August Weismann is regarded by many biologists, including Ernst Mayr from Harvard University, to be second only to Charles Darwin for progressing our understanding of evolution by natural selection. In this book, excerpted from the larger commemorative tome, Darwin and Modern Science, edited by A.C. Seward and others, Weismann tackles many of the difficult questions confronting natural selection. In the process, Weismann offers a penetrating critique of Lamarck and provides the reader with rich and robust understanding of evolutionary theory. This volume has been selected and slightly edited by Professor David Christopher Lane, Ph.D.