Ɛpsilon

To George Henslow   23 October [1876]1

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Oct. 23.

My dear Sir

I am sorry to say that we differ greatly, but it would take much too much space to discuss all our differences.2

My book will be published early in next month, & I will do myself the pleasure to send you a copy, & you can then read it (if your patience lasts out) & see what I think & my evidence.—3

I have not attended at all to the order of development of the whorls, & it will be interesting if you can prove a relation between the order & a protandrous & protogynous condition. But I feel rather doubtful, as this condition is sometimes variable & is affected by temperature (I have given evidence, & might have added Gärtner),4 & differs in the individuals of the same monœcious & a few hermaphrodite species (cases given in my book);5 & I can hardly suppose that the order of development of the whorls differs in the individuals of the same species, & is affected by temperature &c.

It is quite new to me that dwarfed flowers which are not commonly self-fertile become self-fertile from this cause: I presume that you know, (judging by the close of your sentence) that the penetration of the stigma by the pollen-tubes, is not an absolute proof that seeds will be produced: Eschscholtzia & homomorphic unions of Lythrum salicaria offer instances of this.—6

Pray excuse my not writing at greater length: the subject is really too large for a letter. I sincerely hope that your health is considerably improved & remain, My Dear Sir, Yours faithfully | Ch. Darwin

1
The year is established by the relationship between this letter and the letter from George Henslow, 20 October 1876.
3
Henslow’s name appears on the presentation list for Cross and self fertilisation (see Appendix III).
4
Karl Friedrich von Gärtner’s work is cited often in Cross and self fertilisation, especially Gärtner 1844. In Cross and self fertilisation, p. 441, CD remarks that in varieties of Pelargonium the period at which the sexual elements of the flower mature varies according to temperature.
5
In Cross and self fertilisation, CD used the terms ‘proterandrous’, referring to flowers in which stamens mature before pistils, and ‘proterogynous’, referring to flowers in which the reverse occurs; for examples of protandry and protogyny in different individuals of the same monoecious and hermaphrodite species, see pp. 390 and 440.
6
In Origin 3d ed., pp. 285–6, CD had discussed cases where a plant had a pistil too long for the pollen-tubes to reach the ovarium, or where the pollen-tubes were unable to penetrate the stigmatic surface, or where the male element was incapable of causing the development of an embryo. On self-sterility in Eschscholzia californica (the California poppy), see the letter from George Henslow, 20 October 1876 and n. 7. CD had compared the fertility of homomorphic and heteromorphic unions in Lythrum salicaria (purple loosestrife) and other species; he found that homomorphic (also called ‘illegitimate’) unions often failed to produce seed (see ‘Illegitimate offspring of dimorphic and trimorphic plants’, p. 397).

Manuscript Alterations and Comments

3.3 sometimes] interl
3.7 of the whorls] interl
4.1 which … self-fertile] interl
4.1 commonly] above del ‘sel’
5.1 not] interl

Please cite as “DCP-LETT-10648,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10648