340 



MOTION IX ANIMALS AND PLANTS. 



the elootrodo away from the liofaturo in oithor direction it disappears. 

 The phenomenon which is thus brought to liofht is that to which the 

 cjreat founder of animal electricity. Du Bois-Keymond, applied the 

 term '"muscle current." and when the method I have described is 

 employed it presents itself in its utmost simplicity, for by the act of 

 tiohteninjr the lio-ature previously applied under an electrode you at 

 once lirincj into existence a state of thing's in which the constricted 

 part is negative to the living parts on either side. 



What happens in this case? What is the ditference between the 

 state of the surface of contact inuuediately before and inuuediately 

 after the tightening of the ligature { Nothing more can be said than 

 that a certtiin process which was going on there and which provisionally 

 we call ••life." being ignorant of its nature, has been annulled. What 

 we actuall}' observe may be represented diagrammatically thus: 



D'ia(ji\iiti ,>. 



Tho divided line represent? the graduated wire of a potentiometer; at d i^ a ligature 

 as yet not tightened round a musele; p and </ are equipotontial. The galvanometer 

 is at zero and the slider of the potentiometer is up to the lilock. The ligature is 

 tightene<l; at ouee the needle indicates a current directed from d to p, but can be 

 brought by the slider agai'n to zero. 



The contacts are as shc)wn in the diagram. Before tightening the 

 ligature between them they are equipotential. because they both rest 

 on muscle in the same physiological state. I represent the electrical 

 concomitant of that state by an arrow, by which I mean nothing more 

 than that if it wei-e possible to connect j) with some other part of the 

 muscle, without passing through another electromotive surface, there 

 would be a current in that circuit from j) to the galvanonu^ter. But 

 inasmuch as the actual circuit passes through d where tlu^ same condi- 

 tions exist as at p. but opposed in direction, there is no current. If 

 by tightening the ligature I annul the eti'ect of </, the eti'ect of y> comes 

 into evidence. This statement is simple, and seems to arise naturally 

 from the observed facts, but can not be received Avithout question, for 



