The Variation of Animals and Plants Under Domestication is a book by Charles Darwin that was first published in January 1868. A large proportion of the book contains detailed information on the domestication of animals and plants, but it also contains in Chapter XXVII a description of Darwin's theory of heredity which he called pangenesis. The Variation of Animals and Plants Under Domestication went on sale on 30 January 1868, thirteen years after Darwin had begun his experiments on breeding and stewing the bones of pigeons. He was feeling deflated, and concerned about how these large volumes would be received, writing "if I try to read a few pages I feel fairly nauseated ... The devil take the whole book". In his autobiography, Darwin estimated that he had spent 4-year 2 months "hard labour" on the book. Source: Wikipedia (en)