Ever since the introduction of roentgenotherapy in medicine, constitutional reactions following irradiation have been observed. These reactions are manifested clinically by symptoms which may appear any time after irradiation, from a few minutes to a day or more, usually from four to six hours, and which may run the gamut from slight headache and malaise, anorexia, nausea and vomiting to complete prostration, compelling the patient to remain in bed two or three days. Ordinarily, the symptoms subside in a few hours. The exact cause of these manifestations is not known. Several theories as to their origin have been offered, the merits of which, with one exception, it is not the purpose here to discuss. Lange,1 on the basis of the fact that the administration of sodium bicarbonate seemed to ameliorate or to prevent the onset of postirradiation symptoms, suggested that acidosis might be the cause. It is assumed that the