CH. XLIX.] FUNCTIONS OF CEREBELLUM 703 



in the last chapter conjugate deviation of head and eyes. The higher 

 cortical centre gives the general word of command to turn the head 

 and eyes to the right : the subsidiary centres or subordinate officials 

 arrange that this is to be accomplished by the external rectus of the 

 right eye supplied by the right sixth nerve, the internal rectus of the 

 left eye supplied by the left third nerve, and numerous muscles of 

 neck and back of both sides supplied by numerous nerves. We thus 

 see how the complicated intercrossing of fibres and connections of the 

 centres of the various nerves are brought into play. 



The functions of the cerebellum are investigated by the same two 

 methods of experiment (stimulation and extirpation) that are employed 

 in similar researches on the cerebrum. The anatomical connections 

 of the cerebellum with other parts of the cerebro-spinal axis (see 

 p. 651) have been chiefly elucidated by the degeneration method. 



FIG. 509. Pigeon after removal of the cerebellum. (Dalton.) 



Each side of the cerebellum has three peduncles : the superior peduncle 

 connecting it to the opposite hemisphere of the cerebrum, the inferior 

 peduncle connecting it mainly to the same side of the spinal cord, and 

 the middle peduncle contains fibres which link the two halves of the 

 cerebellum together in a physiological though not in an anatomical 

 sense. The upper end of the inferior peduncle terminates in the 

 vermis ; in some of the lower animals the vermis is practically the 

 only part of the cerebellum which is present, and it is this part of 

 the cerebellum which is principally concerned in the co-ordination 

 of the bodily movements. The cerebellar hemispheres are especially 

 connected with the opposite cerebral hemispheres ; and possibly just 

 as the different regions of the body have corresponding areas in the 

 cerebrum, so also they are similarly represented in the cerebellum ; 

 but localisation of function in the cerebellum has not gone sufficiently 

 far yet to make this a certainty. 



