THAT cortisone is able to suppress the inflammatory reaction irrespective of the nature of the causative agent is now a generally accepted fact. The site at which it is able to exert this effect remains uncertain; but it has recently been shown that cortisone can prevent or nullify an increase in capillary permeability1, and that its administration is associated with an increase of arteriolar tone2. The latter authors consider that these two vascular effects are the most significant factors in the modification of the inflammatory processes.