Evolution in Modern Thought by Høffding, Harald Thomson, J. Arthur (John Arthur) Weismann, August Bouglé, Célestin Charles Alfred Morgan, C. Lloyd (Conwy Lloyd) Schwalbe, Gustav Albert Haeckel, Ernst Bury, J. B. (John Bagnell) Bateson, William Waggett, P. N. (Philip Napier)
 is a Project Gutenberg book, now on Github.