108 



Mr. J. S. R. Russell. The Abductor and [Mar. 31, 



showed that excitation of certain bundles produced no effect on the 

 vocal cord, while excitation of others produced abduction or adduction 

 of the vocal cord on the same side, according to the bundle of fibres 

 stimulated; and, as far as could be ascertained, those fibres excita- 

 tion of which produced abduction of the cord were situated internally 

 to those which produced adduction, i.e., the former are situated on 

 the side of the nerve next to the trachea. But of this point it is 

 difficult to be absolutely certain, as the difficulties of preserving the 

 nerve in its normal position during the investigation are very 

 great. 



Section 2. Relative Vitality of the respective Bundles. — It was found 

 that if the bundles of nerve fibres were separated, as has been already 

 explained, and the abductor and adductor bundles of fibres thus 

 isolated placed upon a piece of cork, and left exposed to the air of 

 the room under exactly similar circumstances, the abductor fibres 

 ceased to conduct impulses in response to electrical excitation long 

 before there was the slightest sign of similar failure on the part of 

 the adductors. The same strength of current and the same number 

 of interruptions per second were employed in each case, with the 

 result that the abductor fibres ceased to conduct impulses in about 

 twenty to thirty minutes, on an average, after transverse section of 

 the nerve and separation of its component bundles; while the adductor 

 fibres would continue to conduct impulses well for three hours and 

 more.* 



That this death of the .abductor fibres did not take place throughout 

 the whole length of the nerve at the same time is proved by the fact 

 that when the portion under observation ceased to conduct impulses, 

 an effect could be often produced by stimulating some portion of the 

 bundle situated nearer the peripheral end of the nerve, until at last 

 even stimulation of the nerve ends in the muscle failed to produce 

 any effect. The adductors meanwhile acted well to the original 

 strength of stimulus, even when applied to the original seat of separa- 

 tion of the bundles. As is well known, if all the fibres of the recur- 

 rent laryngeal nerve be stimulated simultaneously in the adult dog, 

 adduction of the vocal cord results ; while the same procedure in the 

 young dog results in abduction of the vocal cord. (See all previous 

 observers from Legallois to Semon and Horsley.) In such young 

 animals, even after separation of the different bundles of nerve fibres 

 in the trunk of the nerve from each other to the extent of an inch to 

 an inch and a-half, it is at first impossible to get any other effect than 

 abduction of the corresponding vocal cord. But there comes a time 

 when stimulation of one of the separated bundles results in abduc- 

 tion, while stimulation of another results in adduction. Still later 



* The experiment was never continued longer than a little over three hours, as 

 there seemed no necessity for it. 



