PHYSICAL AND LITERARY. 30J 



rates much more flowly in deftroying the 

 heart's motion in frogs, than it does when 

 the animals are in tire (N° 6* compared with 

 N°7.); it follows^ that it muft produce its 

 eiFeds chiefly, if not wholly, by its adion on 

 the brain, fpinal marrow, and nervous fyflern* 

 The heart of the frog N° 7. whofe brain 

 and fpinal marrow had been deftroyed, beat 

 27 times in a minute, after the animal had 

 lain thirty fix minutes in a folutlon of opium ; 

 which was only three pulfations lefs than the 

 heart of the frog N° 5. performed thirty five 

 minutes after the deftrudtlon of its brain and 

 fpinal marrow, altho' it was not expofed to 

 the ad;ion of opium. 



(e) When opium injeded into the veins, 

 and thus mixed with the blood, leffens or 

 deftroys the fenfibility and moving power of 

 animals much in the fame way as when it 

 is applied to their ftomach^ guts, or cavity 

 of the abdomen (N° 24) ; is it not probable, 

 that it produces thefe effects by its action on 

 the extremities of the nerves which termi- 

 nate upon the internal furface of the heart 

 and whole vafcular fyftem ; and perhaps, 

 alfo, by affeding immediately the medulla 

 cerebri itfelf ? And when a folution oi opium 



applied 



