REVERSED POLAR EFFECTS IN LIVING TISSUES 205 



transition stage. In the next experiment, the tendency to 

 reversal will be shown to have become predominant. 



In this third experiment with another specimen, an 

 E.M.F. of 220 volts was again used. At make, there was 

 an immediate energetic fall of the anodic leaflet, while that 

 at the kathode was slight, and delayed for some time. At 

 break, moreover, there was no effect on the anode, and a 

 slight and delayed excitatory effect was distinctly perceptible 

 at the kathode. From this we see that the anode is now 

 appropriating the normal action of the kathode, and vice versa, 

 reversal having set in unmistakably. 



Reversed action in protozoa.— These experiments will 

 probably be found to explain the assumed anomaly in the 

 case of protozoa. In experimenting on ActiuospJuurium, for 

 example, Verworn found that ' at closure of the current in 

 the first place, the pseudopodia, both on the anodic and 

 kathodic side of the globular body, become varicose and 

 begin to contract. If the circuit be opened the pseudopods 

 on the kathodic side become varicose in about the same 

 degree as had taken place immediately after the closure of 

 the circuit.' x In this experiment, where both anode and 

 kathode exhibit excitation at make and only the kathode at 

 break, we have a case exactly parallel to that of the third 

 experiment with Mimosa, which has just been described. 

 That, as in the case of plant-tissues, a fairly high E.M.F. was 

 instrumental in producing reversal appears probable, from 

 the fact that it is specially mentioned in the account of the 

 experiment, that ' in consequence of the high resistance in the 

 circuit, a comparatively high E.M.F. had to be used.' 



Experimental verification of B stage effect. — I could 

 not obtain with Mimosa at 220 volts complete cessation of 

 excitation at the kathode at make, but I succeeded in doing 

 so with Averrhoa, in the autumn and winter seasons. With 

 this .plant, I observed all these A stage effects, which have 

 already been described in the case of Mimosa ; and that of 

 completed reversal, or the B stage effect, was obtained in 



1 Biedermann, Electro- Physiology, English edition, 1 896, vol. i. p. 302. 



