When considering the subject of hypertension, one is impressed with the indefiniteness of our knowledge. Some of the sequelae of hypertension have long been recognized and life insurance companies have been emphasizing the importance of hypertension, even though unaccompanied by other symptoms. Fahr1estimates that approximately 50,000 persons in the United States die each year from "hypertension heart," and that probably an equal number of deaths reported as apoplexy and Bright's disease are actually the result of hypertension. This would mean that hypertension ranks foremost among the causes of death in this country.2But even with the general realization as to the importance of the condition, we are unable as yet to draw a sharp line between normal blood pressure and low grade hypertension, and we lack definite information concerning the age at which hypertension makes its first appearance. Alvarez,3in an attempt to determine what constitutes normal blood pressure