182 INFLUENCE OF THE 



of acid into the duodenum even after section of both vagi and 

 splanchnics, or destruction of the spinal cord, or after complete 

 extirpation of the solar plexus. 



These experiments clearly shut out the central nervous system 

 from participation in the supposed reflex, but the observers, still 

 clinging to the belief that the phenomena before them arose from 

 nervous activity, accommodated their views to the additional 

 experimental facts, by receding to the conclusion that the secretion 

 arose from a peripheral reflex act. Popielski concluded, from 

 finding that the secretion occurred after removal of the solar plexus, 

 and also after separating the duodenum with the pylorus from 

 the stomach, but not if the duodenum were cut across a short 

 distance below the pylorus, that the centres for the supposed 

 peripheral reflex were in the scattered ganglia of the pancreas 

 of which the most important were to be found near the pylorus, 

 and were cut off when the duodenum was cut across near to the 

 pylorus. Wertheimer and Lepage accepted the peripheral reflex 

 explanation, but as they found that injection of acid into the 

 jejunum also called out a secretion diminishing in intensity as the 

 distance from the duodenum increased, they came to the conclusion 

 that the centre for the supposed reflex varied according to the 

 region of intestine stimulated by the acid, and that while the 

 secretion in the case of the duodenum might result from stimulation 

 of pancreatic ganglia, that from the jejunum probably was set 

 up by stimulation of the solar plexus. The experiment of injec- 

 tion of acid into a loop of jejunum, after extirpation of the solar 

 plexus, or after severance of the mesenteric nerves of the loop, 

 was not performed by these observers. They found that the 

 secretory effect was not abolished by administration of atropin, 

 but instead of arousing any suspicion that the secretion might 

 not after all be of nervous origin, this fact was only correlated 

 to the absence of effect of this drug upon the sympathetic salivary 

 secretion. 



The possibility of the secretion induced by acid in the duo- 

 denum being due to chemical action was not unthought of entirely, 

 however, by the St. Petersburg school, and is discussed by Pawlow 

 in his book, in which he states that the acid works either locally 

 by exciting the peripheral end-apparatus of the centripetal nerves 

 in the mucous membrane, or else it is absorbed into the blood 

 and stimulates either the secretory centre or the gland cells 



