FUNCTIONS OF THE CEREBELLUM. 371 



white columns, except that when they are divided at several 

 points, we invariably have want of coordination in the gen- 

 eral muscular system. 1 Whpn the posterior white columns 

 are disorganized in the human subject, we have loss or im- 

 pairment of coordinating power, even though the general 

 sensibility be not affected, as in the disease called locomotor 

 ataxia. 



Confining ourselves still to the interpretation of experi- 

 ments upon living animals, and leaving for subsequent con- 

 sideration the phenomena observed in cases of disease or 

 injury of the cerebellum in the human subject, we are led 

 to the following conclusions : 



There is a necessity for coordination of the movements 

 of the general voluntary system of muscles, by means of a 

 nerve-centre or centres. 



Whatever other functions the cerebellum may have, it 

 acts as the centre presiding over equilibration and general 

 muscular coordination. 



The cerebellum has its nervous connection with the gen- 

 eral muscular system through the posterior white columns 

 of the spinal cord, a fact which is capable both of anatomical 

 and physiological demonstration. 



If the cerebellum be extirpated, there is loss of coordi- 

 nating power ; and if the posterior white columns of the 

 cord be completely divided, destroying the communication 

 between the cerebellum and the general system, there is 

 also loss of coordinating power. 



When a small portion only of the cerebellum is removed, 

 there is slight disturbance of coordination, and the disor- 

 dered movements are marked in proportion to the extent of 

 injury to the cerebellum. 



After extirpation of even one-half or two-thirds of the 

 cerebellum, the disturbances in coordination immediately 



1 The reader is advised to study, in this connection, that portion of the 

 chapter on the spinal cord as a conductor, which treats of the probable func- 

 tions of the posterior white columns (see page 289). 



