50 PRACTICAL TREE REPAIR 



with these long scars in the tree is to clean them 

 of frayed and isolated bark and loosened wood 

 and to paint them. 



There is no certainty, after all, that this treat- 

 ment will end the story, for lightning affects trees 

 in strange ways. In some cases physiological in- 

 juries accompany the physical ones and cause im- 

 mediate or gradual death. Again, a tree will be 

 killed by lightning without the infliction of any 

 physical injury. In still other cases, trees stand- 

 ing near a tree will succumb with it, although 

 apparently unhurt. 



Dr. G. E. Stone, in a bulletin of the Massachu- 

 setts Experiment Station, says that more fre- 

 quently than they are severely shocked, " trees 

 receive only a slight discharge, which burns out 

 a small hole near the cambium, and the result of 

 such a discharge will not be noticeable until two 

 or three years afterward. In such a case a ridge 

 forms on the bark, revealing the path of dis- 

 charge. An examination of the tissue will dis- 

 close a small hole, usually not larger than the head 

 of a pin, running down near the cambium layer. 

 A wound even of this size acts as a stimulus and 

 induces a marked growth of the cambium. These 

 cases are very common but often overlooked." 



In another bulletin Dr. Stone describes and 

 illustrates the effect of " earth discharges " 

 through trees. The cases he cites are largely 



