96 
Mycologia 
when it breaks away from the stalk, and thickening above to its 
union with the columella. The scales on its surface are not sepa- 
rate from it, but when caught with forceps and peeled off, the tissue 
tears deeper and deeper into the peridium. The summit of the 
columella is continuous with the peridium and of similar structure. 
In our 9 mm. specimen, there is a layer of open-meshed “ neu- 
tral tissue” just within the gleba, surrounding the lower part of 
the columella. This layer is broadest where the peridium joins 
the stalk. It probably represents the layer of stem tissue which in 
Agaricus campestris is torn off with the annulus in the expansion 
of the cap. It appears only in this one specimen. In the 13 mm. 
specimen, the pileus or peridium joins the stipe by a broad conflu- 
ence of tissues, representing the undifferentiated partial veil. At 
the line of junction, the hyphae appear greatly tangled, for the 
hyphae of the stipe run approximately longitudinally and are con- 
tinuous with those of the columella, and the prevailing direction 
in the peridium is meridional. It is doubtless along this tangled 
region that marginal dehiscence occurs. 
The Hymenophore . — The hymenophore appears in the 3 mm. 
specimen as a horizontal ring of deeply-staining tissue within the 
globular fungous body and near its summit (PI. 157, fig. i). The 
hyphae composing this ring are rich in protoplasm and very 
densely tangled together. They do not appear to follow any one 
direction more than another. Their ends are simply rounded. 
In the 3.8 mm. specimen (PI. 157, fig. 2), this dense ring of 
hyphae has organized a distinct palisade of round-tipped threads. 
A median longitudinal section of the carpophore shows this al- 
ready in two deeply stained lunate areas, concave downward. The 
tissue beneath these patches is very loose and open, with an occa- 
sional lacuna (fig. 4). No sign of gills yet appears in tangential 
sections (fig. 3). Already, however, the palisade hyphae are 
swollen at the ends to form basidia and under these basidia the 
first formation of the gill chamber takesplaceby a tearing away of 
the underlying hyphae. The palisade is evidently spreading both 
centripetally and centrifugally. The centripetal advance en- 
croaches on the stipe for a short time and then ceases. This 
causes the decurrence of the lamellae, mentioned later. The cen- 
trifugal spreading is much more rapid and continues as the “mar- 
