188 ALBERT KUNTZ 



presence of food in the digestive tube and that their impulses are 

 transmitted to motor neurones with which they form physiolog- 

 ical contact. The axones of some of these 'receptive' neurones 

 in the submucous plexus may be traced into the commissures 

 connecting the ganglia of the submucous plexus or into those 

 connecting this plexus with the myenteric plexus. Furthermore, 

 dendrites as well as axones extend from the myenteric plexus into 

 or through the submucous plexus. The anatomical relationships 

 of the sympathetic neurones in the myenteric and the submucous 

 plexuses, doubtless, are such as to provide both shorter and longer 

 reflex arcs involving both sensory and motor neurones. We may, 

 therefore, conceive of sympathetic reflexes which are strictly local 

 in character while others pass through several or even many gan- 

 glia and thus transmit impulses from one level of the digestive 

 tube to another separated from it by an appreciable interval. 

 Still other reflexes stimulated in the same manner may involve 

 centers in the prevertebral sympathetic plexuses or in the sympa- 

 thetic trunks. Besides these types of reflexes, doubtless, sympa- 

 thetic reflexes occur which involve centers in the spinal cord and 

 the brain. The fact that the motor activities of the digestive 

 tube may be carried on more or less normally when the paths for 

 these longer reflexes are severed, however, seems to indicate that 

 the nonnal nervous control of the digestive functions is exercised 

 primarily by the local sympathetic mechanism. 



The schematic diagram in the accompanying figure (fig. 5) is 

 introduced to illustrate some of the probable relationships of the 

 sympathetic neurones in the myenteric and the submucous plex- 

 uses. The motor neurones in the diagram are stippled while 

 those which are supposedly sensory appear solid. 



That all the types of reflexes described above actually occur in 

 the sympathetic nervous system has not been demonstrated 

 experimentally. As has been pointed out, however, the orienta- 

 tion of the sympathetic neurones in the myenteric and the sub- 

 mucous plexuses and the peripheral distribution of their axones 

 and dendrites is obviously such as would be required by a system 

 of shorter and longer reflex arcs. Therefore, the conclusion that 

 all the types of sympathetic reflexes above described are possible 



