36 PROTEOLYTIC PANCREATIC FERMENT 



the special technical difficulties. He proceeded to bring a 

 patch of the duodenal wall surrounding the orifice of the 

 excretory duct to the skin surface and stitched it into the 

 cutaneous margins of the wound. In this way he obtained a 

 permanent fistula and the advantage of continuous observa- 

 tion of the glandular activity at his convenience. Even 

 with this advance in technique the results obtained were not 

 thoroughly satisfactory because of the activation of the 

 secretory fluid obtained from the fistula by the enterokinase 

 (v. infra.) of the mucous membrane surrounding it. Only 

 by careful removal of this mucous membrane which had 

 been healed into the cutaneous wound and by isolating the 

 orifice of the duct by stitching it to the margins of the wound 

 can there be obtained sufficient approach to physiological 

 conditions to insure that really normal pancreatic fluid will 

 be obtained. 



Such conditions being established it is possible to de- 

 termine the influences by which the pancreas is normally 

 stimulated. Undoubtedly the most important factor in this 

 connection is the entrance of the acid content of the stomach 

 into the duodenum. The hydrochloric acid is, it is safe 

 to say, the most effective stimulant to pancreatic secretion ; 

 the influence of the fatty substances of the food is apparently 

 more or less questionable 4 ; but a psychic agency must in all 

 likelihood be recognized. As to the method by which the 

 secretion of the gland is set in operation, doubtless both 

 nervous and chemical mechanism must be held possible. 



Secretin. Bayliss and Starling were able to demonstrate 

 that the introduction of acid into an intestinal loop will 

 maintain the pancreas in activity even after section of both 

 vagi and the splanchnic nerves, and after extirpation of the 

 solar plexus. After exclusion of all nervous communication 

 between the intestinal loop and the rest of the body the flow 

 of pancreatic juice is quite as free as if the nerves were in- 



*O. Cohnheim and Ph. Klee, Zeitschr. f. physiol. Chem., 78, 464, 1912. 

 (Soaps apparently have more influence than do the neutral oils.) 



