466 PHYSIOLOGY CHAP. 



appropriate compensation movements directed to the maintenance 

 of its equilibrium which cause the irregularity of its gait. 



In a later publication (1903) Stelani came back on his old 

 theory, and recognised that it was inadequate, and that " in the 

 actual state of our knowledge the best hope of completing it lies 

 in blending it with the theory of Luciani, who regards the 

 cerebellum as the centre of muscular tone. Luciani has demon- 

 strated the existence of a cerebellar tone, Ewald the existence of a 

 labyrinthine tone. To complete the two theories and fuse them 

 into one we need only assume that the cerebellar tone, as demon- 

 strated by Luciani, arises in the labyrinth, and is therefore adapted 

 to the requirements of equilibration and orientation, as already 

 suggested by Dreyfuss in Germany and Gaglio in Italy." 



It is not, however, a matter of indifference whether the cere- 

 bellum is termed the organ of equilibrium, or of orientation, or of 

 tone. The tonic reflex activity controlled by the cerebellum is 

 not merely exerted on the muscles that function during posture 

 and locomotion, but it extends more or less to all the skeletal 

 muscles whatever their function. In moving the eyes, in speaking 

 or singing, in writing, playing the piano, sitting down, in all these 

 actions there must certainly be intervention of the tonic influence 

 of the cerebellum, although the resulting movements are quite 

 different in character from those of equilibration. Again, when 

 standing and walking the cerebellum intervenes less as the organ 

 for preserving equilibrium than as the organ which regulates the 

 tone and contraction of the muscles to the right extent and in the 

 proper combination. Stefani is unfortunate in citing Gaglio in 

 support of his hypothesis ; for the latter expressly denies Goltz' 

 theory that the head possesses a special sense of equilibrium in 

 the labyrinth, " since the general conditions of sensibility whicli 

 control the sense of equilibrium in other parts of the body must 

 suffice." 



VIII. In The Cerebellum (1891) we made a comparison between 

 the primitive rudimentary theory of Eolando and that of Flourens, 

 and expressed the following opinion, which we still hold to be 

 legitimate : " Eolando looked upon the disturbance of co-ordination 

 a the effect of partial destruction of the cerebellum, owing to 

 which there was unequal and irregular' transmission of the normal 

 influence of the cerebellum to the different parts, and he erroneously 

 characterised the asthenia as paralysis. Flourens fortunately 

 avoided this error ; he expressly defines as weakness what Rolando 

 termed paralysis, but erred in regarding not this weakness but 

 the inco-ordination of movements as the main symptom of the 

 loss of the specific function of the cerebellum. In an animal 

 deprived of its cerebellum, he says, ' tous les mouvements partiels 

 subsistent encore ; la co-ordination seule de ces mouvements est 

 perdue/ 



