ZYMOLOGY FERMENTS AND FERMENTATIONS 221 



strychnin and alkaloids generally, and quinin, assist the action of pepsin. 

 Antipyrin and antifebrin and other similar coal tar derivatives retard its 

 activity somewhat while strong solutions of cane sugar (40 per cent.) check 

 its activity considerably. Some authorities ascribe a bacteriolytic power 

 to pepsin, whereas others declare that the apparent germ-destroying power 

 is due to the acid present. 



The first change in pepsin digestion is a swelling of the albumens or 

 albuminoids, which action is due to the acid present. The pepsin then 

 splits up the albumens into peptones and albumoses which are diffusible. 

 The peptones are the true end products and differ from the albumoses 

 in that they are more diffusible and that they are not precipitated by acid- 

 ulated ammonium sulphate, neither are they precipitated by boiling, 

 by acid s or by calcium ferrocyanide. Pepsin digestion is indeed a complex 

 process and the student desiring further information is referred to standard 

 works on physiology and dietetics. 



Commercial pepsin is obtained from the stomachs of recently killed 

 hogs. Its digesting power is based upon its proteolytic action upon hard 

 boiled egg albumen. According to the U.S.P., one part of properly pre- 

 pared hog pepsin should digest at least 3000 parts of coagulated egg al- 

 bumen. Higher grades are, however, found on the market, such as give 

 1-4000, 1-5000 and 1-6000 and even 1-20,000. 



2. Trypsin. Trypsin is the albumen digesting ferment of the pan- 

 creas derived from a proferent, the trypsinogen. It is also found in the 

 small intestine. On its action on albuminous substances it is much like 

 pepsin, though in its behavior with certain modifying influences it is quite 

 different. It is most active in slightly alkaline media (one per cent, solu- 

 tion) though it is also active in neutral and slightly acid solutions. Bile 

 aids trypsin digestion, especially in the presence of lactic acid, also in 

 the presence of hydrochloric acid. Strongly acid and alkaline solutions 

 check its action very promptly while neutral salt solutions increase its 

 activity, especially the sodium salts. 



Trypsin is somewhat more resistant than pepsin, in most of its general 

 characteristics and properties it is, however, closely similar. Its digesting 

 power can be determined much in the same manner as for pepsin. Trypsin 

 is especially active in the digestion of casein and of gelatin. 



The commercial article pancreatin is a mixture of the enzymes of the 

 pancreas, of the hog, the ox, and of other animals. Its chief value depends 

 upon its peptonizing and diastatic power. According to the French 

 Pharmacopoeia pancreatin shall peptonize 50 times its weight of fibrin 

 and convert 40 times its weight of potato starch into sugar. The active 

 ferments of pancreatin are trypsin (protease), amylopsin (amylase), 

 steapsin (lipase) and the milk curdling agent rennin. 



