JOHN H. NORTHROP 



503 



of the various possible assumptions.^^ The following possibilities 

 present themselves and may be compared with the experiment 

 shown in Fig. 4 and Table X. The values are the mean of 4 to 6 

 determinations. 



TABLE IX. 



Effect of Increasing Casein Concentrations on the Amount of Casein Digested. 

 pH 8.0. Phosphate buffer. 34°C. 



Casein concentration, per cent 



Increase of amino nitrogen per cc. solution after 

 1 hr., cc 



0.5 



0.20 



1.0 

 0.33 



2.0 

 0.45 



3.0 



0.54 



5.0 

 0.55 



0.5 1.0 



Time in hours 



Fig. 4. Digestion curves for 4 per cent casein, 3 per cent gelatin, and a mixture 

 containing both 3 per cent gelatin and 4 per cent casein with the same concentra- 

 tion of trypsin. 



^* This case was considered by Henri and des Bancels (Henri, V., and des Bancels 

 L., Compi. rend. Soc. biol., 1903, Iv, 866), who, however, failed to distinguish 

 between the rate of hydrolysis and the amount of hydrolysis. 



