GHAF. VI. §. n. IN THE NERVOUS TISSUE. 69 



The object of these experiments was, I believe, for 

 the purpose of ascertaining vsrhether any electric 

 current traversed the nerves. I shall have occasion 

 to allude to them again in a subsequent chapter. 



Why the effects should , be so decided in this 

 instance, when compared to those that are observed 

 in muscles, may arise from the greater mass of the 

 brain, and to the circumstance of the blood coming 

 directly from it, and thus the conditions may be 

 better . adapted to shew the effect, than when the 

 muscle and vein were formed into a circuit in the 

 thigh. If the experiment be performed with the 

 sciatic nerve, placing one electrode in contact with 

 the divided surface, or the external surface, and the 

 other in contact with the blood coming from the 

 vein of the nerve, then the effects are similar to 

 those observed with the muscles. Eepeating Du 

 Bois Keymond's experiment, viz. forming the divided 

 and external surfaces into a circuit, the same result 

 was obtained, the external surface was positive to the 

 other ; but the effects were not so great as when the 

 same parts of a muscle were formed into a circuit ; 

 nevertheless the effects were decided and definite. 



I need not repeat the arguments that were used 

 respecting the blood being add, in order to account 

 for the effects ; and with regard to the external 

 surface of the nerve being positive, to the divided or 

 transverse section ; this may be considered as due to 

 the same circumstance as was observed with the 

 muscular fibre, viz. the positive state being indttced 



