POLAR EFFECTS OF MODERATE CURRENTS 223 



undergoing closure in the intra- and two pairs in the extra- 

 polar regions. No effect was induced to the left by anode- 

 make A'm. Nor was there any effect induced at break of 

 current, Kb or A'b. On reversal, the left contact showed 

 the excitatory reaction of K'm, two pairs of leaflets under- 

 going closure in the intra- and none in the extra-polar 

 regions. The difference in the extent of transmitted excita- 

 tion as given in Km and K'm is here due to the fact that 

 the left leaf was slightly the older and less sensitive of 

 the two. On break there was no effect induced at either 

 kathode or anode. I carried out in this way more than 

 fifty experiments regarding the excitatory effect of feeble 

 current on the leaflets of Biophytum. The minimally effec- 

 tive e.m.f. in these cases varied from 4 to 8 volts, and the 

 range of e.m.f. through which the effects of Type I. persisted 

 was found to be between a minimum of 4 volts and a maxi- 

 mum of 20 volts or thereabouts. In all these experiments of 

 the first type excitation took place only at kathode-make 

 and not at kathode-break, or anode-make or break. This 

 result was without a single exception. The characteristic 

 excitatory formula for Biophytum, under feeble current, is 

 thus, as in leaflets of Mimosa, Km. 



The following table gives the result with feeble 

 current : — 



Table IV. — Effect of Feeble Current on Leaflets of Biophytum 

 e.m.f. = 4 volts ; current = -5 micro-ampere 



Effect of moderate current. — Taking another specimen, I 

 applied an e.m.f. of 22 volts between two points in the same 

 leaf, the intensity of current being 2*1 micro-amperes. In 



