484 



Norway) lightning almost never strikes pine trees. Tiiese ditferences in 

 the composition of the cell contents, however, become of less importance if 

 the place of growth causes a high electrical tension, as, for example, if the 

 tree stands on impervious layers of soil where water has collected, or on the 

 banks of rivers, ponds, etc. 



Pig. 98. Ci-oss-section throuf^h a spruce with niimeroiis ovcrsiown wounds due to 

 lightning-. (After Hartig.) 



The water content of the wood plays a \ery small part in this question 

 of the attraction of lightning by trees. 



The electrical spark under high tension seeks the shortest path and then 

 strikes through even poorer conductors. 



Often in the course of years a tree will be repeatedly struck by light- 

 ning and cases will thus occur when a trunk shows small roundish or longish 

 traces of lightning on its whole outer surface which might lead to the sus- 

 picion of hail injuries, Hartig (loc. cit., p. 241) thinks, however, that the 



