POLY POR ALES 



437 



(spores hyaline) those with cystidia and gloeocystidia (Fig. 279); in 



Epithele (Fig. 280), Veluticeps and Mycobonia those with curious sterile 



hyphal pegs, etc., springing from the subhymenial tissue and projecting 



above the hymenium. In short the system only gives first aid and 



hence is variously treated by different 



authors. Cytologically, of all these 



forms only Corticium lacteum, C. 



bombycinum, Peniophora Sambuci and 



Hymenochaete tenuis (Hypochnus sub- 



tilis of Harper) (Maire, 1902; Harper, 



1902; Kniep, 1913) have been studied. 



Fig. 279. — Gloeocystidivm clavuligerum. Fig. 280. — Epithele Typhae. Section of 



Section of hymenium showing basidia and hymenium showing a peg of hyphae. 



gloeocystidia. (X 385; after Hoehnel and (X 255; after Hoehnel and Litschaucr, 1906.) 

 Litschauer, 1906.) 



Coniophora cerebella develops very thick (often 0.5 mm.) crusts, at 

 first fleshy and membranous, later dry and brittle. This species is as 

 important a cause of dry rot of coniferous timber in the United States as 

 Merulius lacrymans in Europe. Corticium centrijugum, C. Stevensii and 

 C. radiosum (C. alutaceum) form bul- 

 bils (sclerotia) which when dried retain 

 their ability to germinate for several 

 years and under favorable conditions 

 develop to mycelia. 



In Peniophora Candida (P. Aegerita 

 and Kneiffia Aegerita) these bulbils 



Fig. 281. — Peniophora chordalis, showing Fig. 282. — Peniophora chaetophora. (X200; 

 basidia and cystidia. ( X 265; after Hoehnel after Hoehnel and Litschauer, 1907.) 



and Litschaucr, 1906.) 



consist of single much-branched hyphae whose branches are much 

 intertwined; generally, in the young stages, the peripheral hyphal ends 

 swell terminally and each cuts off one, seldom several, thin-walled conidia. 

 These bulbils often appear in such large quantities that the hymenium is 

 not formed; they loosen from the hyphal cushion and undoubtedly play 



