598 THE GUM FERMENTATION OF SUGAR CANE JUICE, 



It is apparent that no dextrose has been utilised in the forma- 

 tion of gum, and indeed this was to be expected from the absence 

 of the opalescent appearance which is so marked in the saccharose 

 cultures. A portion of the 15 days' culture at 22° was treated 

 with alcohol when a slight llocculent non-adhesive precipitate was 

 thrown down. This was estimated and found equal to 0-046 %. 



Cultures were also made in solutions containing lactose, levulose 

 and maltose respectively. Alcohol did not throw down a pre- 

 cipitate from the lactose culture, but slight loose, llocculent, non- 

 adhesive precipitates similar to that obtained in the glucose 

 culture were precipitated from the media containing levulose and 

 maltose. 



From these tests it is apparent that gum is not formed in 

 solutions of the commonly occurring sugars, and this has been 

 the experience of all who have investigated the action of similar 

 saccharose-gum fermenting bacteria. 



The Gum is Probably the Swolleiv or Diffluent Capsule 

 OF the Bacillus. 



Whether the gum is formed from the sugar by an enzyme 

 extracellularly, or whether it is the diffluent sheath or capsule of 

 the organism, is difficult to prove absolutely. Happ and also, 

 according to Lehmann and Neumann, Ritsert believed that 

 the gum was formed extracellularly, and did not arise from the 

 swelling of the cell membrane, because the swollen capsule could 

 not be demonstrated microscopically. Marshall Ward and 

 Reynolds Green believed that the gum formed by their bacterium 

 was nothing more than the extremely diffluent walls of the cell. 



My own observations upon this bacillus lead me to think that 

 the latter hypothesis is probably correct. The gum is the capsule 

 which has dilated so much that it has ceased to be a capsule, and 

 has become a part of the culture fluid. The dilation or swelling 

 is hastened by the excreted acid, which is thus a protection, or 

 rather assistance, to the organism, inasmuch as the growth is 

 accelerated by the removal of what would otherwise be a 

 hindrance to the free movement of the organism. The gum is 

 easily soluble in dilute mineral acids, and slowly soluble in 



