HISTORT of the SOCIETT. 19 



the abdomen, for inflance, it almofl immediately impairs the 

 adlion of the heart. It is only, however, when applied to an 

 extenfive furface that it has this efFedl ; and if Dr Wilson's 

 obfervations be j uft, this effe(fl is not produced through the me- 

 dium of the nervous fyflem ; but is the confequence of the 

 opium deftroying the mufcular power, and, confeqviently, the 

 circulation in thofe veffels to which it is applied ; thus fud- 

 denly diminifliing the fupply of blood to the heart, and at the 

 fame time oppofing an additional obftacle to its perfedl evacua- 

 tion. The experiments, next related, demonftrate that opium, 

 immediately applied to the brain itfelf, although it excites vio- 

 lent and univerfal convuHions in all the mufcles of voluntary 

 motion, is incapable of affecfling at all the contra<flions of the 

 heart. It even appears, from thefe experiments, that although 

 opium be applied at the fame time to the brain and fpinal mar- 

 row of a frog, in confequence of which, (if the folution employ- 

 ed be ftrong), the animal inftantly expires, as if thunderftruck, 

 the motion of the heart is not in the lead affedled by it. It 

 continues to beat with the fame frequency and force after,, as it 

 did before, the application of the opium. We arrive, then, at 

 this conclufion, that opiixm, applied to a diflant part of the body, 

 does not aiFecfk the motion of the heart, through the medium of 

 the nervous fyflem ; nor, on the other hand, docs opium, ap- 

 plied to the heart, affedl any other part of the body, through 

 the fame medium. But the heart is not the only mufcle, which 

 opium, applied to a diftant part, feems incapable of affefting 

 through this medium. Many confiderations render it highly 

 probable, that the fame is true of all the mufcles of involuntary 

 motion, without exception. That it is fo of the mufcular coat 

 of the alimentary canal, which, next to the heart, may be con- 

 fidered the chief of this clafs of mufcles, appears from the ex- 

 periments next related. On comparing the experiments above 

 alluded to, with thofe in which opium thi"own into the ftomach 



c 3 and 



