To Daniel Oliver   12 [April 1862]1

Down Bromley Kent

12th

My dear Sir

I seldom see anyone, so it is a great pleasure to me to receive a scientific letter & I thank you for your very interesting one.2

First for Primula; I should like to see (pollen of) P. farinosa; but it really is of little importance, so tell your correspondent not to give himself much trouble; I send copy of my paper.—3 I had noticed difference in size of ovules, but slurred the case over, & concluded that I had taken buds of different ages: I have just looked at a couple of large flower-buds of Primrose; in these the ovules were largest in the short-styled, just the reverse of what you say! Have you written “long”-styled for “short”-styled? or is the size a variable point?4 The short-styled certainly produce a greater number of seed; but I did not attend to number of ovules: I will look at a few more of buds of equal age.—

Your discovery about Campanula seems to me extremely interesting; & I am specially surprised at the gradation of the two states on the same(?) plant; I am very glad you will read a paper on this.5 Twice I have had Campanulas & Violets for experiments, & twice I have been prevented observing.6 I can see at least 3 classes of Dimorphism,—Primula & co:—Thymus & co:—Campanula. Violets & co. For the latter cases I have theorised from what I have seen & read on Violets that the final object of the imperfect flowers is to produce seed safely, without any crossing. (so your remarks on the structure please me); the perfect flowers being adapted for getting an occasional cross; but I have not space here to give my reasons for coming to this provisional conclusion.— You will see that according to my notion, the final object of the dimorphism in Violets &c is exactly the reverse of what it is in Primula.—

With respect to Fumaraceæ, I had attended a little to them, when 3 or 4 years ago Asa Gray (& so does Vaucher) advanced this order as one with perpetual self-fertilisation;7 this made me attend more carefully to it, & I am convinced the whole structure of the flower is beautifully adapted to favour an occasional cross.— I have many recorded observations, but God knows whether I shall ever have time to make use of them.8 I write this letter only from memory.

Insects are not indispensable, for all that I have tried set seed without insect aid. It is really pretty to watch a Humble-bee visit Dielytra (& allied forms) Adlumia &c &c & see how neatly its hind-legs rest on the projecting plates on each side of the hood over the stamens & pistil, & push it to one or the other side, & get its body covered with pollen, against which the stigma is rubbed.— This tube has nectary on both sides & the “hood” can be pushed either way & the pistil is straight— Next look at Corydalis tuberosa? & allies (purple flower with white tube & now in bloom) here secreting nectary on only one side, & the hood can be pushed off only on one side, & the pistil is curved (it is straight in Dielytra) towards the gangway into the nectary.—9

Pray look at Corydalis lutea, with nearly similar structure; but with additional curious contrivance; when Bee (as I have often seen) visits flower, it pushes back the hood, & then the pistil moves with a jerk or spring forward.— This movement determines at once the act of fertilisation, though it will take place if the flower is never visited & the pistil never snaps off. (but flowers in this case are less fertile)   But I must not run on; & I have written so briefly that you will not understand me.—

With respect to Bees biting holes; this occurs in almost all flowers occasionally, which are difficult to enter; I have never seen it occur in any Fumariacieæ, at least I think not.— But I know of no single instance of this always occuring in any plant— When it does occur, there can be no crossing as you say, & I have some reason to believe that the fertility of flower is diminished; certainly in some cases it would be quite stopped. Oddly this biting of holes occurs chiefly when large masses of the same species are grown together; I shd. like to hear what species of Fumaria you have seen with bitten corolla.—

I am pleased to hear that you are going to discuss Dimorphism in Nat. Hist R. for I have no doubt you will make a very valuable paper.—10 By the way I have been much interested by your Atlantis paper, & rejoice at your conclusion;11 I think, however, you might have made it more popularised, & I will add another criticism, viz that you ought (as I think) to have laid much more stress on migration having taken place during former warmer period.— I wish that your Lectures did not take up so much time, so that you might write on various subjects.12 I do not know whether the diagrams of Catasetum would be worth your taking away from Linn. Soc; but if so they are at your service; & there was a diagram of Primula there.—13 This reminds me that Mr Fitch drew for me cuts of Primula, would you be so very kind as to ask him what I am indebted to him for his kind assistance; though perhaps the Linn. Soc paid for the drawings on the wood.—14

I am nearly certain that Asa Gray (perhaps also in his Manual) told me that the imperfect flowers of some N. American Campanula produced more seed than the perfect.—15 But I keep my notes in such a stupid manner that I cannot refer to single points, only to whole large subjects.

