DIGESTION 235 



not to the stomach itself, but to the skin of the epi- 

 gastrium, just as pain is in cases of gastric hypersesthesia 

 and gastralgia. There can be little doubt, too, that in 

 everyone centripetal impulses reach the lower centres 

 from the stomach, which are concerned in producing the 

 ' sensation ' which we call appetite, and it is possible that 

 anorexia is due to a subnormal state of gastric sensibility. 

 On the other hand, it is also possible that in certain 

 states of the nervous system the centripetal impulses 

 from the stomach actually penetrate as far as the seat of 

 consciousness, and are 'felt' as pain, or, at least, as 

 vague discomfort. It would appear, too, that pain can 

 be produced even in an otherwise normal stomach by 

 any excessive or irregular contraction of its muscular 

 coat, just as it may be so produced in any other hollow 

 viscus, and many cases of dyspeptic pain are probably 

 thus brought about. Again, traction on the cardiac or 

 pyloric ends of the stomach affects the nerves of the 

 subserous connective tissue, and is extremely painful. 

 It is probably to this that the pain which may result 

 from the presence of gastric adhesions owes its origin. 



Secretion. 



The secretion of gastric juice is not the result of 

 mechanical stimulation of the mucous membrane of the 

 stomach by the contact of food, as was once supposed, 

 but of the action of nervous impulses reaching the 

 stomach through the vagus. Mechanical stimulation is 

 merely followed by a flow of alkaline mucus, which is 

 designed to protect the delicate lining membrane, and 



