Membrane Physiology is a soft-cover book containing portions of Physiology of Membrane Disorders, published in larger, hard-cover form in 1978. The parent volume was divided into five parts, described in detail in the Preface to the hard-cover edition, which is reproduced in this volume. The present version of Membrane Physiology incorporates the first three of these parts, including a section on the Nature of Biological Membranes, a section on Methods for Studying Membranes, and a section on General Problems in Membrane Biology. It is the hope of the Editors that this smaller volume will be of value to individuals interested in general physiology, the methods for studying general physiology, and its potential application to problems of clinical and physiological relevance. The Preface to Physiology of Membrane Disorders indicates our general reasoning for developing such a volume. THOMAS E. ANDREOLI JOSEPH F. HOFFMAN DARRELL D. FANESTIL Vll Preface to Physiology of Membrane Disorders The purpose of this book is to provide the reader with a rational frame of reference for assessing the pathophysiology of those disorders in which derangements of membrane transport processes are a major factor responsible for the clinical manifestations of disease.