BY R. GREIG SMITH. 



231 



It is evident that the bacterium practically cannot form gum 

 from dextrose, and also that this sugar is not inert in its action; 

 it prevents the utilisation of levulose and consequent production 

 of slime. The next step in connection with the action of dextrose 

 was to see the effect of adding varying quantities of the aldose, 

 dextrose, to the ketose, levulose. 



The Depressing Action of Dextrose upon Levulose. 



No sugar 

 Levulose 2% 



+ dextrose 0-25% 



0-5 



1-0 



1-5 



2-0 



Grams of Slime from 

 100 c.c. of medium.* 





 22 

 22 

 21 

 16 

 11 



Fig. 3. — The Prohibitive Action of Levulose. 



The depressing influence of dextrose ujDon levulose is again 

 clearly shown. With a proportion of dextrose to levulose as 1 

 to 8, the dextrose has no depressing action, but as the ratio 



Asparagine 0"1, sodium s\;ccinate 0-5, tannin 0*1, agar 2, water 100. 



