10 CONNECTICUT GEOL, AND NAT. HIST. suRVEY. [Bull. 
it then follows the upward growth of the plant, often not giv- - 
ing evidence of its presence until it breaks out in its spore 
stage in the fruiting organs of the host two or three months 
later. This is the case with the oat smuts, wheat and barley 
smuts, and the grain smut of broom-corn. In this latter case 
the mycelium has traveled upward through six to ten feet of 
the cane. In other species infection may take place through - 
any very young tissue of the host upon which the germs may 
be blown or washed into contact. This is the case with corn, 
and the corn smut appears soon after infection in its smutty 
outbreaks, the mycelium usually remaining localized. With 
the Entylomas the infection is largely confined to the leaves, 
and apparently the mycelium is limited to the vicinity of the 
sorus. 
ECONOMIC IMPORTANCE. 
Injury. While most of the smuts occur on plants of no 
economic importance, there are at least twenty-five species in 
America that do more or less injury to cultivated plants. Some 
of these cause such serious injury that they are counted among 
the worst species of parasitic fungi. It is with the cereals that 
the smuts do most damage. Wheat, oats, barley, rye, and corn 
are all subject to attacks from one or more species. With the 
first three hosts the smuts break out in the inflorescence, en- 
tirely preventing the formation of the seed. It thus becomes 
an easy matter to determine rather accurately the per cent. of 
loss in fields of these grains by counting the number of smutted 
and of free heads in a given area. Oat smut, for instance, in 
our. central states generally claims from one to fifteen per 
cent. of the grain, and in some few fields as high as thirty or 
forty per cent. has been destroyed. In Illinois there is perhaps 
an average loss per'year of one million dollars worth of oats, 
caused by the two smuts of this plant. In Indiana Arthur 
found one field of wheat where fifty per cent. of the grain was 
destroyed by the stinking smut. In the northwestern states, 
in the wheat districts, the loss caused by this latter smut is 
very great, as it is one of their worst fungous pests. When 
abundant it renders the grain inferior for milling purposes, as 
the spores may be so numerous in the flour that they darken 
