286 DIGESTION. 



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. Antiperistaltic movements, producing discharge of matters which had been 

 introduced into the lower end of the intestine, were frequently observed. 



As far as has been ascertained by observations upon the human subject and warm- 

 blooded animals, the regular intestinal movements are excited by the passage of alimen- 

 tary matter from the stomach through the tube during the natural process of digestion. 

 By a very slow and gradual action of the muscular coat of the intestine, its contents are 

 passed along, occasionally the action being reversed for a time, until the indigestible 

 residue, mixed with a certain quantity of intestinal secretion, more or less modified, is 

 discharged gradually into the caput coli. These movements are apparently not continu- 

 ous, and they depend somewhat upon the quantity of matter contained in different parts of 

 the intestinal tract. If we are to judge from the movements in the inferior animals after 

 the abdomen has been opened, the intestines are constantly changing their position, prin- 

 cipally by the action of their longitudinal muscular fibres, so that the force of gravity does 

 not oppose the on \vard passage of their contents as much as if the relative position of the 

 parts were constant. There are no definite observations concerning the relative activity 

 of the peristaltic movements in different portions of the intestine ; but, from the fact that 

 the jejunum is constantly found empty, while the ileum contains a considerable quantity 

 of pultaceous matter, it would seem that the movements must be more vigorous and 

 efficient in the upper portions of the canal. 



The gases which are constantly found in the intestine "have an important mechanical 

 function. They are useful, in the first place, in keeping the canal constantly distended 

 to the proper extent, thus avoiding the liability to disturbances in the circulation and 

 facilitating the passage of the alimentary mass in obedience to the peristaltic contrac- 

 tions. They also support the walls of the intestine and protect these parts against con- 

 cussions in walking, leaping, etc. The gases are useful, likewise, in offering an elastic 

 but resisting mass upon which the compressing action of the abdominal muscles may bs 

 exerted in the acts of straining and expiration. If we could suppose the intestinal tube 

 to be entirely free from gaseous contents, it is evident that the functions above mentioned 

 would be performed imperfectly and with difficulty. 



There can be hardly any question that the normal movements of the intestine are 

 due principally to the impression made upon the mucous membrane by the alimentary 

 matters, to which is added, perhaps, the stimulating action of the bile. It is difficult to 

 determine with accuracy what part the bile plays in the production of these movements, 

 from the fact that the normal action of the intestine is not easily observed. In the case 

 of intestinal fistula so often referred to, when food was introduced into the lower end of 

 the canal, there was at first an abundant evacuation every twenty-four hours ; but sub- 

 sequently it became necessary to use enemeta. As there was no communication between 

 the lower and the upper end of the intestine, this fact is an evidence that the peristaltic 

 movements can take place without the action of the bile. Experiments upon the inferior 

 animals concerning the influence of the bile upon the peristaltic movements are somewhat 

 contradictory. When the abdomen is opened during life, vigorous movements may some- 

 times be excited by pressing bile into the intestine from the gall-bladder; and the same 

 result is occasionally observed when the bile is applied to the peritoneal surface in an 

 animal recently killed. But the various experiments in which the bile has been diverted 

 from the intestine and discharged by a fistula, taking the frequency of the alvine dejec- 

 tions as a test, show that regular peristaltic movements may take place without the in- 

 tervention of the bile. 



The vigorous peristaltic movements which occur soon after death have been explained 

 in various ways. It has been shown that these movements are not due to a lower- 

 ing of the temperature or to exposure of the intestines to the air. The latter fact 

 may be easily verified by killing a rabbit, when vigorous movements may be seen through 



