CITJP. XXIV.] PRINCIPAL PARTS OF THE BRAIN. 497 



3. The Functional Relations of the Cerebellum with 

 the Cerebral Hemispheres and the Spinal Cord. 



We pass now to another subject of surpassing interest 

 but of great obscurity. What are the functions of the 

 Cerebellum ? This is a question which seems most simple, 

 though it is one that has perplexed physiologists for 

 over two centuries, and may still be considered to hold its 

 place as a thoroughly unsettled problem. The most 

 varied views have been entertained by different physiolo- 

 gists on the subject. 



Willis and others have regarded the Cerebellum as the principal 

 regulative centre for involuntary movements as well as for the 

 functions of vegetative life; Foville and others have regarded it as 

 a'sensorium commune,' or principal centre for ingoing conscious 

 impressions ; Gall and some of his followers looked upon it as an 

 organ chiefly concerned with the 'instinct of propagation' or the 

 ' sexual appetite '; Flourens, Longet and others have taught that 

 the Cerebellum is the seat of a faculty for co-ordinating voluntary 

 and other muscular movements; Lussana, endeavouring to explain 

 the mode in which it co-ordinates voluntary movements, makes it 

 the seat of the ' muscular sense' ; Eeil, Eolando, and some modern 

 writers, such as Luys, Weir-Mitchell and others, have regarded the 

 Cerebellum as an organ for engendering and distributing the nerve- 

 force needed for the instigation of all kinds of movements, and 

 even for stimulating other non-motor nerve centres. This by no 

 means exhausts the list of views which have, atone time or another, 

 been held concerning the functions of the Cerebellum. Other no- 

 tions in regard to this organ will, indeed, be referred to in subse- 

 quent pages. 



How are we to choose from amongst these bewildering^ 

 different theories ? Vulpian,* after carefully reviewing 

 the whole subject in 1866, felt unable to accept any one 

 of them. He contented himself in the main by drawing 

 certain negative conclusions. " The Cerebellum," he 

 * " La physiolog. du Syst. Nerveux," pp. 601-641. 



K K 



