232 



BACTERIAL ORIGIN OF GUMS OF ARABIN GROUP, 



becomes narrower the depression becomes more and more con- 

 spicuous. 



The use of other sugars, e^c— The influence of other commonly 

 occurring sugars and nutritive alcohols upon slime-formation is 

 shown in the table which follows. The experiment was made at 

 a time when the laboratory temperature was rather high (20°-22°), 

 and this accounts for the poor yield with levulose as compared 

 with the yields in other experiments. 



The IxFLUiiNCE of various Sugars, etc., upon Some-formation. 



Slime in grams from 

 100 c.c. of medium* 



The substances that aid slime-formation are seen to be levulose, 

 saccharose, maltose, mannite and glycerine; and of these it is 

 interesting to note the part played by glycerine. It is curious 

 that maltose, which hydrolyses to dextrose, is a nutrient, while 

 dextrose itself is not. 



Various sources of carbon and nitrogen compared. — As it 

 appeared possible that the nitrogenous food might influence the 

 effect of these carbonaceous nutrients, an experiment was made 

 in which asparagine, urea and peptone were compared. The 

 incubation temperature was about 17°, the temperature of a 

 refrigerator. The peptone, asparagine and urea were added in 

 quantities containing approximately equal amounts of nitrogen. 



* Asparagine O'l, (sugars, etc., 2-0), tannin O'l, potassium citrate O'l, agar 2*0, water 100. 



