<P> Darwin made attempts to open discussions about his theory with his close scientific colleagues . In January 1842 Darwin sent a tentative description of his ideas in a letter to Lyell, then prepared a "Pencil Sketch" of his theory . He worked up his "Sketch" into an "Essay" in 1844, and eventually persuaded Hooker to read a copy in January 1847 . His geology books and publication of Beagle findings were completed in 1846, when he began what became eight years of research into classification of barnacle species, exploring the immense amount of variation in nature . </P> <P> In September 1854 Darwin had the last of his barnacle monographs ready for publication, and he turned his attention fully to questions about how species originated . He freely discussed his intention to write a book on the subject, and planned avenues of research with other scientists . He went over his previous notes and writings on the topic, and drew up proposals for investigations and research into the implications of his theory . One topic was explaining geographical distribution of organisms; he got information from international correspondence, and experimented on the viability of methods of dispersal . He widened his investigations into variability in nature, and experimented on plant hybridisation and cross-fertilisation . </P> <P> Variation under domestication became a major topic of research: in 1855 he began to develop a web of contacts, both in the UK and worldwide, to get information on the origins and variation of domesticated animals, particularly poultry, ducks, rabbits, and pigeons . He got extensive information, specimens and ideas from Edward Blyth in India, who put him in contact with Edgar Leopold Layard in South Africa . At the suggestion of William Yarrell, Darwin began pigeon breeding at Down House to investigate varieties of domestic pigeons, and gained access to the expertise of William Bernhard Tegetmeier who was glad to research aspects of interest to Darwin . From March, he also got information and specimens from his relative William Darwin Fox who bred poultry and ducks at his rectory in the parish of Delamere, Cheshire . </P> <P> In 1856 he was gradually bringing his friends round towards accepting evolution as a process, but was far from convincing them about the mechanism, when Wallace's entry into the discussion brought a new urgency to publication . </P>

When was charles darwin's theory on evolution published