36S 



BOTANY 



Order 2. Auricularieae 



The basidia, as in the case of the UrccUucae, are transversely septate, with four 

 long sporiferous sterigmata ; they spring directly from the mycelium without any 

 previous formation of chlamydospores. But few forms are included in this order. 

 Among the most familiar is Auricularia sainbucina (Judas' ear), found on old Elder 

 stems. It has gelatinous, dark-brown fructifications, which are shell-shaped and bear 

 on their inner sides the basidial hymenium. 



Order 3. Pilacreae 



This order comprises only the genus Pilacre, occurring on the bark of deciduous 

 trees. The transversely septate basidia with four sessile spores arise within stalked, 

 capitate fructifications which attain only a small size. 



Order 4. Tremellineae 



The basidia are longitudinally divided (Fig. 286, B). The hymenium is situated 

 on the surface of the fructifications, which are generally gelatinous and irregularly 

 lobed or folded. The few genera included in this order are saprophytic on decaying 

 wood and tree-trunks, from whose surface the fructifications are produced. 



Order 5. Hymenomycetes 



The basidia are undivided, and bear four spores at the apices of slender sterig- 

 mata (Fig. 290, b, sp). In the simplest forms these autobasidia spring directly 

 from the mycelium, but in the majority of cases stalked fructifications surmounted 



by a cup-like expansion, the 

 pileus, are produced, which 

 bear definite hymenial layers, 

 composed in addition to the 

 basidia of paraphyses (Fig. 

 290, p), and also of sterile 

 cystids (e) or club - shaped 

 tubes characterised by their 

 larger diameter and more 

 strongly thickened wall. In 

 this order, in contrast to the 

 Uredineac, the formation of 

 chlamydospores is of rare 

 occurrence, and is correspond- 

 ingly of subordinate import 

 ance. 



Most of the Hymenomy- 

 cetes develop their profusely 

 branched, white mycelium in 

 the humus soil of forests or 

 in decaying wood, and pro- 

 duce fructifications, often of 

 considerable size, protruding from the substratum. The mycelium of the forms 

 vegetating in the soil spreads further and further, and dying in the centre as it 

 exhausts the food material of the substratum, occupies continually widening con- 

 centric zones. In consequence of this mode of growth, where the development has 



Fig. 290. — Russula rubr:t. Portion of the hymenium. sh, Sub- 

 hymenial layer ; &, basidia ; s, steriginata ; sp, spores ; p, 

 paraphyses ; c, a cystid. (x 540.) 



