First published in 1983, this book summarises the principles of structure and functions of membranes at the molecular level where so much living activity occurs. The dynamic nature of the molecular activity is stressed and examples are drawn from the range of living organisms from bacteria to higher plants and to man. The descriptions and hypotheses in the text are illustrated with some electron micrographs but especially with diagrams based on space-filling atomic models to illustrate the molecular movements. The first four chapters are concerned with the molecular constituents, their packing and their movements. Two chapters deal with membranes in energy transduction, two with trans-membrane diffusion, transport, absorption and secretion and one with excited membranes and signal transmission. the membrane-bound reactions of hormones, antibodies and synthesis are outlined. Finally, membranes are discussed in relation to life's origin and evolution.