These are letters and papers relating to North America chiefly from the official correspondence of the Gardens and the correspondence of its two directors, Sir William Jackson Hooker and Sir Joseph Dalton Hooker. There are 2 reels of letters from Asa Gray to the Hookers, in addition to other Gray letters elsewhere in the collection. A few letters (1787) from Americans to William Forsyth, superintendent of the Royal Gardens of St. James' and Kensington.

These are mainly letters written from British botanists to James and William Sowerby concerning flowers and botany in England. Most of the correspondents are represented by only one letter and include Charles C. Babington, William H. Baxter, Joseph D. Hooker, Daniel Oliver, and W. T. Thiselton-Dyer.

A variety of topics are discussed in these letters, mainly on plant specimens and botanical subjects in relation to England, India, and other parts of the world. The most voluminous correspondence is with Henry Walter Bates, Sir Henry Cole, Sir Richard Strachey, Dawson Turner, and William Crawford Williamson.

Thomas Henry Huxley (1825-1895) was an eminent Victorian-era biologist, best known as a passionate defender and popularizer of Darwin's theory of evolution. His partisanship earned him the nickname of "Darwin's Bulldog," although he did not accept the theory uncritically. In addition to his work in biology, he performed original research in zoology and paleontology. He is also remembered as the progenitor of a family of highly successful scientists and thinkers. This collection is made up of letters, primarily written by Huxley, on a variety of topics including the age of man, evolution, education, natural history, science, geology, spiritualism, and vivisection. The most voluminous correspondence is with Sir James Thomas Knowles (30 letters) and with Huxley's daughter, Ethel Huxley Collier, "Babs," (44 items). The 30 letters to Knowles appear in neither the Life and Letters, nor are they listed in Dawson's guide to the Huxley Papers at the Imperial College. The other major correspondents include Charles Edward C. Appleton, Matthew Arnold, William B. Carpenter, Sir Henry Cole, George Dixon, Sir John Donnelly, Thomas Campbell Eyton, Sir William Henry Flower, Sir Joseph Dalton Hooker, Leonard Huxley, Sir William Jenner, Sir Charles Lyell, Louis Compton Miall, Alphonse Milne-Edwards, Sir James Paget, Harry Quilter, Harry Govier Seeley, Alfred R. Wallace, and William Crawford Williamson.

This is a miscellaneous collection of letters, to and from Lubbock, concerning his lectures and his interest in paleontology, as well as references to political matters, particularly the Irish question, and numerous mentions of the legislative bills with which he was involved. There are letters concerning his publications, "Prehistoric Times" (1865), and "Sense and Intelligence of Animals" (1888).

A prime exponent of evolutionary theory in the late nineteenth century, the British naturalist Alfred Russel Wallace arrived independently at the theory of natural selection nearly simultaneously with Charles Darwin. The numerous publications that emerged from his extended field excusions into the Amazon Basin and the Malay Archipelago (Indonesia) Wallace resulted in major contributions to evolutionary theory, biogeography, ecology, and ethnography, and made Wallace, by the end of his life, one of the best known naturalists in Britain. A Socialist, social progressive, and Spiritualist, Wallace's distinctive take on evolutionary change differed from the Darwinian mainstream in significant ways. The Wallace Collection is a miscellaneous assemblage of letters written by and to Alfred Russel Wallace, primarily during the last twenty five years of his life. Varied in content, the letters touch on Wallace's views on evolution, Spiritualism, and to a less degree, his progressive social commitments.

There is correspondence concerning geology, botany, natural history, natural selection, evolution, British science and scientists, and other scientific topics. Most of the letters are written by Lyell, with a very few items by others.