932 CENTRAL NERVOUS SYSTEM 



It will be of interest to consider for a moment the possible causes for the 

 ultimate disappearance of the symptoms of cerebellar extirpation. These 

 are either: (1) an organic compensation by the uninjured parts of the cere- 

 bellum, or (2) a functional compensation by the voluntary centers of the 

 cerebrum. Although the former of these methods of compensation may 

 sometimes develop after partial destruction of the cerebellar cortex, it can 

 not of course explain the recovery which we have seen to occur after the 



, e 



Fig. 235. Footprints after destruction of the cerebellum in a dog: a, before the operation; 

 b, four days after; c, five days after; d, a month after; e, two months after. (From Luciani.) 



entire cerebellum has been removed. The most important compensation no 

 doubt is effected by the cerebrum, as the following observation clearly in- 

 dicates. If half of the cerebellum of a dog is destroyed, and the animal 

 kept alive until the symptoms of cerebellar extirpation have entirely dis- 

 appeared, it will then be found, if the cerebral center on the opposite side 

 is removed, that the symptoms return in their original severity. After this 

 second operation the powers of standing in the erect position and of 

 walking are permanently lost. 



