242 RESEARCHES ON IRRITABILITY OF PLANTS 



with Biophytum. We here observe excitation initiated 

 at the anode at break, two pairs of leaflets undergoing 

 closure, and the further progress of the excitatory wave is 

 arrested before reaching the depressed region of kathode- 

 break. 



(4) Break of ascending current. — Excitation occurs in a 

 nerve-and-muscle preparation at the break of strong ascend- 

 ing current. Here the anode is proximal, and excitation 

 induced at break reaches the terminal organ without 

 hindrance. 



In the corresponding experiment with Biophytum we 

 observe five pairs of leaflets undergoing closure in the 

 terminal extra-polar region, the excitation being initiated 

 at the anode at break. Excitation also traversed the 

 intra-polar region, two pairs of leaflets undergoing closure. 

 Further progress in this direction was, however, arrested 

 by the depressing action of kathode-break. 



Summary 



The contrasted effects of anode and kathode are exhibited 

 by appropriate modification in the pulsating activity of 

 Desmodium gyrans. 



The anodic effect of expansion is seen in the reduction 

 of normal limit of systolic contraction. 



The kathodic effect of contraction is observed in the 

 reduction of normal limit of diastolic expansion. 



The immediate effect of break is the reverse of that at 

 make or continuation of current. 



The diastolic arrest by anode is followed at its break by 

 systolic contraction. 



The systolic arrest by kathode is succeeded at its break 

 by diastolic expansion. 



In nerve-and-muscle preparation the effects of ascending 

 and descending currents are found modified by the intensity 



