The pathogenesis of varicose veins and the concomitant abnormalities of the circulation are not clearly understood. My purpose in this paper is to record observations made in the course of study of the blood gases in a series of patients with apparent abnormalities of the veins of the extremities. Although these observations are insufficient for significant conclusions concerning the pathogenesis of conditions peculiar to varicose veins, they are sufficient for definite conclusions concerning certain fundamental facts that must be considered hereafter in similar studies. Most of the observations on the gases of the blood of peripheral vessels have been made for normal persons, and usually the blood of the upper extremities has been studied. De Takáts, Quint, Tillotson and Crittenden1 recently reported studies in which the carbon dioxide and oxygen contents of the blood of varices of the leg were compared with those of the blood from the cubital