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. 



FIG. 84. Cross section of Monostroma latissima (X 450). 



When an electrical current passes from a salt solu- 

 tion into a living cell, ions must enter the protoplasm. 2 

 An increase in the permeability of the protoplasm to ions 



Fio. 85. Cross section of Ulna lactuca, var. latissima (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. Cf. Stiles and Jorgensen (1914). 



