Darwin, Charles (1809-1882); Wallace, Alfred Russel (1823-1913).
"On the tendency of species to form varieties...." In: Journal of the Proceedings of the Linnean Society, 1858, vol. 3, pp. 45-62.
Darwin got the shock of his life in June, 1858, when he opened a letter from far-off Ternate in the Malay Archipelago, written by Alfred Russel Wallace, and containing a manuscript called “On the tendency of species to depart indefinitely from their original type.” Wallace asked if it was worth publishing. In fact, it was a perfect précis of Darwin’s concept of evolution by natural selection. Darwin sought advice on what to do, and his good friends Charles Lyell and Joseph Hooker recommended that Darwin send Wallace’s paper to the Linnean Society of London, along with a short paper by Darwin, drawn from his letters and manuscripts. This was done, and both papers were read on July 1, 1858. Darwin was not present, and there appears to have been no reaction, pro or con, to this initial presentation of the idea of natural selection.
Fortunately, Darwin at last saw the handwriting on the wall, and he immediately set himself to the task of writing a book-length presentation of his evolutionary theory, leaving out footnotes and anything else that would slow him down. The manuscript was completed in just over a year. The path to the Origin of Species was nearly at an end!