rvoL. in 



346 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



of Sphaeropsis malorum on the P medium was found, by 

 Kjeldahlization of the mat and solution collectively, to have 

 lost 6.77 mgm. of N ; and one on P medium , 3.42 mgm. Similarly 

 a 20-day P+ culture of Diplodia natalensis lost 7.97 mgm. N, 

 and a 20-day P— culture, 9.106 mgm. On the 3 media in which 

 inorganic N served as the N source none of the cultures decreased 

 in total N content. The continued acidity of the (NH«),S04 

 and NH 4 NO, media prevents the evolution of NHi, while the 

 small amount of NH t produced in alkaline KNOi cultures is 



p ■ 



9*rqSO; 



NIXNQf 

 HNOf — 



3 4 S 6 T 



OAY^ 



Fig. 6. Dry weights of fungous mats. Aspergillus niger, second and third series. 



precipitated as MgNHJ^O^HiO or easily held in solution as 

 NHiOH. This strengthens the probability that the NHi 

 evolved under the alkaline conditions of the P + and P — media 

 is responsible for the N loss in these cultures. 



Waksman ('18) did not make sugar- and dry- weight deter- 

 minations and consequently could not legitimately connect the 



appearance of ammonia with autolysis and the disappearance of 

 sugar. The sugar of his cultures had probably disappeared at 

 the end of 3 to 5 days and consequently the obedience of the 

 accumulation of NH t to the law of autocatalysis could not have 

 been due to the presence of the carbohydrate, as he claimed. 

 He is probably correct in assuming that a definite quantity of 

 NH, may always be produced from protein materials, as a waste 

 product, independently of the presence of available carbohydrate. 



