1923] 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



321 



maltose, and sucrose with urea and acetamide in different pro- 

 portions. Other fungi, including Botrytis cinerea and an Oidium, 

 behaved quite differently under these conditions, remaining alive 

 for months and not producing excess NHi. 



Terroine, Wurmser, and Montaine ('22) investigated the total 

 IS" content of Aspergillus niger grown under various conditions. 

 With the development of the fungus the N percentage of the mat 

 was found to decrease; this was not influenced by the concentra- 

 tion of the N of the medium. In the first part of the incubation, 

 when the N content of the medium was 0.5 per cent (NHO1SO4, 

 an increase in the sucrose or glucose was followed by an increase 

 in the N fixed; in the latter part, by a decrease. Urea or NaNOi 

 substituted for (NH 4 ) s SO< resulted in a slight fall in the per- 

 centage of fungous N, but peptone and guanidine caused a decline 

 respectively of 18.3 and 45.0 per cent. Xylose and arabinose 

 with (NH 4 )»SO« served in this respect exactly as glucose or su- 

 crose, but galactose caused a reduction of 21 per cent. The 

 mycelium of a normal culture washed and placed in Czapek's 

 solution minus N lost over 50 per cent of its N in 5 davs' in- 



cubation at 37° C. 



Butkewitsch ('22) grew Aspergillus niger and Citromyces spp. 

 on culture solutions containing the usual minerals plus 0.2 per 

 cent ZnSO< and respectively 2.5, 5.0, 10.0, and 20.0 per cent 

 peptone and determined the oxalic acid, the ammonia, and like- 

 wise the dry weight of fungus produced in 10-, 20-, 30-, and 40- 

 day periods of incubation. Hydrion concentration determina- 

 tions were not made, litmus being employed to indicate the re- 

 action. Ammonia was estimated by distillation with MgO or 

 CaO in vacuo, and (COOH) 2 by precipitation as calcium oxalate 

 and titration with KMnCh. The results were interpreted as 

 showing that the proportion of (COOH)j to NH 8 approached 

 that of neutral (COONH 4 )», but generally showing a predomi- 

 nance of NH,. The younger cultures were acid because in ad- 

 dition to (COOH) » they contained the acids freed in the de- 

 amidization of the amino acids by the fungus; the older cultures 

 were alkaline because of the excess NH3 not bound with acids, 

 but as (NH4) 2CO3. Most of the NH 8 was produced in the period 

 of mat development, 90 per cent of it being formed in the first 



