THE CURRENT OF M. GASTROCNEMIUS. 201 



different points on its outer surface will now easily be 

 understood, and are as represented in fig.. 54. It is 

 most especially necessary to notice that a strong current 

 must be generated on the interconnection of the upper 

 with the lower end of this muscle, and that the current 

 within the arch is directed from the upper to the lower 

 end of the muscle. The upper end must be strongly 

 positive ; for it represents the middle of the- longitu- 

 dinal section. The lower end must be strongly negative ; 

 for it is the acute angle of an oblique cross-section. 

 There are very few points so alike in the matter of ten- 

 sion that no current results from their connection. A 

 case of this kind is, however, shown in the fourth 

 arch. 



10 



