] 895. J Influence of the Cerebral Cortex on the Larynx. 237 



behaviour of water is exceptional, and hence it is particularly ill 

 suited for the use to which it has been put. Again, on account 

 of the smallness of the rotation in water, the unavoidable in- 

 accuracies in determining its rotation, and thus estimating the 

 strength of the magnetic field, produce a larger percentage error in 

 the results than if a liquid, such as benzene, having a considerably 

 higher rotation than water, were used for this purpose. 



V. "The Influence of -the Cerebral Cortex on the Larynx." 

 By J. S. RISIEN RUSSELL, M.D., M.R.C.P., Assistant Physi- 

 cian to the Metropolitan Hospital. Communicated by 

 Professor VICTOR HoRSLEY, F.R.S. Received June 5, 1895. 



(From the Pathological Laboratory of University College, London.) 

 (Abstract.) 



This research was undertaken in order to attempt to differentiate 

 an abductor centre in the cerebral cortex of the dog, bat, as several 

 new observations were made during the course of the investigation, 

 similar experiments were performed in the cat in order to compare 

 the results obtained in this animal with those obtained in the dog. 



Among the preliminary considerations was the question as to what 

 influence the condition of the peripheral laryngeal apparatus in an 

 animal has on the effects obtained from its central nervous mechanism, 

 and the conclusion arrived at was that the influence must be compara- 

 tively insignificant, as abduction or add action of the vocal cords could 

 be obtained on excitation of the appropriate area of the cerebral 

 cortex, irrespective of whether abduction or adduction was obtained 

 on excitation of the recurrent laryngeal nerves in the same animal. 



No evidence of unilateral representation of the movements of the 



- vocal cords in the cerebral cortex was obtained ; and in testing this 



point one recurrent laryngeal nerve was divided transversely, when it 



was found possible to influence the vocal cord whose nerve was 



intact, with equal ease on stimulation of either cerebral hemisphere. 



The question of inhibition of antagonistic muscles by electrical 

 excitation of the cerebral cortex, on the lines adopted by Sherrington 

 with regard to antagonistic muscles in other parts of the body, was 

 tested by first dividing the adductor fibres in both recurrent laryn- 

 geal nerves, leaving the abductor fibres intact, and then exciting the 

 adductor centre with strong induced currents ; but no evidence of 

 inhibition of the abductor muscles was obtained. 



The major part of the paper deals with the movements of the vocal 

 cords which could be evoked on excitation of different foci in the 

 cerebral cortex. It was found that both in the dog and cat there 



