POLAR EFFECTS OF MODERATE CURRENTS 227 



are necessary. On starting the current, a pair of leaflets 

 at the kathode underwent an excitatory fall. No effect 

 was induced at the left anodic contact. At break there 

 was no effect at either. On reversal, the left contact became 

 kathode, resulting in the excitatory fall of a pair of leaflets. 

 This local character of excitation was due to feeble con- 

 ductivity. It is only under much stronger polar excitation 

 that a moderate amount of transmission takes place. At the 

 anode there was on this occasion no effect at make — nor 

 was there any excitation at break of kathode or anode. 



This experiment was repeated in the case of ten different 

 specimens, the result being invariably the same. 



Table VIII. — Effect of Feeble Current on Leaflets of 



Averrhoa carambola 



e.m.f. = 22 volts ; current = 4 micro-amperes 



Effect of moderate current. — In order to obtain the 

 characteristic reactions of Type II., the e.m.f. has generally, 



Table IX. — Effect of Moderate Current on Leaflets of 



Averrhoa carambola 



E.M.F. = 50 volts; current = ii micro-amperes 



Km 

 C 



R. Contact. 



Kb 

 O 



Am 

 O 



Ab 

 C 



L. Contact. 



K'm 

 C 



K'b 

 O 



A'm 

 O 



Excitation formula — Km Ab 



A'b 

 C 



in the case of Averrhoa carambola, to be raised to 50 volts or 

 thereabouts. Thus in a given experiment, under the action 

 of 50 volts and with a current intensity of 11 micro-amperes, 



Q 2 



