496 DIGESTION 



influence gastric digestion by preventing the contact of the food with 

 the mucous membrane, and by interfering with the efficiency of the peri- 

 staltic waves in moving the food. Considerable gas therefore retards the 

 emptying of the stomach, as has been shown experimentally by x-ray 

 observations on animals fed with the standard amount of food followed 

 by the introduction of air. It was noted that the air did not diminish 

 the frequency or strength of the peristaltic waves, but that these could 

 not efficiently act on the food. When along with gas there is also atony 

 of the stomach w r alls, the retardation in the discharge will, of course, be 

 still more pronounced. The temperature of the swallowed food does 

 not appear to have much influence on the stomach movements or on the 

 the rate of discharge from the organ. 



