PRINCIPLES OP MICROBIAL METABOLISM 



375 



either to reactions of auto-catalysis, as 'suggested by Robertson, or 

 perhaps more likely to the development of a certain balance between 

 the reproduction of the cells and the accumulation of injurious products 

 of metabolism. 13 Miyake, 14 using the results of Lipman and asso- 

 ciates 15 on ammonia accumulation and of Warington on nitrate accum- 

 ulation in the soil, calculated that these processes are autocatalytic 

 chemical reactions. The maximum rate occurs when the total amount 



C / J" J + S 6 7 8 i) /& 7/ /<? 7J 7<f SJ /J / 7 



//7cvba//0f7 //? flays 



Fig. 13. Rate of ammonia formation from peptone by Asp. niger (after Waks- 

 man). 



of production is half completed. The amount of ammonia or nitrate 

 increases according to the formula: 



13 Meller, R. tTber den Verlauf des Wachstums bei Bacillus {Proteus) vul- 

 garis in seiner Abhangigkeit von einigen Stoffwechselprodukten. Centrbl. 

 Bakt., I, 64: 1-32. 1925. 



14 Miyake, K. On the nature of ammonification and nitrification. Soil Sci., 

 2: 481-492. 1916. Jour. Biochem. Tokyo, 1: 123-130. 1922. 



15 Lipman, J. G., Blair, A. W., Owen, I. L., and McLean, H. C. Experiments 

 on ammonia formation in the presence of carbohydrates and other non-nitrog- 

 enous organic matter. N. J. Agr. Exp. Sta. Bui. 247, 1912. 



