DIGESTION 243 



food is probably due to a slight active contraction of the 

 wall, which is reflexly brought about and is designed to 

 resist the mechanical pressure of the contents. Failure 

 of this reflex contraction has been alleged to play a large 

 part in the development of 'atonic dilatation' of the 

 stomach, by allowing the fluid pressure of its contents 

 to exert its distending effect unopposed.* 



Watree of 

 constriction; 



FIG. 16. FUNCTIONAL DIVISIONS OF THE STOMACH. 



2. Active Movements. From the point of view of its 

 active motility, the stomach may be divided into two 

 distinct parts (1) the fundus, (2) the antrum (Fig. 16). 

 These are separated from each other by a muscular con- 

 striction the transverse band situated a little to the 

 left of the pyloric orifice, and no mixing of the contents 



* See a paper by Ageron, Archiv. /. Verdauungskrcmkh., 1905, 

 xi. 460. 



162 



