304 ESSAYS AND OBSERVATIONS 



applied to the bare abdominal mufcles of 3 

 frog deprived of its brain and fpinal marroWj 

 does, after a long time, confiderably impair 

 the heart's motion j is it not realonable to 

 think, that this is owing to the finerparts 

 of the opium being abforbed by the bibulous 

 veins and carried to the -heart, and thus 

 brought into contact with the nerves of this 

 organ ? N" 7. compared with N° 9. 



(f) Since opium^ without entering the 

 blood or being carried to the feveral parts of 

 the body, deftroys the power of feeling in 

 animals merely by afting on the nerves to 

 which it is applied {c) (d)^ it follows, that 

 the nerves are the inftruments of fenfa- 

 tion, or, at leaft, neceflary to it. Nor is it 

 fufficient to deftroy this conclufion, that 

 there have been inftances of animals endow- 

 ed with feeling whofe brains were fo greatly 

 difeafed, as iofeem incapable of performing 

 their fundllons. It is far from being fafe to 

 build theories in phyfic upon a few mon- 

 ftrous appearances in nature. 



(g) It appears from N^ 4. and 5. com- 

 pared with N^ 3, 6, 8, 10 and 11. that de- 

 collation and the deftruflion of the fpinal 

 marrow does not weaken or deftroy the 



heart's 



