FUNCTIONS -OF THE CEREBELLUM. 365 



phenomena which follow injury or extirpation ,of the cere- 

 bellum in animals. 



Extirpation of the Cerebellum in Animals. In birds, 

 and in certain mammals in which the operation has been 

 successful, the more or less complete extirpation of the cere- 

 bellum is followed by well-marked phenomena, presenting 

 always the same character, but somewhat differently inter- 

 preted by various experimenters. Experiments of this kind 

 were first made by Flourens ; and the accuracy of his obser- 

 vations has never been successfully controverted, whatever 

 may have been said of his physiological deductions. In- 

 deed, there are few if any important points in the phenom- 

 ena following partial or complete removal of the cerebellum 

 that escaped the attention of this most accurate observer. 



Laying aside, for the present, the deductions to be made 

 from experiments on animals, the phenomena noted by Flou- 

 rens and by all who have repeated his observations on the 

 cerebellum are as follows : 



" I extirpated the cerebellum by successive layers in a 

 pigeon. During the removal of the first layers, there only 

 appeared slight feebleness and want of harmony in ^the 

 movements. 



" At the middle layers, there was manifested an almost 

 universal agitation, although there was not added any sign 

 of convulsion ; the animal executed sudden and disordered 

 movements ; it heard and saw. 



" On the removal of the last layers, the animal, the facul- 

 ty of jumping, flying, walking, and maintaining the erect 

 position being more and more disturbed by the preceding 

 mutilations, lost this faculty entirely. 



" Placed on the back, it was not able to recover itself. 

 Far from resting calm and steady, as occurs in pigeons de- 

 prived of the cerebral lobes, it became vainly and continually 

 agitated, but it never moved in a firm and definite manner. 



" For example, it saw a blow with which it was threatened, 



