TO the surgeon, and especially to the surgeon in the United States of America, the death of Dr. W. J. Mayo on July 28 at the ago of seventy-eight years is a major historical event. Born in 1861, in the State of Minnesota, he spent his life and did his work in the small country town of Rochester; and there with his brother Charles, who died two months ago (see Nature of July 15, p. 103), he built up the Mayo Clinic the expansion of which has been very great. In early life he conceived the idea that patients could best be treated by groups of medical men among whom could be found specialists in every disorder. This idea was revolutionary at the time; and although in operation it may best be suited to American conditions, not only did it underly the practical success of the Mayo Clinic, but it has also influenced wider opinion because medical men from all over the world were attracted to the experiment. In Rochester was to be found an organization almost fanatically devoted to the interest of the patient, to the exclusion both of financial considerations and of personal professional renown. For from the beginning of the clinic part of its profits were set aside to be devoted to research not only in clinical subjects and the fundamental clinical sciences, but also in such related sciences as chemistry and physics. The two brothers and their early collaborators deliberately sacrificed wealth; and chose to regard as their reward the knowledge that their Institution was making substantial contributions to medical progress. As funds accumulated they were to expand their efforts, always governed by the same general principles, to postgraduate education; and their system of training young men broadly and encouraging specialization only after a sound basic experience has been watched with interest by the medical academic world, and has frequently been utilized by medical schools both in America and in Europe; for one of the many excellences of the clinic has been its readiness to expound its technical methods and the results obtained by them to visitors of any nationality. There is no doubt that the inception and later the guidance of this great experiment in group practice were controlled by Dr. Mayo; and the success which has attended his aims stamps him as a man of singular vision, broad outlook, indomitable perseverance, possessed of administrative powers of the highest order.