THE CRANIAL NERVES 293 



readily into the stomach on section of the tenth because of 

 the absence of muscular contractions in the esophagus. 



Influence of the Vagus on Respiration. Section of both 

 these nerves temporarily increases the number of respira- 

 tions which soon, however, become exceedingly slow until 

 death ensues. Inspiration is very profound indeed so pro- 

 found as to produce rupture of some of the pulmonary 

 capillaries with consequent hemorrhage and coagulation of 

 the blood and consolidation of the lung in part or whole. 

 Section of only one of the vagi is not usually followed by 

 death. Further notice of the relation of the pneumogastric 

 to respiration is given elsewhere. 



Influence of the Vagus on the Stomach, Intestine and 

 Liver. Stimulation of the pneumogastric causes contraction 

 of the stomach; but since the contraction is not immediate, 

 the impulse is probably carried to it by fibers of the sympa- 

 thetic running with the gastric branches of the tenth. When 

 the vagus is cut during digestion in the stomach the contrac- 

 tions of the muscular wall are impaired and the sensibility of 

 the organ is abolished. Secretion is interfered with, but not 

 stopped. 



Section of the vagus seems also to impair intestinal secre- 

 tion and movements, but it is not improbable that this is be- 

 cause sympathetic fibers joining the vagus high in the neck 

 are distributed with it to the intestine. 



Simple division of the pneumogastrics inhibits the forma- 

 tion of glycogen in the liver; but when the central ends of 

 the cut nerves are stimulated there is an increased pro- 

 duction of sugar even to the point of glycosuria. The irri- 

 tation is probably reflected through the sympathetic; indeed 

 it is not supposed that the vagi are concerned in the glyco- 

 genic function of the liver, except reflexly ; its section only 

 prevents the conduction cephalad of the impressions which 

 usually give rise to a secretion of glycogen. 



The connection of the vagus with the kidneys, spleen and 

 suprarenal capsules is obscure. 



