Influence of Calcium and Barium on the Kidney. i8i 



but this method Is unsatisfactory when it is necessary to obtain 

 the exact amount of urine secreted in a given time since it is im- 

 possible to tell whether the bladder is at any time entirely empty. 

 Solutions of the salts whose actions were tested were introduced 

 into the body intravenously. In rabbits a hypodermic needle was 

 placed in a vein of the ear; in dogs the fluid was forced into one 

 of the superficial veins of the lower limb. When small quantities 

 were injected a hypodermic syringe was used; when larger amounts 

 were introduced a pressure apparatus was employed. This was 

 the apparatus commonly used in injection work, consisting of a 

 pressure bottle connected on one side with a water tap, and on 

 the other with a graduated bottle containing the solution to be 

 injected. In this way a constant pressure could be obtained, and 

 the quantity of fluid injected in a unit of time accurately con- 

 trolled. By causing the fluid to pass through a coil of rubber 

 tubing immersed in hot water before reaching the needle, the 

 solution could be kept constantly at the body temperature. Some 

 of the details of the apparatus were suggested to me by an ap- 

 paratus used by Dr. M. H. Fischer in this laboratory. For such 

 Infusions into the blood only 'Vs solutions were employed; In 

 subcutaneous injections stronger solutions were used. Except In 

 those cases where It was necessary to obtain the eftect of the salt 

 on the normal flow of urine, the secretion was considerably raised 

 and kept constant by the uniform infusion of ""/g NaCl solution 

 throughout the experiment. The effect of the other salts was 

 then obtained by allowing small quantities of '"/s solutions to flow 

 into the vein along with the NaCl solution. In other Instances 

 these salts were Injected into a vein of one ear while the NaCl solu- 

 tion was at the same time flowing Into the opposite ear. In these 

 experiments the ear of the rabbit was securely tacked to the board, 

 and the needle kept from slipping out of the vein by means of 

 bull-dog forceps. 



EXPERIMENTS. 



The results of the experiments on the actions of calcium and 

 barium may be best seen In the following tables : 



I. Dog — small terrier — cannula placed In right ureter. 



Urine secreted In ist lo minutes 3.6 cc. 



2d 10 minutes 3-6 " 



