PLATE IV. 



Fiti. 7. — Slio\vin,u' tU'Cp liuriiiiii;' of 

 larije limb by bigliteiisioii ;iltor- 

 uatiug current wiru. 



Fig. 8. — SliowiDg elm tree killed by 

 direct current (reversed polarity) 

 from electric railway system. Note 

 etfects of Imriiinu- at the Viase of the 

 tree. 



