354 



[Vol. 10 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



NH*N0i medium. The acidity reached is P H 1.6, greater even 

 than in the (NH«)»SO« medium, indicating that the ammonia of 

 the NHi.HNOj is consumed more rapidly than the nitrate ion. 

 The results for ammonium and nitrate N also show this. Boas 

 ('18), in his criticism of Czapek's work, emphasized also the 

 effect of reaction on the comparative assimilability of various 

 nitrogenous compounds, but in his corrective experiments he 

 ridiculously resorted to litmus roughly to indicate the reaction 

 instead of determining active acidity. 





re 



two*-* 



KNOj - 



23+56769/0 



>Z 



1 15 /6 IT 



ju 



Fig. 14. Ammonium N in 50 ml. media. Sphaeropsis m alarum. 



The Diplodia and Sphaeropsis make a relatively slow growth 

 on the (NH 4 )2.SO« medium and very gradually decrease the dex- 

 trose content of the solution, a small quantity of sugar being 

 present even after 38 days of incubation. Similarly, the NH 4 

 and total N content and hydrion exponent gradually diminish 

 throughout the entire period and the trace of NH 2 .N increases 

 slightly. An appreciable odor of ethyl alcohol is evident after 

 7 days' growth. Autolysis in these cultures does not play an 

 important role during the time of the experiment. These results 

 corroborate those of Iwanoff ('21), who found that an acid reaction 

 and the presence of alcohol arrested protein decomposition in 

 fermenting fluids. That the courses of metabolism of these 2 

 fungi on the NH«NO, medium are different is indicated by the 



