Experiments with Bacterial Enzymes 131 



this bacillus is an active alkali-former. The reaction of neutral broth 

 inoculated with B. pyocyaneus becomes speedily alkaline, while gela- 

 tin inoculated at the same time becomes acid, owing to the acidigenic 

 action of the gelatinolytic enzyme. The two cultures accordingly 

 diverge in their reaction. Enzyme formation, however, occurs in 

 both media and apparently takes place to about the same extent 

 in each. Parallel cultures of B. pyocyaneus in broth and gelatin 

 reacted as follows after 24 days at 36°: gelatin 4.0 per cent acid; 

 broth 0.5 per cent alkaline. One-tenth c.c. of fihrate from each 

 culture gave complete liquefaction; o.oi c.c. was negative for the 

 broth culture, but the same amount of the gelatin filtrate produced 

 a slight softening. In another gelatin culture, 26 days old at 20°, 

 alkali formation had almost completely neutralized the acids arising 

 from the gelatin splitting, and the filtrate in this case reacted neutral 

 to phenolphthalein. The gelatinolytic potency of this filtrate, how- 

 ever, was almost exactly the same as in the instance just cited, viz. : 



*o. I c.c + 



0.05 d= 



003 - 



0.01 o 



*In aU the tables the following signs are used: += complete liquefaction; ± = partial liquefaction 

 — = gelatin noticeably softened; o = perfectly solid, like control. 



In another case a culture of B. pyocyaneus in broth was compared 

 with a control culture in gelatin with the following result : 



Forty-eight Hours at 37°. 



Nine Days at 37°. 



0.05 c.c. 



0.03 



0.01 



0.005 



0.003 



Gelatin (+2.5%) 



It is evident from these and manv other observations of the writer 

 in respect to varying reactions among gelatinolytic filtrates that the 

 production of a gelatin-liquefying enzyme is not very dependent upon 



