174 



Transformation of Nitrogen 



product being ammonia; in no case, however, is one form of nitro- 

 gen completely destroyed. A similarity was found in the chemical 

 changes produced by acid hydrolysis and by bacteria. Carbohy- 

 drates exert a depressing effect upon the liberation of ammonia 

 from proteins (Table 35). 



Table 35. Influence of Various Concentrations of Glucose on the Formation 

 OF Ammonia from Casein (from Doryland) 



* Bact. = bacteria in millions. 



Fungi are able to decompose proteins very vigorously. Different 

 species vary greatly in this respect; the nature of the protein, re- 

 action of medium, and presence of available carbohydrates affect the 

 process. A large part of the nitrogen may be left in the form of 

 intermediary products. Organisms like Aspergillus iiiger, which pro- 

 duce large amounts of acid (oxalic and citric) from carbohydrates 

 and even from proteins and which are thus enabled to neutralize the 

 ammonia, accumulate only very small amounts of amino acids in 

 artificial cultures; at the same time appreciable quantities of am- 

 monia are formed in the medium. But when the oxalic acid is neu- 

 tralized with CaCO-?, or when the formation of both oxalic acid 

 and ammonia is prevented by means of insufficient aeration, amino 

 acids accumulate. 



