1 8 Journal of Comparative Neurology. 



nucleus and seem at first sight to be continuous with the outer 

 ends of the spindle cells which are distributed throughout al- 

 most the whole extent of this nucleus. On closer examination 

 every favorably placed cell appears to have a more deeply 

 stained area at the outer end. This area proves to be not a part 

 of the cell but an enlarged ending of the sensory fiber. This 

 ending is shaped like the bowl of a spoon and overlaps about 

 one-fourth or one-third of the cell from the outer end. In 

 Ahlborn's figure ('83, Fig. 49) there appears a light area at 

 one end of the cell, which probably indicates that in his borax 

 carmine preparations the fiber endings failed to take the stain. 



The cells are quite uniform in size and shape. They meas- 

 ure about 8X32 IJ-, and the club-shaped ending of the fiber is 

 about 7 X 12-14/^. The cells are almost perfect spindles and 

 probably regularly bear processes at each end. The peripheral 

 process is sometimes made out in iron haematoxylin sections 

 and in one case where the cell was impregnated with silver 

 there was a good sized dendrite running nearly parallel with the 

 sensory fiber. From the inner end of the cell arises a neurite 

 of medium thickness which grows larger farther from the cell. 

 All these neurites go ventro-mesad and cross in the ventral 

 raphe. Two conspicuous decussations are formed by bundles 

 of these fibers, while many run singly and do not attract atten- 

 tion. One of the decussations lies a little caudal to the VIII 

 root and was called by AHLBORNthe chiasma of the Mullerian 

 fibers (Fig. 10). The other decussation is formed by fibers 

 coming from cells lying in the extreme anterior end of the lat- 

 eral acusticum nucleus. The fibers pass forward and downward 

 and cross in the ansulate commissure close to the decussation 

 of the III nerve (Figs. 2, 24). All these neurites have in all 

 essential respects the relations of internal arcuate fibers and I 

 believe they are to be classed as such. The whole spindle cell 

 apparatus probably does not exist above the Cyclostomes. 



In GoLGi sections there appear many club-like endmgs of 

 lateral line fibers in the acusticum. It is probable that these 

 are the fibers just described, the cells not being impregnated. 



The disposition and ending of the sensory roots in the 



