532 



HANDBOOK OF PHYSIOLOGY. 



The contraction which occurs when the current is closed (closing con- 

 traction) represents irritation at the physiological kathode, while the 

 opening contraction represents irritation at the physiological anode. 



Shin 



Fig. 340. Diagram of skin and subjacent nerve. A, the positive electrode or physical anode; 

 B, the negative electrode or physical kathode. Signs -{-, physiological anodes; signs , physio- 

 logical kathodes. (After Waller.) 



Since there are physiological anodes and kathodes beneath each elec- 

 trode, one or more of four conditions may arise: 



1. Anodic closing contraction, i.e., the effect of the change developed 

 at the physiological kathode, beneath the physical anode (positive pole). 



2. Anodic opening contraction, i.e., the effect of the change developed 

 at the physiological anode, beneath the physical anode (positive pole). 



3. Kathodic closing contraction, i.e., the effect of the change devel- 

 oped at the physiological kathode, beneath the physical kathode (nega- 

 tive pole). 



4. Katliodic opening contraction, i.e., the effect of the change devel- 

 oped at the physiological anode, beneath the physical kathode (negative 

 pole) . 



The following abbreviations of these contractions are used : AGO, 

 AGO, KCO, KOC. 



The closing contractions, KCO and AGO, are stronger than the 

 opening contractions, KOC and AOC. Of the closing contractions, 

 KCC is stronger than AGO. Of the opening contractions, AOG is 

 stronger than KOC. These facts are also shown in a table of the effects 

 of gradually increasing the strength of the current. 



Weak currents. 



KCC 



Medium currents. 



KCC 

 ACC 

 AOC 



Strong currents. 



KCC 

 ACC 

 AOC 

 KOC 



Sometimes AOC is stronger than AGO. 



In diseases which cause degeneration of the nerves going to a muscle, 

 stimulation causes results different from the above, and we get what is 

 known as the reaction of degeneration. 



