58 M. R. CHASE AND S. W. RANSON 



nating. These rootlets contain few, if any, non-medullated 

 fibers. The rootlets of the vagus are of two kinds. Those of 

 Type I, probably efferent in function, are composed of many 

 fine and fewer coarse medullated fibers. The medullated fibers 

 are evenly distributed through these rootlets and there are few, 

 if any, non-medullated fibers. The vagus rootlets of Type II, 

 probably afferent in function, contain large and medium-sized 

 medullated fibers and fewer small ones. The medullated fibers 

 are widely separated by enormous numbers of fine, non-medul- 

 lated axons. 



2. At the level of the upper part of the jugular ganglion the 

 vagus and accessory nerves are fused into a common trunk in 

 which it is possible to distinguish three areas derived respectively 

 from the spinal root of the accessory, the bulbar roots of the ac- 

 cessory, and the roots of the vagus. Each area presents the same 

 histological characteristics as the corresponding roots, except that 

 the fibers from the two types of vagus rootlets are now intimately 

 mingled. 



3. Below the level of the jugular ganglion the spinal part of 

 the accessory, which has maintained its independence through- 

 out the common vagus-accessory trunk, now leaves it as the 

 external branch of the accessory nerve. 



4. The bulbar fibers of the accessory become intimately mingled 

 with the vagus fibers at or above the level of the nodose ganglion. 

 The so-called internal branch of the accessory does not exist as 

 a separate nerve, but is only a fascicle of the common vagus- 

 accessory trunk. 



5. While the vagus and sympathetic nerves are intimately 

 associated in the neck, it is clear that no considerable part of the 

 non-medullated fibers of the vagus are of sympathetic origin. 



6. The pharyngeal branch is composed for the most part of 

 large medullated fibers, but also contains a considerable number 

 of medium and small-sized medullated fibers. It contains few, 

 if any, non-medullated axons. 



7. The superior laryngeal branch contains large, medium and 

 small-sized medullated fibers, with the medium and small ones 

 predominating. It contains non-medullated fibers in consider- 



