692 SYMPATHETIC AND OTHER SYSTEMS OF NERVES. 



vaso-dilator fibres of the chorda tympani have become connected with 

 vaso-constrictor nerve cells of the superior cervical ganglion, and have 

 in consequence ceased to be vaso-dilator and become vaso-constrictor 

 nerve fibres. The experiments point to the conclusion that any pre- 

 ganglionic fibre in the body is capable of forming functional connection 

 with any nerve cell of the sympathetic type wherever found. 



General Comparison of the Cranial, Sacral, and Sympathetic 



Autonomic Systems. 



We have seen that the sympathetic system sends post-ganglionic 

 fibres to the whole of the skin of the body. This distribution is in 

 striking contrast to that of the cranial and the sacral system, which send 

 no fibres to the skin, or only such as spread out into it from an adjoining 

 mucous membrane. In this point, then, the cranial and sacral autonomic 

 systems resemble one another and differ from the sympathetic system. 



As I have said earlier, a comparison of the distribution of the post- 

 ganglionic fibres shows, if we take the matter broadly, that while the 

 sympathetic system supplies the whole of the body, the cranial autonomic 

 system supplies (with the exception of the eye) certain structures at the 

 anterior end of the alimentary canal, and the sacral system supplies 

 certain structures at the posterior end of the alimentary canal. 



We may put the facts, so far as we know them, in a tabular form. 

 Some are still in dispute. 



Autonomic structures having a double nervous supply, sym- 

 pathetic and cranial or sympathetic and sacral. — The muscular coats 

 of the whole of the gut. 



The glands opening into the gut, namely, salivary glands, gastric glands, 

 pancreas, probably liver. 



Parts at the mouth end of the gut ; blood vessels of mucous membrane of 

 mouth and pharynx ; heart ; unstriated muscle of lungs. 



Parts at anal end of gut ; blood vessels of rectum and anus ; blood 

 vessels and unstriated muscle of external generative organs ; muscle coats of 

 bladder. 



Autonomic structures having a single nervous supply only, 

 namely, from the sympathetic system. — The blood vessels, glands, and 

 unstriated muscle of skin. 



The blood vessels of the portion of the gut between the mouth and rectum, 

 and of the glands opening into this portion ; possibly the spleen. 



The internal generative organs. 



It has been asserted 1 that in the gut, the internal generative organs, 

 and the bladder, there is an essential difference between the character 

 of the nerve fibres received from the sympathetic and of those received 

 from the vagus or from the pelvic nerve, of such sort that the sympathetic 

 fibres cause contraction of the circular muscular coat and inhibition of 

 the longitudinal muscular coat ; whilst the vagus and pelvic nerve cause 

 inhibition of the circular muscular coat and contraction of the longitud- 

 inal muscular coat. A considerable number of observations which have 

 been made on the several organs, show that this is not the case. And 



1 v. Basch and Hofmann, Med. Jahrb., Wien, 1877, S. 465 (on uterus) ; Fellner, ibid., 

 1883, S. 571 (on rectum) ; and Centralbl. f. d. med. Wissensch., Berlin, 1887, S. 258 (on 

 uterus) ; Ehrmann, Med. Jahrb., Wien, 1885, S. Ill (on small intestine) ; v. Zeissl, 

 Arch./, d. ges. Physiol., Bonn, 1893, Bd. liii. S. 560 (on bladder). 



