176 EXPERIMENT STATION. [Jan. 



amount of conductive tissue, possessing less resistant qualities 

 in the trees. 



9. The high resistance and consequent nonconductivity of 

 trees serves, no doubt, as a protection for the tree against light- 

 ning stroke and other electrical discharges. 



10. Sap flow did not, so far as we were able to observe, exert 

 any influence on the electrical resistance. 



11. Temperature constitutes a determinative factor in varia- 

 tions of electrical resistance of trees. Other meteorological fac- 

 tors, such as relative humidity, barometric pressure, winds, etc., 

 exert no discernible specific influence. 



