vni THE HIND-BRAIN 4G7 



"Rolando's error was easily corrected by more careful observa- 

 tions ; that of Flourens opens a false track to subsequent workers, 

 and has become a serious obstacle to advance in the physiology of 

 the cerebellum. Rolando's view led him logically to the other error 

 of considering the cerebellum as an organ subservient to sensation 

 (through the agency of the medulla oblongata) or to the will (through 

 the agency of the cerebral hemispheres) ; the mistake of Flourens 

 led him to create an abstract and fictitious entity, the principle of 

 co-ordination or regulation of complex movements or postures, as 

 represented by the various forms of locomotion or position a 

 principle localised in the. cerebellum, and independent of the 

 cerebrum, as the function of the latter remains intact after removal 

 of the cerebral hemispheres. 



: ' However fallacious and poorly founded, Eolando's theory 

 in itself is clear, definite, and complete in fundamentals, while 

 that of Flourens is obscure, imperfect, and unintelligible, since it 

 is impossible to picture in what the supposed co-ordinating or 

 regulating functions of the cerebellum can influence locoinotor 

 movements, which are willed by the cerebrum and carried out by 

 the medullary axis ; nor how this regulation can take place when 

 once the functional independence of the cerebrum and cerebellum 

 has been admitted." 



Lussana, who considered the cerebellum as the centre of 

 muscular sense, offered an explanation of the phenomena of cere- 

 bellar deficiency described by Flourens that was ingenious in its 

 simplicity. 



' For a long time " (he wrote in 1862) " the importance of this 

 (muscular) sense, through which the muscles effectively carry 

 out their voluntary movements, has been recognised. It will 

 suffice to quote two physiologists of undoubted authority, Bell and 

 Panizza. The former recognises that by sensory impressions we 

 can appreciate the degree of contraction of our muscles, and 

 are able by this means to regulate their activity in proportion 

 to the resistance which we have to overcome. In 1834 Panizza, 

 who described ataxia after section of the dorsal spinal roots, 

 wrote : The influence of the will on the muscles that are partially 

 deprived of sensibility is feeble and uncertain, because they no 

 longer feel and are no longer felt." 



" The muscular sense " (adds Lussana) " is par excellence the 

 main factor in co-ordinating voluntary movement ; its central 

 organ is the cerebellum. Far more important and indispensable 

 than the cutaneous sense, the muscular sense serves in animals to 

 make known the resistance met with, and in voluntary movements 

 to regulate the forces of contraction by which the muscle is able 

 to overcome it. ... 



Without the cerebellum the animal no longer feels the solidity 

 of the earth on which it rests in standing and walking, nor the 



