238 



L. A. ROGERS, W. M. CLARK AND H. A. LUBS 



procedures described by Clark and Lubs (1915) (1917b). The 

 results given are those obtained with the old medium (Clark and 

 Lubs, 1915). The differentiation with the new medium (Clark 

 and Lubs, 1917b) agreed perfectly. 



The V oges-Proskauer reaction. Tests for the Voges-Proskauer 

 reaction were made with the synthetic medium of Clark and 



TABLE 1 

 Average gas volumes and gas ratios. Low ratio cultures 



RATIO COj/Hj 



Grain 



Bovine feces. 

 Human feces 



1.06 

 1.06 

 1.05 



TABLE 2 



Change in Ph of glycerol medium by B. coli. Medium: 1 per cent Witte pepton, 

 0.5 per cent K2HPO4, 1 per cent glycerol. Incubation temperature, 30°. Original 

 Ph, 7.6. 



Lubs (1917b) and with pure casein and 10 per cent NaOH as 

 reagents. The results summarized in table 3 are discussed by 

 Clark and Lubs (1917b). 



Gas 'production. In previous studies (Rogers, Clark and Davis, 

 1914; Rogers, Clark and Evans, 1914; Rogers, Clark and Evans, 

 1915) it was found that accurate determination of the gas volumes 

 and gas ratios produced in the anaerobic fermentation of glucose 

 furnished most valuable data. In the present study we have 

 employed the methods for the isolation and analysis of the gas 

 which were described in previous papers. Essentially, the 



