Ɛpsilon

From Francis Darwin   [6 July 1879]

I have been talking about the sieve experiment. It all depends on getting the right degree of dampness of the surrounding air— Phaseolus are said to act well, I will try it here with his sieve in the same place where he does it.1 At Down I failed with Faba but succeeded with Lepidium.2 I am v glad you approve so much of the bean experiment with caustic above & below.3 The air roots dont bend at all even without caps of any kind. I will try caps on Chlorophytum roots in water they are good strong roots.4 It has turned so horribly cold I have put on thick things, & the plants are not growing a bit well

Many thanks for Ubbadubba news.5 | F.D

Will mother tell Bessy I have written today to the Riffel6

ApcS

Postmark: 6 7 79

1
See letter to Francis Darwin, 4 July [1879]. Francis performed experiments to determine the sensitivity of the tip of the radicle to damp air; one of the species tested was Phaseolus multiflorus (a synonym of P. coccineus, scarlet runner-bean). CD described the protocol devised by Julius Sachs (Sachs 1872a, p. 212), in which sieves with seeds germinating in damp sawdust were suspended so that the bottom was inclined at 40° to the horizon, and the tips of the radicles were coated to exclude moisture, in Movement in plants, pp. 180–2.
2
Francis refers to Vicia faba (broad bean) and Lepidium sativum (garden cress). In his letter of 4 July [1879], CD had mentioned he had forgotten which species he and Francis had already tested.
4
See letter from Francis Darwin, 4 July 1879 and nn. 3 and 6. Plants of Chlorophytum (the genus of spider plants) have aerial roots.
5
See letter to Francis Darwin, 4 July [1879]. Ubbadubba was a pet name for Bernard Darwin, Francis’s son.
6
The Riffelhaus, a hotel built in 1853, is near Zermatt in the Swiss Alps. Elizabeth Darwin was on holiday in Switzerland with Mary Elizabeth Atkin; they arrived at the hotel around 10 July 1879 (letter from Emma Darwin to W. E. Darwin, [10 July 1879] (DAR 219.1: 124)).

Please cite as “DCP-LETT-12296F,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-12296F