148 THE SIGNS OF LIFE [LECT. 



ations in support of my choice of the kation rather than the 

 anion as the principal carrier in the case of an action current. 



We have regarded the tension and solution-pressure of 

 metallic, basic, positive sign as increased at the surface of the 

 living core under the influence of the negative pole. 



Under this same influence we should also have a decreased 

 tension and solution pressure of non-metallic, acidic, negative 



sign. 



This second mode of transport seems to me to imply neces- 

 sarily the diminution of a pre-existing state of difference ; 

 whereas the kationic nature of an action current does not 

 necessarily imply any pre-existing state of difference. No 

 doubt, as a rule, all living matter is at least sub-active at low 

 pressure within its internal medium, the lymph. But that is 

 " pre-existing difference " of very different order to a pre- 

 existing difference great enough to permit of the great diminu- 

 tions of difference that should be caused by great augmentation 

 of activity and of pressure. 



On these general grounds, therefore, without wholly dis- 

 regarding the possibilities of anionic transport, I have chosen 

 to consider action currents as effected by kationic transport from 

 the seat of action rather than by anionic transport towards the 

 seat of action. And I say again on these grounds, as well as 

 for reasons given in a previous lecture, that active living matter 

 is zincative. 



One further reason for this preference of the kationic to the 

 anionic view of action currents (vegetable as well as animal, I 

 may remark) may be briefly mentioned now, in anticipation of 

 evidence that I hope to more fully place before you at some 

 future occasion. 



You know that, according to modern theory, the molecules of 

 a neutral salt, such as, e.g., NaCl in aqueous solution, exist not 

 solely as non-electrical molecules of NaCl, but also (and in dilute 

 solutions chiefly) as charged ions Na+ and Cl - . In, e.g., what 

 we ordinarily call " normal saline " in the laboratory, made up 

 to contain T V grammolecule per litre of water, i.e., 5.84 grammes 

 per litre, ^j- of the amount of salt is present in the dissociated or 

 ionised state as Na+ and Cl - , and the only uniting force 



