The treatment of primary polycythemia by repeated bleeding and the administration of hydrazine derivatives gives only temporary symptomatic relief by mechanically or chemically reducing the amount of the circulating blood or red cell mass. Radioactive phosphorus when obtainable is the treatment of choice at present. The development of more effective and rational therapeutic measures has been prevented by our ignorance of the causation of the disease. Recent experimental studies of Schafer 1 on the effects of the resection of the carotid sinus with the cardioaortic proprioceptive nerves and of the paravertebral sympathetic ganglions and nerves on vasotonus, blood pressure, oxygen metabolism and peripheral blood cell mass throw an interesting new light on the possible genesis of polycythemia and may open a new and promising avenue for its therapy.
Schafer observed that a polycythemic reaction, in addition to hypertension, developed in 40 per cent of dogs in which the carotid sinus