1923] 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



347 



My results show that this ammonia is, as Waksman assumes, 

 " reassimilated in the presence of available carbohydrate by the 

 organisms that are able to utilize it readily as a source of N." 

 In the case of Sphaeropsis and Aspergillus "the production of 

 NHi was entirely prevented by the presence of the sugar." The 

 relation also holds with Diplodia. but in cultures of this fungus an 

 appreciable quantity of NH, (17.1 mgm. per culture) appeared 

 when 73 mgm. of glucose were still present. This may have 



TJi%NO } 



" * " PAY$ 

 Fig. 7. Dry weights of fungous mats. Sphaeropsis malorum. 



Jk5 



been due to the fact that the aerial, folded growth of the fungus 

 minimized contact with the medium and thereby lessened ab- 

 sorption from it. In the absence of the dextrose, the strongly 

 proteolytic organisms use the peptone as a source of C and leave 

 much of the N to diffuse into the medium as NH». 



As the alkalinity advanced beyond P H 7.0 crystals formed in 

 all the peptone media for all 3 fungi and in the KNOi medium of 

 Sphaeropsis and Diplodia cultures. In the peptone cultures a 

 strong odor of NH, was apparent, and crystals of MgNHJPO,. 

 6H»0 were precipitated; in the KNOi medium with the Diplodia 



