142 THE SPINAL CORD AND CEREBELLUM 



supposing that when the cerebellum is removed, 

 other allied centres may perform for a time the 

 functions devolving previously upon it, thus enabling 

 the creature to prolong its existence under conditions 

 of diminished vitality. 



It is often said that the removal of the cerebellum 

 leads to no diminution in the psychical powers, and 

 this statement, presumably, applies to animals. As 

 bearing on this point, it is necessary to recall the 

 fact, already mentioned, that sensation is to a con- 

 siderable extent independent of the will. It should 

 also be remembered that in the two cases of defective 

 development of the cerebellum the intellectual powers 

 were decidedly affected. 

 Thefactors But in what way is it supposed that the cerebellum 



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bration. produces effects of equilibration, unless it be by re- 

 inforcing and increasing the ordinary muscular, 

 sensory, and motor impulses ? Does anyone imagine 

 that the cerebellum is a special sense organ, having 

 functions similar to those of the semicircular canals ? 

 There does not appear to be any ground for such a 

 supposition. No one, we fancy, has ever spoken of 

 the cells of Purkinje as sensory cells in that sense. 

 What, then, are the factors in equilibration ? 

 Muscular sensations and ocular impressions and 

 others proceeding from the semicircular canals tell 

 us, let us say, that we are falling. We recognise 

 the need of reaction, and, guided by our sensations or 

 impressions of the kinds enumerated, and by others, 

 it may be, coming from the soles of our feet and skin, 



