208 THYSIOLOGY OF MUSCLES AND NERVES. 



presence of muscle-currents. Due regard being had 

 to all these circumstances, the conclusion may yet be 

 drawn that entirely uninjured muscles situated in their 

 natural position are in themselves electrically active. 

 It is true that this has been repeatedly denied by many 

 observers. Our reason for reasserting it is that the ex- 

 planation of the phenomena on the assumption of the 

 absence of electromotive opposition in uninjured muscle 

 necessitates very forced and complicated assumptions, 

 while our view is able to explain all the known facts 

 very simply and in a thoroughly satisfactory manner. 



3. The electric action of muscles which, though ex- 

 tracted, are otherwise uninjured, is often very weak, 

 and is sometimes even reversed ; that is to say, the 

 natural cross-section is not negative, but positive, in 

 opposition to the longitudinal section. This condition 

 is found chiefly in the muscles of frogs which have 

 been exposed during life to severe cold. It is, however, 

 only necessary to remove, in any way, the natural cross- 

 section with its tendonous covering, in order to elicit 

 action of normal character and strength. In parallel- 

 fibred muscles it is often necessary to remove a short 

 piece, of from 1 to 2 mm. in length, from the end 

 of the muscle-fibres, before meeting with an artificial 

 cross-section in which the action is powerful. 



This phenomenon, which was called parelectronomy 

 by E. du Bois-Keymond, because it differs from the 

 usual electric action of muscles, gave rise to that ex- 

 planation of the electric phenomena according to which 

 the electric opposition between different portions of the 

 muscle is not present in the normal muscle, but only 

 intervenes on the exposure of the muscle. The difii- 

 culty mentioned above, of showing the muscle-currents 



