342 DIGESTIVE ACTION OF THE PANCREATIC JUICE. 



takes place in an alkaline medium, and never in an acid one. In fact, 

 a. 1 per cent, solution of sodium carbonate seems to play the same part 

 in assisting trypsin as a *2 per cent, solution of HC1 does for pepsin in 

 gastric digestion. In gastric digestion there is a by-product, syntonin, 

 formed in addition to the true peptones. In pancreatic digestion a 

 body resembling alkali-albumin, which passes into a globulin-like body, 

 and ultimately into a tryptic peptone, is formed. Of the peptones so 

 formed, one is called anti-peptone, and it is not further changed, but part 

 of the proteid is changed in a by-product, hemi-peptone. This body, 

 when acted upon, yields leucin and tyrosin. When putrefaction takes 

 place, the bodies above-mentioned are also formed. We might represent 

 the action of trypsin thus : 



Proteid -f trypsin -f 1 per cent, sodium carbonate, kept at 38 C = 

 formation of a globulin-like body, and then anti-peptone and hemi- 

 peptone are formed. 



ANTI-PEPTONE HEMI-PEPTONE 



yields yields 



Normal Digestive 

 Products. 



Undergoes Leucin, 



no further Tyrosin, 



Putrefactive 

 Products. 



Indol, 

 Skatol, 



change. Hypoxanthin Phenol, 



Asparaginic Acid. 



Volatile Fatty Acids, 



HC0 2 H 2 S, 



CH 4 K 



It seems that trypsin in pure water can act slowly upon fibrin to 

 produce peptone. Pepsin cannot do this without the aid of an acid.] 



When proteids are boiled for a long time with dilute H 2 SO 4 , we obtain peptone, 

 then leucin and tyrosin (Kiihne) ; gelatin yields glycin. Hypoxanthin and xanthin 

 are obtained in the same way by similarly boiling fibrin, and the former may 

 even be obtained by boiling fibrin with water (Chittenden). 



It is very remarkable that the juice of the green fruit of the papaya tree (Carica 

 papaya) possesses digestive properties (Roy, Wittmack), and the action is due to 

 an albuminous peptonising ferment, closely related to trypsin, and called caricin 

 or papaiin. The milky juice of the fig-tree has a similar action. 



According to Gorup-Besanez, sprouting malt, vetch, hop, hemp during sprout- 

 ing, and the receptacle of the artichoke contain a peptonising ferment. 



Leucin, tyrosin, glutaminic and asparaginic acids, and xanthin are formed in the 

 seeds of some plants ; hence we may assume that the processes of decomposition in 

 some seeds are closely allied to the fermentative actions that occur in the intestine 

 (Salomon). 



Origin of Trypsin. It is formed within the pancreas from a " mother- 

 substance" or zymogen (Heidenhain), which takes up oxygen. The 



