7 o RESEARCHES ON FUNGI 



sterile and hence remain persistently white. 1 Grove has found 

 sterile specimens of Stropharia semiglobata 2 and of Paneolus cam- 

 panulatus? In the latter species he found that the hymenium 

 contained basidia which projected beyond the paraphyses, that a 

 number of the basidia possessed four sterigmata, but that spores 

 were entirely absent. 



The new observations to be recorded here concern Copi'inus 

 lagopus (= C. fimetarius}. It was found that, when this species is 

 cultivated in pure cultures of polysporous origin on sterilised horse 

 dung in the laboratory, sterile fruit-bodies sometimes appear among 

 the fertile ones. Normal spore-bearing fruit-bodies (Fig. 20) have 

 pilei which turn grey just before expansion owing to the spores 

 developing a very dark pigment in their walls. A quite sterile 

 fruit-body (Fig. 21) never turns grey but remains yellowish- white 

 except at the disc which is brownish. There are degrees of sterility, 

 for some fruit-bodies were observed which were quite sterile, some 

 which were sterile in the lower half of the expanded pileus, some in 

 the upper half, while some were sterile on one side of the pileus only. 

 Moreover, certain fruit-bodies, which were completely yellowish- 

 white and appeared to the naked eye to be quite sterile, were found 

 with the aid of the microscope to have developed spores on a very 

 few basidia scattered here and there in the hymenium. 



Completely sterile fruit-bodies, except for their colour, appear 

 to be quite normal in external appearance. They attain normal 

 size, their pilei expand with the usual rapidity, and the phenomenon 

 of autodigestion of the gills is well exhibited (cf. Figs. 20 and 21). 

 As the gills disappear, drops of a yellowish juice collect at the 

 periphery of the pileus under moist conditions. The fact that 

 autodigestion occurs in these sterile fruit-bodies is interesting, 

 because it proves that the process of autodigestion in normal 

 fruit-bodies is not initiated or controlled by the ripening or the 

 discharge of the spores. 



An examination of the gills of a completely sterile fruit-body 



1 E. Fries, sec. Stevenson, loc. cit., p. 128 ; and Massee, British Fungus-Flora, 

 vol. iii, p. 41. 



2 W. B. Grove, " The Flora of Warwickshire," Fungi, 1891, p. 419. 



3 W. B. Grove, "An Agaric with Sterile GUIs," Nature, vol. Ixxxv, 1910, p. 531. 



