Both science and religion are aspects of human endeavor that do not observe political constraints. It is therefore appropriate that contributions should come from many different countries for a series which attempts to chronicle developments in an interdisciplinary field such as membrane research. This volume is an excellent example of the diversity of thinking, background, and approach needed by the working scientist for his re­ search planning. From Canada comes a review by Silverman and Turner of the mech­ anisms by means of which the plasma membrane of the renal proximal tubule acts as a transport mediator. The two chapters that were writtyn by American scientists are excellent examples of the comparative bio­ chemical approach. Inouye feels he must apologize for being interested in the outer membrane of E. coli, but it is obvious, after a reading of his chapter, that no apology is required. On the contrary, we are grateful for his drawing our attention to this system and its unique properties. Holtz­ man, Gronowicz, Mercurio, and Masur are also on a consciousness­ raising mission in summarizing for us a number of integrated functions of membranes using the toad bladder as an experimental system. The other two chapters of this volume come from overseas. N orthcote has again demonstrated his capacity to integrate a complex and difficult field.