AURIC ULARI ALES 541 



it approaches the other hyphal cells. It becomes shorter and stouter 

 than the others, collecting the protoplasm of the cells immediately behind 

 it and passing this into the basidium. Close below this appears the 

 usual branch which projects over the empty basidium and itself develops 

 to a basidium. 



Platygloea (Achroomyces) represents the next step in the formation 

 of simple resupinate fructifications. The hyphae secrete a gel, hence the 

 texture is waxy to gelatinous, often convoluted when fresh. The basidia 

 are united into a loose hymenium, interrupted by paraphyses (?). As 

 in H. orthobasidion, so in Platygloea nigricans {Achroomyces Tiliae), 

 the probasidium, in which nuclear fusion occurs, remains in the mature 

 basidium, recognizable as a slight swelling (Neuhoff, 1924) similar to that 

 shown in Fig. 359, z. The sterigmata of the lower basidial cells continue 

 their growth until they have reached the surface of the gel and then cut 

 off their spores, so that the latter do not adhere to the gel. In P. Lager- 

 stroemiae, the basidia begin to collapse and become distorted as the 

 basidiospores form. The basidiospores germinate in nutrient solutions 

 with sprout cells or secondary spores which are similar in form to the 

 basidiospores, but smaller (Moller, 1895; Coker, 1920). In P. caroliniana 

 there are no sterile hyphae in the hymenium. Swellings at the base of 

 the basidia have not been reported in the North American species. 



In Eocronartium, the fructifications become more definite in form, 

 being cylindrical or clavate in E. muscicola, (Fig. 360, 1, sp.) a perennial 

 parasite on mosses in Europe and North America (Fitzpatrick, 1918). 

 The hyphae penetrate the whole stem, but haustoria and clamp connec- 

 tions are not reported. The origin of the binucleate cells is unknown. 

 The nuclei divide conjugately, with the spindles often perpendicular to the 

 axis of the hypha. Shortly before the formation of the fructification, 

 the intramatrical hyphae emerge between the folded leaves, intertwine 

 and elongate to a cylindrical fructification. In case the sporogonium 

 of the host is already formed, it is surrounded by hyphae. At the sur- 

 face of the fructification, in the terminal cells of the hyphae, the two 

 nuclei approach and fuse (Fig. 360, 4). The zeugites (Fig. 360, 5, z) 

 swell slightly and develop to long basidia (Fig. 360, 6 to 13) bearing four 

 basidiospores on long sterigmata. In nutrient solutions they germinate 

 with germ tubes whose cells are uninucleate. Perhaps plasmogamy 

 occurs early, but it was not observed. 



In Auricularia, the highest member of this family, the fructification 

 is a broad, bilateral bracket. The cosmopolitan A. Auricula- J udae is 

 irregularly lobate, sometimes conchiform or auriform. In fresh condition, 

 it is more or less gelatinous or cartilaginous, drying hard and horny, 

 to revive again when moistened, as in the Marasmieae and Schizo- 

 phylleae of the Agaricales. The hymenium and the sterile surface is 

 smooth or slightly rough in this species, but in tropical species the hymen- 



