INADEQUACY OF PFLllGER'S LAW 



579 



one pair of leaflets before the anode. There was no action 

 at the anode itself at make. After a suitable interval, during 

 which the leaflets re-erected themselves, the current was 

 interrupted. There was now no action near the kathode at 

 break ; but excitation was induced at the anode, as was 

 shown by the fall of three pairs of leaflets in its vicinity (fig. 358). 

 The experiment was now repeated by reversing the direction 

 of the current. The poles being thus reversed, eight pairs of 

 leaflets fell at the new kathode, in and out. There was no 

 effect, however, at the new anode at make. But at break, 

 excitatory reaction was ini- 

 tiated at the anode, and none 

 at the kathode. 



These are the normal 

 effects, falling under Pfliiger's 

 Law, which holds good within 

 a certain medium range of 

 E.M.F. But when the E.M.F. 

 is much higher, I find that 

 these normal effects become 

 reversed. Thus, employing 

 an E.M.F. of 220 volts, it was 

 found that excitation took 

 place at the anode at make, 

 the excitatory depression of 



the leaflets passing slowly thence towards the kathode. At 

 break, excitatory action was initiated at the kathode, the 

 wave of excitation then passing towards the anode. I thus 

 found, by the employment of a very high E.M.F., that the 

 normal polar effects were completely reversed. Intermediate 

 between these two extremes of normal and reversed action, 

 I obtained a transitional phase, in which both anode and 

 kathode were seen to excite at make. At break also there 

 was here occasional excitation, at either anode or kathode. 

 Similar reversals and transitional effects have also been 

 noticed, in the case of certain protozoa by Kiihne and 

 Verworn. Thus Pelomyxa is excited by the anode at make, 



P P 2 



FIG. 358. Make-kathode and Break- 

 anode Effects in Biophytum 



Upper figure shows effect at make, 

 excitation being produced at 

 kathode. Lower figure shows 

 effect at break, excitation being 

 now produced at anode. 



