R. H. Chittenden — Papoid-digestion. 331 



papoid will certainly exhibit marked proteolytic action in the pres- 

 ence of O'l per cent, hydrochloric acid and pepsin, although the 

 conditions may not be favorable for the best action of pepsin. 



This is illustrated by the following experiments : an artificial 

 gastric juice was prepared by dissolving some commercial pepsin 

 (Fairchild's) in O'l per cent, hydrochloric acid, in the proportion of 

 O'l gram pepsin to 25 c. c. of acid. Digestions were then made, 

 with and without papoid, of raw and cooked beef proteids, with 

 the following results: 



The 15 grams of raw beef used contained 4 '0494 grams of dry 

 proteid, while the 10 grams of cooked beef contained 3 '9608 grams 

 of dry proteid (110° C). 



The digestions were kept at 40° C. for 6 hours. 



a. With raw heef proteids. 



Weight of 

 Character of the fluid. undigested residue. 



Proteid 

 digested. 



25 c. c. pepsin-HCl alone 3 3626 grams 



16*9 per cent 



0-5 gram papoid f ^ *°"^ 



63-3 



h. With cooked heef proteids. 





Weight of 

 Character of the fluid. undigested residue. 



Proteid 

 digested. 



25 c. c. pepsin-HCl alone 3-8689 grams 



2-3 per cent. 



0'5 gram papoid \ ^'^^^^ 



44'] 



The action of papoid is prominent here simply because the condi- 

 tions are favorable for its action, while they are not well adapted 

 to the action of pepsin. The two points to be emphasized are, how- 

 ever, first, that the presence of pepsin does not interfere with the 

 action of papoid in an acid medium, where the other conditions are 

 favorable to the latter ferment; and secondly, that any direct com- 

 parison of the digestive action of the two ferments cannot well be 

 made, since they act under such totally different conditions as 

 regards dilution, reaction, etc. Further, in studying the action of 

 acids on any ferment we have to consider not only the influence of 

 a given percentage of acid, but must also take into account the 

 absolute amount of acid, both in proportion to a given quantity of 

 ferment and the proteid matter to be digested. It is hardly neces- 

 sary to detail the several experiments that have led to this conclu- 

 sion; one alone will suffice. The following mixtures were warmed 

 at 40° C. for 6 hours, with 10 grams of cooked beef proteids, with 

 results as indicated: 



