In the past ten years malignant diphtheria has increased alarmingly in Europe and has occasionally assumed epidemic proportions, with a mortality rate of from 30 to 60 per cent, in spite of the administration of large doses of antitoxin. Attempts to explain the high death rate by identifying a new strain of the diphtheria bacillus have been unsuccessful. Furthermore, accompanying infections with other organisms do not seem to play a deciding r\l=o^\lein the development of malignant diphtheria.1 The suggestion that the high rate of mortality was due, in great part, to the physiologic disturbances produced by the diphtheria toxin before the neutralizing effect of antitoxin was obtained, and that therapeutic success required the adequate symptomatic treatment of these disturbances was responsible for the studies reported in the earlier papers of this series.2 In the present article the treatment of malignant diphtheria from the physiologic point of view is discussed. While the number of severe cases of diphtheria seen in the New Haven Hospital has been small, our clinical experience illustrates certain practical pro¬ cedures the application of which may benefit patients with the disease.In previously published reports 2 experimental data were presented which indicated that diphtheritic intoxication produced extensive derangement of carbohydrate metabolism, manifested by changes in the blood sugar and amino-acid nitrogen and by diminished hepatic From the