484 



SELMAN A. WAKSMAN 



possible that the quantity of Na2C03 or the period of aeration 

 were not sufficient to expel all the ammonia, although the medium 

 was shown to be strongly alkaline all through the aeration proc- 

 ess, and a period of three hours was found to be sufficient. 



TABLE 3* 



The accumvlation of amino nitrogen and ammonia by A . niger from 2 per cent 



peptone, in the presence and absence of sugar 



Milligrams of NH2-N and NH3-N per 100 cc. of solution 



* Certain parts of this table have been already published elsewhere (Waksman, 

 1917b). 



4 



The data brought out in table 3 point to a very distinct differ- 

 ence in the accumulation of amino and ammonia nitrogen from 

 peptone by A. niger due to the presence or absence of sugar. 

 The production of amino nitrogen is very small ; there seems to be 

 only so much of it formed as the organism needs for its develop- 

 ment. The gradual decrease in the total amino nitrogen shows 



