SECRETIN AND ACID ACTION. 475 



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 intes- 

 tine, causing a secretion of juice. That a reflex action is here produced 

 is not contradicted by the investigations of POPIELSKI, WERTHEIMER 

 and LEPAGE, FLEic, 1 and others. According to the researches of BAY- 

 LISS 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 hydro- 

 chloric-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 secretin, which accord- 

 ing to BAYLISS and STARLING 2 is the same in all vertebrates examined, is 

 not destroyed by heat ; it is therefore not identical with enterokinase, and 

 is not considered an enzyme. It is formed from another substance, 

 prosecretin, by the action of acids. According to DELEZENNE and POZER- 

 SKi 3 secretin occurs as such in the intestinal mucosa, and the acids act 

 only by the destruction of certain bodies having a retarding action. 

 According to POPIELSKI secretin action is different from acid action: 

 and the secretin action can also be obtained by WITTE'S peptone. He 

 believes that the secretin is not a specific constituent of the intestine but 

 a body widely distributed. On the introduction of intestinal extract into 

 the animal body the blood-pressure is suddenly and very strongly reduced, 

 the blood becomes uncoagulable and a secretion of saliva, tears, pan- 

 creatic juice, gastric juice and bile (not constantly) occurs. The same 

 action is also produced by the injection of an aqueous extract of other 

 organs, and the action is not due to choline, but to a special substance, 

 which is called vasodilatin, and which also occurs in WITTE'S peptone. 

 The proteoses and peptones are themselves without action and the view 

 of PICK and SPIRO (page 311), that their action upon the coagulation 

 of the blood is due to a contaminating substance, a peptozyme, seems to 

 be correct. POPIELSKI and PANEK have suggested another method of 



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

 foot-note 1, p. 472. 



2 Journ. of Physiol., 29. 



3 Delezenne and Pozerski, Compt. rend. soc. biol., 56; Popielski, Centralbl. f. 

 Physiol., 19. 



