ANIMAL ELECTRICITY. — -LECTURE I. 5 



The direction of deflection is as you see such as 

 to indicate current in the voltaic cell from zinc to 

 copper. Whatever you may choose to remember or 

 forget, bear in mind that zinc is the active plate, at 

 which chemical change takes place, and electromotive 

 pressure takes origin. Later on when we come to 

 deal with the electrical response of living nerve, we 

 shall find it of the utmost convenience to make use 

 of language based upon this fundamental notion, to 

 speak of living nerve as being more or less zincative 

 or zincable, as having greater or smaller zincativity 

 and zincability. 



Second Preliminaiy Experiment, — Let us in fact 

 simplify matters further ; omitting the copper plate 



Fig. 3. —A bit of zinc wire held in the right hand and touching one terminal 

 of a galvanometer circuit (while the other hand rests on the other terminal) gives 

 current in the body from right to left, in the galvanometer from left to right. 

 The current is aroused at the contact between the zinc and the slightly moist skin, 

 and is directed from zinc to fluid. (If the galvanometer wire, instead of ending at 

 a metal terminal R, dips into a glass vessel of salt solution, and circuit is completed 

 by dipping the zinc into the same solution, current would run the other way round 

 — /.<?., anti-clockwise instead of clockwise — being as before from zinc to fluid.) 



