1893.] On Lesions of the Cerebellum, $c., in Monkeys. 477 



difference being the greater tendency to roll round the longitudinal 

 axis towards the side of lesion, whichever peduncle was cut. 



Destruction of the clavate and cuneate nuclei caused temporary dis- 

 turbances of attitude and gait, but there was no affection of cutaneous 

 sensibility. 



The degenerations following removal of the lateral lobe of the 

 cerebellum, or section of the superior peduncle, showed that this 

 structure contains an efferent tract to the opposite red nucleus 

 and optic thalamus, and an afferent tract, which appears to be 

 the cerebellar termination of the antero-lateral ascending tract of 

 Gowers. 



Lateral lobe extirpation, or section of the middle peduncle, was 

 followed by diminution of the transverse fibres of the pons Varolii on 

 the side of the lesion, and atrophy of the cells of the nucleus pontis. 

 on the opposite side. 



Lateral lobe extirpation, or section of the inferior peduncle, 

 demonstrated the existence of an efferent tract to the opposite inferior- 

 olivary body, and of an afferent tract to the cortex, chiefly of the lateral 

 lobe. 



Extirpation of the middle lobe occasioned no degeneration in the 

 superior, middle, or inferior cerebellar peduncles, but was followed 

 by degeneration and sclerosis of the tract which passes from the 

 vermiform process to Deiters' nucleus the " direct sensory cerebellar 

 tract " of Edinger. 



We were unable to confirm Marchi's statements as to the existence 

 of a direct efferent cerebellar tract in the spinal cord, or of degenera- 

 tion in the anterior nerve roots, mesial fillet, or posterior longitudinal 

 bundles, after cerebellar extirpation. 



In two cases of lateral lobe extirpation, however, we obtained de- 

 generation in the anterior and lateral columns of the spinal cord 

 respectively, in the position indicated by Marchi. In the case, how- 

 ever, in which there was a marginal degeneration in the anterior 

 column, the nucleus of Deiters, on the same side, was implicated ; 

 while, in that in which degeneration in the lateral column was 

 present, there was a lesion of the tegment of the pons, involving the 

 nucleus of the lateral fillet. The same degeneration was induced by 

 lesions specially made in the lateral fillet. 



Destruction of the clavate and cuneate nuclei was followed by de- 

 generation, on the one hand, through the restiform body into the 

 cerebellum ; and, on the other hand, through the internal and middle 

 arcuate fibres to the opposite interolivary layer and mesial fillet. 

 This latter structure was traced to the anterior quadrigeminal bodies 

 and optic thalamus. 



Owing to lesion in some of the experiments of the roots of the 5th 

 cranial nerve, we were led to make special investigations on its cen- 



