1 1 



heat developed at the point of insertion of the wires or electrodes, 

 neither was there any change in the reading of the milammeter after 

 being connected for some minutes. The latter connection was left 

 on the tree for several months. The attachment with the uninsulated 

 feed wire, however, occasionally became misplaced, and the exact 

 length of time when a definite contact was made is not known. 

 There was a contact during periods of wet weather at which time 

 there was always considerable heat developed where the positive 

 wire was connected with the tree, but not enough to melt soft solder 

 which connected the wires with the electrodes. Examination of the 

 tree ten months later showed that a portion of the tissues near the 

 electrodes had been killed. After removing the dead bark, an oval 

 space, 6 by 1 1 in. was found to be dead about the positive electrode 

 and a space about i*4 *3 in. near the negative electrode. The 

 burned area about the positive electrode was about 95 per cent more 

 than occurred about the negative electrode. In each case it 

 extended about twice as far above and below the point of contact as 

 to the sides of the electrodes, thus showing a tendency of the current 

 to travel in a vertical direction rather than laterally. 



The immediate portions around the electrodes were more affected 

 than those further remote. There was an area of tissue about 5 in. 

 long between the large and small oval burning that was uninjured, 

 showing that burning was confined about the area of the electrodes, 

 and the current did not burn a groove from one pole to the other. 

 The current traversing the film of water on the bark was necessarily 

 small, at least not sufficient to do any damage at a short distance 

 from the electrodes. The results obtained by passing a current for 

 a brief period through 161-2 ft. and 7 ft. of the tree trunk showed 

 no effect on the tissues. A young pear tree, 2 ft. 8 in. high, i ^ in. 

 in diameter at the base, which had been grown one year in a box, 

 14 by 1 6 by 9 inches, and provided with a copper plate in the bottom 

 in direct contact with the roots, showed a current of 2.2 milli- 

 amperes, (1-454 amp.), when one electrode was connected with the 

 copper plate, and the other with the top of the tree. Connections 

 made with a poison ivy plant growing on a tree showed in most 

 cases similar results when the electrodes were inserted into the stem 

 2 in. apart. A stem 3-4 in. in diameter gave a current equal to 4.4 



