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EDWIN O. JORDAN 



heated in the cultures in which they are produced, and even when 

 the enzymes are separated out as far as possible, there remains a pos- 

 sible source of error in the adherent impurities. 



Filtration of gelatinase. Levy 1 has shown that certain enzymes, 

 rennet, for example, are retained by the Berkefeld and Chamberland 

 bougies, while others pass through these niters. A few experiments 

 have been made to determine how far gelatinase is removed by nitra- 

 tion. A 31 day culture of B. pyocyaneus, grown at 37 and reacting 

 0.9 per cent alk. was filtered at 2oC. with the following result: 



Another trial with a different culture of B. pyocyaneus was as 

 follows : 



Several successive passages through a Berkefeld bougie did not 

 remove the gelatinase. 



A similar result was obtained with B. subtilis. (Broth culture, 

 8 days.) 



Jour. Infect. Dis., 1005, 2, p. i. 



