In order to discuss intelligently the question of the relative values of various methods of treatment, let us briefly recall some facts and theories that laboratory experimentation and clinical experience have developed in the centuries of struggle against this decimating disease. 1. Anatomy. A very brief reference to the anatomy of the breast, merely mentioning the circulation, will suffice at this time. The blood supply is very complicated, because of the location of the organ. It is provided for by the innominate and subclavian, the internal mammary, and rami of the intercostal arteries, accompanied by their veins and lymph vessels. The latter drain either into the auxiliary supra- and infra-clavicular lymphatic glands, or, directly into glands which are located close to the mediastinum, and follow the course of the thoracic duct. This is a most important factor, not only because of the possibility of metastases to the chest wall, but also because of the likelihood of early implantations of foci of carcinoma within the intrathoracic region which cannot be reached by the surgeon's knife. Various modifications of the lymph drainage of the breast have been demonstrated, and, according to Handley's permeation theory, they account for differences in distribution of metastases. Thus, in the anastomosis with the opposite side, an appreciation of metastases occasionally occurring in the opposite supraclavicular fossa and the opposite breast and axilla is afforded. Handley stresses the importance of the network of lymph channels which lie above and below the pectoralis fascia, send out branches vertically to the skin and chest wall and connect with the epigastric region, in addition to the other regions mentioned. The axillary lobe of the mammary gland extends far into the axilla, and in a radical operation necessitates an extensive incision. This region frequently is the primary seat of the tumor. This extension of the gland is generally underestimated, because we are not used to seeing coronal but vertical sections. Only the former, however, distinctly show that parts of the gland extend under the skin in the form of flat discs, and that isolated lobules lie far away from the main gland. 2. Pathology and Clinical Appearance. For the sake of completeness we shall touch on the gross pathology of the condition but avoid details. We all remember the large tumors which cause more or less marked increase in the size of the gland and usually grow rapidly, metastasize early, soon ulcerate, frequently bleed seriously, and rapidly sap the life of the host, the medullary carcinoma. Here there are large aggregations of rapidly multiplying cells and but little fibrous stroma. Then, by contrast, there is the small hard one, which shrinks the gland, grows slowly, often appears stationary, and metastasizes late.