142 
Mycologia 
tions (Figs. 6 and 7) show this feature. The central light region 
is the primordium of the trama of the lamella, while the heavily 
staining lateral regions are sections of the hymenium of the 
lamella. The broadening of the lamellae is brought about by the 
downward intercalary growth of fine, sharp-pointed hyphae in 
the trama. When their tips reach the groove at the edge of the 
lamella, they turn horizontally to form the hymenium. The 
hyphae of the hymenium are not large enough at this stage to 
stand out distinctly, but soon distinct, scattered, swollen hyphae 
stand out above the hymenium surface. These are cystidia. 
They are clavate, measure 20-22 /x long and 8-10 /x broad, and 
have large, deeply staining nuclei 4-6 /u. in diameter. 
As the lamellae grow in width, the trama becomes thicker be- 
cause of the intercalary growth of new hyphae. But in a later 
stage, as shown by the sections of older lamellae (Fig. 8), the 
hyphae of the trama have increased in diameter causing the thick- 
ening of the trama in the upper part of the lamellae. At this 
stage, as Allen (1) also observed in Hypholoma, the cystidia 
appear greatly separated, indicating that some intercalary growth 
has taken place in the hymenium. A few observations have led 
to the belief that this hymenial growth is due to the branching of 
hyphae at the clamp connections in the subhymenium. The basi- 
dia are of the typical form and have four spores. 
At an early stage, when the carpophores are about 4 mm. in 
diameter, the portion of the universal veil directly above the 
pileus dissolves into a viscid layer, and the cortical layer of the 
pileus secretes enough viscid substances to keep it coated through 
the rest of its development. In older specimens this viscid layer 
is about 0.1 mm. thick (Fig. 8). However, very small, pure- 
white patches of the universal veil may persist along the outer 
margin of the pileus until late stages. Figures 9 and 10 show 
this character and also the thick partial veil completely conceal- 
ing the lamellae. In a still later stage this partial veil ruptures 
about midway between the stem and the margin of the pileus. 
It is thus left partially appendiculate to the margin of the pileus 
and partially as a distinct, white annulus which is striately lamel- 
late on its upper surface (Figs. 10-12). In some specimens the 
