SECONDARY ELECTROMOTIVE ACTION IN MUSCLE 

 CHAPTER IV., SECTION IV (REVISED) 



Read, In muscle (as in nerve, electrical organs, and irritable protoplasm 

 in general) the passage of the electrical current is followed by certain 

 electromotive reactions, which are intimately related with the action current, 

 and are to a certain extent only a special manifestation of the same. As 

 early as 1834, Peltier discovered that the protracted passage of current in 

 frogs' limbs, in isolated muscles, and even in pieces of muscle, will develop 

 a current in the reverse direction. This he interpreted to mean that oxygen 

 and hydrogen are separated at the interface of animal tissue and conducting 

 fluid, as they would be at an intermediate metal surface. 



Du Bois-Reymond (67), who took up the investigation later, came to the 

 conclusion that the secondary current (after - current) does not depend 

 exclusively, if at all, upon the ions separated at the poles, but is also 

 generated in the tract lying between them. He found, namely, that all 

 sections of the intrapolar tract of a longitudinally-traversed muscle will give 

 electromotive action in the same direction, after opening the polarising 

 current. Accordingly, he advanced the view that this effect mainly depended 

 on what he termed "internal polarisation." 



Many inorganic and organic porous bodies, saturated with an electrolyte, 

 do, in fact, acquire the property of negative internal polarisation. The 

 polarising current then divides itself between the badly-conducting, saturat- 

 ing fluid, and the porous vessel, when the latter becomes polarised from the 

 separated ions. " Each of the many interfaces now gives electromotive 

 action in the reverse direction from that in which it was traversed by the 

 current." The superposition of all these partial currents results in a 

 current through the circuit. Each tract of equal length in any regularly 

 constructed (prismatic, or cylindrical) body will, as a rule, exhibit marked 

 secondary electromotive action after the passage of the current. 



Soon, however, it was observed that living muscle, traversed by the 

 current, behaved in this respect quite differently from dead organic, or 

 inorganic, bodies ; as shown, above all, in the fact that positive, as ivell as 

 negative, after-currents make their appearance under certain conditions. For 

 the investigation of polarisation effects in muscle, du Bois-Reymond generally 

 employed the gracilis and semimembranosus muscles, at a convenient 

 tension. He used one pair of unpolarisable electrodes to lead in the polar- 

 ising current, and another to lead off the polarisation current. The 

 latter were usually placed between the first pair, within the intrapolar 



