IN 1938, an anatomic and pathologic study of the lymphatic spread of carcinoma of the breast was started at the Presbyterian Hospital as a corollary to the work already done by Gilchrist and David on the lymphatic spread of carcinoma of the bowel. Surgical specimens removed by radical mastectomy were washed completely free of blood, fixed in 10 per cent formaldehyde solution for twenty-four hours, and then dehydrated in varying strengths of alcohol from 50 per cent to absolute. The specimens were then cleared in oil of wintergreen. From such cleared specimens all the lymph nodes were removed, their location marked on an appropriate diagram of the thoracic wall and each of the lymph nodes sectioned and examined microscopically. From 1938 through 1942, a total of 87 surgical specimens of carcinoma of the breast were studied in this fashion. These were removed by fifteen different surgeons on the hospital staff,