of Afferent and Efferent Tracts of the Cerebellum. 201 



possible control which the cerebellum may exert on the spinal centres. 

 The state of the knee-jerks afforded no satisfactory information on 

 this point. 



The blnnting of sensibility met with is held to be further proof 

 that the cerebellum is concerned with sensory as well as motor pro- 

 cesses, as was contended by the author in a former paper, 



Faradic excitability of the opposite cerebral hemisphere was found 

 to be less than of that on the side of the lesion, both when the in- 

 ferior cerebellar peduncle was divided, and when partial hemisection 

 of the medulla was performed, leaving the pyramid intact. The 

 most satisfactory explanation of this phenomenon appears to be that 

 the removal of some afferent inhibitory influence from one half of 

 the cerebellum allows this half of the organ to further inhibit 

 the cortex of the opposite cerebral hemisphere ; an explanation in 

 keeping with that offered when the results of ablation of the cere- 

 bellum were under consideration. 



This view is strengthened by the remarkable results obtained by 

 the intravenous injection of absinthe in animals in whom the same 

 lesions had been previously produced, for with the pyramidal system 

 absolutely intact on both sides, there was an entire absence of con- 

 traction of the muscles of the anterior extremity on the side of the 

 lesion, and diminution of contraction of the muscles of the posterior 

 extremity on this side, as compared with those of the opposite limb. 

 Such was the result obtained when the convulsions were induced 

 soon after the lesion, but when induced at some remote period, such 

 as three weeks after, the muscles of the anterior extremity on the 

 side of the lesion contracted, though the contractions were much less 

 powerful than were those of the opposite anterior extremity, and 

 were often largely tonic in character. 



Transverse section of the posterior columns, and their nuclei alone 

 on one side, did not alter the character of the absinthe convulsions in 

 such a remarkable manner as did division of the peduncle and lateral 

 section of the medulla. After such a lesion the muscular contractions 

 in the anterior extremity on the side of the lesion were less power- 

 ful than were those in the opposite anterior extremity, and there was 

 more tonus and less clonus than in the contractions on the opposite 

 side. Both these characters were evident in the early convulsion's of 

 a series, but became much more pronounced in the later convulsions. 

 The author contents himself with recording these facts, and makes 

 no attempt to speculate as to their probable significance. 



The paper is illustrated by tracings obtained of the muscular con- 

 tractions resulting from excitation of the cerebral cortex with the 

 induced current, and from the convulsions evoked by the intravenous 

 injection of absinthe, and demonstrate the points alluded to in that 

 part of the text which deals with these phenomena. 



