4^7 



causes of death (animal and fungi enemies) werei proved to have been 

 excluded, he came to hold the opinion that spray lightning must exist. A 

 division of lightning into two branches was observed by the head forester, 

 Petzold, in the forestry district of Sachsenreid^. 



Blight of Conifer Tops. 



In 1903 V. Tubeuf-, using numerous illustrations, described a case of 

 very extensive blighting of conifer tops in upper Bavaria. These observa- 

 tions led to the conclusion that only one cause, acting once, in the winter of 

 1901-1902, could have existed and that it must be sought for in an equalizing 

 of the electrical potential in zvinter storms. The characteristic symptom is 

 the manner of dying. In the up- 

 per part of the tip of the tree, the 

 bark, bast and cambium are dead, 

 further down only parts of the 

 bark outside the cambium, so that 

 the last can form bast and young 

 wood during summer. "The 

 white, tender bast then can be 

 easily loosened from the sappy 

 wood as in healthy trees. The 

 dead bark zone joined the newly 

 formed bast and, outside this, the 

 green bark was still living. Many 

 strips of dead tissue, enclosed by 

 cork, extended through this green 

 bark. Still further down, the dead 

 bast and bark parts were no 

 longer bands, surrounding the 

 trunk, but were divided into 

 strips ; finally only dead spots are 

 found and some meters below the 



tip of the tree, ever)' sign of disease disappeared. The trunk and the roots 

 were perfectly healthy." (Fig. 100.) In the adjoining illustrated cross- 

 section from a spruce, blighted at the tip, the bark is finally killed only on a 

 few places in connected strips extending from the outside inward. Other- 

 wise, in the bark layer, only scattered smaller centres of browned tissue may 

 be found. Since these lie within the living bark, they are enclosed by a 

 layer of white cork. The bast ring seems browned, but broken in different 

 places by healthy tissue. 



The correspondence of these charactristics with the changes, described 

 by R. Hartig as "lightning traces," led v. Tubeuf to the opinion that this 



Fig-. 100. Cross-section through a bUghted 



spruce tip; from the Forestry Division of 



Starnberg. (After v. Tubeuf.) 



1 Beobachtungen liber elektrische Erscheinungen im Walde. Naturwiss. Z. 

 f. Land- u. Forstwirtsch. 1905, p. 308. 



2 V. Tubeuf, Die Gipfeldlirre der Fichten. Naturwiss. Z. f. Land- u. Forst- 

 wirtschaft. 1903, No. 1. Continuation ibid. No. 7, 8. 



