VII. RELATION OF PLANTS TO ELECTRICITY AND 

 OTHER FORMS OF ENERGY 



156. Nature of Influence of Electricity upon Plants. The rela- 

 tions of electrical energy to plants are but imperfectly known, and 

 but few phenomena are capable of satisfactory demonstration. It 

 is well established that marked differences in electric potential are 

 found in all active plant bodies. Such departures from a state of 

 equilibrium are due in part to the action of currents of water, and 

 also to the conversion of chemical and other forms of radiant 

 energy into electrical force in the metabolic processes. Whether 

 the currents established in this way play any essential part in the 

 organism, or whether they represent total dissipations of energy 

 is not known. It is quite probable however, that the movements 

 of fluids and gases are influenced profoundly by these currents. 

 Large plants, such as trees, with erect trunks extending upward 

 into the air, also serve as points of discharge of static electricity 

 between the soil and air and these discharges are often so intense 

 as to shatter the bodies of the plants. Earth currents exercise a 

 directive influence upon the growth of roots, probably upon 

 other organs also. Electrical energy exercises a very marked 

 stimulating influence upon protoplasm, inducing contractility. 1 



157. Measurement of Differences in Electric Potential. A cap- 

 illary electrometer, a key and a pair of non-polarizable electrodes 

 will be necessary to perform this experiment. The electrometer 

 may be purchased from dealers in physical apparatus, and also 

 any simple key for opening and closing a circuit. The electrodes 

 may be made as follows : Secure two small glass tubes a few cm. 

 in length and close one end of each with a plug of well-kneaded 

 modelling clay, through which projects a small camel's-hair brush. 



1 Stone, G. E. Influence of electricity upon plants. Bot. Gazette. 27: 123 

 1899. 



