480 



SELMAN A. WAKSMAN 



mended by Steel (1910) and others as a general procedure for the 

 determination of ammonia, so as to eliminate the formation of 

 triple phosphate crystals which are formed on adding Na2C03. 

 But Potter and Snyder (1915) have pointed out the fact that the 

 use of NaOH will cause a great deal of the amide nitrogen to be 

 given ofT as ammonia. After the ammonia was completely 

 removed, the solution was neutralized with acetic acid, and a 



TABLE 1 



The formation of amino nitrogen from casein and peptone by microorganisms 



Milligrams of NH2-N per 100 cc. of solution 



PEBIOD OF 

 INCUBATION 



days 



Control 



1 



4 



7 

 14 



1 



4 



7 

 14 



1 



4 



7 

 14 



1 



4 



7 



14 

 Control 



1 



4 



ORGANISMS USED 



A . niger 



A . niger 



A . niger 



A . niger 



A. ochraceus 



A. ochraceus 



A . ochraceus 



A . ochraceus 



B. mycoides 



B . mycoides 



B. mycoides 



B. mycoides 



Act. penicilloides . 

 Act. penicilloides. 

 Act. penicilloides. 

 Act. penicilloides. 

 Trypsin, 200 mgm 

 Trypsin, 200 mgm 

 Trypsin, 200 mgm 



3.14 



1.12 







6.20 



7.44 



2.92 



7.34 



9.02 



12.58 



2.92 



11.84 



12.98 



12.00 



5.10 



5.64 



11.28 



12.58 



6.16 



26.28 



35.04 



10.15 



8.76 



12.12 



3.94 



5.72 



7.00 



9.02 



7.34 



8.00 



4.68 



7.34 



16.36 



13.72 



12.84 



13.60 

 22.20 

 23.60 



portion equivalent to 2 cc. of the original filtrate was used for the 

 determination of amino nitrogen. The micro-method of Van 

 Slyke was used in all cases. Frequent blanks were made in the 

 same manner using 2 cc. of distilled water. The determinations 

 were carefully carried out as directed by Van Slyke (1911, 1912, 

 1913), the amount of amino nitrogen found in the 2 cc. portions 

 being corrected by the use of the blank, then multiplied by 50, 



