228 



LAURENCE F. FOSTER 



rate. As a consequence the amino acid intake of the cells is 

 reduced to a low level. This would account for the increased 

 output in the medium. It has been pointed out that the rise 

 in ammonia production in each culture, starting at the third 

 hour, is correlated with a drop in the amino acid curve (figs. 

 5, 6, 7). The most probable explanation of this finding rests 





/irnifioneitl /Y 



Zi 



II 



20 



79 



16 



It 



I& 



<3 S S Hours 



Fig. 6. Experiment III. CtrLTTjRE (2); 1 Per Cent Glucose, 5 Per Cent 

 Horse Serum Broth (Pleural Fluid Strain) 



upon the supposition that during the early life of the culture 

 amino acids are utihzed by the cells for structural purposes thus 

 reducing their concentration in the medium. As more amino 

 acid nitrogen is assimilated, a larger amount of ammonia is 

 spUt off intracellularly. This is evidenced by a rise in the curves 

 of ammonia production during this period. Such an hypothesis 

 is in accord with the theory of Kendall and Walker (1915) that 



