This book is a collection of up-to-date research reviews dealing with various aspects of the structure and function of excitable cells. Its overall objective is to further the search for a better understanding of the mechanism of excitation on a structural and physicochemical basis. The chapters are written by active investigators from a variety of disciplines, repre senting many different points of view. Their complementary fields of expertise give this book the rare feature of extraordinary breadth. Excitability is a fundamental property of many biological systems. The mechanisms by which nerve impulses are initiated and propagated, and by which rhythmical activities are produced in nerve, muscle, and cardiac cells, can be fully elucidated only when the process of excitation is derived from fundamental principles applied to known structural forms, at both the macroscopic and the molecular level. The problems of excitation are complex, requiring knowledge of many aspects of cells, including their morphology, elec trobiology, chemical physics, and biochemistry.