[Vol. 6 

 198 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



relative rate of ammonia production in the various enzyme 

 cultures. In no case was the gas drawn through the wash bottle 

 for a period longer than three minutes. At the end of this 

 period the actual hydrogen ion concentration 



ogen ion concentration of the distilled 

 water was determined. Sometimes the change was so rapid 

 that it was not necessary to run the experiment for three 

 minutes. In such instances other indicators having a wider 

 alkaline range were substituted for brom thymol blue. In the 

 urea control there was a change from P„ 5.6 to P„ 6.0, and 

 thus, for urea, changes not going beyond P„ 6.0 were considered 

 as negative. The results are tabulated in table in. 



Urease was demonstrated for the three fungi. It was most 

 pronounced in Daedalea confragosa and least in Polyporus 

 lucidus. Only Armillaria mellea showed slight amidase action 

 when acetamid was used as a substrate. There was no amidase 

 action when asparagin was used as a substrate. 



Due to the fact that traces of alkalis or acids cause consider- 

 able shifting of the hydrogen ion concentration in such an un- 

 buffered solution as doubly distilled water it is believed that this 

 method can be used to determine the presence of minute traces 

 of ammonia which would be undetectable by the methods usu- 

 ally employed, and the determination is much more rapid. In 

 the present paper only relative determinations were necessary 

 but there is no valid reason why quantitative determinations 

 could not be made by this method. 



Proteases 



Tryptic and ereptic fermentation was studied by the use of 

 albumin, peptone, casein, legumin, and fibrin in enzyme cul- 

 tures having a neutral, acid, and alkaline reaction. When 

 fibrin was used as a substrate positive results were obtained to 

 show the presence of both trypsin and erepsin in all three of the 

 fungi. These results were most pronounced in the cultures hav- 

 ing an acid reaction and least in those with an alkaline reaction. 

 In the case of the plant protein, legumin, there was very slight 

 indication of the presence of tryptic and ereptic fermentation 

 only in Polyporus lucidus and only when the substrate was acid 

 in reaction. In Polyporus lucidus there was indication of the 



