Without touching on the theories of Garrod and Latham on the one side and Haig and his followers on the other as to the origin, effect and disposition of uric acid, which theories prove ever debatable, the writer of this paper passes to the more simple and practical consideration of a certain condition of the blood which conclusively announces the fact that the kidneys are not performing their function and that the condition is one of danger. For the purposes of this essay the cause of "this certain condition" will be referred to as "urinary solids." Renal insufficiency is failure on the part of the kidney to perform its function. A more practical title to this paper would be, a plea for systematic instruction in the use of water in the tropics. Lack of volume to the circulation means renal insufficiency sooner or later, whether the failure in function on