394 THALLOPHYTES 
study of the formation of these spores shows that they are not 
basidiospores, for they are not formed on basidia. The hyphae 
in the smut ball simply divide into cells which separate and 
become spores. These spores are the so-called brand spores, the 
whole mass of them forming the so-called Smut. The spores are 
very heavy-walled and appear black in mass. This kind of a 
heavy-walled spore, which is simply a transformed vegetative 
cell of the mycelium, is called a chlamydospore, a name referring 
to the heavy protective wall. The spore masses break up when 
mature and the spores are shed. In han- 
dling the grain, especially in thrashing, the 
spores escape in dust-like fogs. The spores 
pass the winter on the ground, straw, grain, 
or wherever they happen to fall. Many 
of the spores lodge on the Oat grain, fall- 
ing down between the lemma and _ palea 
which enclose the Oat kernel. The follow- 
ing spring the chlamydospores germinate, 
each producing a small hypha called a pro- 
mycelium, on which the basidiospores are pro- 
duced. The basidiospores are produced on 
351. — Ger- 
oe af Calon the end and sides of the promycelium as 
mination = 3 4 3 . “a 
doxpores, Ab a shown in Figure 351. Their number is in- 
left, a spore, and at 
the right, a spore 
which has germinated 
and produced a pro- 
definite and they often multiply by budding 
after the manner of the Yeasts. They are 
quite commonly called conidia and often 
sporidia, although they are comparable to the 
basidiospores of the Toadstools and Puff- 
balls. It is on account of the occurrence of 
the promycelium, which is regarded as a 
basidium, that the Smuts are classed as Basidiomycetes. Once 
in contact with a young Oat plant, the basidiospores produce 
hyphae, known as infection hyphae, which penetrate the young 
plant and start the development of a mycelium. 
It has been found that most of the infection in Oat Smut 
results from the chlamydospores which are lodged on the grain, 
and that by soaking seed Oats in hot water (132° to 133° F.) for 
ten to fifteen minutes or in water containing about 1 pint of 
40 per cent formalin to 45 gallons of water, the spores can be 
killed and much loss to the Oat crop prevented. 
mycelium bearing 
basidiospores (c). X 
about 300. 
