The first part of this treatise is devoted to an evaluation of theory of renal secretion. The author is convinced that the weight of evidence favors the theory of filtration and reabsorption. The discussion of the mechanism of diuresis is excellent, but the treatment of the nature of edema is unconvincing. The evaluation of tests of renal function is incomplete, since the author ignores the recent American contributions. The last section is devoted to the classification of renal diseases. Unfortunately he has here completely left out Addis, whose classification is so helpful to American clinicians. The subject has been presented from the physiologic point of view because this is the best way for the clinician to understand renal disease. The author is to be congratulated on the emphasis that he places on this outlook.