350 



ATJGUSTO BONAZZI 



words, referring to equation 1 set forth on page 335 of this 

 memoir we may well express our hypothesis as follows: during 

 the first period of incubation there was a balance between the 

 two functions represented by the equation, while in the second 

 period of incubation the addition of sugar disturbed the balance 

 in such a way that although the first member of the second 

 term was active on 9.1 mgm. of new cellular substance, the 

 second member of this term was active on a total of 9.1 + 18.3 

 = 27.4 mgm. This leads us to the conclusion that the concep- 

 tion of "ferment power" in an organism such as Azotobacter 

 should be carefuUy studied. The following series of experiments 

 was therefore designed to study this phase. 



Experiment 69. Some 250 cc. Erlenmeyer flasks received 

 50 cc. of the following solution together with 0.5 gram of precip- 

 itated calcium carbonate. 



Deep well water 500. 00 cc. 



K2HPO4 0.25 gram 



NaCl 0.25 gram 



FeS04 + 7H2O 0.02 gram 



Glucose 5 . 00 grams 



Ca(N03)2 + 4H2O 0.632 gram 



TABLE 15 

 Sugar consumed per unit of dry matter in cultures of Azotobacter 



After inoculation with equal quantities of a pure culture of 

 Azotobacter chroococcum the flasks were incubated at 30°C. for 

 varying periods of time. One of the flasks was left uninoculated 

 to serve as control. The dry matter in the cultures was deter- 

 mined by acidifying, filtering in the manner referred to above, 

 washing and drying at 110°C. in vacuum over P2O5, while the 

 sugar was determined in the filtrate. The results are set forth 

 in table 15. 



