ELECTROKINETICS 



379 



evidently associated, it should be possible to accelerate the 

 ascent of sap by applying an electromotive force to the terminals 

 of a plant (Fig. 164). Whether we thus aid or retard the 

 movement of sap will depend on the sign of the charge of the 

 flowing water. In the case of glass capillaries, we found it to be 

 positive (page 364) ; in other capillaries it may be the same or it 

 may differ. Most work on cellulose indicates that the capillary 



Fig. 164. 



-A plant in an electrical atmosphere which brings about an increase in 

 flow of sap. {From N. Marinesco.) 



water is positive. In the experiment of Marinesco no direct con- 

 nection between the applied field and the plant is necessary. 

 The latter is simply put in an atmosphere of electricity. 



If it is true that the rate of flow of sap is accelerated by an 

 applied electromotive force, then an apphed external electric 

 field should be expected to have an influence on the rate of 

 growth of a plant. Such experiments in electroculture have 

 been done (page 333), with, however, varying results. 



Cataphoresis. — Relatively little work has been done on the 

 cataphoretic migration of whole plant cells, except for bacteria. 

 There are some observations by Winslow on yeast and the green 

 unicellular alga Chlorella and by others on fungal spores and 



