FUNCTION IN PLANT LIFE 21 



polarity almost instantly. The right needle was quite 

 blackened and the left needle clean. As this discordant 

 result might have been due to leakage through the moist 

 poles or terminals of the vegetable, I painted both with 

 a non-conducting solution and allowed it to dry, in order 

 to see if higher insulation would slow down the rate of 

 discharge. 



The experiment with No. 2 was then repeated under the 

 same conditions but with fresh points of contact. 



After ten minutes' charge D = very rapid off-scale 

 positive. The vegetable then remained short-circuited 

 through 5,000 ohms. D continued off-scale for seventeen 

 minutes, when the vegetable was accidentally knocked over. 



No. 2 (third experiment). The connections were put 

 to earth until the vegetable regained polarity and gave 

 perfect reversals. It was then charged for ten minutes 

 with 1-5 volts, when D = very rapid off-scale positive, not 

 falling to 250 mm. positive until sixteen minutes later. 

 The period of fall from 250 mm. positive to 250 mm. 

 negative was eight minutes, and ten minutes later the 

 vegetable had recovered. The conclusion, or one con- 

 clusion, to be drawn is, of course, that absolute insulation 

 is a factor of primary importance in retention of charge. 



THE ORANGE. 



Circumference 8 J in., weight 5| oz. After ten minutes' 

 charge D = fairly rapid off-scale positive. In ten minutes 

 it fell to 250 mm. positive, and in fifteen minutes more the 

 light had reached 250 mm. negative ; the fruit regaining 

 its former full polarity fifteen minutes later. The right 

 electrode showed a mere trace of electrolysis. The charge 

 in this case remained on the positive side of the scale for 

 nineteen minutes, but the absolute insulation of the orange 

 and lemon is not very high. 



