336 OHIO EXPERIMENT STATION: BULLETIN 214 
Examples may be multiplied to illustrate the range of seed 
infection both by adhering spores and by internal development of the 
mycelium of the invading fungus. Many of these are treated under 
the particular diseases of the crops. ‘The bean, pea, barley, broom- 
corn, flax, millet, potato, 
sorghum, rye, sweet-po- 
tato, and wheat will all 
furnish examples. Not 
only have we to test the 
actual survival ofthe par- 
asites thus found but we 
must discover the behav-_ 
ior of the disease with 
respect to the germina- 
tion and seedling plants 
which grow from such 
infected seeds or tubers. 
Examination for infection 
of seed bulbs and tubers 
may be made either with 
or without the growth of 
Fig. 16. Microscopic photographs 
from centrifuge precipitates of wheat 
washings. 2, from wheat washings, 
narrow, slightly curved anthracnose 
spores, small spherical, loose smut 
spores, large spore of stinking smut 
and portions of the setae of anthrac- 
nose. 4, from wheat washings, small, 
loose smut spores, large stinking 
smut spores and curved scab spores, 
All magnified about 180 times. 
plants from them. With 
potato scab and rosette, 
the external scab effects 
or the sclerotia of Ahz- 
zoctonia are not difficult 
tosee. With the latter the 
moistened tubers show _ > 
marked color contrasts and make the work easier. These diseases 
are reached by seed treatment. 
Where the infection is internal by the threads or mycelium of 
the fungus, the seeds may be germinated in Petri dishes where the 
kernels are surrounded bya moisture retaining, sterile medium 
