The American Journal of Physiology

Practically all investigations attempting to unravel the processes involved in the function of the kidney have been made under conditions of anesthesia and operative interference. This has been necessarily so because the main problem involved, the assigning of functions to the different parts of the renal unit and the discovery of the nature of the processes involved in these functions, has seemed incapable of approach except under simplified conditions where variables could be controlled. Perfusion of the isolated organs represents an extreme case of the artificiality of the conditions of the kidney in the experiment compared to those in a normal animal. Just how far it is justified to transfer conclusions obtained in experiments where the conditions are abnormal to the normal is not known in this case: it is certain, however, that in many instances the wrong conclusion about the functioning of an organ in the intact healthy animal has been made when the experiments giving this conclusion were done on animals subjected to narcosis and operative interference. A second method of approach to a study of the function of the kidney has been a comparison of the changes in the blood plasma and urine under different conditions, a method which can be applied to the normal unanesthetized animal or man. This second method, unfortunately, has not told us much about the main problems involved in kidney function, the nature of the processes occurring in the morphologically different parts of the renal tubule. Although we have here perfectly normal conditions, the process