Dated from the reference to William Townsend Aiton’s house (see n. 2, below).

Hooker had married Frances Harriet Henslow on 15 July 1851. They were waiting to move into the house of the late superintendent of the Botanic Gardens, William Townsend Aiton, where Hooker could work on his Indian collections with the aid of a grant from the Department of woods and forests. According to L. Huxley ed. 1918, 1: 350, in September, when the Hookers were in the process of moving, onerous conditions imposed by the government caused them to give up the house.

The Great Exhibition had opened at the Crystal Palace in Hyde Park on 1 May 1851. Soon after his return to England from India (26 March 1851), Hooker was appointed a juror of the section dealing with ‘Substances used as food’ (L. Huxley ed. 1918, 1: 364).

Of his work as editor of the exhibition reports, Hooker wrote that it was ‘a great bore in some cases and very easy in others; there will be 1600 pages of it’ (L. Huxley ed. 1918, 1: 365). The reports when published came to a total of 749 pages (Exhibition of the works of industry of all nations, 1851. Reports by the juries (London, 1852)). In August 1851, Hooker, as a reporter for his section, wrote the ‘Report on substances used as food’ (ibid., pp. 51–67).

Lyon Playfair was special commissioner in charge of the department of juries of the Great Exhibition and chief advisor to Prince Albert. He served on the Geological Survey, where Hooker also had worked before his departure for India.

Hooker and his wife may have been in Paris in early August, where Hooker would have been invited in his capacity as a juror at the Great Exhibition (see letter to Edwin Lankester, [7 August 1851], n. 2).

James Wilson, Scottish zoologist. In 1841 he began investigating the natural history of fishes of Scotland, particularly the herring, at the request of the fisheries board (J. Wilson 1842). Entries on 8 June 1845 and 15 November 1851 in CD’s reading notebook record his reading of this work, which he considered ‘poor’ (Correspondence vol. 4, Appendix IV, 119: 16a, 23b).

In both Origin, p. 384, and Variation 2: 304, CD mentioned that it was possible to accustom marine fish to live in fresh water and that such changes had been chiefly observed in a state of nature. CD’s earlier interest in crosses between salmon and trout (Salmo ferox is a lake trout) is exhibited in some scraps relating to fish and hybridisation preserved in DAR 205.7 (letters): 283–4. The first, cut from a letter bearing a mourning border, asks: ‘Are the statements of hybrid fishes in the Phil. Trans for 1771 [J. R. Forster 1771, pp. 318–19] to be depended on?—’. The correspondent has not been identified, and it is possible that the letter was not addressed to CD but was passed on to him. The verso bears the following: ‘deposit with me a copy of his entire work to be presented, “when it passes out of my hands, to the Library ⁠⟨⁠    ⁠⟩⁠ establishment. So great a’. This has been deleted in ink. Pinned to this fragment are two notes written in pencil by CD. The first reads: ‘Believes he has seen many mule fish—between trout & salmon.— M^r. Knight. Phil. Trans. 1828. p. 319’. Knight 1828, p. 322, states that: I have never possessed means of obtaining mule fishes; but one kind of fish, which I think is obviously a mule, is found in many rivers where the common river-trout abounds, and where a solitary salmon is sometimes seen. These formerly existed, in some seasons, in considerable numbers, in the river which passes near my residence; but since salmon have become scarce, they have wholly disappeared. I had formerly opportunities of examining a large number of them, without having ever found a single female … They are readily distinguished from the young salmon, by their form being intermediate between that of a trout and of a salmon; by their being all, or nearly all, males; and by their remaining through the summer and autumn in the rivers, long after the young salmon have descended to the sea: they leave the fresh water with the first winter floods, and I believe are not known ever to return … If these be mules, as I do not entertain any doubt that they are, the spawn of fishes must be without sex when it is deposited by the female The second note by CD reads: (recto) ‘Walker [probably Walker 1803a and 1803b, published in Prize Essays and Transactions of the Highland Society of Scotland]’; (verso) ‘N Q | Scropes Days of Salmon Fishing p. 34 M^r Shaw crossed Trout & Salmon [Scrope 1843, p. 34, refers to Shaw 1840 and correspondence with John Shaw on the crossing of trout and salmon]’. CD recorded having read the Philosophical Transactions of 1788 to 1840 on 1 March 1840, Scrope 1843 on 7 October 1844, and the second volume (1803) of the Prize Essays and Transactions of the Highland Society of Scotland in May 1845 (Correspondence vol. 4, Appendix IV, 119: 7a, 14a, 15a). CD also recorded in his reading notebook (DAR 119) that he had made an abstract of Scrope 1843. This abstract is not with CD’s abstracts of scientific books (DAR 71 and 72), and the scrap preserved in DAR 205.7 (Letters) relating to Scrope’s work may have been cut from the abstract.

CD’s number for one of the portfolios in which he kept notes for his projected ‘big book’ on species (Natural selection). The number also occurs in Notebook C: 47e and Notebook D: 12e (Notebooks). All three notes are concerned with variation.