READJUSTMENTS OF REGULATION 39 



expense of the normal elimination of urea. Urea 

 CO(NH 2 ) 2 is a nitrogenous body of neutral reactions 

 in the form of which by far the greater part of the 

 combined nitrogen passing through the body is elimi- 

 nated. In acid poisoning the combined nitrogen goes 

 more and more into the form of ammonia (NH 3 ), 

 which, in virtue of its alkaline reaction when in solu- 

 tion, combines with acids and thus neutralises them. 

 Even under average normal conditions in man the 

 quantity of ammonia eliminated in the urine is about 

 sufficient to neutralise the large quantity of sulphuric 

 acid formed by the oxidation of the sulphur of 

 albuminous substances ; and with an alkaline diet this 

 ammonia practically disappears from the urine. In 

 the Strassburg laboratory it was also discovered that 

 ammonia salts are converted into urea in the liver. 

 We have now every reason to believe that ammonia 

 is formed in large quantities in the intestine by the 

 breaking down under ferment action of albuminous 

 compounds. This ammonia is carried straight to the 

 liver by the portal circulation, and there converted 

 under ordinary conditions almost entirely into urea. 

 But the liver appears to leave unconverted any am- 

 monia needed to regulate the reaction of the blood, 

 and the minutest deviations in reaction serve to regu- 

 late this process. Hence in the ratio between ammonia 

 and total combined nitrogen in the urine we have a 

 valuable index of any tendency towards acidity or 

 alkalinity of the blood, though the composition of the 

 alveolar air is a still more direct index. 



Another known means of regulation is by the kid- 



