From Francis Darwin   [1 May 1876]¹

The date is established by the relationship between this letter and the letter to Francis Darwin, [30 April 1876].

Edward Frankland had offered to analyse two types of soil that CD and Francis Darwin were using in experiments on cross- and self-fertilisation; they wanted to compare the height and vigour of several generations of both cross- and self-fertilised plants and needed to eliminate the nutrient content of the soil as a cause of variation. The first sample was soil that had been burnt, treated with sulphuric acid, and then washed; the second was clayey soil dug up from the Sandwalk at Down House. See letter to J. H. Gilbert, 16 February 1876, and letter to Francis Darwin, [30 April 1876]. In order to rid the soil of most nutrients, CD had been advised to roast sifted clayey soil until all coaly matter disappeared and the resulting porous and friable matter was a brick-red colour (see letter from J. H. Gilbert, 9 March 1876).

Francis’s paper ‘On the glandular bodies on Acacia sphærocephala and Cecropia peltata serving as food for ants’ (F. Darwin 1876d) was read at the Linnean Society on 1 June 1876. Acacia sphaerocephala is a synonym of Vachellia sphaerocephala (bee wattle or bull’s-horn thorn); Cecropia peltata is the embauba or trumpet tree.

CD paid £21 for a typewriter on 2 May 1876 (CD’s Classed account books (Down House MS)). Amy Darwin, Francis’s wife, had presumably made mock keyboards on which to learn the layout of the letters.

Francis probably saw Henrietta Emma Litchfield when he was in London to purchase the typewriter (letter from Horace Darwin to G. H. Darwin, 1 May 1876 (DAR 258: 860)).