SECTION IV 



II 



THE MOVEMENTS OF THE STOMACH 



THESE can be best studied by Cannon's method that is, by direct observa- 

 tion of the movements in a living unanaesthetised animal by means of the 

 Rontgen rays. In order to make the shape of the 

 stomach visible, the food bread and milk is 

 mixed with a quantity of bismuth subnitrate or 

 bismuth oxychloride (Hertz). The presence of 

 this salt does not interfere with the processes of 

 digestion, but renders the. gastric contents opaque 

 to the Rontgen rays. On examining by this 

 means the stomach of a cat which has just taken 

 a meal, the whole of the food is seen to be lying 

 in the fundus. It is marked off by a strong 

 constriction, the ' transverse band,' from the 

 pyloric portion. In about twenty to thirty 

 minutes faint waves of contraction begin a little to 

 the cardiac side of the transverse band and travel 

 slowly towards the pylorus. These waves succeed 

 one another so that the pyloric part of the stomach 

 may present a series of constrictions. Their effect 

 is to force towards the pylorus the food which has 

 been digested by gastric juice and detached from 

 the surface of the mass in the fundus. The 

 pylorus remaining closed, the food cannot escape, 

 and therefore is squeezed back, forming an axial 

 reflux stream towards the cardiac end. These 

 contractions last throughout the whole period of 

 gastric digestion, and become more marked as 

 digestion proceeds. Their effect is to bring the 

 whole of the food in close contact with every 

 particle of pyloric mucous membrane and to 

 cause a thorough mixture of food and gastric 

 juice. At varying periods after a meal, accord- 

 ing to the nature of the food taken, the arrival 

 of one of these waves of contraction at the 

 pylorus causes a relaxation of the orifice, and a few cubic centimetres 

 of gastric contents are squirted into the first part of the duodenum. 



697 



FIG. 337. Shadow sketches 

 of the outlines of the 

 stomach of a cat, imme- 

 diately after a meal (11.0), 

 at various intervals after- 

 wards(12.0,2.0,3.30,4.30). 



c, situation of oesophageal 

 opening ; yz, ' transverse 

 band ' ; wx, junction of 

 cardiac and pyloric por 

 tions. (W. B. CANNON.) 



