226 PHYSIOLOGY OF MUSCLES AND NERVES. 



CHAPTER XIV. 



1. General summary; 2. Fundamental explanatory principles; 3. 

 Comparison of muscle-prism and magnet ; 4. Explanation of the 

 tension in miLScle-prisras and muscle-rhombi ; 5. Explanation 

 of negative variation and parelectronomy ; 6. Application to 

 nerves ; 7. Application to electric organs and glands. 



1. Summing up the most important flicts given in 

 the foregoing chapters, we may make the following 

 statements : — 



(1) Every muscle, and every part of a muscle, luhen 

 quiescent, is positive on its longitudinal section; 

 negative on its ci^oss-section. In a regular muscle- 

 prism, the p)0sitive tension decreases regularly from 

 the centre of the longitudinal section toiuard the ends; 

 and the negative tension does the same in the cross- 

 sections. In a muscle-rhomhus the distribution of 

 the tension is someiuhat different, for in it the 

 greatest positive tension is removed toward the obtuse 

 angle of the longitudinal section, the greatest negative 

 tension totvard the acute angle of the cross-section. 



(2) During the activity of the muscle the diff^erences 

 in tension decrease. 



(3) Entire muscles often exhibit but slight differ- 

 ences in tension, or even none at all; but vje must 

 nevertheless assume the existence of electric opposition 

 in them. 



(4) Nerves are positive on the longitudinal section. 



