To Francis Darwin   [September 1875 or later?]1

My dear F.

Here is a horrid job which I beg you to do pretty soon, i.e. to make out Hoffmann’s conclusions about the fertilisation of Phaseolus. p. 47 to 80.—2 He gives a resumè which will perhaps tell enough.— Phaseolus multiflorus or the Scarlet Runner is plant on which I experimented, & my results (i.e. that it cannot be fertile without insects) has been since confirmed by Ogle & Belt.—3 I am aware that Ph. vulgaris is fully self-fertile.4 If Hoffmann finds that Ph. multiflorus—(which by the way is synonymous with Ph. coccineus of Lamarck) is fertile in Germany when insects are excluded, either climate has affected the plant, which I do not believe or two species are confounded under one name.—5

C. Darwin

Does Hoffman describe at all Ph. multiflorus, as whether it is a tall twining plant with scarlet flowers??6

1
The date is conjectured from the supposition that this letter relates to the writing of Cross and self fertilisation, which CD began in September 1875 or soon after (see ‘Journal’ (Appendix II)). Cross and self fertilisation was published on 10 November 1876 (Correspondence vol. 24, Appendix II).
2
CD refers to Hermann Hoffmann’s Untersuchungen zur Bestimmung des Werthes von Species und Varietät. Ein Beitrag zur Kritik der Darwin’schen Hypothese (Researches on the determination of the value of species and variety. A contribution to the critique of the Darwinian hypothesis; Hoffmann 1869). An annotated copy is is in the Darwin Pamphlet Collection–CUL. Many of the annotations do not appear to be in CD’s hand, and were probably made by Francis. See Cross and self fertilisation, p. 152.
3
William Ogle reported that none of the flowers of the scarlet runner-beans protected from insect visits in his garden had produced a pod (Ogle 1870, p. 168). CD underlined this section in his copy, now in the Darwin Pamphlet Collection–CUL. Thomas Belt reported that in Nicaragua, where Phaseolus multiflorus was not visited by humble-bees, the plant was sterile (Belt 1874a, p. 70). Belt may have sent CD some parts of the book in August 1873 (see Correspondence vol 21, letter from Thomas Belt, 2 August 1873).
4
Phaseolus vulgaris is the common bean; it has several cultivated varieties.
5
Joseph Dalton Hooker had informed CD that Phaseolus multiflorus was a synonym of P. coccineus (see Correspondence vol 21, letter from J. D. Hooker, 30 August 1873 and n. 1). The accepted name is now Phaseolus coccineus. In Hoffmann 1869, pp. 68–9, Hoffmann described experiments where he protected Phaseolus multiflorus from insect visits; he concluded that it could not be fertilised without insect aid.
6
CD evidently wanted to verify that he and Hoffman were referring to the same species. Hoffman described colour variation in the flowers and seeds of different plants of Phaseolus multiflorus with which he had experimented (Hoffmann 1869, p. 60). He referred to a marbled white American variety as P. multiflorus coccineus, but concluded that colour differences were caused by the more extreme American climate and that it was only a variety, not a true species (Hoffmann 1869, p. 78).

Manuscript Alterations and Comments

1.1 i.e.] interl
1.4 i.e. … been 1.5] interl; ‘i.e.’ interl; ‘it’ interl
1.7 synonymous with] above del ‘the same as’
1.7 when] above del ‘when’
1.8 which … believe] interl
1.8 two] after del ‘w’
1.9 confounded] altered from ‘cofoded’
3.1 Ph. multiflorus,] interl

Please cite as “DCP-LETT-9219A,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9219A