104 



RESEARCHES ON FUNGI 



logs in both Europe and America (Fig. 47). It frequently appears 

 in the woods in Manitoba. Its hymenium attracted attention one 

 hundred years ago owing to the fact that it is beset with barbed 

 cystidia. These curious structures were first described and illus- 

 trated by Ditmar in 1817 in Sturm's 

 Deutschlands Flora. 



I have investigated the structure 

 of the fruit-body of Pluteus cervinus 

 in some detail, and I now propose to 

 give an account of the chief facts 

 observed. 



If one examines the gills of a very 

 young fruit-body (A in Fig. 47) in 

 face view and transverse section (Fig. 

 49, A and B), one finds that the 

 cystidia (c) can already be distinguished 

 from the basidia and paraphyses by 

 their much larger size and greater 

 protuberance ; and, at this stage of 

 development, it is evident that the 

 cystidia are growing rapidly at their 

 apices in such a way as to extend 

 into, and more or less cross, the very 

 narrow interlamellar spaces {i in B). 



In an older fruit-body, just before 

 the expansion of the pileus (B in 

 Fig. 47), the gills are still packed 

 closely together. In a cross-section 

 (Fig. 48) they are seen to be slightly 



Fia. 48. — Pluteus cervinus. Transverse section 

 tlirough tlie pileus and gills of the un- 

 expanded fruit-body, B, shown in Fig. 47. 

 The gills have slight flanges at their free 

 ends. As yet all the basidia are immature, 

 for none of them have developed any 

 spores or sterigmata ; but the cystidia 

 are full-grown. The cystidia project across 

 tlie interlamellar spaces and so prevent 

 opposing hymenial surfaces from being 

 pressed together. Magnification, 23. 



