328 B. H. Chittenden — Papoid-digestion. 



starch paste, preferably in the presence of sodium bicarbonate at 

 40° C, slowly converts a portion of the starch into soluble starch, 

 and into a more soluble dextrin. This reaction, though plainly 

 recognizable by the iodine test, is neither rapid nor very pro- 

 nounced. It is not at all comparable in intensity to the proteolytic 

 action, but still it does exist and implies the presence of a starch- 

 convertino^ ferment. 



The best result is obtained in the presence of 2-4 per cent, sodium 

 bicarbonate. A neutral solution of the ferment is also active, but 

 even 0-05 per cent, hydrochloric acid will produce marked inhibi- 

 tion. In the latter case, howevei", the ferment is not destroyed, 

 but simply checked in its action, since neutralization of the acid 

 fluid with sodium bicarbonate (or better, making it alkaline) is fol- 

 lowed by a renewal of the amylolytic action. Experimentally, the 

 most satisfactory method of demonstrating the starch-converting 

 power is to use a mixture composed of O'o gram papoid and 25 c. c- 

 of a ro per cent, starch paste, in which is dissolved O'o gram sodium 

 bicarbonate. 



So far as the writer's experience extends, the amylolytic action 

 is limited to the conversion of starch into soluble bodies giving 

 little or no color with iodine, ordinary soluble starch being first 

 formed. Little or no reducing sugar appears. 



7. — Probable Action of Papoid in the Body. 



Experiments already recorded show that papoid is active in the 

 presence of percentages of sodium carbonate far larger than nor- 

 mally occur in an}" of the secretions found in the alimentary tract. 

 In fact, in the presence of 0-5 per cent, sodium carbonate, the 

 reputed average strength of the pancreatic juice, the proteolytic 

 action of papoid is slightly increased. The question naturally sug- 

 gests itself, however, in this connection, Avhether the alkaline pan- 

 creatic juice might not digest and destroy papoid, thus checking 

 effectually the latter's action. This important question was an- 

 swered by trying several experiments, one of which may be profit- 

 ably reported. An artificial pancreactic juice w:as prepared by 

 warming at 40° C. 1 gram of trypsin (Fairchild's) Avith 100 c. c. of 

 a 1*0 per cent, sodium bicarbonate-solution and filtering from the 

 undissolved residue. With this solution, two digestions were made 

 with cooked beef proteids; one with 25 c. c. of the prepared trypsin 

 solution alone, the other with the same quantity of trj'^psin solution 

 plus 0"5 gram papoid. 



