The determination of purity and viability of seeds has long been the major function of seed laboratories in the United States and other countries. Certain standard techniques have been developed on which rules and recommended procedures for seed analysis have been based. Until recently, as pointed out by the senior author (14, 15,) scant consideration has been given to the importance and significance of organisms carried in or on seeds, although Munn (11) as early as 1919 called the attention of seed analysts to their responsibility concerning the pathological condition of seeds. Since 1930 the large number of samples of field crop seeds received annually by the seed laboratory at Iowa State College has afforded an unusual opportunity to utilize certain phytopathological techniques in the determination of seeding value.