FUNCTIONS OF THE CEREBELLUM. 415 



that of the cerebrum, but arranged after a different fashion, as 

 shown in Fig. 147. 



Besides the gray substances on the surface, however, there 

 is near the centre of the white substance of each hemisphere, 

 a small capsule of gray matter called the corpus dentatum 

 (Fig. 148, c d), resembling very closely the corpus dentatum of 

 the olivary body of the medulla oblongata (Fig. 148, o). 



The physiology of the cerebellum may be considered in its 

 relation to sensation, voluntary motion, and the instincts or 

 higher faculties of the mind. It is itself insensible to irrita- 

 tion, and may be all cut away without eliciting signs of pain 

 (Longet). Yet, if any of its crura be touched, pain is indi- 

 cated ; and, if the restiform tracts of the medulla oblongata 

 be irritated, the most acute suffering appears to be produced. 

 Its removal or disorganization by disease is also generally un- 

 accompanied with loss or disorder of sensibility ; animals from 

 which it is removed can smell, see, hear, and feel pain, to all 

 appearance, as perfectly as before (Flourens ; Magendie). So 



FIG. 148. 



Outline sketch of a section of the cerebellum showing the corpus dentatum (from 

 Quain). %. The section has been carried through the left lateral part of the pons, 

 so as to divide the superior peduncle and pass nearly through the middle of the left 

 cerebellar hemisphere. The olivary body has also been divided longitudinally so as 

 to expose in section its corpus dentatum. c r, crus cerebri ; /, fillet ; q, corpora 

 quadrigemina ; s p, superior peduncle of the cerebellum divided ; m p, middle pe- 

 duncle or lateral part of the pons Varolii, with fibres passing from it into the white 

 stem ; a v, continuation of the white stem radiating towards the arbor vitse of the 

 folia ; c d, corpus dentatum ; o, olivary body with its corpus dentatum ; p, anterior 

 pyramid. 



that, although the restiform tracts of the medulla oblongata, 

 which themselves appear so sensitive, enter the cerebellum, it 

 cannot be regarded as a principal organ of sensibility. 



In reference to motion, the experiments of Longet and most 

 others agree that no irritation of the cerebellum produces 

 movement of any kind. Remarkable results, however, are 

 produced by removing parts of its substance. Flourens 



