DIGESTION 349 



co-ordinated for a common end. The solid food is more or 

 less broken up in the mouth and mixed with the saliva, which 

 its presence causes to be secreted in considerable quantity. 

 Liquids and perhaps small solid morsels are shot down the 

 open gullet without contraction of the constrictors of the 

 pharynx, and reach the lower portion of the oesophagus in a 

 comparatively short time ( T V second) ; while a good-sized 

 bolus is grasped by the constrictors, then by the oesophageal 

 walls, and passed along by a more deliberate peristaltic con- 

 traction. Beaumont saw, in the case of St. Martin, that 

 the oesophageal orifice of the stomach contracted firmly 



FIG. no. SECRETION OF PEPSIN. 



C shows the quantity of pepsin in the mucous membrane of the cardiac end of the 

 stomach at different times during digestion ; P, the quantity of pepsin in the mucous 

 membrane of the pyloric end ; S, the quantity of pepsin in the secretion of the cardiac 

 glands. The numbers marked along the horizontal axis are hours since the last meal. 

 About five hours after the meal S reaches its maximum. From the very beginning of 

 the meal C falls steadily down to the tenth hour, and then begins to rise, i.e. , the gland- 

 cells of the cardiac end of the stomach become poorer in pepsin as secretion proceeds. 



after each morsel was swallowed, and so did the gastric 

 walls in the neighbourhood of the fistula when food was 

 introduced by this opening. Two sounds may be heard in 

 man on listening in the region of the stomach or oesophagus 

 during deglutition of liquids, especially when, as generally 

 happens, they are mixed with air. The first sound occurs 

 at once, and is supposed to be due to the sudden squirt of 

 the liquid along the gullet ; the second, which is heard after 

 a distinct interval (six seconds), seems to be caused by the 



