PHYSICAL AND LITERARY. 297 



lated and contraded alternately for feve- 

 ral hours, and the frequency of* its con- 

 tradions decreafes very gradually j but 

 then its force is inftantaneoully fo greatly 

 impaired, that the blood ceafes from mo. 

 tion in the veflels of the feet. 



Experiments nvith Opium. 



So long ago as the year I7j'4, I had 

 found, by experiments, that a folution 

 of opium applied to the fkin of frogs, ren- 

 dered them motionlefs, and killed them, 

 in the fame way as when applied to their 

 interior parts *. From which it was e- 

 vident, that, if opium aded on animals 

 folely by affeding thofe nerves to which 

 it was primarily applied, and the reft of 

 the nervous fyflem by fympathy, inde- 

 VoL.m. Pp pendent 



* Dr Alfton had before that found, that, If a frog 

 ■was put into water in which opium was diflblved, it died 

 before next morning ; but, in this way of making the 

 experiment, the water with the opium might enter the 

 mouth, or its effluvia the noftrils, &c. See the Med, 

 Eff. vol. 5. art. 12, 



