Influence of Calcium and Barium on the Kidney. 185 



approximately equal. As shown in experiment 4 however the addi- 

 tion of a minute quantity of BaCL (less than y^ cc ""/§ solution) to 

 the blood causes the flow of urine to increase markedly, so that the 

 quantity secreted in a unit of time is far in excess of the quantity 

 of fluid introduced into the blood. If, however, while this active 

 secretion is going on, 5 cc. '"/g CaClg solution be injected into 

 the blood, the flow of urine rapidly decreases, although the total 

 quantity of fluid added to the blood remains constant. The fur- 

 ther addition of BaCU again increases the secretory activity so 

 that the quantity secreted in 10 minute periods which has fallen 

 from 16.4 to 2, under the influence of CaCL is again raised to 8.6 

 by the injection of the barium salt. An apparently contradictory 

 thing, however, happens when a larger amount of barium chloride 

 is suddenly added to the-blood. As shown in the foregoing table, 

 while yi cc. BaCL largely increases the urinary secretion, the 

 injection of ^ cc. in addition to that already present, causes an 

 entire cessation of the flow of urine. In some cases this suppres- 

 sion of the flow of urine is quite abrupt; in other instances it is 

 more gradual, a few drops of urine flowing from the cannula at 

 intervals. As shown in the following experiment, the injection 

 of CaCL sometimes counteracts this action of larger doses of 

 BaClg and causes the urine to flow again. 



5. Rabbit — cannula in bladder; injections intravenous. 



Salts other than "Vg NaCl in- Urine in 



Time. NaCl inj"ected. jected in cc. cc. 



9-55 



10.00 10 



10.15 15 



10.30 15 



10.45 15 



11.00 15 



11.00 I cc Vs BaCU + 4 cc Vs NaCl 



II. 15 10 



11.30 15 



11.45 15 



11.45 5 cc. Vs CaCla 



12.00 10 



12.15 • .15 



12.30 15 



