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ANNALS NEW YORK ACADEMY OF SCIENCES 



(ii) At regions where the resting fiber is not affected by the approach 

 of the impulse, but only by its immediate juxtaposition and its propaga- 

 tion. As shown in figure 3a, this occurs when the impulse propagates 

 from an electrically insulated region of the active fiber to a region 

 where it is in contiguity with the resting fiber. Effects Ai and C2 are 

 prevented by the insulation, the interaction being due to effects Ci and 



Figure 3a. Diagram showing current flow at junctional zone of two previously separated fibers, 

 (i) Impulse at junction give.s Ci effect on resting fiber; (ii) after further propagation, wake of 

 impulse gives A2 effect. 



(i) 



(ii) 



#i^^ 



se 



E*==F 





air. 



w^- 



Figure 3b. Penetrating current generated by impulse arising in one fiber, (i) Ci effect, as im- 

 pulse is initiated ; (ii) A2 effect, in wake of impulse, propagating in both directions from site of 

 origin. 



(i) 



(ii) 



<f- 



Figure 3c. Two fibers connected by double salt bridge, (i) Impulse opposite proximal arm; 

 (ii) impulse opposite distal arm, showing C1A2 action on resting fiber at proximal arm and A1C2 

 action at distal arm. 



A2* A similar effect would also be produced at a region in a passive 

 fiber adjacent to the origin of the impulse in the active fiber (figure 

 3b), and at the proximal arm of a double salt bridge (figure 3c). ^^ 



(iii) At regions where the resting fiber is influenced by the approach 

 and juxtaposition of an impulse, but not by its propagation. Figure 4 



* Cf . Arvanltakl, A.' Figure 4 III ; Marrazzi, A. S.. 8t R. Iiorente de XTd.^" Figure 3. 



