by r. greig smith. 603 



The Affinities of the Gum. 



From the reactions and the laevo-rotatory power both of the 

 gum and the sugar resulting from its hydrolysis, the gum appears 

 to be most nearly related to levulan and to inulin, but there 

 are many characters wliich distinguish it from these. It is also 

 different from the derivatives of inulin, viz., pyro-inulin, met- 

 inulin and leviilin, as well as from sinistrin, triticin, secalose, and 

 myco-inulin. 



From a review of the Irevo-rotatory gummy substances that are 

 hydrolysed to levulose, it appears that this bacterial gum has not 

 hitherto been described. I therefore propose for it the name 

 levan, which was suggested by the polariscopic nature of the gum 

 and derived glucose, and also from the fact that another bacterial 

 gum, which is derived from dextrose, and which yields dextrose 

 on hydrolysis, is known as dextran. 



The Production of Carbon Dioxide. 



During the evaporation of the cultures, a number of small bells 

 formed upon the surface as if a gas were evolved during the 

 process. The most probable gas is carbon dioxide, and to test 

 for it a flask fitted with a rubber cork and lead-away tube was 

 completely filled with a culture, inverted and heated in boiling 

 water. The culture driven from the flask by its expansion, and 

 by the liberation of the dissolved gases, passed through the tube 

 in the cork and was led awa}'- into a vessel. The gases which 

 collected in the flask were transferred to a tube and roughly 

 measured before and after absorption with caustic soda. From 

 300 c.c. of culture fluid, 7*5 c.c. of gas were obtained, and of this 

 5 c.c. were absorbed by the alkali. It is evident that carbon 

 dioxide is evolved during the growth of the organism. As, how- 

 ever, the test as described above was merely qualitative, and as 

 the gas might be formed in quantity, a quantitative test was 

 made. For this purpose 100 c.c. of culture fluid containing the 

 usual amounts of saccharose and salts, but with 1 % of peptone, 

 were placed in a small Erlenmeyer flask and connected with three 

 other similar flasks, each containing 100 c.c. of clear baryta 



