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



muscles directly engaged in bringing about the movement of abduc- 

 tion or adduction, as the case might be. These observations showed 

 that so perfectly could the nerve fibres concerned with the one func- 

 tion be separated from those concerned with the other, that stimula- 

 tion of the one set evoked contraction of the abductor muscle alone, 

 while stimulation of the other set evoked contraction of the adductor 

 muscles alone. 



Section 5. (Control) Degeneration Method. — The difficulties which 

 attended this group of experiments were very great. 



An attempt was made to separate one bundle of nerve fibres from 

 1he others, and to excise a few millimetres of it without injuring the 

 other bundles contained in the nerve trunk, and, of course, without 

 severing the whole nerve trunk. As can be easily understood, the 

 ease with which damage can be done to so delicate a nerve is very 

 great, and in the absence of any means of fixing the nerve (such as 

 was afforded by the ligature in the excitation experiments) without 

 producing damage to any but the bundle of fibres that were to be 

 eliminated, the nerve trunk rolled about so freely that the task was 

 attended by endless difficulties. It is, therefore, scarcely surprising 

 that, out of seven experiments, the results were unsatisfactory in three 

 instances. But those that were successful yielded such striking 

 results that, in view of the great difficulties attending them, further 

 multiplication of these experiments has been considered unnecessary. 

 In one instance, the adductor fibres in the nerve trunk were success- 

 fully separated, and a few millimetres excised. As in all these ex- 

 periments, the wound healed by primary union ; and when the dog 

 was killed, three weeks after operation, the autopsy revealed the 

 following : — The adductor muscles on the side of the damaged nerve 

 were atrophied and degenerated, while the abductor muscle of the 

 same side was normal, as were naturally all the muscles of the opposite 

 •side of the larynx. 



In two instances the abductor fibres were successfully divided 

 without injury to the adductor fibres. During life in one case, there 

 were feeble attempts at abduction during vigorous inspiration, and in 

 the other there were not the slightest signs of abduction. In both 

 •cases the autopsy revealed atrophy and degeneration of the crico- 

 arytenoideus posticus on the side corresponding to that of the injured 

 nerve, while the adductor muscles of the same side and all the 

 muscles of the opposite side of the larynx were normal. In all these 

 three cases direct electrical excitation of the muscles confirmed the 

 conclusions which had already been come to by observing their loss 

 of function and degenerate appearance. In the fourth case, as was 

 supposed at the time of the operation, owing to their position, the 

 bundle of fibres divided was evidently not one of those supplying the 

 muscles of the larynx. Three weeks after the operation the vocal 



