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A TEXTBOOK OF PHYSIOLOGY 



paration. A muscle which has been soaked in normal saline several 

 hours after its preparation is isoelectric. 



If a muscle which is at rest in such an isoelectric condition be 

 -damaged e.g., by heating it is found that there is now an electric 

 -current flowing through the galvanometer. In such an injured muscle 



Fig.1. 



Fig.HL: 



ffl 



El/Ktrotonua, 



FIG. 297. DIAGRAMS TO ILLUSTRATE CURRENT OF INJURY, NEGATIVE VARIATION, 

 CURRENT OF ACTION, ELECTROTONUS. 



the injured part corresponds to the positive element of a galvanic 

 battery. The current therefore flows in the muscle from the injured 

 part to the normal part; outside the muscle it flows through the gal- 

 vanometer from the normal t > the injured part. Tne " current of 

 injury " is usually described in terms of the direction of the current 

 through the galvanometer; therefore, the site of injury is said to be 

 negative (or zincative, like the zinc of the battery) to the normal 



