EFFECTS OF ANODE AND KATHODE 241 



There is no excitation, since feeble anode does not excite at 

 break. 



Effect of Strong Current 



We now take up the question of the effect of strong 

 currents : — 



(i) Make of descending current. — In the nerve-and-muscle 

 preparation there is excitation of muscle at the make. 

 Here the kathode is proximal, and we obtain the normal 

 excitatory effect of kathode-make. 



In the corresponding experiment with Biophytum we 

 find excitation transmitted to the terminal or extra-polar 

 region to the left, five pairs of leaflets undergoing closure. 

 Only two pairs of leaflets closed in the intra-polar region, 

 further progress of excitation being arrested by the 

 depressing action of the anode. 



(2) Make of ascending current. — Unlike the action of 

 feeble current, there is no excitatory effect in the nerve- 

 and-muscle preparation at the make of strong ascending 

 current. This is explained on the supposition that the 

 excitation at the distal kathode cannot traverse the region 

 of the strong anode with its depressed excitability. The 

 proof of this assumption is strikingly afforded by the 

 corresponding experiment with Biophytum. We observe 

 the initiation of excitation at the kathode, but the pro- 

 gress of excitation is arrested near the region of anode. 

 Hence, in spite of the occurrence of excitation, there 

 could be no transmitted effect in the terminal extra-polar 

 region. 



(3) Break of descending current. — In a nerve-and-muscle 

 preparation there is no excitation at break of a descending 

 current. Here, though the distal anode excites at break, 

 the intervening kathodic region is assumed to undergo 

 depression at break. Hence a block occurs to the trans- 

 mission of excitation. 



This is made quite clear in the corresponding experiment 



