This monograph brings together 18 papers of a symposium held to celebrate the opening of the International Research Center for Chemical Microbiology. The monograph is a veritable gold mine of information rarely assembled in one volume. One can only indicate here the range of subjects discussed. For example, C. J. Hinshelwood deals in his paper with growth, adaptation, decline and death of bacterial populations and presents a most provocative idea suggesting that, in the intimate linkage of protein and nucleic acid, the spacings of each affect the mode of synthesis of the other; and that although the production of protein and of nucleic acid are not autocatalytic by themselves, a steady state may ensue in which the two kinds of cell material increase autocatalytically. L. Califano discusses the liberation of nucleic acid from cells under the influence of heat as an index of the heat of inactivation of the organism and of the physiological age of the cell.