STUDIES ON AZOTOBACTER CHROOCOCCUM BEIJ. 



349 



treatment as the others. The results of this experiment are 

 tabulated in table 14. 



* Total quantity of sugar at the beginning of second period. 



Addition of carbohydrate to a culture that has come to a 

 standstill will result in a new utilization of the carbon source 

 with further growth. The first compounds resulting from the 

 first utilization of the sugar had probably all been utilized during 

 the first thirty days of incubation and only such by-products as 

 the cells could not well utilize were to be found when the culture 

 received the fresh supply of sugar; that these were not inhibitive 

 is shown by the utilization of the sugar in the second period as 

 well as by the additional growth. Their nature will be studied 

 elsewhere, and at present it is sufficient to state that they are 

 formed through the cell activity. 



Ferment powers of Azotobacter 



From table 14 we may see that the conception S : c is erroneous 

 with regard to the data for culture 5. In fact while it is true 

 that there was a renewal of growth in the second period with a 

 corresponding increase in dry matter, we are not justified in 

 considering that it was only the 9.1 mgm. additional growth that 

 consumed the additional sugar, but we should deem it possible 

 that the 18.2 mgm. of the cells already present in the culture 

 used the new source of carbon for their maintenance. In other 



