322 JR. S. Chittenden — Papoid-digestion. 



changes in the reaction of the digestive fluid, and in the nature of 

 the proteid undergoing digestion. Some of these points may be 

 briefly summarized. 



In the digestion of coagulated egg-albumin with an alkaline (2'0 

 per cent, sodium bicarbonate) solution of papoid, even when the 

 digestion has been long continued (say 18 hours) at a favorable tem- 

 perature, and the ferment solution strong, there invariably remains a 

 fairly large undissolved residue. At first glance, this would naturally 

 appear to be simply a residue of unaltered, coagulated albumin. On 

 being tested, however, it is found soluble, at least in great part, in 

 warm 0'2 per cent, hydrochloric acid, from which solution it is 

 reprecipitated by addition of 0"5 per cent, sodium carbonate and 

 redissolved by an excess of the alkaline fluid. This residue is, like- 

 wise, directly soluble in warm Q'o per cent, sodium carbonate, and 

 reprecipitated by neutralization. These two reactions clearly indi- 

 cate that the above residue cannot be composed of unaltered coagu- 

 lated albumin, since this substance is wholly insoluble in dilute acid 

 and alkali. The only plausible inference, therefore, is that the so- 

 called undigested residue in this case is composed of an albumose-like 

 body insoluble in 2 per cent, sodium bicarbonate, a possible primary 

 or side-product of the papoid digestion of coagulated egg-albumin. 

 It is evidently a somewhat unique body, differing from hetero- 

 albumose, and from ordinary globulin, by being insoluble in salt solu- 

 tion. Aside from this peculiar insoluble body, the other products of 

 digestion isolated in the single experiment tried were a deutero- 

 albumose, a fairly large amount of peptone and some leucin and 

 tyrosin. Only a trace of protoalbumose was found, and no hetero. 

 Neutralization of the clear, alkaline digestive fluid failed to give any 

 precipitate, as did also boiling the neutralized solution. In fact, all 

 of the ordinary primary products of digestion seemed in this case 

 to be replaced by the above described insoluble albumose, compos- 

 ing the so-called undigested residue. Of the soluble products, 

 deuteroalbumose and peptone predominated. 



In the dio^estion of raw blood-fibrin with a neutral solution of 

 papoid, a somewhat different condition of things was observed. 

 The undissolved residue contained, perhaps, a small amount of the 

 body so characteristic of the digestion of coagulated egg-albumin, 

 but certainly not a large amount. The clear, filtered digestive 

 fluid, however, gave evidence of the presence of a peculiar body 

 which was wholly wanting in the digestion of the coagulated 

 albumin. Thus, the addition of water to the clear neutral fluid gave 



