CHAP. VIII. MUSCULAR AND NEEVOUS TISSUES. 75 



researches, appears to entertain some difficulty in 

 considering what really is the true electro-motor 

 element of the circuit under these circumstances. 

 I have already suggested, that the muscular tissue 

 and the nervous tissue may be considered in the 

 same light as a charged Leyden jar ; that the positive 

 condition of their external surfaces may be caused 

 by induction, the tissue itself being negative, and 

 deposited as such during nutrition. Before we can 

 come to this conclusion, however, it will be necessary 

 to investigate the subject more fully. 



For the convenience of discussion, I may just sum 

 up, in a few propositions, the results which appear 

 to be well established by the researches of Matteucci 

 and Du Bois Eeymond, and such as I have been 

 enabled to confirm by my own experiments, which 

 it will not be necessary to particularize. 



1. Any point of the surface of a muscle is positive in 

 relation to any point of the divided or transverse section 

 of the same muscle. 



S. Any point of the surface of a nerve is positive in 

 relation to any point of the divided or transverse section 

 of the same nerve. 



These two propositions express the law as deduced 

 by Du Bois Keymond in regard to the muscular and 

 the nerve currents. 



Du Bois Eeymond has, however, applied the terms 

 natural and artificial to the different sections. There 

 may be no objection to the employment of these 

 terms; but unfortunately the so-called natural 



