©/' tlie Eighth Pair of Nerves. 3 1 1 



modem times. Referring, therefore, to this testimony, I am 

 bound to believe, that it is perfectly erroneous to assert that 

 digestion directly and invariably stops as soon as the eighth 

 pair of nerves is completely divided. Consequently, the most 

 rational inference appears to be, that animals are affected in 

 different degrees, some, though very rarely, so as to be deprived 

 of all power of digestion, while the generality continue to digest 

 with more or less facility for certain periods. 



Having thus put the question relative to the influence of the 

 par vagum over the functions of the stomach in (I hope) a more 

 satisfactory point of view than it has hitherto appeared in, and 

 shown the fallacy of Dr. Wilson Philip's premises to his theory 

 of the analogy between the galvanic and nervous powers, I shall 

 conclude with some few suggestions relating to the manner in 

 which it appears to me to be probable, that the symptoms fol- 

 lowing the division of the par vagum arise. 



The lungs themselves are supplied by the eighth pair of 

 nerves, whilst the stomach receives branches also from the great 

 sympathetic nerve. All animals which have both lungs and 

 a stomach are found to have the par vagum ; but in those which 

 are not furnished with lungs, I believe no such nerve is to be 

 found. Hence the phsenomena of dividing the par vagum are 

 analogous to the indications of anatomy, w^^ich lead to a con- 

 sideration of this nerve being solely destined to afford sensibi- 

 lity to the lungs, whilst at the same time it assists in preserving 

 the due performance of the functions of the stomach ; but in 

 what precise degree it is difficult, if not perhaps impossible, to 

 determine. The functions of the stomach are carried on in 

 some of the lower animals without the par vagum. In two ex- 

 periments by Mr. Brodie, wherein he divided the stomachic 

 branches of the par vagum below its distribution through the 

 lungs, the animal (a cat) lived and digested, to all appearance, 

 as usual. In the experiments which I have cited, digestion 

 teemed to have gone on as it ordinarily does, till the continu- 

 ance of the distressing symptoms following the division of the 

 nerves rendered the animals no longer capable of supporting 



