To John Scott 19 December 1
Down Bromley Kent
There is no occasion to thank me; it is simply a pleasure to me to aid (if aid it can be called) anyone who really loves science; & you conferred a great favour on me about Acropera.—2 You have taken my little criticisms in the spirit in which they were intended.3 You have reason, in my opinion, to be proud of your paper.—4 By odd chance reading last night some short Lectures just published by Prof. Huxley, I find your observation, independently arrived at by him, on the confluence of two sexes causing variability.—5 I must write briefly.— Difference or similarity of buds & ovules is beyond my tether: I have spoken of them in deference to others as identical, but I have always suspected some fundamental difference.6
Talking of buds, if you can give me any cases of what Gardeners sometimes call sports, & which I shall call “bud-variation” I shall be grateful, as I want to collect all cases like moss—on common rose,—nectarine on Peach.—7
I did not at all know about foliage of Begonia.—8
I shall be very glad indeed of P. farinosa & Scotica.: if in pots in open ground I suppose they will do???9
I can tell you nothing about vars of Verbascum, except that I have in vain tried to get white & yellow vars. of same species.10
If Lælia should set (as does not from what you say appear probable) seed-capsules with pollen put on Rostellum: then if you were to examine one specimen & see whether pollen-tubes penetrated Rostellum it wd., I shd. think, suffice.—11
In my experiments, I have found net, (such as bit enclosed) distended with hoops or fastened on square frame of sticks, answer perfectly in excluding insects, during flowering season, & not injure fertility of plants. Now there ought to be no false delicacy between us followers of science; if any pecuniary assistance is required to purchase pieces of net & pay for making, nets, grant me the favour to apply to me.— Excuse Brevity, as I am tired. I will append about experiments separately.—12
Yours very faithfully | C. Darwin
To the best of my judgment, no subject is so important in relation to Theoretical Natural Science, in several respects, & likewise in itself deserving investigation; as the effects of changed or unnatural conditions, or of changed structure on the reproductive system.
Under this point of view the relation of well-marked, but undoubted varieties in fertilising each other, requires far more experiments than have been tried.
See in Origin the brief abstract of Gärtner on Verbascum & Zea.—13
Mr. W. C. Crocker, lately foreman at Kew & a very good observer is going at my suggestion to work vars of Hollyhocks.14 Climate wd be too cold, I suppose, for vars. of Tobacco.15 I began on Cabbage, but immediately stopped from Early shedding of their pollen causes too much trouble.16 Your knowledge would suggest some.
On same principle it would be well to test peloric flowers, with their own pollen; & with pollen of regular flowers; & try pollen of peloric on regular flowers,—seeds being counted in each case.
I have now got one seedling from many crosses of a peloric Pelargonium by peloric pollen; I have 2 or 3 seedlings from a peloric flower by pollen of regular flower.— I have ordered a peloric Antirrhinum & the peloric Gloxinia, but I much fear I shall never have time to try them.17
The Passiflora-cases are truly wonderful, like the Crinum cases (see Origin).18 I have read in German paper that some varieties of Potatoes (name not given) cannot be fertilised by own pollen, but can by pollen of other vars; well worth trying19
Again fertility of any monster flower, which is pretty regularly produced; I have got the wonderful Begonia frigida from Kew, but doubt whether I have heat to set its seeds.20 If an unmodified Celosia could be got; it would be well to test with the modified Cockscomb. There is a var. of Columbine with simple petals without nectaries &c &c.—21
I never could think what to try; but if one could get hold of a long cultivated plant which crossed with a distinct species & yielded a very small number of seed; then it would be highly good to test comparatively the wild parent form & its varying offspring with this third species: for instance if a polyanthus would cross with some species of Primula, then to try a wild cowslip with it.— I believe hardly any Primulas have ever been crossed. If we knew & could get parent of Carnation it would be very good for this end.—
(Any member of the Lythraceæ, raised from seed ought to be well looked after for dimorphism: I have wonderful facts, the result of experiment, on Lythrum salicaria.—22
Have you any species with two sets of stamens widely dissimilar. It would be better not to try Heterocentron roseum(?) or mexicanum(?) with purple flowers—or Monochætum ensiferum; for I have tried many experiments on these with no sure result, but with plain indications that there is something odd about them; for seedlings produced by the two kinds of pollen differed wonderfully in their rate of growth & in setting seed &c—24
If you have any such & are inclined to operate; first observe whether the pistil retains the same position from time flower opens till it withers: if it does not move, merely try both pollens & mark capsules. The Counting the seed is awful labour, but I would undertake it. (N.B. in all experiments it is quite necessary to wrap up well each ripe capsules in separate paper.)
If pistil moves, experiment is more troublesome, for both pollens shd. be applied to the stigma at the two ages & positions.25 I am completely baffled, but I strongly suspect there is something very strange in these Melastomas. There is nothing odd, as I know by trial, in such genera as Centradenia & Rhexia.26
JS should be proud of his paper ["Nature of the fern-spore", Edinburgh New. Philos. J. 2d ser. 16 (1862): 209–27].
CD has just found that JS’s observations on the confluence of two sexes causing variability were independently confirmed by Huxley.
CD has always suspected a fundamental difference between buds and ovules.
Asks for examples of "bud-variation" or "sports".
Asks JS to test germination of pollen on rostellum of Laelia.
Offers JS money for experimental supplies, e.g., netting, to keep insects out of flowers.
Encloses an outline of crossing experiments with Lythraceae, Primula, Pelargonium, and others, which he feels would be valuable.
Note on melastomids.
Please cite as
Darwin Correspondence Project, “Letter no. 3868,” accessed on 24 August 2016, http://www.darwinproject.ac.uk/DCP-LETT-3868