The study of cell membranes began to attract increasing interest before the turn of the present century with the observations of 0 verton. Since that time many investigators have become interested in the broad problem of structure and function of the membrane and today we find ourselVes at a stage in which several branches of research, particularly physical chemistry, biochemistry, biophysics, physiology and pharmacology have come together, leading to the possibility of obtaining a better perspective of the overall problems. The purpose of this Symposium was to assemble in an orderly sequence representations of the knowledge of membranes achieved to date in the areas of the various disciplines. It was thought that to bring together many points of view on a problem should allow the conferees to see better what had been accomplished, what has been overlooked and what needs further development. It is to be hoped that efforts of this type have and will fulfill the desired purpose. This volume contains the majority of the papers contributed by the participants in the Symposium. In addition, it seemed logical to place at the beginning of each chapter at least one general survey of the subject which would help those who were less acquainted with the problem to derive the most benefit from their reading.

Focus, Organization, and Content This book, like the first edition, deals with the mass transport processes that take place in living systems, with a focus on the normal behavior of eukaryotic cells and the - ganisms they constitute, in their normal physiological environment. As a consequence of this focus, the structure and content of the book differ from those of traditional transport texts. We do not start with the engineering principles of mass transport (which are well presented elsewhere) and then seek biological applications of these principles; rather, we begin with the biological processes themselves, and then - velop the models and analytical tools that are needed to describe them. This approach has several consequences. First of all, it drives the content of the text in a direction distinctively different from conventional transport texts. This is - cause the tools and models needed to describe complex biological processes are often different from those employed to describe more well-characterized inanimate systems. Many biological processes must still be described phenomenologically, using me- odologies like nonequilibrium thermodynamics. Simple electrical analogs employing a paucity of parameters can be more useful for characterization and prediction than complex theories based on the behavior of more well-defined systems on a laboratory bench. By allowing the biology to drive the choice of analysis tools and models, the latter are consistently presented in the context of real biological systems, and analysis and biology are interwoven throughout.