THE EXCITATION OF NERVE FIBRES 303 



stimulating electrode is the cathode. These different contractions are generally 

 represented by capital letters, and the usual relationship is expressed by the 

 statement that CCC is obtained most easily, then ACC and AOC, and finally 

 COG. 



CCC = cathodal closing contraction. 



ACC = anodal closing contraction. 



AOC = anodal opening contraction. 



COC = cathodal opening contraction. 



When the motor nerve to a muscle has undergone degeneration the muscle 

 also begins to degenerate, and we find certain alterations in its response to 

 artificial stimulation. In the first place, the muscle may fail to respond to 

 induction shocks, while it may show an increased irritability for galvanic shocks. 

 In the second place, qualitative alterations in irritability may be present, so 

 that ACC may be obtained with a smaller current than CCC. These alterations 

 are spoken of as the ' reaction of degeneration. ' 



