a. H. Chittenden — Pap old- digestion. 327 



produced a separation of the casein inside of an hour, and in much 

 the same order of time as shown in a previous experiment ; the 

 neutral solution of boiled milk curdling within 5 minutes, while the 

 mixture containing the smallest percentage of sodium bicarbonate 

 curdled last, viz : in 55 minutes. In each case, the initial separation 

 of the casein appeared quite complete, although of course some little 

 allowance must be made for possible error in this direction. The 

 digestive action of papoid was, however, quite apparent to the eye, 

 the precipitated casein visibly diminishing in amount as the diges- 

 tion proceeded. 



The 25 c. c. of milk yielded by precipitation with dilute acid (0-2 

 per cent, hydrochloric) 1-6143 grams of casein dried at 110° C. 

 Following are the results obtained: 



Reaction. 



Weight of 

 undigested casein. 



Casein 

 digested. 





Neutral 



0-9328 gram 



42-2 pel 



• cent 



(Boiled milk) 



1-0311 



( ( 



36-1 



( (. 



0*5 per cent. Bicarb, soda 



0-9868 



(( 



38-8 



i k 



1-0 " 



0-7473 





53-7 



a 



2-0 



0-6979 



(< 



56-7 



i i 



10"0 " Lime water 



1-2799 



(( 



20-7 



li 



From these results, it is to be noted that while boiled milk in a 

 neutral solution is more quickly curdled by papoid than fresh milk, 

 digestion of the precipitated casein is somewhat less rapid. Further, 

 in close agreement with the results found for precipitated casein, it 

 is seen that digestion is most vigorous in the presence of 2-0 per 

 cent, sodium bicarbonate. Somewhat peculiar, however, is the 

 result obtained in the presence of lime water. Digestion in this 

 case appears to have been remarkably slow; certainly not at all in 

 conformity with the previous results with precipitated casein, and 

 other proteids. 



It is evident, however, from all of the previous results, that 

 papoid, especially in the presence of sodium bicarbonate, is particu- 

 larly well adapted for predigesting milk, the casein being converted 

 by it, as by alkaline trypsin solutions, into soluble and more or less 

 diffusible products. 



6. — Action of Pap o id o n Starch. 



In addition to the two ferments already described, viz: the pro- 

 teolytic and rennet-like ferments, there is apparently ])resent in 

 papoid a third ferment ; an amylolytic one, capable of exerting 

 some action upon boiled starch. At all events, papoid added to 



