ANIMAL ELFXTRICITV. LECTURE I. 3 



all points, or what comes to the same thing, equally- 

 active at all points. Any two points being ex 

 hypothesi equally active, are equally electromotive — 

 " isoelectric,"— and if connected by wires to a galvan- 

 ometer, exhibit no current. But stir up B by pinching 

 or pricking or by a touch of a hot wire, and you 

 will at once obtain a current through the ralvan- 

 ometer that indicates the presence of current In the 

 rest of the circuit as shown by the arrows. In the 

 mass of protoplasm which Is no longer uniformly 

 active throughout, but more active at B than at 

 A, there Is current from B to A. In the galvan- 

 ometer the current Is from A to B. 



These two unequally active regions B and A 

 form a w^eak voltaic couple, of which B, the more 

 active spot, where more chemical action Is going on 

 (we shall further on Inquire Into the possible character 

 of such chemical action), Is the generating or electro- 



excitability. A spot of tissue under the influence of the anode 

 is less excitable and more zincable. I have not been willing to 

 use the less inelegant words electromotive and electromobile in 

 place of zincative, zincable, for fear of an ambiguity in the term 

 electromobile which has seriously impaired the precision of the 

 term excitable. A tissue may be more excitable (erregbar) inas- 

 much as it may be aroused to action by a weaker stimulus, or 

 more excitable (leistungsfahig) inasmuch as greater action is 

 aroused by a given stimulus. A more zincable spot, as the name 

 suggests, is capable of greater electropositive action than a less 

 zincable spot. 



