Darwin, and After Darwin, Volume 3 of 3
 Post-Darwinian Questions: Isolation and Physiological Selection

by George John Romanes

"Darwin, and After Darwin, Volume 3 of 3" by George John Romanes is a scientific publication written in the late 19th century. This volume primarily explores post-Darwinian questions related to isolation and physiological selection in the context of organic evolution. It aims to expand on Darwinian principles, addressing new interpretations and factors that influence species differentiation and evolution beyond Darwin's original ideas. The opening of the work lays the groundwork for discussing the principle of isolation as a key factor in the process of organic evolution. Romanes argues for the importance of isolation—both geographic and physiological—emphasizing that it can result from various factors, including breeding practices in natural and artificial contexts. He stresses that to achieve evolutionary change, particularly divergent evolution, intercrossing between populations must be limited to allow for distinct characteristics to develop, thus setting the stage for the intricate exploration of how these evolutionary mechanisms operate within natural populations.