REGULATION OF THE PANCREATIC SECRETION. 223 



to such an extent that stimulation no longer affects the 

 heart. At this time the fibres influencing the pancreatic 

 secretion are, however, still active. 



But the influence of the vagus nerve can also be demon- 

 strated in an experiment performed at a single sitting. Special 

 precautions must be taken, however, to prevent the inhibition 

 of the gland either through nervous reflexes or through the 

 circulation. To do this a dog has his spinal cord divided 

 just below the medulla in order to shut out all peripheral 

 stimuli which might inhibit the activity of the pancreas. 

 After this has been done and artificial respiration started, 

 the thorax is opened and the vagus divided below the heart. 

 If now a cannula is inserted into the pancreatic duct a secre- 

 tion of pancreatic juice is noticed whenever the peripheral 

 end of the cut vagus is stimulated. By thus exciting the 

 vagus in the thorax its influence on the heart is avoided. 



The experiments of POPIELSKI l indicate that the vagus 

 nerve contains fibres which not only augment the secretion 

 of the pancreas but also such as inhibit it. If during the 

 acute experiment described above a solution of hydrochloric 

 acid is poured into the duodenum a vigorous secretion of 

 pancreatic juice is called forth which continues for a long 

 time. If now the vagus nerve be stimulated the secretion is 

 markedly diminished in amount, often stopped entirely. 



The pancreas is influenced also by the sympathetic nerve, 

 as shown by the experiments of KuDREWETZKY. 2 This nerve 

 apparently carries two kinds of fibres to the gland first, 

 vaso-constrictor, and secondly, such as influence the secretory 

 activity of this organ. If the sympathetic is stimulated in 

 the ordinary way by electric induction shocks a slight in- 

 crease in secretion is observed, which lasts, however, only a 

 few seconds; then it ceases entirely even if the electrical 

 stimulation is continued. This is due to the fact that the 



1 POPIELSKI: Centralbl. f. Physiol., 1896, X, p. 405. 



2 KUDREWETZKY: Archiv f. (Anat. u.) Physiol.. 1894, p. 83. 



