THE REACTION OF NORMAL AND ABNORMAL NERVE 155 



(b) On breaking we obtain the so-called anodic opening contraction which 



is due to the excitatory process at the physiological anode beneath the 



physical anode. 

 (2) Cathodic Stimulation: 



(a) On making we obtain the so-called cathodic closure contraction in 



consequence of the excitation developed at the physiological cathode 



beneath the physical cathode. 

 (6) On breaking we obtain the so-called cathodic opening contraction 



which is caused by the excitatory alterations at the physiological anode 



beneath the physical cathode. 



It has been stated repeatedly that the cathodic irritability is 

 stronger than the anodic. For this reason, the two making or closure 

 contractions (C.C.C. and A.C.C.) must be stronger than the two break- 



FiQ. 93. — Diagram Showing Physical and Physiological Anodes and Cathodes. 

 A, the physical anode, or positive electrode; K, the physical cathode, or negative 

 electrode; a, a, a, physiological anodes; k, k, k, physiological cathodes. (American 

 Text-book of Physiology.) 



ing or opening contractions (A.O.C. and C.O.C). Thus, it only 

 remains for us to see why the cathodic closure contraction precedes 

 the anodic closure contraction and why the anodic opening contrac- 

 tion appears before the cathodic opening contraction. In brief, 

 this sequence of the reactions is dependent upon differences in the den- 

 sity of the current. On making, the current acquires a greater den- 

 sity or striking force when the physiological cathode coincides with the 

 physical cathode than when it lies in relation with the physical anode. 

 In the first case, we obtain what might be termed a summation of 

 effects between the inner physiological cathode and the outer physical 

 cathode. The same explanation may be given for the fact that the 

 anodic opening contraction develops before the cathodic opening 

 contraction. The excitation on breaking being developed at the 

 physiological anode, this stimulation becomes more effective if the 

 physiological anode and physical anode coincide. 



The Law of Contraction of Degenerated Human Nerve and Mus- 

 cle. — When called upon to ascertain the functional condition of a 

 certain muscle and its nerve, use should be made not only of the con- 

 stant current but also of the induced current. It should be noted 



