1923] 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



357 



Sphaeropsis and the ninth day for Diplodia this is largely a matter 

 of the differential absorption of the K and NO* ions. When the 

 sugar has been consumed the dry weight of these organisms im- 

 mediately begins to decrease, and autolytic products rapidly 

 change the reaction to strongly alkaline (see page 317 of this 

 article for Waksman's explanation) . The total N (as applied to 

 cultures of Actinomyces) of the culture medium decreases slowly 

 but simultaneously with the rapid diminution of glucose, and 

 this rapidly rises above the minimum when the sugar has dis- 





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tm \ 



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1 



/Jul \\ 







t/o\ V 







JBB\ \ 







\\ Nt%NOf 



\\ KNO* -"V - 





10 



Fig. 17. Total N in 50 ml. media. Aspergillus niger, second and third series. 



appeared. On continued incubation there may be a fall in the 

 total and NH 4 .N content due to the precipitation as MgNH« 

 P04.6H>0 of NHi formed in autolysis; this is observable in the 

 results for the Diplodia series. 



The determinations show that in all the cultures of all 3 fungi 

 on the inorganic nitrogenous media the amino N content of the 

 solution did not attain more than a trace; 7.26 mgm. per 50 ml. 

 of medium was the greatest value determined. This in itself 

 indicates the ready assimilability of this form of nitrogen . 



nitrogen. Con- 

 sider, for example, the 35-day cultures of Sphaeropsis malorum 

 on the KNOi medhfm. Autolysis had decreased the weight of the 

 fungus to almost one-half of the maximum weight attained in 



