PHYSICAL AND LITERARY. S'^9 



(p) It remains, therefore, that opium, by 

 affefting the- extremities of the nerves of the 

 parts to which it is applied, does, by means 

 of their connexion and fympathy with the 

 brain and fpinal marrow, deftroy or prevent, 

 through the whole nervous fyftem, the o- 

 peration of that^oii^r upon which depends 

 fenfation and motion in the bodies of ani* 

 mals. 



(q) Since opium applied to the abdomr-^ 

 nal mufcles of a frog, deprived of its brain 

 and fpinal marrow, does not deftroy the mo- 

 tion of the heart fo foon, as when it is ap- 

 plied t^ the abdominal mufcles of a frog 

 whofe brain and fpinal marrow are intire, 

 (N" 6. and 7.), it follows, that the brain and 

 fpinal marrow, and confequently the nerves 

 derived from them, have a greater influence 

 than any other part of the animal fyftem, 

 upon the motion of the heart 



(r) Opium does not Only deftroy the 

 moving power of the mufcles of animals by 

 intercepting the influence of the brain and 

 fpinal marrow, but alfo by unfitting the 

 mufcular fibres themfelves, or the nervous 

 power lodged in them for performing its of- 

 fice : otherways a folution of opiuniy when 



applied 



