CHAPTEE IX. 



/. Electric phenomena; 2. Electric fishes; 3. Electric organs; 

 4. Multiplier and tangent galvanometer ; 5. Difficulty of the 

 study; 6. Homogeneous diverting vessels; 7. Electromotive 

 force ; 8. Electric fall ; 9. Tension in the closing arch. 



1. As yet in examining the essential qualities of 

 muscles and nerves we have disregarded a series of 

 important phenomena common to both, in order that 

 we may now treat them as a whole. We refer to the 

 electric actions which proceed from these tissues. 

 Muscles and nerves are especially distinguished among 

 all other tissues of the animal body by the fact that 

 they exercise very regular and comparatively powerful 

 electric action ; and from the relation existing between 

 electric currents and the excitability of muscles and 

 nerves it may be inferred that these independent elec- 

 tric actions bear some relation to the essential qualities 

 of muscles and nerves. 



It is true that electric action is exhibited in other 

 animal, as well as vegetable tissues ; but these are very 

 slight, and are apparently insignificant. 1 Electric cur- 

 rents are so easily generated under all circumstances 

 that it is not very surprising that traces of them are 



1 An exception is perhaps afforded by the electric phenomena 

 of the leaves of Diuncea miiscijmla which will presently be men- 

 tioned. 



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