To James Torbitt   14 April 1876

Down,

Apr. 14, 1876.

My dear Sir,

Prof. Ansted’s letter which I return, is a very good one.1 The more I reflect on your scheme the more I believe it is the one plan for succeeding in getting a sound variety.2

During the last 10 years I have been experimenting on crossing plants and shall publish the results in the autumn. The flowers of the genus Solanum do not produce nectar and are but little visited by insects, tho’ I have seen some on the flowers of the potato. Nevertheless they probably do not get intercrossed so much as the flowers of most other plants.3 Therefore I would strongly advise you to intercross any two varieties, (and the more they differ in all respects the better) that is if you can get two varieties which are moderately free of the pest. I know that there is the strongest probability that seedlings raised from a cross of this kind would not only grow more vigorously, but would possess greater constitutional vigour, so as to be less liable to disease of all kind and death.

Hoping that you may be successful | I remain, my dear Sir | Yours faithfully | Ch. Darwin.

[Enclosure]

“Athenenæum Club, London,

10th April, 1876.

Dear Sir—

… … …

I have long felt, with you, that the continued repetition of the individual by buds, at least in plants which have the reproductive organs in different individuals, is a very undesirable thing. … . . With regard to the potato and the vine, I can well imagine that the attacks of disease by fungoid growths are greatly facilitated by constitutional weakness, incident to a constant multiplication of tubers, cuttings, or grafts. … I have read your essay with great interest. … Natural selection of the strongest, by natural destruction of the weakest, is supported by experience and common sense. … . If I can help you with any experiments I shall be very glad. …

Yours very faithfully, | D. T. Ansted.”

Copy

1
See Correspondence vol. 24, letter from James Torbitt, 12 April 1876. The letter from David Thomas Ansted to Torbitt has not been found, but extracts from it were published in the Belfast News-Letter, and are reproduced here. The ellipses are in the original. This letter was originally published without the enclosure in Correspondence vol. 24.
2
Torbitt’s scheme for growing potatoes from seed and preserving the seeds of disease-resistant plants from each generation is explained in Torbitt 1876.
3
Cross and self fertilisation was published on 10 November 1876 (Freeman 1977). Solanum is the genus of nightshade; it includes the potato (S. tuberosum). Although potato flowers lack nectar, they are visited by some species of humble-bee (bumble-bee) whose vibrations (buzzing) cause the pollen to be released from specially shaped anthers. Christian Konrad Sprengel had described the behaviour in Sprengel 1793, p. 129. In Cross and self fertilisation, pp. 387–8 n., CD expressed regret that he had not experimented on plants with inconspicuous flowers that were only occasionally visited by insects, like some species of Solanum. He noted that the potato had more conspicuous flowers than other Solanum species that did not secrete nectar and were seldom visited by insects. He added: ‘some of the varieties did not bear seed when fertilised with pollen from the same variety, but were fertile with that from another variety.’

Please cite as “DCP-LETT-10451,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10451