108 STUDIES IN CLINICAL PHYSIOLOGY 



SENSATION IN THE ALIMENTARY CANAL. 



In his recent Goulstonian Lecture, Hertz shows 

 that the sensory functions of the viscera are much 

 more limited than those of the skin. The stomach 

 and intestine do not possess any temperature sense 

 or any tactile sense, nor is cutting painful, but pulling 

 on the serous coat gives rise to severe pain. The 

 feeHng of heat or cold after swallowing liquids is 

 appreciated by the lower end of the oesophagus. 

 Temperature and tactile sense are quite well developed 

 in the oesophagus, and localization is very accurate — 

 seldom more than an inch out. 



Hydrochloric acid may be poured into the stomach, 

 either through a stomach-tube or a gastrostomy 

 wound, without producing any sensation at all, 

 even if the percentage rises to 0*5 or even 2, and this 

 is true also in cases of gastric ulcer. Alcohol does 

 excite a burning feeling. Distention of the stomach 

 causes a sensation of fullness ; the amount of dis- 

 tension necessary depends on the tonicity of the 

 gastric muscles. Gastralgia, whatever its cause, is due 

 to colicky, irregular contractions of the muscle, the 

 pylorus remaining closed. There is often a referred 

 pain or tenderness in the cutaneous area also. The 

 pain of peritonitis is probably quite a different thing. 

 Sensation in the intestine corresponds closely in its 

 physiology to sensation in the stomach. The anal 

 canal, however, can detect thermal and tactile stimuli. 



Carlson has recently shown, in a patient with a 

 gastric fistula, that the sensation which we call 

 hunger is due to waves of peristalsis in the empty 



