ATKINSON: LEPIOTA CRIST ATA AND L. SEMINUDA 211 



normal organization and development of the young basidiocarps. 

 The material was sectioned, and stained with fuchsin, by the 



writer. 



Differentiation of pileus and stem fundaments .—The youngest 

 basidiocarps examined were rather long-ovate in form, i mm. 

 long by 0.5 mm. in diameter (fig. i). At this stage there is no 

 differentiation into pileus and stem primordia. But the young 

 fruit body is slightly differentiated into a basal area of a more 

 compact texture, oval in form, the rounded apex extending into 

 the upper area of looser texture which fits over it somewhat like 

 a mitrate calyptra, the elements of the two areas merging along 

 the border zone. The basal area takes the stain more deeply, 

 the hyphae are rather intricately interwoven, while those of the 

 upper region extend more or less in a longitudinal direction. In 

 the mitriform area the general direction of the hyphae is also 

 longitudinal, but they are more or less interwoven. Those over 

 the apex, or crown, are thus more or less perpendicular to the 

 surface, while those on the lateral face below the crown are parallel 

 with the surface. _ ^ , 



The basal portion of the young fruit body is the foot, the 



basal part of the stem, corresponding to the bulb. From the 



apex of this the stem fundament arises endogenously by new 



growth of hyphal branches upward and by interstitial elongation. 



This new growth area progresses toward and partly into the 



mitriform area above, where it begins to expand laterally, forming 



the pileus primordium. Stem and pileus primordia at this stage 



form an internal area somewhat sheaf-shaped in outline as shown 



in FIGURE 2. The mitriform area at this stage belongs chiefly 



to the blematogen, but the boundary between blematogen and 



pileus primordium is very indefinite. The blematogen also 



extends down on the stem fundament. The hyphae of the 



blematogen layer above and on the flanks of the pileus fundament 



are radial and somewhat interwoven, but are more nearly parallel 



in their arrangement than in younger stages represented by 



FIGURE I. • 7- T-U 



Origin and development of the hymenophore prtmordtum.— lhe 

 pileus primordium continues to enlarge by radial growth and by 

 the origin of new hyphal branches. On the lower marginal 

 periphery numerous new hyphal branches arise, extending laterally 



