Intracellular Transport

Dr. Danielli asked me to introduce this conference on membranes by reviewing the development of some of the current viewpoints about membrane structure and in particular the development of the unit membrane concept. I believe it was his intention that I review the subject in a very general way and bring it up to date so that those of you who have not been working actively in the special field of membrane structure will know the way the current ideas have originated. It is necessary that this be repetitious since most of the material that I shall deal with has been published in one form or another elsewhere. This paper is thus intended only to serve as a brief introductory review providing background for the physicochemical topics that are dealt with in this volume.