THE CEREBRO-SPINAL SYSTEM OP NERVES. 687 



inward by the vagus. One of the widest tracts in the body 

 for. afferent impulses giving rise to reflexes is connected with 

 the nerve-centers by the branches of this nerve, as evidenced by 

 the many well-known phenomena of this character referable to 

 the pharynx, larynx, lungs, stomach, etc., as vomiting, sneez- 

 ing, coughing,' etc. This nerve plays some important part in 

 secretion, no doubt, but what that is has not been as yet well 

 established. 



Pathological. — Section of both vagi, as might be expected, 

 leads to death, which may take place from a combination of 

 pathological changes, the factors in which vary a good deal 

 with the class Of animals the subject of experiment. Thus, the 

 heart in some animals (dog) beats with great rapidity and tends 

 to exhaust itself. In birds especially is fatty degeneration of 

 heart, stomach, intestines, etc., liable to follow. 



Paralysis of the muscles of the larynx renders breathing 

 laborious. From loss of sensibility food accumulates in the 

 pharynx and finds its way iuto the larynx, favoring, if not 

 actually exciting, inflammation of the air-passages. 



But it is not to be forgotten that upon the views we advocate 

 as to the constant influence of the nervous system over all parts 

 of the bodily metabolism, it is plain that after section of the 

 trunk of a nerve with fibers of such wide distribution and va- 

 ried functions the most profound changes in so-called nutrition 

 must be expected, as well as the more obvious functional de- 

 rangements ; or, to put it otherwise, the results that follow are 

 in themselves evidence of the strongest kind for the doctrine of 

 a constant neuro-metabolic influence which we advocate. It 

 ■will not be forgotten that the depressor nerve, which exerts re- 

 flexly so important an influence over blood-pressure, is itself 

 derived from the vagus. 



The Spinal Accessory or Eleventh BTerve.— This nerve arises 

 from the medulla oblongata somewhat far back, and from the 

 spinal cord in the region of the flfth to the seventh vertebra. 

 Leaving the lateral columns, its fibers run upward between the, 

 denticulate ligament and the posterior roots of the spinal nerve 

 to enter the cranial cavity, which as they issue from the cra- 

 nium subdivide into two bundles, one of which unites with the 

 vagus, while the other pursues an independent course to reach 

 the sterno-mastoid and trapezius muscles, to which they furnish 

 the motor supply; so that it may be considered functionally 

 equivalent to the anterior root of a spinal nerve. The portion 



