1923] 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



359 



zymes in Aspergillus niger and other fungi. The theoretical 

 equation for this would show the NH, group hydrolytically 

 split off as ammonia, leaving the hydroxy group in the corre- 

 sponding place in the acid molecule, as was pointed out by 

 Ehrlich. Ammonia thus formed is not detectable; therefore, it 

 seems reasonable to assume that it is not formed, and that the 

 NH, group is united directly to the non-nitrogenous units, the 

 excess hydrogen increasing the acidity of the solution. The 

 initial rise in H-ion concentration of all the P+ cultures may be 

 partly due to this as well as to organic acids from the sugar. 



DAYS 



Fig. 19. Total N in 50 ml. media. Diplodia natalensis. 



For Aspergillus niger the NH t ion is more serviceable than the 

 NO 3, as the results show greater absorption of the former than 

 the latter from N H «N , . And j udged by the weight of the fungus 

 the (NH 4 ) ,SO< is superior to KNO, in spite of the acidity produced 

 as a result of the use of the first named. Sphaeropsis malorum 



the NHiNOs medium absorbs the NO 



;htly greater 



rate than the NH 4 , and the organism on the KNO 3 medium 

 makes a faster and larger growth than on the (NH<) ,SO«, showing 

 that it is more sensitive to the free H,SO* than is the Aspergillus. 

 Judged by the rate of absorption of the ions of the NH«NO, 

 medium, the Diplodia, on the other hand, shows a slight prefer- 

 ence for NH 4 . The sensitiveness of this organism to the hydrion, 



