Thanks for information on sexual differences.
Orchids; self-sterility and difficulty of getting seeds to germinate.
Down. | Bromley. | Kent. S.E. May 26 My dear Sir
I thank you much for your information on sexual differences with the pretty
little sketch of the male crab, & for the great trouble which you
have taken in copying the long extract from Claus, All
such facts interest me much. I shall also be very glad for answers to
any of my questions on the expression of negros. Your additions about the self-sterile orchids are
particularly valuable, & I shall give an abstract of all the
information which you have so kindly given me. The
comparison of the pollen with that when species are crossed makes the facts
much more curious. The analogous cases which have been
observed in Europe I have always attributed to the unnatural condition under
which the orchids were grown; but it now appears that this is an error; I
fear however that I shall not be able to alter the place in my book where I
give these facts. As D
Only 3 plants of your Plumbago are alive, but they are doing well. Hundreds
I dare say your observations in crossing orchids will be very interesting; they already illustrate most of the leading laws; but I fear their interest will be greatly lessened by the crossed seeds not germinating. One single man in Europe has found out how to make these seeds germinate, & he keeps it a secret in his trade of nurseryman. He also has made some strange crosses between distinct genera, & these hybrids have flowered.
I presume this strange difficulty in making the seeds germinate explains their astonishing number, which you and others have shewn. I am not able to do much this summer in experimenting as all my time is taken up in getting my book thro' the press; it progresses very slowly & is I fear hardly worth the great labour it costs me.
With cordial thanks for your never failing kindness I remain my dear Sir | yours very sincerely | Ch. Darwin
- f1 5551.f1The year is established by the relationship between this letter and the letter from Fritz Müller, 1 April 1867.
- f2 5551.f2See letter from Fritz Müller, 1 April 1867. CD refers to Carl Friedrich Claus.
- f3 5551.f3See letter to Fritz Müller, 22 February , and letter from Fritz Müller, 1 April 1867. CD was seeking material for Expression.
- f4 5551.f4In `Fertilization of orchids', p. 154 (Collected papers 2: 150), CD referred to Müller's work on the structure and manner of cross-fertilisation of orchids in Brazil but stated that he had not had `space or time to give an abstract of his many discoveries'. CD cited Müller frequently in the second edition of Orchids for information that Müller had sent him.
- f5 5551.f5See letter from Fritz Müller, 1 April 1867. Müller had discovered that when he tried to self-pollinate self-sterile species, the pollen placed on the stigma became discoloured and decayed, whereas when a cross was attempted between distinct plants of the same species or of different species, the pollen stayed fresh (see also Variation 2: 134--5).
- f6 5551.f6CD discussed Müller's findings in Variation 2: 134--5.
- f7 5551.f7CD refers to Hildebrand 1866a. For Müller's suggestion that Corydalis might be dimorphic, see the letter from Fritz Müller, 1 April 1867.
- f8 5551.f8Müller had sent CD seeds of Plumbago (letter to J. D. Hooker, 24 [March 1867]), possibly with his letter of 2 February 1867; he sent seed of Gesneria with his letter of 1 January 1867.
- f9 5551.f9Max Kuhn made this announcement in his article `Einige Bemerkungen über Vandellia und den Blüthenpolymorphismus' (Botanische Zeitung, 1 March 1867, p. 67). There is an annotated copy of this issue in the Darwin Pamphlet Collection--CUL.
- f10 5551.f10CD probably refers to John Dominy, a gardener for James Veitch & Son, who produced the first known artificial orchid hybrid, between Calanthe furcata and C. masuca, in 1856. Orchid hybrids were produced only at Veitch & Son's nursery for fifteen years. See Shephard 2003, pp. 127--9; see also Correspondence vol. 10, letter from J. D. Hooker, [23--5 March 1862] and n. 3.
- f11 5551.f11See Correspondence vol. 11, letter to John Scott, 24 March , and letter to Hermann Crüger, 25 May  and n. 8.
- f12 5551.f12Müller had estimated that a seed capsule of Maxillaria contained well over one and a half million seeds (see Correspondence vol. 14, letter from Fritz Müller, 1 and 3 October 1866; see also `Fertilization of orchids', p. 158 (Collected papers 2: 155), and Orchids 2d ed., p. 278).
- f13 5551.f13CD was working on the page-proofs of Variation.