SUMMARY. OF THE PlfEUMOGASTEICS. 255 



sibility of tlie mucous membrane of the oesophagus, as well 

 as the movements of its muscular coat, depends upon these 

 branches. Division of the nerves paralyzes the oesophagus, 

 and galvanization of the roots of the pneumogastrics causes 

 the tube to contract in its entire length. When the nerves 

 are divided, the oesophagus may become distended with food 

 forced in by the constrictors of the pharynx, but little or 

 none passes to the stomach. Uegurgitation of food some- 

 times occurs under these conditions, the muscular coat of 

 the oesophagus contracting under the direct stimulus of dis- 

 tention. 



The function of the abdominal branches has been studied 

 chiefly by operating on the pneumogastrics in the cervical 

 region. Division of the nerves produces congestion of the 

 liver, and sometimes slight extravasation, and renders the 

 bile somewhat watery. It also arrests, in from one to two 

 days, the glycogenic function of the liver. Galvanization 

 of the peripheral ends of the divided nerves has no effect 

 on the liver. Galvanization of the central ends exaggerates 

 the glycogenic function and renders animals diabetic. The 

 inhalation of irritating vapors or of anaesthetics has the same 

 effect. This action is reflex, and the direct stimulus to the 

 liver does not pass through the pneumogastrics, for division 

 of the nerves between the lungs and the liver has no influ- 

 ence on the production of sugar. Irritation of the floor of 

 the fourth ventricle, opposite the origin of the pneumogas- 

 trics, exaggerates the glycogenic function. The stimulus is 

 not propagated through the pneumogastrics, for the effect is 

 the same after both nerves have been divided. It probably 

 operates through the sympathetic,, for diabetes cannot be 

 produced after the branches going to the solar plexus have 

 been divided. 



Section of the pneumogastrics in the neck paralyzes, 



nearly but not entirely, the muscular coats of the stomach. 



AYhen the section is made in an animal in full digestion, the 



mucous membrane, from being tense and full of blood, be 



117 



