SMUTS 237 
much crowding and distortion of these soft-walled spore- 
bearing filaments, but here and there this structure may 
be made out. When the spores are ripe, the gelatinous 
walls dissolve and, the watery portions evaporating, 
leave a dusty mass of black spores. The spores germinate 
by sending out a short septate filament (promycelium) 
upon which minute sporids are formed laterally, much 
as in the Wheat rust. Like other smuts, that of Corn 
is capable of growing as a saprophyte in the decaying 
vegetable matter of the soil, producing an abundance of 
conidia. It has been found that when the sporids or the 
conidia germinate upon the meristematic parts of the 
growing plant or the projecting styles of the developing 
ears they penetrate the surface layers, and thus secure 
admission to the tissues of their host. 
408. Other Smuts, as Wheat smut or Black Blast 
(Ustilago tritict) of wheat, Oat smut (U. avenae), Barley 
smut (U.hordez), etc., have a structure and mode of devel- 
opment closely resembling the foregoing, but with most of 
these the hosts can be infected only when very young, i.e. 
during or shortly after germination, or through their 
stigmas at the time of flowering. 
409. The Bunt or Stinking smut of wheat (Tilletia 
tritici and T. foetens) represent an allied family (T7lle- 
tiaceae) in which the sporids are formed ina whorl at the 
end of the non-septate promycelium. 
Laboratory Studies. (a) Collect specimens of cluster cups 
(from barberry, buttercups, or evening primroses, etc.); ex- 
amine first under a low power without making sections. Note 
the cups filled with yellowish or orange conidia (aeciospores). 
Note spermogones (minute dark spots) generally on the opposite 
side of the leaf. 
(b) Make very thin cross-sections through a mass of cups so 
as to obtain vertical sections of the cups and the spermogones. 
(c) In May, June or July collect leaves of wheat, oats, or 
