188 THE PLANT CELL. 



wherever chemical actions are proceeding, however small these 

 may be, there will variations in electrical potential be produced, 

 a current flowing from the regions of greater activity to those 

 of less. 



Strong electric currents have the eflfect of causing an .imme- 

 diate contraction of the cytoplasm of a cell {Spirogyra, or Elodea 

 Canadensis), from which recovery is impossible. Currents of a 

 less intense nature cause either a partial retraction from the 

 cell-wall, with, later on, after the current has been stopped, 

 resumption of function. Upon swarmspores and antherozooids 

 swimming in water, a strong current has the peculiar effect of 

 polarising these bodies, so that they set with either one or the 

 other extremity facing in a definite direction — viz., either with or 

 against the direction of flow of the current. 



