134 



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' has shown that certain enzymes, 

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

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

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

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

 0.9 per cent alk. was filtered at 2o°C. with the following result: 



Berkefeld Bougie 

 60 m. X15 m. 

 One filtration 



0.05 c.c 



0.03 



0.02 



Another trial with a different culture of B. 

 follows : 



pyocyaneus was as 



0.0s c.c 



0.03 



0.02 



O.OI 



Unfiltered 



+ 

 + 

 + 



Berkefeld Bougie 



6om.Xsom. 



One filtration 



+ 

 + 

 + 



Chamberland Bougie 

 200 m. X20 m. 

 One filtration 



+ 

 -1- 

 -1- 



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., 1905, 2, p. i. 



