Approves specimen sheet [of Origin]. Sorry book will be so long. Has now written half of last chapter; it is as long as his estimate of the entire chapter. Now thinks it will run to 6000 or 7000 words. Will do his utmost to improve his style. Anxious to publish soon; he knows of two men already writing on the subject, starting from his Linnean Society paper ["On the tendency of species to form varieties", Collected papers 2: 3–19]. Will send a diagram for the book.