 One cannot always distinguish between “popular” and “professional” receptions of Darwin. The simplest solution is to confine the latter designation to those who embraced Darwin’s version of a general theory of descent with modification by people with professional research and teaching positions in universities and scientific societies, those who were intimately familiar with the empirical evidence and the technical scientific issues under debate in the 1860s in geology, comparative anatomy, embryology, biogeography, and classification theory. This group can usually be distinguished from lay interpreters who may not have made distinctions between the views of Lamarck, Chambers, Schelling, Spencer, and Darwin on the historical development of life. But this only gives a crude instrument of analysis.