CHAPTER XII 

 EXPERIMENTS ON THE CEREBELLUM 



The experiments on the cerebellum support to a 

 certain extent the observations mentioned in the 

 preceding chapter. 



The cerebellum, like the cerebral hemispheres, is 

 a structure which clearly expresses inequality of 

 growth. Both may be considered as evaginations 

 and appendages of the segmental nervous system. 

 The cerebellum is connected with the central nervous 

 system by three crura, the crura cerebelli ad medullam 

 oblongatam, the crura cerebelli ad pontem, and the 

 crura cerebelli ad corpora quadrigemina. The latter 

 extend forward in a pretty straight line, the first ex- 

 tend backward, and the peduncles to the pons at right 

 ano-les to both. Ma^endie discovered and Flourens 



o o 



confirmed the fact that lesion of these tracts possess- 

 ing so characteristic an orientation to the chief axes 

 of the body produces " forced " movements whose di- 

 rection bears a simple relation to the orientation of 

 the severed peduncle. If a peduncle of the pons 

 be severed on one side the animal rolls about its 

 longitudinal axis. If the crura cerebelli that extend 

 forward be severed the animal rushes forward with 



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