THE DIGESTIVE SYSTEM. 



309 



that pepsin exists in the gland cells in the form of a precursor, and it 

 is probable that lipase, as well as rennin, if the latter exists as an in- 

 dependent ferment, are also represented in the chief and pyloric gland 

 cells as granules of a zymogenic nature. 



THE MOVEMENTS OF THE STOMACH. 



The movements of the stomach are most conveniently studied by 

 direct observation with the aid of Rontgen rays after the administra- 

 tion of a meal mixed with a quantity of oxychloride of bismuth. In 



FIG. 120. Shape of human stomach, in vertical position, shortly after a bismuth 



meal. (Hertz.) 

 U, umbilicus ; 0, oesophagus ; F, fundus; P.O., pyloric canal ; I. A., incisura angularis. 



these circumstances the organ is seen to consist of two parts, the axis 

 of the larger portion being nearly vertical, and forming an angle with 

 the smaller pyloric portion, which is again subdivided by a constriction 

 into two parts, the pyloric vestibule and the pyloric canal (fig. 120). 

 The pyloric canal is about 3 centimetres in length, while the pyloric 

 vestibule or antrum is less constant in size. 



After the ingestion of a meal, the muscular wall of the body and 



