50 



for the practice of end-to-end anastomosis of the 

 intestines, any 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 controlled 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. 



The rectum is of course under direct control of 

 the centre near the tip of the spinal cord, the motor 

 path being the pelvic visceral nerves from the second 

 to the fifth sacral roots ; the sympathetic system 

 also supplies the rectum. The physiology of defeca- 

 tion is well known, and need not detain us. 



In the caecum and the ascending, transverse, 

 descending, and pelvic portions of the colon, however, 

 the motor functions are involuntary, as in the small 

 intestine, but with a striking difference. In the 

 small intestine antiperistalsis, that is, peristalsis in 



