The Ferment-action of Bacteria. 



545 



II. 



Having regard to the fact that the peptonising action in gela- 

 tine was slow, and in two cases partial, it was next sought to de- 

 termine whether more active liquefaction of the gelatine could be 

 obtained by growing the microbes in some other albumenoid soil. 



Two culture fluids were made with meat broth as follows : — 



A. Meat broth — B. Meat broth — 



Peptone, 1 per cent. NaCl 0*5 per cent. 



NaCl 0-5 „ 



Both were rendered faintly alkaline with the carbonate of soda. 



The bacteria grew well in both of these media, and so rapidly and 

 abundantly in B. that further experiments were made with it only, 

 i.e., without peptones. For each culture, 100 c.c. meat broth were 

 used. After inoculation and four days' incubation at 37° C, the 

 broth was filtered, and the bacterial deposit washed with sterile 

 distilled water. It was then sterilised as already described, and 

 10 c.c. added to tubes of 10 per cent, gelatine. These tubes were 

 placed in the incubator, as well as control tubes of sterile gelatine. 

 When taken out, and placed in ice-cold water, the following results 

 were obtained : — 



(1.) After 24 hours : 



Scurf bacillus ") y . . 



Welford bacillus J 



Koch's spirillum "1 a . ,. . , 

 -n— . . ii , . .I, > bemi-liquid. 

 h inkier s spirillum J 



Putrefactive micrococcus ) AT v £ 



> No hqueiaction. 

 Control gelatine J 



Control plates. No colonies. 



(2.) After 48 hours : 



Koch's spirillum 1 T . . 1 

 „,.,■,,..„ ? Liquid. 

 h mkler s spirillum J 



Putrefactive micrococcus ] XT n - « 



> -No liquefaction. 

 Control gelatine J 



Control plates. No growth. 



From these experiments it will be seen that the enzyme developed 

 in meat broth is more active than that formed in gelatine. In 

 twenty-four hours the gelatine was liquefied by the scurf and Welford 

 bacilli ; in forty-eight hours by Koch's and Finkler's comma spirilla. 

 Again the putrefactive micrococcus gave negative results. 



Conclusions : — 



1. An enzyme is formed in meat broth which liquefies gelatine. 



