568 



PRINCIPLES OF SOIL MICROBIOLOGY 



assimilation and dissimilation taking place in the cell and bringing about 

 its development. The rate of growth is more rapid at the early periods 

 and, since nitrogen fixation is a function of the growth of the organism, 



weeKs of N 2 fixation 

 • 2 3 4 5 



T 



,0 20 30 40 



da^a of CO a producttor\ 



q CO^. pfooluction 



© M 2 fixation 



Fig. 40. Rate of nitrogen fixation and energy consumption (after Krainsky 

 and Bonazzi). 



it will be most active in the early periods; later, however, a great deal 

 of the energy is spent for sustenance of the cells without further growth. 27 



27 Hunter, O. W. Stimulating the growth of Azotobacter by aeration. Jour. 

 Agr. Res., 23: 665-677. 1923. 



