[Vol. 10 



344 



THE MISSOURI BOTANICAL 



than is required in respiration, protein synthesis, and other life 

 processes; accordingly the excess N appears as NH t . In the 

 case of Aspergillus niger this rapid excretion of NHf in the 

 oentone minus dextrose" medium comes about 2 days before 



a 



that in the "peptone plus dextrose" medium, and respectively 

 about 3 and 5 days earlier for cultures of Diplodia and Sphae- 



De 



ropsis, showing the protective action of the sugar. 



weight of the fungus indicates autolysis and the consequent 



diffusion of autolytic products into the medium. Ammonia is 



likely one of the products of this 



The results for 



<£ 



KN0j'~ 



Fig. 4. H-ion change of media. Diplodia natalensis . 



total N are also strikingly suggestive in this regard. With the 

 decrease in weight of the fungi the N content of the media in- 

 creases above its minimum, indicating that the autolytic products 

 are in part nitrogenous. The results for amino, amide, arid peptid 

 N are not suggestive in this regard; in fact the peptid N of the 

 medium in general decreased in quantity during the incubation 

 of all 3 fungi. There is, however, a slight increase in the peptid 

 N content of the medium of the Aspergillus cultures at the end 

 of the incubation. These results indicate that NH,.N is the chief 

 nitrogenous product of autolysis. The quantity of NH t excreted 

 reaches nearly a third of the total N of the medium in 18 to 20 



