This collection of papers is presented to Sir JOHN ECCLES by his former and present collaborators to commemorate the award of the 1963 Nobel Prize in Medicine, which was shared with A. L. HODGKIN and A. F. HUXLEY. Sir JOHN’S interest in, and influence on, the study of physiology, particularly that of the nervous system, is reflected by the range of topics discussed, and by the distri bution of the various authors in laboratories throughout the world. Those who have been privileged to work with him in Oxford, Sydney, Dunedin or Canberra have enjoyed a good discipline in scientific thought, as well as in the use of neurophysiological techniques. Basic knowledge is always transferable, and the inspiration which comes from association with a great scientist is not confined to anyone field of physiology. The contributors to this volume were requested to review briefly that aspect of physiology of current interest to them, and it is hoped that the resulting papers will serve as an up to date review of many physiological problems. The editors are greatly indebted to the publishers, Springer-Verlag, particu larly to Dr. H. GOTZE for his advice and interest. It is also a pleasure to thank Mrs. H. WALSH for her unfailing assistance during the preparation of this book. Canberra Melbourne 1965. III CONTENTS Rhythmic thalamic activity. P. Andersen.