74 Dr. J. S. R. Russell. J he Origin and Destination of -, 



of a large number of the arciform fibres by the lesion, degenerated 

 fibres were traced to the opposite inter-olivary layer, and well marked 

 degeneration of the opposite fillet, consequent on this, could be traced 

 to the region of the corpora quadrigemina. So too, fibres passing to 

 the inferior olives were interrupted by the lesion, and degenerated 

 in consequence. 



Division of the restiform body, unattended with accidental com- 

 plication, resulted in degeneration of afferent fibres to the cerebellum, 

 and of efferent fibres to the formatio-reticularis, and the inferior 

 olives ; no tract in the spinal cord being found degenerated after 

 this lesion. 



In dealing with the results of section of the direct sensory cere- 

 bellar tract it is insisted that this structure ought to be regarded as 

 totally distinct from the restiform body, and it is further pointed 

 out that it is most difficult to sever this connection of the cerebellum 

 without injury to Deiters' nucleus, which is imbedded in the fibres of 

 this tract. 



No efferent tracts were found degenerated other than those con- 

 sequent on injury to Deiters' nucleus, and no afferent fibres were 

 found degenerating from this nucleus to the nucleus globosus in the 

 cerebellum. 



Severance of the nucleus of Deiters from its connections with the 

 medulla resulted in degeneration of an efferent tract passing through 

 the formatio-reticularis of the same side of the medulla, to form a 

 well marked antero-lateral tract on the same side of the spinal cord, 

 extending to the lumbo-sacral region. Other degenerated fibres pass 

 to both posterior longitudinal bundles, and others beyond these 

 structures to terminate in the opposite formatio-reticularis. Of 

 those which enter the posterior longitudinal bundles, some have a 

 caudal course and reach the anterior columns of the spinal cord, on 

 both sides, to terminate in the lower cervical region; while others 

 pass cephalwards and can be traced to the region of the quad- 

 rigeminal bodies, where they appear to terminate. Some de- 

 generated fibres pass from the seat of lesion across the raphe to the 

 region of the opposite superior olive, some of them appearing to enter 

 this structure, while others become intimately associated with the 

 opposite fillet, and pass with this structure to the region of the 

 anterior corpora quadrigemina. 



Section of the posterior columns and their nuclei in the medulla 

 was performed with a view to control certain of the other experi- 

 ments, but it was found that beyond degeneration of fibres passing 

 to the cerebellum in the restiform body, and of the arcuate fibres to 

 the opposite interolivary stratum, with consequent degeneration of the 

 opposite fillet, none of the degenerations previously described in con- 

 nection with the other lesions were met with. 



