1892.] Adductor Fibres of the Recurrent Lainjngeal Nerve. Ill 



cord on that side performed its excursions perfectly normally, as did 

 that of the opposite side. Separation of the abductor and adductor 

 fibres was then effected in the remainder of the nerve trunk, and ex- 

 citation of these bundles evoked their respective movements of the 

 vocal cord on the same side. Finally, on post-mortem examination in 

 this case, none of the muscles on either side of the larynx were found 

 atrophied or degenerated. It consequently served as a gratifying 

 control of the other degeneration experiments. 



Summary axd Conclusions. 



The results of these experiments show clearly : — 



1. That the abductor and adductor fibres in the recurrent laryngeal 

 nerve are collected into several bundles, the one distinct from the 

 other, and each preserving an independent course throughout the 

 nerve trunk to its termination in the muscle or muscles which it. 

 supplies with motor innervation, a condition of things the possibility 

 of which was suggested by Dr. Semon more than ten years ago, from 

 the evidence of pathological facts. 



2. That while in the adult animal simultaneous excitation of all 

 the nerve fibres in the recurrent laryngeal nerve results in adduction 

 of the vocal cord on the same side, abduction is the effect produced 

 in a young animal by an exactly similar procedure. 



3. That when the abductor and adductor fibres are exposed to the 

 drying influence of the air under exactly similar circumstances, the 

 abductors lose their power of conducting electrical impulses very 

 much more rapidly than the adductors, in other words, they are 

 more prone to succumb than are the adductors, a fact which has for 

 long been recognised and insisted on by Dr. Semon as being the casein 

 the human subject, and in support of the truth of which that observer 

 has adduced so many powerful arguments. 



4. That, even in the young dog, the abductor nerve fibres, though 

 preserving their vitality much longer than in the case of the adult 

 animal, nevertheless in the end succumb before the adductor fibres. 



5. That this death commences at the point of section of the nerve, 

 and proceeds gradually to its peripheral termination, and does not 

 take place in the whole length of the nerve simultaneously. 



6. That it is possible to trace anatomically the abductor and 

 adductor fibres throughout the whole length of the recurrent laryngeal 

 nerve to their termination in the one or other group of laryngeal 

 muscles, and that these fibres appear to bear a fixed relationship to 

 each other throughout their course, the abductors being situated on 

 the inner side of the nerve or that next to the trachea, while the 

 adductors are on the outer side. 



7. That it is possible to so accurately separate these two sets of 



