Much of the very abundant literature on diseases of the kidneys during the past five years has consisted in reports of clinical investigations of renal function in nephritis and hypertension as revealed by inulin and diodrast clearance tests. These two substances possess certain qualities that render them particularly useful for this purpose, and these tests appear to rest on a theoretically sound basis. The object of most of these investigations has been to measure the degree of competence of the kidneys to perform their function of elimination and to formulate a concept of the conditions that must exist in these organs in order to give rise to the observed results of these tests. There are few or no available observations based on a comparison of the actual pathologic changes in the kidneys and inulin and diodrast clearances. It is my object in this paper to reverse this clinical point of