Nichols—Binuclcaied Cells m Some Basidiomycetes. 41 
which form the external covering’. This covering is doubtless 
a simple type of volva. 
In a carpophore which is a little further developed the cells 
above the basal tangle have enlarged and elongated. By the 
increase in size of the cells the hyphae are pressed close together 
and with the elongation of the stipe are forced into very nearly 
vertical series. At the same time the cells in the pileus increase 
in size but remain more or less intertwined. There is no differ¬ 
entiation of hyphae for the formation of gills as yet. As the 
stipe elongates the outer covering of parallel hyphae is irreg¬ 
ularly broken in several places, and now appears as small par¬ 
ticles or scales which, soon disappear. The protoplasm in the 
eells, which are rapidly increasing in length, forms a much thin¬ 
ner peripheral layer, the central vacuole having increased greatly 
in size. A longitudinal section through a young carpophore just 
before the breaking of the veil shows the gills already formed. 
Sections which pass through the center of a gill show the struct¬ 
ure very clearly. The hyphae that spread out to form the pileus 
are very irregularly twisted about each other. Near the lower 
side of the cap there is a narrower layer of much straighter 
hyphae which extends from the stipe to the margin of the pileus. 
From the lower half of the pileus but especially from this 
layer of straighter hyphae, branches are formed that grow down¬ 
wards in parallel series forming the trama. The hyphae of the 
trama branch freely, the branches forming a layer near the sur¬ 
face of the gills, the subhymenium. The hymenium is formed 
of closely packed basidia which are terminal cells of the hyphae 
in the subhymenial layer. Fig. 24 is from a section showing 
the connection of a basidium with the subhymenial hyphae. The 
large basidium has two nuclei lying near together at the center 
of the cell which is separated from the stalk cell by a cross wall. 
A second basidium is just forming from the basal cell but does 
not as yet contain any nuclei. 
The hyphae at the margin of the pileus are continuous with 
the outer covering of the hyphae on the stipe and form the veil. 
The original external covering of parallel hyphae has disap¬ 
peared with the exception of a few small fragments near the 
base of the stipe. All of the cells are regularly binucleated. 
