PAWLOW'S RESEARCHES. 501 



the sodium chloride in the blood. Under normal circum- 

 stances the hydrochloric acid is reabsorbed from the ali- 

 mentary canal with the reformation of sodium chloride. In 

 Pawlow's dogs, however, the hydrochloric acid being allowed 

 to flow away through the fistula, the soda set free in the 

 blood had to be excreted by the kidneys. 



Since the sodium chloride is split up to form the hydro- 

 chloric acid of the gastric juice, it seemed worth while to 

 find out what would happen if the Na CI in the blood were 

 replaced by Na I or Na Br. Dogs which had been operated 

 on in the usual way were fed on meat, milk, and bread which 

 had been baked without the addition of salt. To their diet 

 was added first two grammes and then six grammes of 

 sodium iodide or sodium bromide as might be desired. In 

 the experiments, in which sodium bromide was added, the 

 dogs became, after fourteen days, so ill and sleepy that the 

 experiment had to be stopped, and one dog died. Sodium 

 iodide, however, did not seem to affect the does in the 

 slightest respect. The dose could be increased far above 

 the amounts mentioned above without producing any ill 

 effects. What is the cause of this difference between the 

 two drugs ? The examination of the urine and gastric juice 

 in the two sets of experiments at once threw light on the 

 cause of this divergence. In the dogs which were fed with 

 sodium bromide, the gastric juice was secreted normally 

 and its acidity was slightly increased, but the acidity was 

 due largely to the presence of free hydrobromic acid. In 

 one sample more than one half the total acidity was due to 

 hydrobromic acid. In this way a large amount of the 

 bromide taken in was eliminated. A certain amount was 

 also got rid of in the urine, and it is worth noting that the 

 excretion of bromide in the urine continued for many days 

 after the administration of the bromide had been discon- 

 tinued. On the other hand, in the dogs fed with sodium 

 iodide the gastric juice contained only minute traces of hydri- 

 odic acid or of iodide, the chlorides present being sufficient 

 to account for the total acidity. In these animals practically 

 the whole of the iodide was eliminated by the kidneys, the 

 elimination being complete within two or three days after 

 discontinuing the drug. 



