JOHN H. NORTHROP 



69 



Days at ZV 



Fig. 7. Action of trypsin on gelatin partially hydrolyzed by alkali. 500 cc. 

 of 5 per cent gelatin solution containing 50 cc. of 1.0 M NajCOa kept at 90°C. 

 25 cc. samples pipetted out at intervals, and kept at 3° until all had been collected. 

 1 cc. of 10 per cent dialyzed trypsin then added to each sample and the solutions 

 kept at 22°. Formol titration was run on 5 cc. The figures plotted have been 

 calculated on the basis of 10 cc. of 5 per cent gelatin. 



