68 



COMPARATIVE HYDROLYSIS OF GELATIN 



^'-•10 



NaOH 



12 3 4 



Day5 at 20** 



Fig. 6. Action of trypsin on gelatin partially hydrolyzed by pepsin. 500 cc. 

 of 5 per cent gelatin solution brought to pH 2.2 with HCI, 20 cc. of 5 per cent 

 pepsin solution added and the solution kept at 38°C. 25 cc. samples pipetted 

 out at intervals, 5 cc. of 1 .0 M Na2C03 added and the samples kept at 3° until 

 all had been collected. 1 cc. of 10 per cent dialyzed trypsin then added and the 

 samples placed at 22°. Formol titration was run on 5 cc. samples. The values 

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



