原文 (英语)

By Charles Darwin A RECORD OF HIS WORK IN A SERIES OF HITHERTO UNPUBLISHED LETTERS EDITED BY FRANCIS DARWIN, FELLOW OF CHRIST'S COLLEGE, AND A.C. SEWARD, FELLOW OF EMMANUEL COLLEGE, CAMBRIDGE IN TWO VOLUMES Transcriber's Notes: All biographical footnotes appear at the end of Volume II. All other notes by Charles Darwin's editors appear in the text, in brackets () with a Chapter/Note or Letter/