The Ferment-action of Bacteria. 



551 



precipitates obtained with Fehling, &c, indicate the presence of a 

 reducing sugar. The failure with Barfoed ! s reagent suggests that 

 the sugar is in great part, at any rate, maltose. 



3. With regard to Koch's spirillum and Finkler's, though they 

 evinced a diastatic action, it was feebler than in the former case, 

 only traces of a reducing sugar being detected after the addition of 

 sulphuric acid. The red and violet coloration with iodine points to 

 the formation of dextrin (erythro- and achroo-dextrin). 



At any rate, in the scurf and Welf ord bacilli we have two microbes 

 which evince a marked diastatic action ; and a demonstration of the 

 fact that the same germ can produce both a diastatic and a 

 peptonising ferment. 



VIII. 



Can we demonstrate the action of the diastatic enzyme apart from 

 the bacteria ? 



Starch cultures of the scurf bacillus and the Welford bacillus (two 

 days' growth) were treated with chloroform water (1 per cent.) till 

 they became sterile. 



The fluid was then added to fresh starch, and incubated at 37° C. 



In eight to ten days the iodine reaction had disappeared. On 

 boiling with caustic soda the fluid became yellow. Fehling's solution 

 was reduced. The fluid lost its opalescence. Control plates — no 

 growth. 



These experiments point strongly to tbe existence of a diastatic 

 enzyme capable of isolation, and of acting apart from the bacteria. 



IX. 



That the peptonising enzyme bears the closest analogy to the 

 pancreatic ferment will be seen from the following experiments. 

 Sterile meat broth, in which Finkler's spirillum and the Welford 

 bacillus had been cultivated, was added to 10 per cent, gelatine tubes 

 of differing reaction : — 



Gelatine. Results. 



A. Acidified with dilute hydrochloric acid. . No liquefaction. 



B. Alkaline by adding sodic carbonate .... Liquefied. 



C. Neutral Liquefied. 



D. Boiled after adding the ferment No liquefaction. 



X. 



The digestive action of the microbes was tested on several other 

 bodies. 



