6 JOUENAL OF THE MiTCHELL SoCIETY [May 



The carotid pressure was recorded in the usual way, and a 

 relative idea of the heart volume was obtained along with the 

 pressure tracing by means of a Hiirthle manometer. 



The left kidney was surrounded by a rubber bag filled with 

 water, and the kidney with its surrounding water cushion placed 

 in a copper oncometer. The oncometer communicated by means 

 of a rubber tube with a water manometer which registered on an 

 arbitrary scale graduated in millimeters the increase or the 

 decrease in the volume of the organ. 



Into each ureter was placed a ureter canula. Observations 

 of the urine flow were made only from the right kidney, on ac- 

 count of the fact that the flow from the left kidney was possibly 

 influenced by the mechanical disturbance necessarily associated 

 with the use of the oncometer. 



The various diuretic solutions were given intravaenously 

 through the femoral vein, due care being taken of their tempera- 

 ture. 



The experiments were of such a nature that they would 

 necessarily require considerable time for consecutive observa- 

 tions of the action of the different diuretics. On this account 

 it seemed advisable to employ some method to maintain a 

 fairly constant body temperature. For this purpose a cop- 

 per water box was used, similar to the ones employed in SoU- 

 mann's laboratory. The upper surface of the box is concave 

 and holds a wooden rack in which the animal is placed. With 

 such an apparatus the animal's body temperature can be fairly 

 accurately maintained. 



At the termination of the experiments, the kidneys were at 

 once removed and tissue fixed for microscopic study in both 

 corrosive-acetic and in formaline. 



Five of the twenty-three animals employed in this investiga- 

 tion were either purposely or accidentally killed before or at 

 the commencement of the anesthetic. Kidney tissue from these 

 animals was fixed for histological study. 



In the remaining eighteen animals the physiological response 

 of the nephritic kidney was studied under the influence of : 



