168 BACTERIOLOGICAL CHEMISTRY LESSON 



contents of the membrane, slowly and gradually, into an 

 excess of alcohol : a precipitate appears. 



(8) Filter at once, and collect the residue. 



(9) Dry the latter, and remove the alcohol by means of 

 heat at 40 C., and complete the drying in vacuo over 

 sulphuric acid. 



Test the resulting powder (invertine) as described 

 above (vide p. 165). 



E. PROTEOLYTIC (TRYPTIC) ENZYMES OF MICRO-ORGAN- 

 ISMS WHICH LIQUEFY GELATINE (Fermi). 



(1) Prepare thirty roll tubes severally of 



(a) Bacillus prodigiosus ; 



(b) Bacillus pyocyaneus ; 



(c) Vibrio Finkler-Prior ; 



(d) Vibrio cholerse Asiaticse. 



(2) When the gelatine is liquefied collect the contents 

 of the tubes in small flasks. 



(3) To 200 cc. of liquefied gelatine culture add 200 cc. 

 of dilute alcohol, viz. : 



(a) in the case of the Bacillus prodigiosus, 65 per cent 



alcohol ; 



(b) in the case of the Bacillus pyocyaneus, 75 per cent 



alcohol ; 



(c) in the case of the Vibrio Finkler-Prior, 70 per cent 



alcohol ; 



(d) in the case of the Vibrio choleras Asiaticse, 65 



per cent alcohol. 



