Electricity — Radium-, N-, and X-rays 



PoUacci's careful experiments with flowering plants 

 also led him to believe that plants are distinctly in- 

 vigorated and assimilate more under electric currents. 

 His statement that plants can form sugar in the dark 

 when so stimulated has not yet been confirmed by 

 other observers. 



The effect of electric currents on roots is still very 

 obscure. When a current is passed through water in 

 which there are seedlings growing, the rootlets often 

 turn towards the positive pole. This is supposed to 

 be due to some kind of electrolysis, injurious products 

 accumulate at this pole, and the turning of the little 

 roots towards them may be compared to the usual 

 bending of injured roots towards the source of irrita- 

 tion.^ This would mean that the electric current may 

 in itself have no effect upon them. 



But many ingenious and interesting experiments have 

 shown that it is possible to use electricity in order to 

 help to accelerate the growth of plants. 



A Scotchman, Maimberg, tried to stimulate two 

 myrtle bushes in 1746, but his results (the first to be 

 attempted) were not conclusive. 



Next came the Abbe Nollet, who grew pot plants on 

 an iron tray supported by silk threads. The plants so 

 isolated were charged by means of an electrostatic 

 induction machine. Both maize and mustard seed 

 germinated much more rapidly. 



Bertholet set up a tall pillar with cupped points, so 

 collecting atmospheric electricity, which was conducted 

 into a series of plants at the base of the pole. Another 

 ingenious system consists in sinking plates of copper and 

 zinc in the soil of a greenhouse, and connecting them 

 by a wire. Speschnew, a Russian, invented this method, 

 which has also been followed by Priestley in 1906.^ 



Others have used an arrangement of wires supported 



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