Conard: Secotium Agaricoides 
97 
ginal growth of the pileus ” until the mature size of the carpophore 
is reached. The boundary of the pileus is first evident in the 
upper part of the 3.8 mm. specimen. Thus, the hymenophore 
distinctly precedes the pileus and the gill chamber in differentia- 
tion. 
Just how the circle of palisade gives rise to the gill system, 
my material does not show. My next stage (9 mm., fig. 5, 6) has 
a ring of well-formed gills extending from the cap toward the 
columella. The gills are much branched and anastomosing. They 
run primarily in a radial direction. Near the apex of the body, 
the gills are united with the columella, or in other words are de- 
current (fig. 6, a). An older specimen shows the tramal tissue 
apparently continuous with the columella in many places. This 
is doubtless the result of a secondary mingling of hyphae, for in 
mature specimens the gleba is everywhere adherent to the colum- 
ella, while in the 10 mm. specimen there is a distinct air cavity be- 
tween the gills and the columella. Growth of the gills is chiefly 
marginal, though apparently folds may originate and develop at 
any place. The extension of the gill system as a whole takes place 
in the. region where the peridium joins the stem; corresponding 
to the marginal or centrifugal extension of agarics (fig. 6, b). 
In this region, the hyphae are narrow, protoplasmic, densely 
crowded, nearly parallel, and curved downward and inward. 
They have simple rounded ends. As general growth of the fertile 
portion of the carpophore goes on, a loosening of the tissues be- 
tween this growing zone and the stem occurs and into this loose 
region the hymenophore hyphae constantly penetrate. Quickly 
the hyphae branch and form a dense hymenium of long, clavate 
basidia. 
The mature gills are much branched and folded. The tramal 
tissue consists wholly of long, branching, and nearly parallel 
hyphae, whose ultimate branchlets form the densely crowded 
basidia. There are no cystidia or other aberrant cells. From 
a fairly dense web in growing stages, the trama becomes looser 
toward maturity and finally becomes dry and fragile. From the 
above account, it is clear that the carpophore of Secotium agari- 
coides presents in its origin and development an exact counter- 
part of that of Agaricus (Atkinson 1906, 1914a). There is at 
