378 DIGESTION. 



to thoroughly incorporate the food with the digestive fluids 

 and expose those parts which have been completely liquefied 

 to the absorbent action of the mucous membrane. 



Though the mechanism of the propulsive movements of 

 the intestine may be studied in living animals after opening 

 the abdomen, or, better still, in animals just killed, the 

 movements thus observed do not entirely correspond with 

 those which take place under natural conditions. In vivi- 

 sections, no movements are observed at first ; but soon after 

 exposure of the parts, nearly the whole intestine moves like a 

 mass of worms. In the normal process of digestion, the 

 movements are never so general nor so active; they take 

 place more regularly and consecutively in those portions 

 in which the contents are most abundant, and the move- 

 ments are intermittent, being interrupted by long inter- 

 vals of repose. In Prof. Busch's case of intestinal fistula, 

 there existed a large ventral hernia, the coverings of which 

 were so thin that the peristaltic movements could be read- 

 ily observed. In this case, the general character of the move- 

 ments corresponded with what has been observed in the in- 

 ferior animals. It was noted that the movements were not 

 continuous, and that there were often intervals of rest for 

 more than a quarter of an hour. It was also observed that 

 the movements, as indicated by flow of chymous matter 

 from the upper end of the intestine, were intermitted with 

 considerable regularity during part of the night. After ten 

 or eleven p. M., no discharge took place for six or seven hours. 

 Antiperistaltic movements, producing discharge of matters 

 which had been introduced into the lower end of the intes- 

 tine, were frequently observed. 



As far as has been ascertained by observations upon the 

 human subject and warm-blooded animals, the regular intes- 

 tinal movements are excited by the passage of alimentary 

 matter from the stomach through the tube during the natu- 

 ral process of digestion. By a very slow and gradual action 



1 Loc. cit. 



