viii.] SOLUTION-PRESSURE 147 



the kathode, of anions from the kathode viz., attraction of the 

 former, repulsion of the latter, as regards the surface of separa- 

 tion between core and bath. 



The attraction of the kation to the surface of the core is in 

 this view of the matter to be regarded as the essential factor of 

 excitation (and of increased excitability), inasmuch as such 

 attraction is equivalent to an increased " solution-pressure " of 

 kations. The living core, under the influence of the kathode, is 

 rendered more active and discharges into the surrounding 

 solution a greater number of electro-positive ions since the 

 pressure-difference of such ions in the core and in the solution is 

 increased. As mentioned in a previous lecture, this is the state 

 of things that I conceive to exist when I make use of the 

 expression that active (or excited) living matter is " zincative " 

 to resting living matter. I imagine " current of action " as 

 being conditioned by the discharge from active stuff of free 

 kations, and I choose zinc by name as the representative kation. 

 But, you say perhaps, why have you specified the kation 

 rather than the anion as the effective agent in the produc- 

 tion of an action current ? Is not current from an excited to 

 an unexcited spot accounted for by a transport of negative 

 electricity by anions towards an excited spot, as well as by 

 a transport of positive electricity by kations away from an 

 excited spot ? 



Or again, you definitely object that it is wrong to think 

 of kations as travelling against current, or anions with current. 

 To the second of these possible objections in your mind, I 

 answer at once that we are not considering simple passage of 

 the exciting current through the electrolyte, but the excited 

 current arising at the exciting pole of the former viz., at the 

 kathode. And, if you are in any doubt about this kathodic 

 action current produced during the passage of the exciting 

 current, perhaps you had better consider on similar lines the 

 post-anodic action current that is witnessed after an exciting 

 current has been stopped. In this case we clearly have to do 

 with a sudden release of kationic pressure, as the repellant 

 influence of the anode terminates. 



To the first point I have to offer you at least two consider- 



