Set in Imprint 11 on 12 point and printed in Great Britain at THE ALDEN PRESS. OXFORD au Professeur Jean BRACKET, mon maitre et mon ami Contents PAGE Preface 1. Induced synthesis of enzymes in micro-organisms 2. Repression of enzyme synthesis in micro-organisms 3. Mechanisms of repression and induction 4. Induced transformation of an enzyme 5. Permeases and enzyme synthesis 6. Enzymic adaptation in animal tissues B. Non-mendelian hereditary factors in enzyme synthesis C. Changes in protein synthesis during differentiation D. The formation of antibodies Subject Index Author Index 207Preface Knowledge on the biosynthesis of proteins is increasing so rapidly, and relevant data are obtained from such a variety of approaches that it is more and more difficult to keep abreast with the progress of research. Chemistry, crystallography, genetics, cytology, cellular physiology, embryology, immunology, microbiology, enzymology all contribute to the analysis of the process. It is obviously impossible to master all these sciences, and each worker must go his own way, trying his best with what he can do. But he must from time to time stop and look around to appreciate the advances made along the other lines of research, lest he might lose contact altogether with the other approaches. The author felt this necessity for himself and for the students in his laboratory, and he tried to outline a picture of the whole field of protein biosynthesis as he sees it presently. The outcome of his attempt was this little book, in which well established facts were merely summarized, and greater emphasis was laid upon recent developments and new perspectives. It is realized that the discussions and interpretations of recent data that this book contains will soon become obsolete : this is unavoidable in a field of research which is developing so rapidly. The picture presented here should be regarded as a snapshot taken at the end of 1960; blurred spots on the picture are due in part to the lens, and in part to the fog that still covers large regions of the field.