covering their surface (_C_). Almost as soon as the umbrella opens,
the spores are shed, and the whole structure shrivels up and
dissolves, leaving almost no trace behind.

If we examine microscopically the youngest specimens procurable,
freeing from air with alcohol, and mounting in water or dilute
glycerine, we find it to be a little, nearly globular mass of
colorless filaments, with numerous cross-walls, the whole arising
from similar looser filaments imbedded in the substratum (Fig. 48,
_G_). If the specimen is not too young, a denser central portion can
be made out, and in still older ones (Fig. 48, _H_) this central
mass has assumed the form of a short, thick stalk, crowned by a flat
cap, the whole invested by a loose mass of filaments that merge more
or less gradually into the central portion. By the time the spore
fruit (for this structure corresponds to the spore fruit of the
_Ascomycetes_) reaches a height of two or three millimetres, and is
plainly visible to the naked eye, the cap grows downward at the
margins, so as to almost entirely conceal the stalk. A longitudinal
section of such a stage shows the stalk to be composed of a
small-celled, close tissue becoming looser in the cap, on whose
inner surface the spore-bearing ridges ("gills" or _Lamellae_) have
begun to develop. Some of these run completely to the edge of the
cap, others only part way. To study their structure, make
cross-sections of the cap of a nearly full-grown, but unopened,
specimen, and this will give numerous sections of the young gills.
We find them to be flat plates, composed within of loosely
interwoven filaments, whose ends stand out at right angles to the
surface of the gills, forming a layer of closely-set upright cells
(basidia) (Fig. 48, _D_). These are at first all alike, but later
some of them become club-shaped, and develop at the end several
(usually four) little points, at the end of which spores are formed
in exactly the same way as we saw in the germinating teleuto spores
of the cedar rust, all the protoplasm of the basidium passing into
the growing spores (Fig. 48, _E_, _F_). The ripe spores (_E_, _sp._)
are oval, and possess a firm, dark outer wall. Occasionally some of
the basidia develop into very large sterile cells (E, _x_),
projecting far beyond the others, and often reaching the neighboring
gill.

Similar in structure and development to _Coprinu