Ball, and Dr. Van R. Potter for having served as chairmen in the three sessions of the symposium, which they did with skill and discretion. My appreciation is also extended to the administration and staff of the Marine Biological Laboratory for their unfailing cooperation and efforts to make the meeting a success. Finally, my thanks go to Mr. Robert Kitchen and Miss Lillian Blaschke for serving as volunteer messengers during the symposium, and to Mrs. Sally Hayashi and the staff of the American Physiological Society, who deserve the major credit for the editing and assembling of this volume.