In this book, the author traces the development of the concept of evolution in the minds of naturalists from the ancient Chinese, Babylonian, and Egyptian cultures to the present day. Four historical periods are dealt with: the early period culminating with Aristotle; the speculative period dominated by the philosophers of the 17th and 18th centuries; the formulative period of the 19th century embracing the work of such biologists as Erasmus, Darwin, Lamarck, Cuvier, and Wallace; and the modern experimental period, which dates from the rediscovery of Mendel's work in 1901. In this section, emphasis is placed on the relationship of evolution and genetics. The appendix contains supplementary technical material and an extensive bibliography. This book should appeal to those interested in the philosophical and historic approaches to biology.