I have had the privilege of conversing with Professor palladin on numerous occasions during the last 15 years of his life. In these years, after the age at which most people retire, he was still a most admirable man, with an active interest in science, and a wide and wise approach to its many facets. I was always impressed by his enthusiasm for, and lm. owledge about, studies of the nervous system, both his own and those of others. He was interested in myriads of details, which he was able to synthesize into concepts and systems. The present book reflects, in addition to his warmth and wit and wisdom, Dr. Palladin's approach and style: how he and his collaborators came to their conclusions after careful consid eration of all the facts. The references in this book, for example, show the great number of works that were found worthy of quoting and including. The reader can see the stepwise emergence of a concept as he reads the pages of this book. Facts are not given for facts' sake, but to try to present a picture based on a large number of observations, by most of the scientists who studied this aspect of the nervous system. The work emerges as from a community; there is .no attempt to minimize results of others or to maximize those of Palladin's laboratories. Palladin's working lifespan covered over six decades, and many stages in biochemistry."

Volume V deals with the problems of turnover in the nervous system. "Turnover" is defined in different ways, and the term is used in different contexts. It is used rather broadly in the present volume, and intentionally so. The turnover of macromolecules is only one aspect; here "turnover" in dicates the simultaneous and coordinated formation and breakdown of macromolecular species. The complexities of cerebral protein turnover are shown in aseparate chapter dealing with the synthesis ofproteins, in another on breakdown, and in still another on the relationship ofthese two (showing how the two halves of turnover are controlled). The fact that most likely the two halves of protein turnover, synthesis and breakdown, are separated spatially and the mechanisms involved are different further emphasizes the complexity of macromolecular turnover. "Turnover" is used in a different context when the turnover of a cycle is discussed; but he re again a number of complex metabolic reactions have to be interrelated and controlled; some such cycles are discussed briefly in this volume, additional cycles have been discussed with metabolism, and some cycles still await elucidation or discovery.