This book comprises six lectures delivered at Cornell University in 1945 under the title "Messenger Lectures on the Evolution of Civilization." The first two lectures, by H. J. Muller, deal with genetic fundamentals. In nontechnical language, the cytologic basis of the reproductive process and of the distribution of the genetic material among the cells of the body is explained. Some interesting paragraphs are devoted to fundamental problems which are usually not stressed in textbooks of genetics: How genes, alike in all parts of the embryo, cause the parts to differentiate; what the gene does chemically, and how the gene reproduces itself. The causes and the mechanisms of gene mutations are discussed. The modern geneticists' view of the process of evolution is briefly described and interpreted.
C. C. Little contributes chapters entitled "Parental Influence" and "Growth and Individuality." The relation of mammalian genetic experiments to problems of human medicine is pointed