POLAR EFFECTS UNDER STRONG CURRENTS 261 



when the current had been increased to 12 micro-amperes, 

 excitation took place at both kathode-make and kathode- 

 break and also at anode-make and anode-break. Here we 

 have the characteristic effects of Type IV. — namely, Km 

 Kb Am Ab. The following table gives a synopsis of these 

 results : — 



Table I. — Effects of Currents of Increasing Intensity 

 ON Leaflets of Mimosa 



These conclusions were uniformly supported by the 

 results of no fewer than thirty different sets of experiments 

 on the leaflets of Mimosa. The only variations between 

 different experiments lay in the fact that with less sensitive 

 specimens a relatively higher current was required. Thus 

 in a leaf which was somewhat older, and therefore less 

 sensitive, the intensity of the current necessary for Type I. 

 was I micro-ampere ; for Type II. 3 micro-amperes ; for 

 Type III. 7'4 micro-amperes ; and for Type IV., 15 micro- 

 amperes. 



Leaflets of Biophytum 



With leaflets of Biophytum I obtained results which were 

 practically the same as those given by leaflets of Mimosa, 

 Thus with a given experimental specimen, the characteristic 

 effect, Km of Type I. was exhibited under a current-intensity 

 of '5 micro-ampere. When the current was increased to 2 

 micro-amperes the response was transformed to Km Ab, 

 that of Type II. At 3*5 micro-amperes the characteristic 

 effects of Type III. — Km Am Ab — made their appearance. 



