118 
which conjugate in pairs. Infection threads are either produced by these 
sporidia capable of penetrating the host plant or, as is usually the case, 
secondary sickle-shaped sporidia are borne on short filaments and these 
sporidia produce infection threads. The formation of sporidia greatly in- 
creases the chances of the fungus to infect the host. 
The infection of the wheat plant takes place soon after the germina- 
tion of the grain and even befcre the first leaves are put forth. Hoffman 
believed that the infection threads can enter only the sheathing primary 
leaf or the collar between the root and stem while they are yet very young 
and delicate and concludes that anything which would hasten the growth 
of the young plant would tend to lessen the chances of infection... Bolley 
believes that infection does not take place unless there is a large num- 
ber of sporidia in close contact with the seedling during the infection 
period.2) The mycelium after gaining entrance to the young plant pushes 
its way upward with the growth of the host, the older mycelium dying and 
its contents passing upward into the young advancing ends, and finally 
fruits in the ovaries by the production of chlamydospores from sporogenous 
hyphae that have developed abundantly in them. The Stinking Smut 
differs from the Loose Smut of Wheat in that the destruction is entirely 
confined to the ovary contents. The ovary coat is left intact, so that one 
would easily fail to recognize any infection unless he made particular ob- 
servation or noticed the disagreeable odor characteristic of the fungus. 
The affected kernels are somewhat larger than healthy ones and this in- 
crease in size causes the florets to spread, making the head more open 
than a healthy one. When the kernels are cut open they are found to 
be filled with a mass of olive-brown spores of a greasy character. 
Tue Loose SMUT OF OATS. 
Ustilago avenae (Pers.) Jens. and 
THe Hippen Smut or Oats 
Ustilago levis (I<ell. & Sw.) Magnus on Avena sativa. 
There are two distinctive species of oat smut called respectively the 
Loose and the Hidden Smut of Oats. Both are much alike in their methods 
of development and both succumb to the same method of treatment. Us- 
tilago avenae is by far the commoner and is the one which causes the 
1. Note from Kellerman and Swingle, Report on the Loose Smut of Cereals. 2d 
Ann. Rept. Kan. Exp. Sta. 1889, pp. 213-238. 
2. Bolley, H. L., New Studies upon the Smuts of Wheat, Oats and Barley N. Dak. 
Bul. 27, 1897. 
