250 



PHYSIOLOGY 



CHAP. 



owing to paralysis of the vaso-constrictor fibres. Under normal 

 conditions, therefore, the splanchnics have a restraining influence 

 on the intestinal movements, which ceases after section of these 

 nerves. 



This conclusion is strengthened by the result of stimulating 

 the peripheral end of the cut splanchnic immediately below the 

 diaphragm, after inserting a small exploring balloon into a loop of 

 intestine. As shown by Fig. 84, after a somewhat prolonged latent 

 period, there is a complete cessation of the rhythmic movements 

 with marked relaxation of the intestinal wall. When stimulation 

 ceases, there is a long after-effect, followed by gradual return of 

 the rhythmical movements, and increased tone of the wall. 



Fio. 85. Intestinal contractions. Balloon method. (Bayliss and Starling.) Stimulation of right 

 vagus in neck of dog, after atropin. /, inhibition ; CP, carotid pressure ; E, length of 

 excitation. 



The influence of the vagus nerves on the movements of the 

 intestines has also been the subject of not a little controversy. E. 

 Weber, Budge, Ludwig and Kupfer, Engelmann with many others, 

 maintained that they have a motor action, and, notwithstanding 

 some differences of detail, it might be concluded from their results 

 that this was the exclusive effect. Bunch, however, observed in 

 certain rare cases out of a large number of experiments, that the 

 stimulation of the vagus may, like that of the splanchnic, produce 

 inhibition. Ott (1904), again, expressly declared that peripheral 

 stimulation of the vagi has an inhibitory effect. This harmonises 

 with the conclusions of Bayliss and Starling, which may be briefly 

 summarised. 



According to these authors, no tonic influence on the intestines, 

 such as is apparently exercised by the splanchnic, can be attributed 

 to the vagus. Generally speaking, division of the vagi has no 



