1923] 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



349 



amphoteric amino acids is slightly more utilized than the non- 

 nitrogenous part, leaving some carboxyl groups in excess. It 

 appears probable that this differential utilization by the extremely 

 fast-growing young germ tubes from the many spores of the 

 inoculum produces a brief state of hyperacidity before autolysis, 

 respiration, and other processes which make for alkalinity have 



come into full 



This temporary increase in acidity was 



produced by Sphaeropsis and Diplodia in the P— medium; with 

 these fungi the inoculum was a relatively large quantity of 



NH,NO,r 

 KNOi 



lOVT-sS 



Fig. 9. Rates of carbohydrate consumption; amount of dextrose in 50 ml. media 



Aspergillus niger, second series. 



mature mycelium in which respiration and autolytic processes 

 were already predominant. The amount of autolysis, as indi- 

 cated by decrease in dry weight from the maximum, is propor- 

 tional to the weight the fungous mat attains. 



The fact that after the period of rapid development of the 

 fungus, the amount of NHt.N remains small and relatively 

 constant, while the ' ' peptid " N of the P + and P — media regularly 

 decreases, indicates that amino N is a very readily assimilable 

 form, and that the amino acids and possibly the reconstructed 

 peptids, liberated during autolysis of the fungous proteins, are 

 quickly assimilated by the living protoplasm because they are in 

 directly utilizable forms. The results of Zaleski and Israilsky 



