816 REPORT— 1894. 



recuiTeiit and spinal accessory were exposed and divided, and the proximal end 

 of tlie accessory was sutured to the distal end of the recurrent. 



The only convenient test which could be employed to ascertain what progress 

 the animal was making after the operation was that afforded by galloping it. 



In one case, a few months after the above nerves had been united, there was 

 only a slight harshness in the breathing during inspiration, even when the horse 

 was severely ' pressed ; ' whereas, unless nerve impulses were passing down the 

 accessory and through the recurrent to the larynx, the animal should have suffered 

 from intense dyspnoea, as the whole of the dilator muscles of one side of the larynx 

 would have been paralysed. 



In a second case, the recurrent, before suture to the accessory, was known to 

 have been degenerated for at least two years. This animal continued to have 

 noisy breathing up to the time it was destroyed (twelve months after the operation), 

 but it was unaccompanied by distress. 



In the first case only an ordinary post-mortem examination was made to 

 ascertain whether the nerves were united ; in the second horse the nerves were 

 stimulated electrically immediately after death, and a careful microscopical 

 examination of the parts made. 



On stimulating that portion of the recurrent in connection with the larynx 

 the muscles actively responded ; on stimulating the accessory well above the 

 nodule uniting it with the recurrent, the muscles of the larynx again actively 

 responded. 



These observations were repeated several times by Professor Delt5pine, of 

 Manchester (who kindly associated himself with me as an independent observer 

 in the, post-nwrttm examination), and the results are beyond doubt. 



The muscles of the larynx of the above case, supplied by the accessory- 

 recurrent nerve, were smaller and decidedly paler in colour than the healthy ones 

 on the opposite side ; on directly stimulating the muscles every portion of them 

 actively responded to a weak current. 



Professor Del6pine examined the united nerves microscopically, and found in 

 the recurrent between the point of union and the larynx small bundles of medul- 

 lated nerve fibres and an amount of epi- and peri-neurium larger than normal. The 

 place occupied by the old funiculi was quite distinct, but the nerve fibres occupied 

 only a portion of the spaces thus indicated. The nerve fibres were all of smaller 

 diameter than normal ; most of them had a very thin myelin sheath which stained 

 well with osmic acid. Professor Del^pine was of opinion from this and the other 

 observations that partial regeneration had certainly taken place, and that regenera- 

 tion was progressing at the time of death. 



By the tests employed it was not possible to say whether co-ordination of the 

 laryngeal muscles occurred, but it is proposed in future observations to examine 

 closely into this subject, and employ the laryngoscope to ascertain whether the 

 impulses to the larynx are sent at the right moment. 



At present it would almost appear to be possible to educate a nerve centre to 

 perform a duty it was never intended for. 



4. On the Causes and Prevention of Suffocation in Mines. By J. S. 

 Haldane, if. a., M.D., Lecturer on Physiology, University of Oxford. 



Evidence was brought forward by the author that most of the deaths caused 

 by colliery explosions and tires in the workings are due to suffocation, so that a 

 thorough investigation of the subject is of great practical importance. 



He concluded that poisoning Isy carbonic acid is never the cause of death ia 

 cases of suffocation by choke-damp, black-damp, or after-damp; that deprivation 

 of oxygen is always the cause in the cases of choke-damp or black-damp, and 

 usually the cause in the case of after-damp, although after-damp, even when 

 much diluted, is sometimes poisonous from the presence in it of products of in- 



