iv DIGESTION IN THE INTESTINE 239 



It is evident that the character of the intestinal movements 

 differs from that of the oesophageal ; contraction of the intestine 

 from a local stimulus may spread under certain conditions in both 

 directions, although normally it progresses from the pylorus 

 towards the ileo-caecal valve ; the contraction of the oesophagus, 

 on the contrary, is always propagated from above downwards, in 

 the direction of the cardia. Another essential difference between 

 the movements of the oesophagus and those of the intestine 

 appears from the fact that the former continue to spread from 

 above downwards after transverse section of the gullet (Mosso) ; 

 the latter, on the contrary, are arrested at the edge of the section. 

 These, then, are true peristaltic motions, propagated through the 

 continuity of the tissue ; the movements of the oesophagus, on the 

 contrary, are (as we have seen) always propagated reflexly by 

 means of the cerebrospinal centres, and may therefore be termed 

 pseudo-peristaltic. 



Conflicting opinions are held by various experimenters in 

 regard to the influence of the vascular and circulatory conditions, 

 active hyperaemia, venous congestion, ischaemia, and asphyxia, 

 upon the intestinal movements. Nasse, S. Mayer, von Basch 

 contradicted Schiff's statement that obstruction of the aorta evokes 

 or strengthens intestinal contractions ; they observed arrest for a 

 time, after which the movements returned with increased vigour. 

 Betz, van Braam-Houckgeest, and Mall, however, found that 

 anaemia inhibited all movements of the intestines. In asphyxia, 

 on the contrary, Mayer and von Basch found increase of the 

 intestinal movements. 



The effect of heat on the movements of the gut is also interest- 

 ing, as shown by Claude Bernard's experiments. He placed the 

 quiescent intestine of a rabbit in a box with glass walls, at a 

 low temperature. As soon as a current of warm air was passed 

 through the box, visceral movements were exhibited, even before 

 the thermometer registered a rise of temperature. Horvath, too, 

 saw that the intestines of dogs, cats, rabbits, frogs, and guinea-pigs 

 remained quiescent between and 19 C., and began to move above 

 that temperature. 



Bayliss and Starling (1899), by means of the graphic method, 

 confirmed the statement that obstruction of the aorta arrests the 

 movements of the intestines. They inserted a balloon fastened 

 to a tube, with a recording apparatus, through a small longitudinal 

 incision in the loop, closing the slit with stitches, one of which is 

 taken round the tube. The capsule is distended with air under a 

 pressure of about 10 cm. water, after which the loop is returned 

 to the abdominal cavity. Under these conditions the intestine is 

 seen to be the seat of continuous rhythmic contractions, which are 

 fairly regular, and sweep down the intestine at a low rate. As 

 shown in Fig. 77, instantaneous occlusion of the aorta produces 



