THE EVACUATION OF FECES. 283 



The small intestine exhibits peristaltic movements in a classical 

 manner. The progressive constriction of the canal, which forces the 

 contents before it, always passes from above downward. After death 

 and on exposure of the coils of intestine to the air, peristalsis is often 

 seen to develop in several parts of the intestine at the same time, and as a 

 result the intestinal loops acquire the appearance of a mass of crawling 

 worms. In addition to these movements, pendulum-like movements of 

 the intestine also occur, by which the contents are moved some distance 

 first in one direction and then in the other. The advance of new intestinal 

 contents and the resulting increased distention of the tube due to solid 

 contents or gas causes renewed movement. 



The large intestine exhibits less active and less extensive move- 

 ments. When the abdominal walls are thin, or in the sac of a hernia, 

 peristalsis may be felt and even seen. Herbivora exhibit more active 

 peristalsis than carnivora. Perhaps the transmission of peristalsis takes 

 place directly through the musculature, as in the heart and the ureter. 

 The ileo-cecal valve, as a rule, does not permit the usually more con- 

 sistent contents of the large intestine to pass back into the small intes- 

 tine. During sleep, at night, the movements of the stomach and the 

 intestines cease. 



If fluid material is gradually introduced into the rectum from a height of 

 one meter of water-pressure through an intestinal tube, it may pass upward through 

 the ileo-cecal valve into the small intestine, and, with great care, it may reach 

 the stomach and esophagus, and even escape from the mouth and nose. In this 

 way the entire intestinal tract in the living subject can be irrigated, and with cura- 

 tive results ; as, for instance, in cases of cholera (i or 2 per cent, solution of 

 tannic acid in 7.5 per cent, solution of sodium chlorid). Eight or nine liters are 

 sufficient to fill the entire alimentary canal. 



A crystal of sodium chlorid applied externally to the intestine causes con- 

 traction at that point, with upward peristalsis, while potassium chlorid induces 

 only local contraction. Particles saturated with sodium-chlorid solution and in- 

 troduced into the rectum are carried upward, in part even to the stomach, through 

 the mediation 'of nervous irritation, perhaps of the muscularis mucosae. 



Pathological. -If an inflammatory or catarrhal condition of the intestinal 

 mucous membrane develops rapidly in consequence of an acute inflammatory 

 irritation, contractions of the inflamed portion, at first marked, occur in the full 

 intestine. When the affected portion has been emptied the movements are no 

 longer more marked than normal. If further contents reach the inflamed portion, 

 the peristaltic downward movement takes place more rapidly than normal and 

 diarrhea results. At times a greatly contracted piece of the intestine is pushed 

 into a neighboring portion (invagination, intussusception). Reduction in the 

 bodily temperature is followed by a decrease in the peristalsis. 



That antiperistalsis, that is a movement upward toward the stomach, occurs 

 was formerly considered proved by the appearance of fecal vomiting in connection 

 with intestinal obstruction due to stenosis in human beings with occlusion of the 

 bowel. The investigations of Nothnagel, however, throw doubt upon this con- 

 clusion, as he failed to observe effective antiperistalsis after artificial occlusion of 

 the bowel. The fecal odor of the vomited matter may also depend upon its pro- 

 longed sojourn in the duodenum, whence, as the well-known bilious vomiting 

 shows, ingesta may be returned into the stomach. 



THE EVACUATION OF FECES (DEFECATION). 



The contents of the intestine remain in the small intestine about 

 three hours, and for a further twelve hours in the large intestine, where 

 they become inspissated, and in the lower portion formed into the 

 fecal mass. Through the peristaltic movement, the feces are forced 

 onward to a point somewhat above that portion of the rectum which 



