44 CELLULAR 



transfer of ions through the protoplasm as 

 indicated by some older experiments and more 

 recently made highly probable by investigations 

 carried out in my laboratory by Mr. L. R. 

 Blinks. In that case the increase in conductivity 

 (as measured by the alternating current) which 

 occurs when a cell is injured may be regarded as 

 analogous to the change by which a condenser 

 becomes a conductor. If the cell surface is 

 covered with a non-conducting substance injury 

 might alter this substance in certain places, so 

 that the conductivity would increase. If this view 

 should turn out to be correct we should never- 

 theless continue to regard the measurements of 

 the electrical conductivity of living tissues by 

 means of the alternating current as of great 

 value in detecting changes of permeability. The 

 reasons for this have been given in discussing 

 the electrical method. 



If we adopt the hypothesis that ions can enter 

 normal protoplasm only very slowly it is evident 

 that injury and death are accompanied by in- 

 creased permeability to ions. There is good 

 evidence that this is the case. 



