STUDIES ON AZOTOBACTER CHROOCOCCUM BEIJ. 



337 



One hundred cubic centimeters of this solution were placed in 

 the flask together with 0.50 gram of precipitated CaCOs. After 

 sterilization and inoculation with a pure culture of Azotohacter 

 chroococcum the whole apparatus was sealed and incubated at 

 25°C. for forty-eight days. A gas analysis at the start of the 

 incubation period and at the end gave the results shown in 

 table 2. 



TABLE 2 



Gas changes in culture of Azotohacter chroococcum 



Calculating the ratio C02:02 we obtain the value 1.08 which 

 closely approximates the value 1.02 obtained by Krzmieniewsky 

 in his work with glucose. But under such high partial pressure 

 of CO2 the solution in the flask can contain appreciable quanti- 

 ties of this gas in solution. In fact by titration of the solution 

 with Na2C03 and H2SO4 it was found to contain 50.70 mgm. of 

 carbon dioxid. Gravimetrically then, the quantity of CO2 in 

 the air would be 607.80 mgm., and that in solution 50.70 mgm., 

 giving a total quantity of 658.50 mgm. of carbon dioxid in the 

 system. The oxygen consumption was of 286.20 cc. correspond- 

 ing to 408.80 mgm. of O2. A sugar analysis showed the following 

 changes in the solution: 



Uninoculated 1840.0 mgm. CeHiaOe 



Inoculated 41.2 mgm. C6H12O6 



Total sugar consumed 1798.8 mgm. 



Assuming the oxygen to be utiUzed in the combustion of the 

 sugar according to the following equation (equation 2) which 



