The date is established by the relationship between this letter and the letter to John Scott, 9 February [1864].

Hooker refers to George Bentham, the president of the Linnean Society, and to John Scott.

Hooker may refer to regulations regarding associate members that resulted from new bye-laws established in 1861; these limited associates to twenty-five in number and to ‘such persons as usually reside in the British Dominions’ (1861 Charter and Byelaws of the Linnean Society of London, Chapter 5, Section 2, Library of the Linnean Society). Hooker may also refer to a resolution that he had submitted as a vice-president of the Council of the Linnean Society regarding election of associates; this was adopted by the Council on 6 March 1862 and required associates living in or near London to attend a certain number of meetings, while those living at a greater distance were required to make one scientific communication each year. If these conditions were not met, after three years the associate was to withdraw (‘Resolution of Council regarding election of Associates’, 6 March 1862, Library of the Linnean Society, and Gage and Stearn 1988, pp. 59, 61; see also letter to John Scott, 9 February [1864]and n. 8). The associateship was an honour that was restricted to those who were not financially able to offer their candidacy and whose work as naturalists was expected to benefit the Society (Gage and Stearn 1988, p. 198).

William Henslow Hooker.

Leonard Horner, who was 79 years old, was terminally ill; he died on 5 March 1864 (K. M. Lyell ed. 1890, 2: 366–7).

Charles Lyell was Leonard Horner’s son-in-law.