STUDIES ON THE LUMINOUS FUNGUS. 3 



scaly, breaking up into triangular scales which are distinct in the 

 central parts and become smaller and less conspicuous towards the 

 margin. The pileus is usually lateral in relation to the stem and 

 half- moon-shaped or reniform except in very small specimens, in 

 which it is roundish with the stem attached near the center. It 

 easily splits in the margin on being handled. The color is a light 

 brown tinted with yellowish or rosy ; in old specimens it is a 

 dark brown with purplish tint. Flesh white, thick, reaching 1*3- 

 2*0 cm. in thickness near the stem in large specimens. Stem 

 attached to pileus usually at the edge, short, 1-4-2*5 cm. long and 

 1*5-3*0 cm. (in largest specimens even 4 or 5 cm.) thick, firm, 

 tough, fibrous, showing in sections a dark purplish central part. 

 Gills white, acquiring a light yellowish tinge with age, 0*9 5-1 "8 

 cm. broad, 0*6-1-5 mm. thick, straight, not branching throughout; 

 shortly decurrent, all ending abruptly in a line at the remnant of 

 the ring-like prominence in the upper part of stem. Spores 

 spherical, 13-17/* in diameter, white when caught in a mass on 

 paper, slightly tinged with lilac color. 



The plants grow in clusters on decaying beech trunks in the 

 mountainous parts of Japan during the autumn. They are luminous 

 and very poisonous. 



Eemarks. — So far as external features go, the present species 

 somewhat resembles Pleur ot us sapidus Kalckbr. as well as 

 Pleur otus ostreatus Jacq. However, the former has several 

 pilei starting from a common stem and the gills running down 

 deep over the stem. The latter species is more like the present 

 one in habitus, but is characterized by having smaller spores of 

 an elliptical outline. Moreover, both the species mentioned are 

 non-luminous. Pleurotus oleareus D. C.,'with which Hennings 

 confounded the present species, diners from this markedly in having 

 comparatively slender stem which is from one to three times as 



