THE FORMATION OF SPORES BY BACTERIA 



115 



time the maximum population of vegetative cells is reached. I should 

 mention that the oxygen demand was determined by measuring the 

 rate of disappearance of dissolved oxygen from an aliquot sample of 

 the culture by means of a dropping mercury electrode and a polaro- 

 graph. By making frequent measurements of the dissolved oxygen con- 

 tent in such a sample we could plot a curve showing the change in con- 



OXYGEN DEMAND 



700 



600 



500 



X 



-< 



o 



m 



o 

 400 m 



> 



z 

 o 



300 



RESIDUAL GLUCOSE 



> 



200 



100 



8 



TIME IN HOURS 

 Figure 2. pH, oxygen demand, and residual glucose vs. time. 



