ENDOGENOUS CATABOLISM 



13 



produced by the same yeast on each of the successive 

 days were 6.70%, 4.16%, 2.30%, 1.19%, 0.74% and 



Table 1. — Nitrogen Losses by Fermenting Yeast 



Time 



Mg. 

 nitro- 

 gen in 



yeast 



Relative 



N 

 quantities 



Micro- 

 scopic 

 counts 

 (millions) 



Plate 



counts 



(millions) 



Relative 



numbers 



of viable 



cells 



Yeast in 20% sucrose solution at 38°C. for three days 



Start 



After 3 days.. 



100 



78 



Yeast changed every twenty-four hours to a new solution of 10% 

 sucrose, at 28°C. 



Start 



After 1 day 



2 



3 



4 



5 



6 



100 

 84.4 

 70.9 

 59.8 

 50.3 

 42.3 

 30.0 



84,600 

 62,845 

 66,605 

 66,950 

 88,600 

 105,400 

 101,600 



0.52%. Towards the end, the yeast had almost entirely 

 lost the power to ferment. 



A similar observation was made by Meyerhof (1916a) 

 in his studies of the Nitrobacter. This organism builds 

 its entire cell from nitrite, minerals, oxygen and CO2. 

 Meyerhof observed that the rate of oxidation slowly 

 decreased if CO2 was removed from the atmosphere. 



