OF THE ALIMENTARY CANAL 103 



bowel contents which may be pushed through the 

 junction will start a fresh wave of peristalsis on the 

 distal side of the union. Though the movements are 

 not dependent on nerves, they can be influenced by 

 the central nervous system, as every one knows who 

 has suffered from an attack of " exam-funk diarrhoea." 

 The vagus stimulates peristaltic movements ; the 

 splanchnic nerves inhibit them. In the small intestine 

 peristalsis is normally only from stomach to colon, 

 and a bismuth meal makes the journey in about 

 four hours. There is a sort of pendulum swing- 

 swang of whole loops of bowel going on at the same 

 time. In the large intestine the conditions are very 

 different, and have an important bearing on certain 

 operative procedures. The movements in man may 

 be studied by skiagraphy after bismuth meals or 

 bismuth enemata, and by observations on patients 

 who have suffered various forms of colostomy, 

 ileosigmoidostomy, and exclusion operations. When 

 the abdomen is opened, intestinal peristalsis soon 

 comes to an end on account of the rapid loss of CO.j, 

 from its walls. Sahne solution saturated with CO^ 

 restores the movements to normal. 



Hertz has recently drawn attention to the functions 

 of the ileocaecal sphincter, which guards the passage 

 through the ileocsecal valve, and delays the entry 

 of the contents of the small intestine until time has 

 been allowed for proper absorption of food-stuffs. 

 Skiagraphy after bismuth meals shows that the last 

 few inches of the ileum remain full for four or five 

 hours after the stomach is empty. In cases of 

 chronic appendicitis this sphincter may remain 



