A prolific and diverse scholar, Hans Friedrich Gadow (1855-1928), wrote on such topics as birds, Mexican peoples and animals, reptiles, and other vertebrates. Born in Germany in 1855, Gadow studied anatomy with Ernst Haeckel in Germany before moving to England, where his research on avian anatomy and systematics had broad influence. He was Curator of the Stricklandian Collections at Cambridge University and a Reader on the morphology of vertebrates. The Gadow Papers consists of twenty letters (1907-1914) from Hans Gadow to William Morris Colles and to Colles' firm 'Author's Syndicate' that discuss Gadow's work "Through Southern Mexico" (1908). Colles was an agent who helped writers to publish their work. The early letters deal with editorial changes to the book, the later letters are about A & C Black, a publishing firm, which Gadow believed had not properly compensated him for his contributions to "The Lost Link," a book he co-authored with Ernst Haeckel. Most of the letters are very brief and do not discuss personal matters in Gadow's life nor do they contain much information on Gadow's scholarly work, except for references to the editorial process. Similarly, they provide no information on Gadow's travels to Mexico.

These letters, mostly in German, refer to evolution, Darwin, monism, phylogeny, radiolaria, morphology, and anatomy, and other scientific work of Haeckel and his correspondents.

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).

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.