.->X4 A TEXTBOOK OF PHY810LO: . v > 



When the polarizing current is broken, there occur '' after-electro 

 tonic currents." In the intrapolar region it is in the opposite direction 

 (unless the current has been strong and of short duration, when it is 

 in the same direction); outside the kathode it is, as before, away from 

 the polarized area; outside the anode it is at first towards, and after- 

 wards away from, the polarized area. 



Anelectrotonic Previously Katelectrotonic 



area polarized area area 



first > < > 



then < 



If the nerve be excited by a tetanic current, the electrotonic currents 

 are weakened and the polarizing current strengthened by the " current 

 of action." 



The "paradoxical contraction" of muscle takes place when the 

 branch of a divided nerve is stimulated with a constant current, and 

 is due to the electrotonic current spreading along the branch towards 

 the point where the nerve-branches come together, and thus exciting 

 the fibres of the nerve which supplies the muscle. 



