8 



ANIMAL ELECTRICITY. LECTURE 



its nerve are still alive — and at the same time you see 

 that the spot of light deflected one way by the current 

 of injury from T to L, moves the other way {i.e., under- 

 goes a negative variation) when the muscle contracts. 

 This negative movement of the spot means that the 

 chemico-physical change taking place in the con- 



FiG. 4. — Muscle currents. 



The "current of injury" is from T to L in the muscle. The "current of 

 action " (negative variation of the current of injury) is from L to T in the 

 muscle. 



tracting muscle is greater at L than at T, or that L 

 has become zincative to T. 



A little reflection will soon convince you that this 

 fact falls under our key principle. We started with 

 a current of injury due to a difference between T and 

 L ; T was active and zincative, therefore less capable 

 of further activity, i.e., less zincable than L. When 

 by exciting its nerve, we stirred up the whole muscle, 

 T and L included, we obtained a greater augmenta- 



