MOVEMENTS OF THE INTESTINES 819 



contraction, i.e. one which involves contraction of the gut above 

 the food mass and relaxation of the gut below. If a balloon be 

 inserted in the lumen of the exposed gut, it will be found that pinching 



3 AO 



C>>B 



3 n v_/ J \ J \ J \ I x -^ ' U 



4 obooooo 



FIG. 341. Diagram of the ' segmentation ' (pendular) movements of the intes- 

 tines as observed by the Rontgen rays, after administration of bismuth. 

 (CANNON.) 



1. A continuous column, intestinal movements being absent. 2. The 

 column broken up into segments. 3. Five seconds later, each segment 

 divided into two, the halves joining the corresponding halves of adjacent 

 segments. 4. Condition (2) repeated five seconds later. 



the gut above the balloon causes an immediate relaxation of the 

 muscular wall in the neighbourhood of the balloon. This inhibitory 

 influence of the local stimulus may extend as much as two feet down 

 the intestine towards the ileocaecal valve. On the other hand, 



FIG. 342 Intestinal contractions (balloon method). In this dog all the abdo- 

 minal ganglia had been excised, and both vagi cut. Showing propagated 

 effects of mechanical stimulation, above and below the balloon. 

 (1) pinch above, (2) pinch below, (3) pinch below balloon. 



pinching the gut half an inch below the situation of the baUoon causes 

 a strong continued contraction to occur at the balloon itself (Fig. 342). 

 Stimulation at any portion of the gut causes contraction above 

 the point of stimulus and relaxation below the point of stimulus 

 (the ' law of the intestines '). The same effect is produced by 

 introduction of a bolus of food, especially if it be large or have 



