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AUGUSTO BONAZZI 



disappearance of sugar than can be accounted for by the actual 

 oxygen consumption; and the carbon dioxid production should 

 be correspondingly diminished. That this is what actually 

 happens is shown by the following experiment. 



TABLE 8 

 Nitrogen balances of Azotobacter 



Experiment 79. A number of heavy walled Erlenmeyer flasks 

 of 300 cc. capacity received 50 cc. of a solution of the following 

 composition : 



Deep well water 500.00 cc. 



K2HPO4 0.25 gram 



NaCl : 0.25 gram 



FeS04 + 7H2O 0.025 gram 



Glucose 5.00 grams 



Another set of flasks received 50 cc. of this same solution to 

 which had been added 0.115 per cent of KNO3. The flasks 

 were all fitted as is shown in the accompanying figure 3 with 

 manometer tubes. 



They had all received in addition to the solution 0.25 gram of 

 precipitated CaCOa. One flask in each series (nos. 1 and 5) was 

 left uninoculated to serve as control while the others were inocu- 

 lated with a pure culture of Azotobacter chroococcum. After 

 varying periods of incubation at 27°C. the gas was pumped out 

 of the flasks by means of a mercury pump until the solution 

 boiled at about 30°C.; then boiling was continued for a few 

 minutes, and the gas mixture thus obtained was analyzed. The 



