The Ferment-action of Bacteria. 



549 



distilled water, and 5 c.c. of a \ per cent, chloroform water. Car- 

 bonate of soda was finally added to render the fluid faintly alkaline. 



In each flask was placed a small piece of boiled fibrin. After four 

 days in the incubator they were taken out and examined : — 



A. From each, gelatine plate cultures were made. 



B. The appearance of the fibrin was noted. 



C. After filtration the filtrate was tested for digestive products. 



A. Some of the plates showed bacteria. The flasks from which 

 these had been made were rejected; only those were used which 

 had remained sterile. 



B. In none did the fibrin break up and disappear. But it became 

 thinned and frayed at the edges. This was most marked with the 

 scurf and Welford bacilli. 



C. The filtrate was examined for soluble products : — 



On neutralising with dilute hydrochloric acid a precipitate ap- 

 peared. This was filtered off and the filtrate tested for peptones. 

 A solution of caustic soda was added, and then a highly dilute solution 

 of cupric sulphate was filtered down the side of the test tube. At the 

 line of demarcation the rose-coloured peptone reaction was strongly 

 marked. 



The simple boiled solution of the ferment only gave the faintest 

 peptone reaction. 



These results were obtained with the scurf and Welford bacilli, 

 and Koch's and Finkler's spirillum. To sum up : — 



1. The fibrin was visibly affected. 



2. Neutralisation produced a precipitate. 



3. The peptone reaction was very distinct. 



The enzyme therefore, apart from the bacteria, can form soluble 

 products from fibrin, and amongst these peptones. 



VII. 



Are the microbes capable of forming a diastatis, as well as a pep- 

 tonising ferment ? 



A. Scurf bacillus. 



Welford bacillus : — 



Starch was heated with water so as to form a thin paste. To this 

 was added sodic chloride (0*5 per cent.). About 100 c.c. were placed 

 in each flask, which was then plugged with cotton wool and 

 sterilised. 



After inoculation they were placed in the incubator (37° C.) along 

 with flasks of sterile starch paste. 



Flasks were opened on successive days and examined : — 



