III. — Papoid-digestion. By R. H. Chittenden. 



" Papoid," a therapeutic agent, noted especially for its peculiar 

 proteolytic power, is prepared from various parts of the papaw 

 plant, Carica Papaya. As pointed out by Martin,* the occurrence 

 of such a proteolytic ferment in the vegetable kingdom is in itself 

 remarkable, and its discovery, together with that of other vegetable 

 ferments, maj^ eventually throw important light on the assimilation 

 of animal food by carnivorous plants, as well as on the character of 

 the proteolytic changes in the reserve proteids of plants in general. 



Furthermore, such vegetable ferments when properly isolated may 

 prove of great value in medicine as therapeutic agents, and it is 

 with this point in view that the following study of papoid has been 

 undertaken. 



The researches of Martinf have shown that papaw juice is pecu- 

 liarly rich in a variety of proteids, with one or more of which the 

 proteolytic ferment is associated. Hence, it would naturally be ex- 

 pected that any active preparation of this ferment would contain a 

 large proportion of proteid or albuminous material. This is the 

 case with papoid, and the proteids present^ as seen from the follow- 

 ing reactions, are of several kinds. 



1. General Heactions of Papoid. 



Papoid, treated with distilled water, yields on filtration, a yellow- 

 ish colored solution, leaving a small, flocky, insoluble residue. The 

 solution is almost neutral, showing, however, a faint alkaline reac- 

 tion when tested carefully. A drop or two of dilute acid does not, 

 however, give any neutralization precipitate. The matter insoluble 

 in water is partially dissolved by a 5 per cent, solution of sodium 

 chloride, the fluid giving a fairly heavy precipitate with concen- 

 trated nitric acid, which on heating turns yellow, but does not dis- 

 solve, thus indicating the presence of a glohalin. This residue of 

 globulin is also soluble in 5 per cent, sodium carbonate and in 0*2 

 per cent, hydrochloric acid, from both of which solutions it is re- 

 precipitated by neutralization, again dissolving in a slight excess of 

 either dilute acid or alkali. That portion of the residue not dis- 



Journal of Physiology, vol. 5, p. 213. f Ibid., vol. 6, p. 341. 



