Periodical Literature. 285 



Lightning frequently strikes in the most 

 Bifects unexpected places and, according to Baltz, 



of no precautions can be depended upon for 



Lightning. immunity. Danger is greatest in the open 



fields because here a man is the most elevated 

 object on the landscape. Trees standing alone in the open coun- 

 try are only correspondingly more liable to be struck and are to 

 be avoided altogether. Lying flat on the ground is undoubtedly 

 the safest thing to do when overtaken by a thunderstorm. 



In the woods some kinds of trees are more frequently struck 

 than others and popular notion that an oak is more liable to be 

 struck than a beech tree seems to be justified, but even beech 

 trees are struck at times. There is no evidence indicating that the 

 danger is greater when carrying a gun. 

 Der Blitz %ind seine Wirkung. Silva, Sept., 191 1. 306-7. 



The dying back of the upper branches 



Cause characteristic of stagheadedness has always 



of been attributed to a change in the tran- 



Staghead. spiration current. Light admitted to the 



bole and lower crown stimulates leaf activity 

 there ; this foliage evaporates water and so reduces the supply of 

 water available at the top of the crown that whole branches die 

 back for lack of it. Dr. Miinch, Forstamtsassessor in Stiftswald, 

 near Kaiserslautern in the Bavarian Palatinate has made the re- 

 markable discovery that stagheadedness in the oak is caused by a 

 parasitic ascomycete which attacks the bark, destroys a small area 

 and then enters the outermost annual ring of the wood. Through 

 this it extends up or down the tree and may pass back to the bark 

 again. Apparently sound trees of all ages and in stands of all 

 densities are alike subject to attack, but a season of drought ap- 

 pears to favor infection. Dr. Miinch was formerly at Munich ; he 

 is best known for his work on the blue stain of pine wood. 



Leits'dtze zu den Mitteilungen iiber die Gipfeldiirre der EicJien. Silva, 

 Dec. 191 1. 415-416. 



The "oak-mildew" so abundant on the con- 



Identity tinent of Europe during the past few years 



of the is shown by Arnaud and Foex to be the 



Oak-mildezv. o'idial stages of the cosmopolitan fungus, 



Microsphaera alni (Wallr.) Salm., or, as 



the authors prefer to call it, Microsphaera qitercina (Schw.) Bur- 