I have written you a frightfully long letter not worth the trouble of decyphering. Another thing just occurs to me which I meant to say whenever we met: viz that if ever you had leisure, you might make a grand essay on the charater of Fr. Water plants, taking, I presume, those whose roots were always covered with water. I presume no one could treat of more than Europe & N. America, though some Tropical country ought to be included.— It would be interesting to see how many had sent one or two colonists into the water: but what would be most curious would be to consider the nature of affinities, & degree of organisation of those groups, in which all the species were aquatic; I strongly suspect they would come out a queer set.— Do think of this.—

Forgive me scribbling at such length, & believe me Yours very sincerely

C. Darwin

1
The date is established by the relationship to the letter from Daniel Oliver, 10 April 1862, and to the letter from Daniel Oliver, 14 April 1862.
3
See letter from Daniel Oliver, 10 April 1862. CD refers to ‘Dimorphic condition in Primula’.
4
On the letter from Daniel Oliver, 10 April 1862, CD wrote ‘short-styled’ above Oliver’s ‘long-styled’ (see CD annotations). Oliver repeated his conclusions without modification in [Oliver] 1862c, p. 237. See also letter from Daniel Oliver, 14 April 1862, and letter to Daniel Oliver, 15 April [1862].
5
Oliver had planned to report to the Linnean Society of London on an observation he had made on Campanula (see letter from Daniel Oliver, 10 April 1862), but subsequently decided against it (see letter from Daniel Oliver, 14 April 1862).
6
CD had intended to carry out experiments on the cleistogamic flowers of Viola and Campanula in the summer of 1860, but his attempts were frustrated (see Correspondence vol. 8, letters to J. D. Hooker, 7 June [1860] and 12 [June 1860], and letter to Daniel Oliver, 24 [September 1860]).
7
CD refers to his correspondence with Asa Gray during 1857 and 1858 (see Correspondence vol. 6, letter from Asa Gray, 7 July 1857, and letter to Asa Gray, 29 November [1857], and Correspondence vol. 7, letter from Asa Gray, 21 June 1858). CD also refers to Vaucher 1841, 1: 143; there is an annotated copy of this work in the Darwin Library–CUL (see Marginalia 1: 812–15).
8
CD’s initial notes on various members of the Fumariaceae, dated May and June 1858, are in DAR 76: 13–18; further notes, dated 1861 and 1863, are in DAR 76: 17–21. Some of CD’s observations on species of Fumaria were eventually published in 1876, in Cross and self fertilisation, as part of a discussion of plants that are fertile without insect aid (p. 366). CD also published a notice on pollination in Fumariaceae in Nature 9 (1874): 460 (Collected papers 2: 182–3). See also Correspondence vol. 9, letter to Daniel Oliver, 9 April [1861].
9
CD described this phenomenon in Variation 2: 58–9.
11
Oliver 1862b. Oliver argued against Oswald Heer and Franz Unger’s suggestion that the relationship between the Tertiary flora of Europe and the present flora of eastern North America indicated the existence of an Atlantic land connection between Europe and America during the Miocene period (Heer 1857 and 1861a, and Unger 1860). Oliver concluded that the botanical evidence did not favour ‘the hypothesis of an Atlantis’; he went on to say (Oliver 1862b, pp. 164–5): it strongly favours the view that at some period of the Tertiary epoch, North-eastern Asia was united to North-western America, perhaps by the line where the Aleutian chain of islands now extends, since there is sufficient ground to believe that the temperature in that latitude was high enough to allow the migration of types, which at the present period, are characteristic of lower latitudes CD annotated this essay in his copy of this issue of the Natural History Review. CD’s copies of the journal are in the Darwin Library–CUL.
12
In addition to his duties at the Royal Botanic Gardens, Kew, Oliver was professor of botany at University College London.
13
CD refers to the illustrations for his papers ‘Three sexual forms of Catasetum tridentatum’ and ‘Dimorphic condition in Primula’ (see letters to Richard Kippist, 18 March [1862]).
14
CD marked this request with two vertical lines in the left margin. Walter Hood Fitch was a botanical artist at the Royal Botanic Gardens, Kew. The Linnean Society paid Fitch’s 10s. bill (see letter from Daniel Oliver, 14 April 1862).
15
North American species of Campanula are described in A. Gray 1856, pp. 243–4, but the point to which CD refers is not mentioned.

Manuscript Alterations and Comments

2.1 (pollen of)] interl
2.2 much] interl
2.5 of Primrose] interl
2.6 the reverse] ‘the’ interl
2.6 "long"] above del ‘short’
2.7 is the] ‘the’ altered from ‘this’
2.7 size] interl
2.8 number of ovules] ‘number of’ interl
2.8 look at] before omitted point
3.6 latter cases] before del caret
3.6 from what … Violets] interl
3.7 the imperfect] interl
3.10 provisional] interl
4.2 (& so does Vaucher)] interl and square brackets in MS
4.6 this letter] interl
5.1 insect] interl
5.2 Dielytra] ‘ie’ over ‘ei’
5.2 Adlumia] ‘A’ over ‘ad’
5.2 Adlumia &c &c 5.3] interl
5.4 the stamens] ‘the’ added
5.4 to] above del ‘on’
5.4 the other] ‘the’ interl
5.5 covered] after del ‘ru’
5.5 This] after del ‘Next’
5.6 & the pistil is straight] interl
5.7 & allies] interl
5.8 secreting] interl
5.8 only] interl
5.9 the pistil] ‘the’ interl
6.4 at once] interl
6.5 (but flowers … fertile)] interl
7.4 as you say,] interl
8.3 rejoice] after omitted point
9.1 also] interl
10.8 groups] interl before del ‘families’, above del ‘genera’

Please cite as “DCP-LETT-3504,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-3504