466 DIGESTION 



(2) as a swift movement called the peristaltic rush, which sweeps with- 

 out pause for much longer distances along the canal. 



Further analysis of the peristaltic -wave can readily be made by the 

 balloon method (Fig. 162). If the gut is pinched above the balloon, a 

 marked relaxation occurs over it, and this relaxation extends for about 

 two feet down the intestine. If, on the other hand, the gut is pinched 

 a little below the situation of the balloon, a long-continued contraction 

 occurs over the latter. The conclusion that we may draw from this result 

 is that the stimulation of the gut causes contraction, above the point of 

 the stimulus and relaxation below, this being known as ''the law of the 

 intestine" (Bayliss and Starling). We have seen that it applies also in 

 the case of the cardiac and pyloric sphincters. 



Fig. 162. Intestinal contractions (balloon method) after excision of the abdominal ganglia and 

 section of both vagi. Mechanical stimulation above (/) and below (2) the balloon causes relaxa- 

 tion and contraction respectively. (From Starling.) 



THE PHYSIOLOGIC NATURE OF THE RHYTHMIC AND PERISTALTIC MOVEMENTS 



Interesting information in this connection has been gained by obser- 

 vation of the behavior of the movements after the application of drugs 

 to the gut or after cutting the nerve supply. The rhythmic movements 

 are not affected by the application of nicotine or cocaine. Since these 

 drugs paralyze nervous structures it has been concluded that the rhythmic 

 movements are myogenic in origin. The question is not a settled one, 

 however, for it has been found by Magnus that, although strips of the 

 longitudinal muscle, isolated in oxygenated saline solution, will continue 

 to beat, they do not do so if the adherent Auerbach's plexus of nerves 

 is stripped off from them. The nature of the peristaltic contractions is 

 more definite; they must clearly depend upon a local nervous struc- 

 ture, since they are paralyzed by the application to the gut of cocaine or 

 nicotine. This local nervous system no doubt also resides in Auerbach's 

 plexus, which must therefore be considered as complex enough to be (see 



