430 



BA8IDI0MYCETES. 



E. Hartii;- ^ has investigated in detail the phenoineua accom- 

 panying the \V(jod-destruction in tiie oak. This begins in the 

 branches and extends in wliite or yellow concentric zones 

 throughout the stem, so producing that appearance which has 

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

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

 white colour. In the white strips the wood has been transformed 

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

 that of the yellow parts has not undergone this transformation 

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





Fio. 200. — .SVt/'«i(i/i jrusti^losum. Destniction of Oak-wood. Longitmlinal 

 section showing the brown 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 tlie size of a finger-nail, but generally occur 

 in numbers together. The hymenial 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 hymenial layer for the following year. 



' H. Hartig, Zerstlziuig.sa:scheiiiuu<jen d. Hohes, 18/8, Plate XVIII. 

 - R. Hartig, Zersetzimgstrscheinuwien, Plate XIII. 



