en〈d〉 subserved by the closing of the stigmatic chamber in B. rhizophoræ; I may remark that in m〈any〉 of 〈the〉 species exhibiting the phenomenon, 〈it is evidently〉 subservient to a highly beneficial end in affo〈rd〉ing more genial conditions for the perfect development of the pollen-tubes; than could otherwise be afforded in the naturally upturned and fully exposed condition of their stigma〈s〉 In others, however, it must be admitted that no such relation is evident: species whose stigmatic chamber closes being equally as well protected from physical injuries, as others in which it remains open. This, however, may be simply due to inheritance with modification; at least, it will be so regarded by those of us who believe that species are the modified descendants of previously existing species.
Supports, in his orchid paper, CD’s view that sterility occurs at random [Trans. Bot. Soc. Edinburgh 7 (1863): 543–50].
Cannot get his Drosera paper published [abstract in Edinburgh New Philos. J. 2d ser. 17 (1863): 317–18].
Please cite as
Darwin Correspondence Project, “Letter no. 4174,” accessed on 13 February 2016, http://www.darwinproject.ac.uk/DCP-LETT-4174