430 



BASIDIOMYCETES. 



E. Hartig ^ has investigated in detail the phenomena accom- 

 panying the wood-destruction in the oak. This begins in the 

 branches and extends in white or yellow concentric zones 

 throughout the stem, so producing that appearance which has 

 given rise to the name " fly-wood." Portions of the wood appear 

 only white-striped, other parts have a more regular yellowish- 

 white colour. In the white strips the w^ood has been tmnsformed 

 into cellulose and the middle lamellae of the walls dissolved out ; 

 that of the yellow parts has not undergone this transformation 

 into cellulose, but the destruction has begun from the cell-cavity. 



Fig. 260. — Stereum yi-ustuloBum. Destruction of Oak-wood. Lougitudinal 

 section showing the browu wood with isolated hollow spots containing white 

 mycelium, (v. Tubeuf phot.) 



Stereum frustulosum Fries. (Thelephora perdix Hartig).^ 

 {Britain and U.S. America.) The sporophores form greyish- 

 brown plate-like crusts with concentric markings ; they are small, 

 never exceeding the size of a finger-nail, but generally occur 

 in numbers together. The hymeuial layer is composed of club- 

 shaped basidia beset with hair-like outgrowths ; some of the 

 basidia produce four spores, others are sterile and grow on to 

 form the hyinenial layer for the following year. 



' R. Hartig, ZerselzungserncTieinungen d. Holzes, 1878, Plate XVIII. 

 -B. Hartig, Zemetzungserscheimmgen, Plate XIII. 



