io6 



RELATION OF PLANTS TO ELECTRICITY 



contact with the compacted seeds. Connect the wires to the 

 electrodes with an ammonia, or preferably an Edison-Lalande 

 battery. Place a milliammeter, mercury key rheostat in the cir- 

 cuit. Stimulate for one minute, with 

 the rheostat adjusted to give a current 

 to two-tenth milliampere. Remove 

 the seeds and carefully select fifty, and 

 place them in a germinating dish, and 

 an equal number of untreated seeds 

 in another dish kept at a suitable tem- 

 perature, and at intervals of twelve to 

 twenty-four hours note the number 

 of seeds germinated in each lot. At 

 the end of forty-eight or seventy -two 

 hours measure the radicles and hypo- 

 cotyls, and from the average length 

 obtained determine the percentage 

 of accelerated growth. Determine 



whether the same results can be ob- 

 FIG. 49- A, normal specimen tained by the use of dried seeds i ( See 

 of Mimosa. B. after shock. - i i / 1 \ 



any handbook of physics). 



163. Effects of Continuous Stimulation. Procure two large 

 glass funnels and support them by glass cylinders. Fill both 

 with earth, and place copper electrodes at the bottom and top of 

 the cone of each funnel. Connect the electrodes of one funnel 

 with a gravity cell battery, leaving the other funnel unconnected. 

 Insert resistance and a milliammeter in the circuit, keeping the 

 current at about two-tenth milliampere. In case the milliam- 

 meter is not used determine the E.M.F. and the resistance of the 

 soil, regulating the strength of current with the rheostat. Ger- 

 minate peas or beans in sawdust, and when the radicles reach a 

 length of one inch, select twenty showing exactly the same de- 

 velopment and growth capacity. With a wire make some chan- 

 nels in the soil close to the glass sides of the funnels and insert 



1 Kinney, A. S. Electro-germination. Hatch Exp. Sta. Bull. 43. 1897. 



