14 PHYSIOLOGY OF BACTERIA 



The nitrate bacteria were starving for CO2, and that 

 prevented a normal formation of the oxidizing agent in 

 the cells. 



Table 2. — Oxygen Consumption by Nitromonas, with and without 



Carbon Dioxide 



(mm. 3 oxygen consumed per 2 hour period by 2 c.c. of culture) 



After 4 hours After 6 hours After 8 hours 



WithCOz.... 

 Without CO2. 



45.5 

 44.5 



49 

 39 



50 mm. 3 O2 

 31mm.3 02 



The chemical nature of the nitrogenous compounds 

 excreted by living yeast is quite unknown while the 

 autolytic products have been studied extensively. It 

 is very probable that most of the excretions of living 

 yeast cells cannot again be assimilated by the same 

 yeast while by far the largest amount of the autolytic 

 products can be used again for cell construction (Lindner, 

 1905). 



Probably, all data on the endogenous catabolism of 

 yeast have quite a high degree of error, because they 

 may represent not only the products of living cells, but 

 also of a certain percentage of dead cells. This per- 

 centage is practically unknown in all experiments. 

 Since autolysis of dead cells proceeds much more rapidly 

 than that of living cells, a relatively small number of 

 dead cells will cause a considerable error. 



The contention of Rubner (1908), that the more rapid 

 rate of endogenous catabolism in small organisms is 

 caused by the relatively larger surface, seems rather 

 improbable since the compounds to be decomposed are 

 already within the cells. Two further explanations seem 

 possible: either the higher organisms re-utilize a large 

 amount of the decomposed protoplasm, or the yeast 



