1 1 2 THE IN VOL UNTAR Y NER VO US S YSTEM 



both she and Kuntz state that all the cells which enter into the 

 intestine belong to this vagal system, and none reach it from the 

 sympathetic system ; that is to say, the cells of Auerbach's 

 plexus are all vagal cells. The embryological evidence thus 

 confirms the physiological, for the injection of nicotine, which 

 prevents the action of the vagus nerves, both in the heart and 

 in the gut, but does not prevent the action of the sympathetic 

 nerves in either case, is proof that vagal cells alone exist in both 

 the heart and the gut. 



There is to my mind a difficulty in accepting the 'evidence 

 given by both Kuntz and His as a complete proof of the wander- 

 ing out of vagus motor cells to the periphery, for in both cases 

 free nerve cells in the shape of neuroblasts are said to move inde- 

 pendently peripheral-wards and afterwards to become connected 

 with the central nervous system and to send fibres to the muscles 

 and gland cells. Such a conception seems to me so highly im- 

 probable as to throw some doubt on the soundness of the observa- 

 tions. Still if we take simply the observations of these authors 

 and leave out of account their statement that the cells in question 

 are free wandering neuroblasts, it could then be said that the re- 

 lative positions of these vagus nerve cells with respect to the central 

 nervous system on the one side, and the peripheral organ on the 

 other, does vary in the course of development in the direction of 

 a more and more peripheral situation. 



The evidence already given leads to the conclusion that the 

 nerve fibres, which arise from the motor or inhibitory cells of the 

 involuntary nervous system, terminate directly in their correspond- 

 ing musculature, possibly by means of a fine plexus or network 

 of nerve fibres immediately embracing those muscles, and do not 

 terminate in any other nerve cells before reaching the muscle. 

 From this it follows that in such cases as the heart and 

 small intestine, where the inhibitory cells belong to the sym- 

 pathetic system, and are situated outside the organ, there are 

 no cells belonging to that system situated in the organ, and 

 therefore that all nerve cells found in the heart or small intestine 

 belong to the vagus system. 



Those observers who look upon both heart and intestine as 

 possessing an intrinsic nervous system complete in itself, and 

 independent of the central nervous system, consider that this 

 system is connected to the central nervous system by nerve 



