THE SYMPATHETIC NERVE. 575 



several ganglia. And as with the ganglia of the sympa- 

 thetic and their nerves, so with the medulla oblongata and 

 its nerves distributed to respiratory muscles, if these 

 nerves or the medulla oblongata itself be directly stimu- 

 lated, the movements that follow are convulsive and 

 disorderly ; but if the medulla be stimulated through a 

 centripetal nerve, as when cold is applied to the skin, then 

 the impressions are reflected so as to produce movements 

 which, though they may be very quick and almost con- 

 vulsive, are yet combined in the plan of the proper res- 

 piratory acts. 



Among the ganglia of the sympathetic nerves to which 

 this co-ordination of movements is to be ascribed, must be 

 reckoned, not those alone which are on the principal trunks 

 and branches of the sympathetic external to any organ, 

 but those also which lie in the very substance of the 

 organs ; such as those discovered in the heart by Remak. 

 Those also may be included which have been found in the 

 mesentery close by the intestines, as well as in the sub- 

 mucous tissue of the stomach and intestinal canal (Meiss- 

 ner), and in other parts. The extension of discoveries 

 of such ganglia will probably diminish yet further the 

 number of instances in which the involuntary movements 

 appear to be effected independently of central nervous 

 influence. 



Respecting the influence of the sympathetic nerve in 

 nutrition and secretion, we may refer to the chapters on 

 those processes. 



The influence of the sympathetic nerves on the blood- 

 vessels has been already referred to in the Section on the 

 Arteries. It was stated that the muscular tissue of the 

 blood-vessels were supplied by sympathetic nerve-branches, 

 called from their distribution and function vaso -motor 

 nerves ; and that by these the condition of the vessels with 

 respect to contraction or relaxation, and therefore to the 

 stream of blood which flowed through them in a given 



