ix TRYPTIC ENZYMES 169 



(4) Allow to stand for twenty-four hours, and then filter 

 through paper. 



(5) To each of the four filtrates add absolute alcohol in 



excess : a precipitate appears. 



(6) Filter, and dry the four precipitates at 40 C. in the 

 ordinary manner. 



(7) .Dissolve the dry residues severally in 100 cc. of 

 saturated thymol water : enzyme solutions. 



Tests for tryptic enzymes 



(1) To four tubes of thymol gelatine (7 grammes of 

 gelatine and 100 cc. of thymol water) severally add 5 cc. 

 of the ferment solutions. 



Allow the tubes to stand at 15 C. 



The gelatine will be liquefied after a time. 



(2) Place '5 gramme of dried fibrin in two test-tubes. 



Add to one of them 5 cc. of the enzyme solution of 

 the Bacillus prodigiosus, and to the other 5 cc. of 

 the enzyme solution of the Vibrio Finkler-Prior. 



Examine the tubes after eight hours : the fibrin is 

 almost entirely liquefied in the case of the former 

 enzyme, and partially so in the case of the latter. 



F. TRYPTIC ENZYMES OF BACILLUS PRODIGIOSUS OR 

 BACILLUS PYOCYANEUS (Fermi). 



(1) Grow the Bacillus prodigiosus or the Bacillus 

 pyocyaneus in the following solution : 



