POLARISATION PHENOMENA IN NERVE 283 



PARADOXICAL CONTRACTION. If the sciatic nerve of a frog be 

 dissected out, and one of the two branches into which it divides be cut, 

 and the central end of this branch stimulated, the muscles supplied by the 

 other half of the nerve contract to each stimulus. Ligature or crushing 

 of the nerve x (Fig. 130) between the points stimulated and the point 

 which joins the main trunk puts a stop to this effect, showing that it is 

 not due to a mere spread of current. The fibres passing down n are in 

 fact stimulated by the electrotonic current developed in x during the 

 passage of the exciting current. 



