462 PHYSIOLOGY 



CHAP. 



brought out clearly the almost complete identity of these with the 

 fundamental phenomena of cerebellar deficiency. 



We must confine ourselves to stating that the main symptoms 

 due to defect of the labyrinth are according to the minute 

 observations of Ewald abnormal relaxation of the affected 

 muscles, diminished energy during activity, and diminished pre- 

 cision of the movements in which they are concerned. All the 

 special symptoms which animals without a labyrinth present in 

 comparison with normal animals can easily be interpreted as the 

 effects of atonia during repose, and of asthenia and astasia during 

 muscular activity. 



The symptoms of the early post -operative period are also 

 phenomena of deficiency, as recognised by Flourens, and are 

 accordingly of the same character as the residuary symptoms of 

 the later period. This appears from Ewald's work, and still more 

 obviously from the researches of Gaglio (1889) on the effect of 

 cocainisation of the membranous labyrinth. When cocaine is 

 applied to the divided semicircular canals all the motor disturb- 

 ances consequent on the lesions persist, while if the canals are 

 intact it produces for a period of thirty to sixty minutes the same 

 effects as result from cutting or destroying them. 



The difference in the motor disturbances in animals a short 

 time and a longer period after loss of the labyrinth is only 

 quantitative, and is due to the intervention of compensating 

 phenomena. Ewald showed that after almost total disappearance 

 the motor disorders consequent on destruction of the labyrinth 

 reappeared after removing the motor zone of one cerebral hemi- 

 sphere, and return in their original intensity and persist after 

 removing both motor regions, so that the parallel is almost 

 complete between our studies on the cerebellum and those of 

 Ewald on the labyrinth. 



The fact that the motor disorders produced by destruction of 

 the labyrinth are phenomena of deficiency led Ewald to conclude 

 that these peripheral sense-organs normally send a continuous 

 excitation to the nerve-centres, which reaches the muscles reflexly, 

 keeps up their tone, and thus makes their normal function 

 possible. 



What are the centres through which the labyrinth reflexly keeps 

 up muscular tone ? Owing to the great resemblance between the 

 phenomena of labyrinthine and cerebellar deficiency, it seems 

 legitimate to conclude that the labyrinth exerts its tonic action 

 on muscle through the cerebellum. Ewald, however, is not 

 in favour of this conclusion, on the strength more particularly of 

 the experiments of his pupil Lange, who demonstrated that in 

 pigeons which had been deprived of their cerebellum some time 

 previously lesions of the labyrinth induced the same character- 

 istic phenomena as were observed when the cerebellum was intact, 



