BY H. G. CHAPMAN. 93 



juice. Other observers [Bernstein'^, Gottlieb'], earlier and later, 

 had shown that stimulation of the peripheral ends of the vagi 

 could inhibit an already established flow. Attempting to eluci- 

 date this, Popielski^ observed that the flow evoked by .stimulation 

 of one vagus might be inhibited by stimulation later of the same 

 or other vagus; and further, that the flow produced by the intro- 

 duction of acid into the duodenum was regularly inhibited by 

 stimulation of the vagus. He also found that the flow following 

 upon the introduction of 0*4% HCl into the duodenum occurred 

 after section of the vagi and of the sympathetic trunks. From 

 these results he concluded that the reflex centre must lie in the 

 abdominal cavity. His attempts to localise its position were not 

 successful. Later^ he showed that the flow resulting from the 

 acid occurred after section of both vagi and the splanchnic nerves, 

 or after destruction of the spinal cord, or after extirpation of the 

 solar plexus. 



Wertheimer and Lepage^" found that the introduction of acid 

 into the small intestine produced a flow which became less as the 

 injection was made nearer to the caecum. 



Bayliss and Starling^^ repeated these experiments, and found 

 that the injection of from 30 to 50 c.c. of 0-4 % HCl into a loop 

 of jejunum, after a latent period of two minutes, produced a 

 marked flow of pancreatic juice. This effect was still produced 

 after section of the vagi, section of the spinal cord at the foramen 

 magnum, destruction of the spinal cord, section of the splanchnic 

 nerves, extirpation of the solar plexus, or any combination of 

 these operations. On introducing acid into a loop of intestine 

 separated from the body except for the artery and vein, a flow of 

 pancreatic juice was evoked. The mucosa was then scraped from 

 this loop, ground up with sand and acid, and the extract filtered. 

 This was introduced into the jugular vein, and called forth a 

 copious flow of pancreatic juice, Wertheimer and Lepage^- had 

 already shown that the injection of acid into the circulation was 

 without effect upon the secretion of pancreatic juice. Further 

 investigation revealed the exceeding potency of the body in the 

 extract, to which the name of secretin was given. 



