A. INTRODUCTION Although great advances continue to be made in many fields of medicine, essential hypertension remains a baffling problem. It is still a leading cause of death, and its origin and cure are still one of the persistent prolems confronting research workers. It is generally accepted that arterial hypertension is produced by narrowing of the peripheral arterioles, at first from vasospasm and after some years from diffuse hyperplastic vascular sclerosis. Most physicians still regard the condition as an "entity," but in a series of papers Hamilton and others (1954) express doubt on this view and suggest that those with essential hypertension represent that section of the population with arterial pressures higher than an arbitrarily selected value and with no disease to which these pressures can be attributed. Two factors concerned in the pathogenesis of so-called hypertension were considered by these investigators, namely, age and inheritance, but, as these did