For centuries man knew about the lightning of the sky (atmospheric or physical electricity) and the numbing effects from contact with powerful electric fishes (animal electricity). Then, after proper experimentation and a synthetic ration­ ale, it began to appear that physical and animal electricity were related in fundamental respects. This realization was made at the end of the eighteenth century, since when the pages of history have been replete with exciting dis­ coveries and developments in electricity and magnetism, electrochemistry, and electrophysiology. It is hoped that this manual will enable some students to relive some of that excitement. The author remembers vividly the excitement when, as an undergraduate, he saw his first action potential. This book is not intended for any particular group of students; it should prove to be of some value to students in secondary schools, colleges, and gradu­ ate schools. Based on personal experience, the author feels that many teachers will also find it of use. Nor is the manual intended solely as a laboratory manual for an introductory course in neurophysiology. Some of the experiments might be introduced into the formallaboratory schedule of general or animal physiology courses. Alternatively, the various experiments might provide the bases for the beginning of special projects lasting for a full semester or even longer.