796 Electeo-Culture. . [Dec, 



iijg crop when the discharge is most effective. Wire networks 

 charged to a high voltage (4,000-16,000 crest value) were sus- 

 pended at various heights above the plants; the current passing 

 through plants was led off from the bottom of the insulated 

 pots to a micro-ammeter reading to 0.01 microamp. The networks 

 were made positive, except for one set of experiments in 1921. 

 The control pots were " earthed " in all cases. 



In 1918 and 1919 the high tension discharge was obtained 

 by the use of a mercury interrupter and an induction coil, 

 Lodge valves being employed for rectification. In the experi- 

 ments of 1920 and 1921 the installation consisted of a small 

 rotary converter giving 70 volts A.C., and a wax-impregnated 

 transformer made by Messrs. Newton and Wright. The over- 

 head networks, when alternating current was used, were con- 

 nected directly to the transformer; when direct current was 

 required rectification was obtained by means of Lodge valves. 

 The plants themselves were able to bring about some slight 

 rectification. 



The discharge in these pot experiments was usually given 

 for about six hours each da}'. There were two experiments 

 with wheat, nine with maize, and nine with barley. 



In 1918 it was found that (under the conditions of the 

 experiments) currents passing through the plants of the order 

 10 X 10 — 9 amp. were injurious in the case of the early 

 vegetative stages of maize. Currents as low as 0.3 x 10 — 9 

 amps, appear to have an accelerating action on growth. The 

 experiments of 1920 suggested that alternating current is as 

 effective as direct current, if not more effective; the results 

 obtained that year with direct current were, however, less 

 satisfactory than in previous years. 



The experiments of 1921 confirmed the results of 1920 that 

 alternating current is usually as effective as, or more effective 

 than, direct current. They further suggested that an upward 

 current through the plant can increase growth in the same 

 way as a downward current: and. lastly, they suggest that 

 a discharge apj^lied for the first month only of the growing 

 season may be at least as effective as one continued throughout 

 the growing season— -'a result, if confi.rmed, of great importance 

 since it shows that the rnnnin<: costs of crop electrification can 

 b(^ markerlly reduced. 



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