The role which the kidneys play in the genesis of arterial hypertension has been the subject of discussion since the days of Richard Bright. For many years it was believed that increased arterial pressure was accompanied by disease of the kidneys. Gull and Sutton1were the first, however, to suggest that high arterial pressure might be attributed to "arterio-capillary fibrosis." The present conception of "essential" hypertension, a condition in which the blood pressure is elevated without failure of the kidneys, is an outgrowth of the contributions of Allbutt,2Janeway3and Volhard and Fahr.4The term "essential" hypertension continues to connote a condition characterized by theabsenceof diseases to which elevated arterial pressure is considered secondary and as such is of inexact meaning. Since the work of Goldblatt5in producing experimental hypertension by interference with the renal blood supply, the importance of the kidneys in