196 INJURY, RECOVERY, AND DEATH 



the two phenomena may be closely connected. If this is 

 the case it may be possible to use electrical conductivity 

 as a measure of permeability. 



Let us consider this from the standpoint of the per- 

 meability of protoplasm to salts. 



r^ 



Fig. 84. — Cross section of Monoslroma latiiaima (X 4S0). 



When an electrical current passes from a salt solu- 

 tion into a living cell, ions must enter the protoplasm.^ 

 An increase in the permeability of the protoplasm to ions 



Fig. 85. — Cross section of Ulva lactuca, var. laiissima (sea lettuce). (X 450). 



must decrease its electrical resistance, and vice versa. 

 The electrical resistance of the protoplasm may there- 

 fore be regarded as a measure of its permeability to ions. 



"In this connection it should be noted that experiments have been 

 made with direct currents. Of. Stiles and Jorgensen (1914). 



