224 FUNDAMENTALS OF AGRICULTURE. 



of sap is not so active, the odors are not as a rule so 

 marked. If only one root becomes affected with gas, 

 that part of the tree nearest it will show the effect first, 

 and if the poisoning has not extended to the tree trunk, 

 amputation of the affected root is the best remedy. 

 Such fungi as Schizophyllum, Polystictus and others 

 often appear on trees soon after they are affected, and 

 their presence is sometimes significant. 



Detection of Leakage. Certain devices may be em- 

 ployed at no great expense when installing a system 



me',.: V 



ONE EFFECT OF ALTERNATING CURRENT ON TREES. 



of lines which will quickly detect a source of leakage 

 and prevent gas from escaping into the soil, but little 

 can be done for a tree when the soil near it has once 

 become saturated with gas. 



Electrical Injuries occur from three causes : alter- 

 nating currents, direct currents and lightning. Alter- 

 nating currents seldom completely kill a tree, causing 

 only local burning at the point of contact with the 

 wires. It is true that a large limb or even the top of a 

 tree may be killed by the branches being burned off, 

 but it would require an exceptionally high potential to 

 affect a tree as a whole. 



Do Not Attach Wires to a Tree. Sometimes a tree 

 may be injured a few feet below the point of contact 

 with the wire, but that is all. There is always danger 



