

1920] DOCGLAS—IXOCYBE 215 



(figs. 24, 25, 37, 42, 56, 74). At first the extent of growth of these 

 fibers is very unequal, and in consequence the primordial surface 

 is very uneven. Gradually, however, the ends of the hyphae 

 become more blunt and even, and beginning at the stem a palisade 

 layer commences to extend outward toward the margin of the 



pileus. The newest elements are always the smallest. These 

 occur nearest the stem where they are also the most crow r ded. 

 As the palisade layer passes outward into the primordium the 

 elements appear to be less crowded, more irregular, and larger in 

 diameter. The primordium of the hymenophore gradually passes 

 into pileus margin, where the hyphae are strongly hyponastic and 

 grow irregularly into the blematogen over the stem (fig. 67). 



Absence of marginal veil. — As the interstitial growth of the 

 hyphae pushes the margin of the pileus outward, the gill cavity 

 becomes larger and larger, and in consequence the blematogen, 

 which lies between the pileus and stem, is constantly reduced. 

 Whatever fibrils or scales are left on the margin of the pileus are 

 remnants of this. No instance could be found which showed 

 clearly any additional growth of fibers from the margin of the 

 pileus or from the stem into the fundamental tissue which lies 

 between these two regions. The pileus margin is strongly hypo- 

 nastic and its hyphae, curving downward and inward, grow into 

 the blematogen, but do not reach completely across to the stem 

 (figs. 11, 31, 56, 61, 67, 74, 77, 79). The delicate cobwebby fibrils, 

 which cover the gill cavity in young buttons and usually rupture 

 very early (fig. 65), are evidently of blematogenous origin. In 

 the forms studied here there is no marginal veil in the sense of 

 Atkinson, who considered it a structure at least in part "sui 

 generis " (2, 3). This condition is what we should naturally expect, 

 as one of the characteristics of the genus Inocybe in the systematic 

 works is the absence of a marginal veil. By the time the period of 

 vigorous lateral expansion of the pileus is reached, scarcely a trace 

 of the blematogen remains (fig. 65). 



Development of gills. — The gills develop in exactly the same 

 manner as has been described previously for all endogenous forms 

 (excepting those of the Amanita type), very careful and detailed 

 accounts of which may be found in Atkinson's later papers (6, 7). 



