THE RHYTHMIC AND PERISTALTIC MOVEMENTS in 



travelled out from the central nervous system to reach their des- 

 tination. Certainly, as far as the sympathetic is concerned, the 

 cells were originally in the central nervous system, and all the 

 cases of reflex action described in this system have been shown 

 by Langley and Anderson to be of the nature of axon reflexes. 

 It does not however follow that the cranial and sacral out- 

 flows have been formed in precisely the same way as the sym- 

 pathetic. Their cells tend to be scattered in the meshes of a nerve 

 plexus rather than grouped in definite ganglia, as in the latter 

 case, and their systems behave quite differently to adrenaline. 



In Chapter I, I have taken it for granted that the 

 motor cells connected with the connector nerve fibres of the 

 vagus and pelvic nerves have travelled out from the central 

 nervous system similarly to the sympathetic cells. The evidence 

 given by Onodi was purely morphological, and had nothing 

 to do with the function of the cells. According to this author a 

 mass of cells exists in close contiguity to the cells of the posterior 

 root ganglion throughout the spinal cord, which ultimately 

 separate out and become peripheral. There is no reason to sup- 

 pose that the same procedure does not take place in the sacral 

 region, and thus form the peripheral cells belonging to the pelvic 

 nerve, but as far as I know this has not as yet been shown to be 

 the case. 



There is a considerable amount of evidence that the nerve 

 cells of the vagus system found in the heart and alimentary canal 

 were originally in the central nervous system, and have travelled 

 out to reach their destination. In the first place His junior has 

 shown that the cells of the heart at first are not in the heart but 

 in the course of development " travel " into it ; he looks upon 

 them as including sympathetic cells as well as vagus cells, and 

 his evidence has been largely accepted as proof that these cardiac 

 cells were originally situated more centrally, and have travelled 

 farther away from the central nervous system during development. 

 The evidence given by Kuntz and by Miss Abel both con- 

 firm the observations of His junior with respect to the travel- 

 ling of the vagus nerve cells into the heart, and both deny any 

 evidence of any such inclusion of nerve cells from the sympathetic 

 system. Further, Miss Abel states that the vagal wandering cells 

 are seen at first close against the root ganglion of the nerve, from 

 whence they can be traced to the heart and the intestine, and 



