1923j 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



323 



teresting because of its capacity for fixing free N, (Duggar and 

 Davis, ' 16) , is now under way. The investigation of other forms, 

 including yeasts and bacteria, is contemplated. 



The organisms were grown on Duggar 's solution for fungi, 1 

 the nitrogen source being varied to give 5 different kinds of media. 

 The solution consisted of the following chemicals per 50 ml. 



Dextrose . . . 

 KH,PO«... 

 MgSO«.7H 2 



N source . . . 



ml. 



0.5 M solution 25 



. 25 M solution 10 



.0.11 solution 5 



M solution 10 



In addition to the above 0.1 ml. of 0.001 M FeCl,.6H,0 was 

 added to each culture. The KH 2 PO«, MgSO«.7H 2 0, and 

 FeCl 3 .6H,0 were Merck's highest purity grade. The inorganic 

 N sources used were KNOs (Merck's reagent crystals), NHUNOi 

 (H. P. Merck), and (NH 4 )iSO« (Merck's reagent grade). The 

 salts were dissolved in warm distilled water (P H 5.3), cooled to 

 20° C, made to volume, placed at a temperature of 7° C. for 3 

 days, and filtered. The stock solutions were kept in the dark at 

 a temperature of 7° C; before use they were brought to room 



temperature (20-23° C). "Bacto" dextrose, having less than 

 1.0 per cent H 2 0, usually about 0.25 per cent, wasused. "Bacto" 

 peptone was used in the concentration of 11.65 per cent through- 

 out the work. The glucose and peptone solutions were made 

 up just before using, thus necessitating but one sterilization 

 which, for the peptone, was important in keeping comparable 

 the amount of hydrolysis. The 5 different media are character- 

 ized in the data by the N source, namely, "peptone plus" (No. 1), 



(No. 2), (NHO.SO4 (No. 3), NH,NO, (No. 4), 

 ). The media numbered 1, 3, 4, and 5 have 



<< 



minus 



t> 



and KNO, (No. 5). 



glucose as a carbon source, but in No. 2 the peptone serves as 



the source of both C and N, the 25 ml. of dextrose being replaced 



by 25 ml. H a O. 



Quantities of 50 ml. of the media were placed in 300 ml 

 meyer flasks. The flasks were in all cases first thoroughly cleaned 

 by washing in warm tap-water and cleaning solution, followed by 



of hot tap-water and finally with distilled 



Being published. 



