The Variation of Animals and Plants Under Domestication, both volumes in a single file

The second edition. Darwin explains in the Preface: "During the seven years which have elapsed since the publication in 1868 of the first edition of this Work, I have continued to attend to the same subjects, as far as lay in my power; and I have thus accumulated a large body of additional facts, chiefly through the kindness of many correspondents. Of these facts I have been able here to use only those which seemed to me the more important. I have omitted some statements, and corrected some errors, the discovery of which I owe to my reviewers." According to Wikipedia: "Charles Robert Darwin (12 February 1809 – 19 April 1882) was an English naturalist, who realised and demonstrated that all species of life have evolved over time from common ancestors through the process he called natural selection. The fact that evolution occurs became accepted by the scientific community and the general public in his lifetime, while his theory of natural selection came to be widely seen as the primary explanation of the process of evolution in the 1930s, and now forms the basis of modern evolutionary theory. In modified form, Darwin’s scientific discovery remains the foundation of biology, as it provides a unifying logical explanation for the diversity of life."