200 



N. TANAKA. 



which consists of thicker- walled nnd shorter-celled hyphœ, forming a 

 compact tissue without interstices (Fig. 4, b). In its younger stage 

 the surface of the rind is felted over wnth the remains of dead hyphae 

 (Fig. 4, c). A series of five ditferent colours — white, yellow hrown, 

 dark brown, rose violet, and dark violet hrown — may he seen in the 

 ordei- stated, from the centre outwards in the section of the Sclerotium. 

 As the mycelial strands gradually grow upwards, they aggregate 

 into a few flat thick strands, more than 1 mm. broad. These strands 

 spread themselves from the a|)ices and unite into a thin broad layer, 

 consisting of reticulated hyphal filaments and covering the base of the 

 shoots of the host plant. As the development of this layer proceeds, 

 the pi lens is formed from it. The pileus is an irregularly roundish 

 flat disk witli a smooth velvety surface, and takes a purplish brown 

 colour, leaving its margin whitish (PL. XXIV, Fig. 2, a). Thin 

 radial sections of a ftdly developed pileus, show that its medullary 

 stratum is composed of loosely anastomosing branclied hyphœ, dark 

 violet brown in colour, and 3-4 u. in diameter (PL. XXYII, Fig. 5). 

 Towards the outer surface of the pileus these hyphte take a vertical 

 position, and produce short and blunt branches (PL. XXVII, Figs. 

 6, 7). These branches of hyphœ are colourless and shortly septate, 

 and form the hymenial layer. Some of them elongate here and 

 there, and form the basidia, which are curved and 5-8 u. in diameter. 

 From the convex surface of the basidium are produced four sterigmata, 

 which are pointed, slightly curved and 6-10 U. in length (PL. 

 XXVII, Figs. 8, 9, 10). The spores are formed singly on the apices 

 of the sterigmata ; they are ovoid, curved, 10-12 u. long and 5-7 u. 

 broad (PL. XXVII, Fig. 11). The portion of the pileus attached to 

 the substratum produces hairs or rhizoids on its inner surface, which 

 penetrate into the substratum. But the horizontally projecting part 

 of the pileus produces the hvmenium on both surfaces, when it does 



