42 PHYSIOLOGY OF ALIMENTATION. 



causes a stoppage of the oesophageal movements. Simple 

 ligature of the oesophagus without injury to the nerves does 

 not, however, keep the cesophageal movements from passing 

 over the entire length of the oasophagus. A piece can even 

 be cut out of the oesophagus and if the nervous connections 

 between the upper and lower ends have not been injured the 

 swallowing movements inaugurated in the upper end pass 

 (by way of the nerves) over the lower end also. It seems 

 therefore as though the ordered act of deglutition which is 

 started through stimulation of certain afferent nerves is 

 dependent in the last analysis upon impulses which pass 

 from an excited "centre" by way of certain efferent nerves 

 to the oesophagus, one segment after another of which is 

 thereby made to contract. 



The stomach is supplied with cranial nerves by way of the 

 two vagi, and with sympathetic nerve fibres by way of the 

 spianchnics and the solar plexus. The vagi contain fibres 

 which not only bring about movements in the stomach 

 but also such as inhibit movement. Under ordinary circum- 

 stances, more especially when the stomach contains food, 

 stimulation of the vagi brings about a contraction of the 

 cardiac end of the stomach; or one or a series of contractions 

 arise in the preantral portion of the stomach; or, finally, 

 the musculature of the whole stomach may go into a state 

 of tonic contraction which gradually increases and then 

 after a longer or shorter period of sustained contraction as 

 gradually relaxes. Under certain circumstances stimulation 

 of the vagi may have an opposite effect. Especially after 

 the administration of pilocarpin may stimulation be followed 

 by muscular relaxation. The sympathetic nerves supplying 

 the stomach in a certain sense antagonize the action of the 

 vagi. If the splanchnic nerves are stimulated a decrease in 

 the tonus of the gastric musculature as well as a decrease 

 in the rhythmical contractions of the stomach are usually 

 observed. 



In addition co the nerves which run into the wall of the 



