ENDOGENOUS CATABOLISM 11 



Autolytic action occurs, as far as is known, after the 'death' of all 

 cells and tissues; but it is not only in the dead cells that the own 

 protein is attacked . . . 



. . . Several investigations tell us about the behavior of yeast in 

 relatively large amounts of water, with or without disinfectants. If 

 no nitrogenous food is offered . . . the yeast loses its own protein. 

 This loss may be temporary and need not lead to the death of the 

 cell. It may be supposed that the same reactions take place even 

 under normal conditions, but are covered up partly or entirely by 

 synthetic processes. This process shall be called 'endoproteolysis.' 



If this endoproteolysis is not compensated by constructive proc- 

 esses, then, finally, those protoplasmic groups which are indispensable 

 for cell life will be attacked. The cell loses the power of reproduction 

 and undergoes complete destruction. This latter process of dissolu- 

 tion shall be called autolysis. This autolysis which starts at the 

 death or afterwards, is essentially an irreversible process initiated by 

 endoproteolysis . ' ' 



(6) ENDOGENOUS CATABOLISM OF YEAST 



The amount of nitrogenous living matter changed 

 per day has been found with man to approximate 0.1 gm. 

 of nitrogen per kg. of body weight. If this same ratio 

 would hold with microorganisms, the task of deter- 

 mining catabolism would seem hopeless, for the total 

 solids of the cells in one liter of broth culture of Bad. 

 coll amount to only 220 mg. and their catabolic prod- 

 ucts per day would total only 0.2 mg. of nitrogen per 

 liter. 



But this ratio does not hold. Rubner (1908) has 

 pointed out that in animals, the relative amount of 

 endogenous catabolism increases with the decrease in 

 size, and Rubner believed the surface to be the important 

 factor determining the rate of endogenous catabolism. 

 But even under these favorable circumstances, the 

 amount of catabolized nitrogen is so small, owing to the 

 minute quantity of living matter in a bacterial culture. 



