1917] SAW YER—PHOLIOTA 215 
development of the blematogen, which is probably present from the 
first appearance of the fruit body primordium. 
DIFFERENTIATION OF STEM FUNDAMENT.—As_ development 
proceeds, the hyphae in the base of the primordium take on more 
active growth than the others, and by interstitial increase form a 
very dense structure. This new area of growth, which is the stem 
fundament, is shown as a deeply stained region in the base of the 
fruit body in fig. 25. As growth continues, the cone-shaped stem 
fundament advances toward the apex of the fruit body. In fig. 26 
the most deeply stained portion represents the rapidly growing, 
progressive apex of the stem fundament; the more compact tissue 
below represents its earlier differentiated base; and the outer zone 
of loose tissue surrounding the whole is the blematogen. 
DIFFERENTIATION OF HYMENOPHORE AND PILEUS PRIMORDIA.— 
The first evidence of the hymenophore primordium is the appear- 
ance of a ring of compact, slender hyphae which surrounds the 
upper part of the stem fundament and grows down into the ground 
tissue, clothing the latter. The appearance of these differentiated 
hyphae marks off the pileus area from the stem fundament. In 
some cases the pileus fundament probably exists before the appear- 
ance of the hymenophore primordium, as indicated by seg ape : 
divergence of the hyphae from the apex of the stem fundament or _ 
by the more rapid growth in the region of the future pileus; “but 
no sharp distinction can be drawn b 3 OF P 
_and stipe u rig OFS 4°. rors eee +. atc Pa 
An early stage in the development of the latter i is shown in fig. 30. _ 
As development continues, the pileus and hymenophore progress 
Pedr in growth in a centrifugal manner. New ieneseg from 
the pileus pease contribute to the hymenophore 
takes plac ce e in +h 5 Oe oa 
