"It is only when the full etiology of disease is known that the medicine of our day can become the medicine of the future—that is to say, hygiene in its widest sense."—Pawlow. CONTENTS. Introduction—Methods—Selection of material—The effect of alcohol, ether, chloroform and amyl nitrite inhalations—The effect of injury of the kidney by the hypodermic needle, and of normal saline solution, adrenalin and alcohol solutions injected directly into the renal parenchyma—The effect of adrenalin and gelatin solutions injected directly into the veins—Summary of experimental results—Discussion on the etiology of chronic nephritis—Conclusions—Bibliography. INTRODUCTION. With the knowledge that the combined death rates from heart and kidney diseases have almost doubled within the past twenty-five years in the cities of Boston, New York and Chicago,1 there has been offered no sufficient explanation for the cause of this increase, or of the widespread occurrence of nephritis, and no means of prevention are proposed offer