It is now generally recognized that to obtain satisfactory results in the treatment of cancer, an early diagnosis is necessary; if an operation for cancer is to be successful, the diagnosis must be made almost always before the classic symptoms appear, often a matter of great difficulty. It is imperative, also, that no time be lost in making a decision and in planning the operation, for the scope of the latter, when the tumor is benign, is entirely different from that when the growth is malignant, and it is often most difficult to change during the course of the operation from one type of procedure to another. For instance, the extensive exposure and preliminary vascular ligation which may be necessary in a resection for cancer of the tongue, jaw, uterus or rectum are quite unnecessary in the case of a benign tumor, and to change the whole scheme after the