CHAPTER XVI 



THE CONTRASTED EFFECTS OF ANODE AND KATHODE 



Polar effects of currents on pulsation of Desmodium gyrans — Reduction 

 of systolic contraction by anodic action — Diminution of diastolic 

 expansion by kathodic action — Arrest at systole by make of kathode 

 and diastolic expansion by break of kathode — Arrest at diastole by 

 make of anode, and systolic contraction by break of anode — Effects 

 of ascending and descending currents of feeble and strong intensity in 

 nerve-and-muscle preparation — Parallel effects in petiole-and-pulvinus. 



We have seen that under currents of moderate intensity the 

 polar effects of anode and kathode are more or less antithetic. 

 The kathode excites at make, whereas the anode excites at 

 break. If the kathode at make induces contraction, then 

 it would appear probable that at the make of anode there 

 may be produced an expansion. At break, again, supposing 

 the same antithesis to be maintained, the contractile effect 

 at the anode will have a contrasted effect of expansion at 

 the kathode. 



Biedermann has shown that in a beating heart the point 

 of appHcation of the anode, during make, remains expanded 

 as a dark red blistered swelling, even when the rest of the 

 heart, during contraction, is becoming pallid. This shows 

 that during the continuation of the anode an expansive 

 reaction is induced in the tissue. An effect similar to this 

 is induced at the kathodic point at break. 



I have been able to demonstrate the contrasted effects 

 of anode and kathode, in a still more striking manner, in 

 the case of rhythmic pulsation of the leaflet of Desmodium 

 gyrans. 



In a future chapter it will be shown how remarkable 

 are the similarities of the rhythmic tissue of the plant and 



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