Alfred Russel Wallace (1823-1913) is regarded as the co-discoverer with Darwin of the theory of evolution. It was an essay which Wallace sent in 1858 to Darwin (to whom he had dedicated his most famous book, The Malay Archipelago) which impelled Darwin to publish an article on his own long-pondered theory simultaneously with that of Wallace. As a travelling naturalist and collector in the Far East and South America, Wallace already inclined towards the Lamarckian theory of transmutation of species, and his own researches convinced him of the reality of evolution. On the publication of On the Origin of Species, Wallace became one of its most prominent advocates. This second, corrected, edition (1871) of a series of essays published in book form in 1870, shows the development of his thinking about evolution, and emphasises his admiration for, and support of, Darwin's work.