ELECTRICAL EXCITATION OF MUSCLE 



217 



excitation, it is desirable to bring forward as much, and as well- 

 substantiated, experimental evidence as possible in its favour. 

 Although the results already quoted might seem to be sufficient 

 proof, the reaction of partially injured muscle to the passage of 

 an electrical current is of special interest, since it not only affords 

 a direct proof of polar excitation in v. Bezold's sense, but is also 

 of great moment in the theoretical action of the current. 



If the sartorius of a deeply-curarised frog is exposed as care- 



FIG. 87. a, Closure contraction, ascending direction of current (the kathode lies at the pelvic 

 end of the sartorius). The lower line corresponds with the kathodic half, b, Closure con- 

 traction, descending current. The upper line corresponds with the kathodic half of the 

 muscle. 



fully as possible, and stretched in Bering's double myograph, the 

 make excitation which previously appeared in approximately 

 equal proportions with either direction of current will, when 

 one end of the muscle is crushed by forceps, be altogether 

 abolished or considerably weakened, while the effect of the closing 

 excitation, if current is reversed so that the kathode falls on the 

 uninjured end of the muscle, remains unaltered. The break 

 excitation seldom comes about even after long-protracted passage 

 of current, if the anode is on the injured side (26) (Fig. 88). 



