GIL XXXVII.] 



INTESTINAL MOVEMENTS 



561 



75 per cent, of water, is not finally attained until they arrive in the 

 pelvic colon, where they are retained until defaecation takes place. 



Peristalsis in the colon occurs much more slowly than in the 

 small intestine, and the accompanying diagram gives the time in 

 hours after the taking of a bismuth meal that the shadow appears at 

 various points in man. It reaches the hepatic flexure of the colon 

 about two hours after it appears in the caecum ; another two hours 

 approximately brings it to the splenic flexure (nine hours after the 

 meal). The distance from the caecum to the splenic flexure is 2 

 feet; the contents take as long to travel this distance as the 

 contents of the small intestine take to travel 22 J feet, that is, from 



Hepatic flexure - 



Ascending colon - 



Cuecum - 



Pelvic colon - 



Pelvis - 



Splenic flexure. 



Descending 

 colon. 



Umbilicus. 



-\ - - Iliac colon. 



Rectum. 



FIG. 369. Semi-diagrammatic view of the large intestine; the figures give in hours the average times 

 after taking a meal that its debris reaches the various parts. (Hertz.) This diagram shows the 

 transverse colon in a higher position than it occupies when the man is erect, and rather higher 

 than the average even in the horizontal position. 



the pylorus to the caecum. A further two hours is occupied in the 

 journey along the descending colon, and six hours more brings it to 

 the end of the pelvic colon which leads at an angle into the rectum. 

 The total journey from the caecum to this point occupies thirteen and 

 a half hours. These times were confirmed by auscultation or listening 

 over various parts of the abdomen; the gurgling and splashing 

 sounds made by the arrival of food-material are distinctly audible. 

 These observations were made in the daytime ; during sleep the rate 

 of progress may be slower. 



Some observers have stated that retro-peristalsis occurs in the 

 colon, especially in its ascending portion. Waves of this kind would 



2 N 



