550 



SUMNER L. KOCH 



5 micra. Sections of a pyridiiie-silvcr preparation of the IXth 

 nerve of the cat, just proximal to the superior ganghon, showed 

 few large myelinated fibers 12 to 15 micra in diameter", many 

 small myelinated fibers, 3 to 6 micra, and a few unmyelinated 

 fibers. Sections of the IXth nerve of the rabbit showed a 

 similar picture. No connections with the sympathetic system 

 distal to the petrous ganglion were seen in any preparations. 



The bulbar rootlets of the accessory nerve are composed chiefly 

 of small myelinated fibers 2 to 5 micra in diameter. The spinal 



Fig. 5 From a section of the hypoglossal nerve of the dog, showing bundles 

 of darkly stained unmyelinated fibers joining the nerve. Pyridine-silver. Ocu. 

 0, Obj. 8. 



portion was composed of large and small myelinated fibers in 

 about the ratio of five to one. The majority of the large fibers 

 were 9 to 12 micra in diameter, with a few larger fibers of 14 to 

 16 micra; the small fibers 2 to 5 micra. In several preparations 

 at the point of its separation from the vagus, a few unmyelinated 

 fibers could be seen in the ramus externus, arranged in three or 

 four groups. Bundles of sympathetic fibers could be traced for 

 some distance in the sheath of the Xlth nerve, finally entering 

 it (fig. 3) and forming well marked clusters of fibers within its 



