384 



PHYSIOLOGY OF BACTERIA 



separated from this solution by centrifugation, and was 

 resuspended in a new sugar solution. This was repeated 

 after each twenty-four hour period. 



The death rates increase in both experiments for the 

 first five days. This is in accordance with our expecta- 



Table 126. — Yeast in Daily Renewed Sugar Solution Without 

 Nitrogenous Food 



Plate counts 



Death rates 



Rate of 

 nitrogen loss 



II 



II 



II 



Start 



After 1 day. 

 After 2 days 

 After 3 days 

 After 4 days 

 After 5 days 

 After 6 days 



20,355 



20,898 



13,728 



824 



218 



8. 



38,700 



24,800 



12,300 



2,300 



187 

 80 



6.2 



0.000 

 0.086 

 0.464 

 0.492 

 0.679 

 0.586 



0.193 

 0.249 

 0.409 

 0.579 

 0.537 



0.074 

 0.074 

 0.075 

 0.074 

 0.075 

 0.087 



0.038 

 0.058 

 0.062 

 0.070 

 0.073 

 0.074 



tion. The rate of nitrogen loss of the yeast cells also 

 increases slightly in one experiment while it is constant 

 in the other. There is no strict parallelism between 

 loss of reproductive power and loss of nitrogen. 



(d) THE FUNDAMENTAL REACTION IN STARVATION 



Leaving aside all the possible reactions which might 

 cause death in starvation experiments without being 

 essential to starvation, such as cold-shock, traces of 

 toxic compounds in water, diffusion of electrolytes, etc., 

 two possible causes present themselves : it may be either 

 a hydrolysis, or an oxidation of some essential molecules 

 in the cell. Both of these reactions have been already 



