R. H. Chittenden — Ferments of Pineapple Juice. 289 



ments, and further that the neutralized juice is considerably more 

 active than the unneutralized fluid. Apparently, the proteolytic 

 action of the ferment increases with the decrease in acidity, until the 

 neutral point is reached. 



With blood fibrin, on the other hand, juice of the natural acidity 

 appears to have a greater digestive power than the neutralized fluid, 

 although on this point we have only a single experiment to offer. 

 This may perhaps be explained simply by the swelling of the fibrin 

 in the dilute organic acid, this condition possibly facilitating the 

 action of the ferment. 



Experiment lY. — The acidity of the pineapple juice was equal to 

 0*525 per cent. HCl. Necessary to neutralize 100 c. c. of filtered 

 juice, 15-2 c. c. 5-0 per cent, solution of Na^COg. Weight of dry 

 albumin contained in 10 grams of moist coagulum, 1 "4486 grams. 

 Weight of dry fibrin (at 110° C.) contained in 6 grams of washed 

 blood fibrin,* the amount used in the digestions, 2*5273 grams. 

 The digestive mixtures were warmed at 40° C. for 2 hours. 



Blood tibriu . 

 Egg-albumin 



Pineapple Undissolved Per cent, 



juice. Reaction. proteid. digested. 



j 100 c. c. natural acidity 1*2435 grams 50*8 



i 100 neutralized 1*4321 43*3 



j 100 natural acidity 1*0325 28*8 



I 100 neutralized 1*0096 30*3 



The most noticeable feature in this experiment, aside from the 

 point already mentioned, is the far greater digestibility of blood 

 fibrin as compared with egg-albumin, a fact which might naturally 

 be expected, since the same is true in the case of other well-known 

 proteolytic fei*ments. 



The proteids of muscle tissue are likewise more readily digested 

 by pineapple juice than coagulated egg-albumin, full 60 per cent, of 

 the former proteids being converted into soluble products during 

 one hour's warming at 40° C. This is plainly shown in the follow- 

 ing experiment, in which also the muscle proteids, like egg-albumin, 

 are seen to be more rapidly digested in the neutralized juice than in 

 the acid fluid. 



Experiment V. — The acidity of the pineapple juice employed was 

 equal to 0*507 per cent. HCl. Necessary to neutralize 100 c. c. of 

 juice, 14*7 c. c. of a 5 per cent, solution of Na^COj. Weight of dry 



* Washed with water and salt sohition, then boiled in water, alcohol, and lastly in 

 water. 



