64 CUEEENT FOECE CHAP. VI. §. I. 



which the zinc is made to communicate with the 

 platinum, the current is always in the same direc- 

 tion The chemical actions of nutrition evolve 



electricity*." It has always been a source of great 

 surprise to me, that Matteucci has never attempted, 

 as far as I am aware, to ascertain the correctness 

 of this opinion or the result of the experiment, viz. 

 that of forming a circuit between the muscular fibre 

 and the blood, as it was the only evidence required 

 to prove his conclusion. 



I now performed the experiment in the following 

 manner. Laying bare the muscles of the animal at 

 the upper and inner part of the thigh, one electrode 

 was inserted into the substance of the muscle, or, 

 which is better still, placed in contact with the 

 divided transverse section of the muscle, and the 

 other electrode was inserted into the blood flowing 

 from a neighbouring vein; a slight effect occurred 

 upon the needle indicating the blood to be positive. 

 If the electrode he placed on the external surface 

 of the muscle instead of its divided surface, the effects 

 are doubtful. If both electrodes were in contact, 

 one with the divided surface of the muscle and the 

 other with its external surface, then the latter elec- 

 trode was positive to the former ; the result being the 

 so-called muscular current. That the effects should 

 be null or difiBcult to be obtained when the external 

 surface of the muscle and the venous blood are 

 formed into a circuit, need not be surprising, since 

 ^ Philosophical Transactions, 1845, p. 301. 



