THE N. GLOSSOPHARYNGEUS. 99 



central connections are unknown. The largest root fibres 

 are fully 12 micra in diameter and the average size of all 

 of the fibres is about 8 micra, while the smallest fibres are 

 scarcely 3 micra. 



About two-thirds of the distance between the exit of 

 the r. lateralis and its ganglion it receives a small bundle 

 of fibres (about 20 in number) from the IX root. This 

 little twig is of great interest and has been carefully 

 worked out in a number of specimens. The fibres are of 

 small or medium size, considerably smaller than the later- 

 alis fibres, but larger than the average communis fibres, 

 the largest ones being 3 or 4 micra in diameter. After 

 leaving the IX root, they pass dorsad and caudad along 

 the mesal face of the ramulus ampullae posterioris and 

 close to the medulla oblongata to enter the ventro-lateral 

 surface of the r. lateralis. On the opposite side of this 

 specimen and in two others they run first up the mesal 

 side of the r. lateralis, then laterally around the dorsal 

 side of this ramus, finally to enter it in the same position 

 as before described. 



Neither these nor the other fine fibres of the lateralis 

 root could be separately traced through the ganglion. 

 This ganglion contains medium -sized ganglion cells, much 

 larger than those of the VIII ganglion, but smaller than 

 the largest of the vagus ganglion. There are a few larger 

 cells among them. A considerable number of finer fibres 

 leave the lateralis ganglion which are presumably related 

 to those which enter it. Their further courses will be 

 described below. 



II. — The N. Glossopharyngeus. 



The organization of the IX nerve is exceptionally 

 simple. Its peripheral area is limited to one demibranch. 

 It lacks the r. supra-temporalis, which is present in 



