MOVEMENTS OF THE INTESTINE 289 



tion. If now the splanchnics be cut, after some fifteen to twenty minutes 

 the intestine begins to move as above described (page 288). These results 

 show that the splanchnic under normal circumstances exercises a tonic re- 

 straining influence on the intestinal musculature. This inhibition appears 

 still more clearly if the splanchnic be stimulated while the intestinal move- 

 ments are in progress: the contractions immediately cease, and the tonus of 

 the wall decreases. 



Since the splanchnic conveys vasoconstrictor fibers for the intestinal vessels, 

 it might be supposed that the cause of the intestinal calm following stimulation 

 is to be found not in a specific inhibition, but in the resulting anaemia. But it 

 is to be observed against this hypothesis that the necessary parallelism is want- 

 ing between the two phenomena. The increase in blood pressure is sometimes 

 very considerable while the inhibition at the same time is only slight. The 

 inhibitory effect is not evident at the first stimulation of the splanchnic and 

 decreases with each succeeding stimulation, while the blood pressure goes on 

 increasing. And finally, inhibition of the intestinal movements can be demon- 

 strated even after the circulation is completely stopped by extirpation of the 

 heart. 



Many authors agree also that the vagus is a motor nerve for the intestine, 

 while others have obtained no effect at all on the intestine by vagus stimula- 

 tion. It is possible that this failure is due to the inhibiting influence of the 

 splanchnics, wherefore it is recommended to sever the splanchnics first in such 

 experiments (Jacobi). In order to prevent disturbances to the circulation 

 resulting from stoppage of the heart by stimulation of the vagus, either the 

 stimulation must be applied below the cardiac branches, or the latter must 

 be paralyzed by atropine. Under such circumstances Bayliss and Starling 

 and also Bunch have observed as the typical result of vagus stimulation, first 

 a brief inhibition and then a contraction which be- 

 comes stronger and stronger. It would thus seem 

 that the vagus contains both inhibitory and motor 

 fibers, the former with a short and the latter with a 

 long latent period. In the opinion of some authors 

 these effects extend to both muscle layers; in the 

 opinion of others the vagus inhibits the longi- 

 tudinal fibers and excites the circular fibers (Ehrman, 

 Winkler). 



As soon as the intestinal contents pass into the FlG - 1 17. Schema iiius- 

 large intestine a powerful contraction of the c^cum 

 and colon can be seen with the Eontgen rays (Can- after Cannon, 

 non) to take place, and the contents are moved 



toward the rectum. A moment later peristalsis is succeeded by antiperistalsis, 

 and the latter in rhythmical order now represents the usual form of move- 

 ment of the ascending and transverse colon. Finally, however, it ceases, the 

 contents collect in the transverse colon and are driven into the descending 

 colon. 



As for the innervation of the large intestine and rectum, Bayliss and Star- 

 ling have shown that the former deprived of its nerves acts just as .does the small 

 intestine under the same circumstances. The vagus is said to contain motor 



