498 DIGESTION. 



The way in which the trypsinogen is converted into trypsin is still 

 unknown and is the subject of dispute. According to one view, proposed 

 by PAWLOW and defended by BAYLISS and STARLING, the trypsinogen 

 is transformed into trypsin by the action of the kinase. In the opinion 

 of DELEZENNE, DASTRE, and STASSANO, and others, 1 the trypsin, on the 

 contrary, is a combination of the kinase and trypsinogen, analogous to 

 the cytotoxines, which, according to EHRLICH'S side-chain theory, are 

 combinations between a complement and an amboceptor. (See page 

 69.) 



The specific excitants for the secretion of pancreatic juice are, 

 according to PAWLOW and his collaborators, acids of various kinds 

 hydrochloric acid as well as lactic acid and fats, the latter acting 

 probably by virtue of the soaps produced therefrom. Alkalies and 

 alkali carbonates have, on the contrary, a retarding action. It appears 

 that the acids -act by irritating the mucosa of the duodenum. Accord- 

 ing to LONDON and SCHWARZ the secretion can also be excited from the 

 entire jejunum and the upper part of the ileum. The secretion becomes 

 weaker the further away the exciting source is from the duodenum. 2 

 Water, which causes a secretion of acid gastric juice, likewise becomes, 

 indirectly, a stimulant for the pancreatic secretion, but may also be 

 an independent exciter. The psychical moment may, at least in the 

 first place, have an indirect action (secretion of acid gastric juice), 

 and the food seems otherwise to have an action on pancreatic secretion 

 by its action on the secretion of gastric juice. 



The most important excitant for the secretion of juice is hydrochloric 

 acid, but opinions are not in unison as to the manner in which the acid 

 acts. PAWLOW'S school claims that the acid acts reflexly upon the 

 intestine, causing a secretion of juice. That a reflex action is here pro- 

 duced is not contradicted by the investigations of POPIELSKI, WERT- 

 HEIMER and LEPAGE, FLEIG, S and others. According to the researches 

 of BAYLISS and STARLING, which have been confirmed by CAMUS, GLEY, 

 FLEIG, HERZEN, DELEZENNE, and others, a second factor must also be 

 active here. BAYLISS and STARLING have shown that a body which 

 they have called secretin can be extracted from the intestinal mucosa 

 by a hydrochloric-acid solution of 4 p. m., and this when introduced into 

 the blood produces a secretion of pancreatic juice, bile, and in the 

 opinion of some investigators also of saliva and intestinal juice. The 



1 Bayliss and Starling, Journ. of Physiol., 30 and 32, which also cities the other 

 investigators and also O. Cohnheim, Bioch. Centralbl. 1, 169 and S. Rosenberg, ibid., 

 2, 708. 



2 Zeitschr. f. physiol. Chem. 68, 346 (1910) which also contains the literature. 



3 Fleig, Centralbl. f. Physiol., 16, 681, and Compt. rend. soc. biol., 55. See also 

 footnote 1. 



