of the Eighth Pair of Nerves, 293 



windpipe, in a great proportion of animals, passing from th« 

 brain down the neck, and distributing branches to the thoracic 

 and abdominal viscera; and experiments were occasionally- 

 made by fastening ligatures upon this nerve, to which the an- 

 cients gave the name of par vagum from its general distribu- 

 tion ; and, it was also at times divided on each side of the 

 neck, for the purpose of observing the effects of these neiTes 

 upon the organs they supply. 



Similar experiments have been subsequently repeated to the 

 present day, and varied agreeably to the views of those en- 

 gaged in the pursuit. The ultimate fatality of the operation 

 of dividing the eighth pair of nerves is generally noticed. All 

 else that can be collected from Rufus and Galen is, that the 

 animal loses its voice. The cause of death in animals sub- 

 mitted to this experiment was by many attributed to the dis- 

 turbance and cessation of the heart's motions, directly pro- 

 duced by the division of the nerve. Willis and others main- 

 tained this notion, whilst some, who also repeated the experi- 

 ment, were of a contrary opinion, observing, that if this expla- 

 nation were true, animals could not live so long as they are 

 known to do after the operation. While others attributed the 

 death of animals to inanition, from their being unable to eat. 

 Valsalva remarked frequent efforts to vomit, and subsequent de- 

 rangement of the digestive functions, and that food filled the oeso- 

 phagus, and the mouth was covered with foam tinged with 

 blood. Hence he concluded that blood-vessels were ruptured by 

 the efforts to vomit, and that the animals died of heemorrhage. 

 Some noticed similar appearances, but attributed them to con- 

 gestion'of the lungs, which stopping the circulation killed the 

 animal. Haller also divided the par vagum, and noticed the 

 dyspnoea consequent to the operation. He adds, that the di- 

 gestive powers fail, and the contents of the stomach become 

 putrid. Cruickshanks and others obsei-ved the congestion of 

 the lungs, and supposed it to be the cause of death. Bichat 

 frequently performed the experiment in order to discover 

 the cause of its fatal tendency, with the view of illustrating 

 the influence of the ne.ves on the thoracic and abdo- 



