592 THE GUM FERMENTATION OF SUGAR CANE JUICE, 



boiling, an apparent solution was obtained. The gum was pre- 

 cipitated by alcohol, and redissolved in water several times until 

 a comparatively white precipitate, free from sugar, was obtained. 

 The aqueous solution was easily precipitated by alcohol. 



On warming with dilute tartaric acid, a reducible sugar was 

 formed (saccharose treated similarly was not inverted). These 

 tests show that the viscous substance is of the nature of dextran 

 or fermentation gum, but the identification was deferred until a 

 greater quantity had been prepared from a medium containing a 

 more definite substance than grass infusion, some of the carbo- 

 hydrates of which would be precipitated with the gum. 



The Fermentation of Saccharose. 



The action of the organism, which had by this lime been found 

 to be a sporulating rod or bacillus, is of considerable importance, 

 for it appears to be an undoubted fact that the gum is formed 

 from the sugar. There may, also, be a further loss of saccharose 

 from the formation of hexoses, if the organism secretes invertase. 

 To test these points, a culture medium containing the following 

 constituents was prepared. 



Saccharose... 



Potassium chloride 



Sodium phosphate... 



Peptone 



Tap water ... 



Sterile litre portions of this medium were infected with large 

 loops of an agar culture of the bacillus, and incubated at 22°, 28° 

 and 37° C. respectively. The cultures soon became white and 

 opalescent like dilute separated milk. A thin film formed on the 

 surface, and when the flasks were allowed to stand without 

 shaking, a layer about a centimetre thick of a mucilaginous or 

 starch paste-like substance formed at the bottom of the liquid. 

 "When this was removed by continued shaking, it remained 

 suspended in the milky medium. The layer, when undisturbed, 

 disappeared on continued incubation. The culture fluid contained 



