208 ENDOSPOBE^. [lycogala. 



more or less separated from each other by narrow tubular air-passages. 

 Sections of such an sethalium, when hardened and stained, show the 

 inner veins to measure from 40 to 50 ^ diam., while the more super- 

 ficial veins are about 100 fi diam. At a later stage the outer convolu- 

 tions become deeply lobed, flattened and folded on themselves ; tubular 

 air-passages are enclosed between the folds, which, together with the 

 deeper air-passages and the surface of the sethalium, are bounded by 

 a delicate membrane. At a still later stage, when the cortex is form- 

 ing, the periphery is . differentiated into two layers, an outer and an 

 inner. The former bears on its surface isolated' thick- walled lobes 

 or vesicles, 20 to 200 ju diam., containing nucleated, deeply-staining 

 protoplasm ; the nuclei remain sharply defined till after the spores 

 are formed in the aethalium, when they degenerate and disappear. 

 This outer layer consists of unstaining, hyaline substance, destitute 

 of nuclei, and traversed by thick-walled interlacing air-passages. The 

 inner layer is finely granular, faintly staining, homogeneous, and 

 devoid of nuclei ; through it the air-passages of the cortex communi- 

 cate with those of the interior ; the latter remain thin-walled, and 

 form the so-called capillitium. In examining a young aethalium after 

 the cortex has formed, but some hours before the karyokinetic division 

 of nuclei, preparatory to the formation of spores, takes place, the. 

 capillitium tubes are found to be completely formed, and are filled 

 with air, though lying in the fluid sporeplasm! This appearance shows 

 that they are the air-spaces which existed among the convoluted 

 sporangia when producing the aethahum, bounded by a membrane 

 corresponding to sporangium-walls. In L.flavo-fuscum this membrane 

 is more dehcate than in L. miniatum, and is in some parts perforated 

 with irregular lattice-work openings. The presence of spores in the 

 tubes, which is occasionally found in L.flavo-fuscwm, may be explained 

 by the penetration of sporeplasm through such openings. 



KEY TO THE SPECIES "DF LTCOGALA. 



Cortex of aethalia smooth or areolated. 1. L. Jlavo-fuscum 



Cortex of sethalia warted — 



^thalia subglobose. 2. L. miniatum 



.iSIthalia conical; 3. L. coniawm 



1. L. flavo-fuscum Eost., Versuch., p. 3 (1873). Plasmodium? 

 .^thalia rounded, sessile, or subpyriform, and shortly stalked, 

 2 to 5 cm. diam., oohraceous-brown or purplish -brown, smooth, 

 minutely areolated ; cortex " thick, of three layers, the outer 

 membranous, the middle consisting of a dense aggregation 

 of yellow vesicles, 50 to 80 fx, diam., intermixed with the peri- 

 pheral ends of the capillitium, the inner layer homogeneous, 

 pierced by the capillitium threads ; mass of capUlitium and spores 

 pale buff. Capillitium of irregularly branching, nearly colourless, 

 wrinkled tubes, 6 to 20 /a diam., or more, with numerous blunt- 

 ended free branches. Spores almost colourless, minutely reticu- 

 lated over the greater part of the surface, 5 to 6 /* diam. — Mon., 

 p. 288 ; Cooke, Myx. Brit., p. 76 ; Macbride, in Bull. Nat. Hist. 

 Iowa, ii., p. 127 ; Mass. Mon., p. 124; Zopf, in Schenk, Handb. 

 der Bot., ui., 2, p. 167. Dipktherium fla/oo-fusoum Ehrenberg, 

 Sylv. Myc. Berol., pp. 14, 27 (1818). 



