M. H. Chittenden — Ferments of Pineapple Juice. 307 



and not readily dissolved by an excess of the acid. This same body 

 is likewise formed by the action of fresh pineapple juice in neutral 

 or weak alkaline solutions, and also by the isolated ferment as pre- 

 pared by the methods previously described. 



Boiling the acid digestive fluid gives no noticeable coagulum, and 

 addition of moderately strong nitric acid likewise fails to produce 

 any precipitate. Neutralization of the acid digestive mixtui-e may 

 give rise to a small amount of a neuti'alization precipitate, resembling 

 acid-albumin. On evaporation of the neutralized fluid, the solution re- 

 mains fairly clear, and when sufliciently concentrated addition of strong- 

 alcohol gives a gummy precipitate of proteose and peptone, while 

 from the alcoholic solution crystals of tyrosin can be obtained and, 

 in lesser quantity, leucin also. Tyrosin appears to be present in 

 much larger amount than leucin. On dissolving the alcohol precipi- 

 tate in water and saturating the solution with ammonium sulphate a 

 heavy precipitate of proteose is obtained, while in the flltrate a large 

 amount of true peptone is found, which after removal of the sulphate 

 by dialysis gives a bright red color with the biuret test, etc. So far 

 as our experiments extend, the proteose is composed mainly of a 

 deutero-like body, only a small precipitate being obtained by satura- 

 tion with sodium chloride, either in a neutral or slightly acid solution. 

 An experiment like the preceding carried out with coagulated egg- 

 albumin gave essentially the same results. 



When pineapple juice of neutral or faintly alkaline reaction, or a 

 neutral or slightly alkaline solution of the proteolytic ferment, is 

 warmed with blood fibrin, for example, the digestion appears much 

 the same as the preceding, but on heating the filtered solution a very 

 pronounced milk}^ turbidity appears, which on addition of a drop 

 or two of acetic acid changes to a heavy flocculent pi-ecipitate, insol- 

 uble in excess of the acid. 



Further, addition of nitric acid to the neutral or slightly alkaline 

 digestive fluid gives a heavy curdy white precipitate, insoluble on 

 application of heat, and likewise insoluble in an excess of the acid. 

 Heated with an excess of acid, the precipitate takes on an intense 

 yellow color. This precipitate produced by nitric acid is likewise 

 insoluble in a 10-per cent, solution of sodium chloride, at least in the 

 presence of the acid. 



This body, so characteristic of bromelin digestion in neutral or 

 faintly alkaline solutions, is very resistant to the action of the fer- 

 ment, being still present even after a long-continued digestion. It 

 seems probable that this substance results from the action of the fer- 



Trans. Conn. Acad., Vol. VIII. 41 Jan., 1892. 



