1923] 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



305 



Brenner ('11) gave neither his biochemical methods nor any 

 tables of results in his paper dealing with the nutritive value 

 to Aspergillus niger of 30 various N sources. He stated that the 

 assimilability was judged by determining the time required for 

 the cultures to reach a maximum weight. Not considering the C 

 of the organic N compounds, dextrose was the sole C source 

 employed. The temperature of incubation was 35° C. All N 

 sources were used in the concentration equivalent to 0.5 per cent 

 NH 4 C1. Free NH„ NaN0 2 , ammonium valerianate, and KCN 

 were poisonous to this fungus in the strength used. Tetra- 

 methyl-ammonium chloride, nitroguanidine, nitromethane, iso- 

 amylacetate, pyridine chloride, and piperidine chloride were not 

 assimilable. Four groups were made in the descending order 

 of their assimilability : 



1. Ammonium lactate, ammonium tartrate, asparagin, am- 

 monium succinate, and ammonium oxalate. 



2. NH 4 salts of H,SO„ HC1, HNO„ and H,PO„ likewise 



carbamide. 



3. CHaCOONH,, HCOONH,, nitrosodimethylamine chloride, 



NaNOj, pyridine nitrate, normal and isobutylamine chloride, 



guanidine nitrate, and chloride. 



4. Isoamylamin chloride, hydroxylamine sulphate,benzylamine 



sulphate, dicyandiamid acetonitrile. 

 He stated that his study of the composition of the fungus and 



changes in the medium showed that after a growth period of about 

 4 days degenerative processes began in parts of the fungus. 

 These were accompanied by the secretion of N as NH» or organic 

 N. As a rule, regardless of the nature of the N source, about 

 one-half of the N present in a solution containing the equivalent 

 of a 0.5 per cent NH<C1 solution was taken up by the first crop 

 of the fungus grown. Subsequent crops, having less N at their 

 disposal, contained a lower percentage of N than the first crops 

 on the same solution. 



A clearer conception of the course of protein synthesis in 

 yeasts and other fungi is given by the illuminating qualitative and 

 quantitative work of Ehrlich ('09, '11, '16, '17) and his associates. 

 Following the lead of Duclaux ('64) and Pasteur ('58, '59) Ehrlich 

 found that yeast could transform amino acids into alcohols 



