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The importance of physiologic specialization in the oat smuts is 
brought out by some of our studies on the inheritance of smut 
resistance. In most of our studies, the Missouri races of loose 
and covered smuts have been used, the specific reaction of the 
parental varieties to these having been determined. In a series 
of hybrids between Fulghum and Black Mesdag, however, an 
entirely different race of smut has been used. The reaction of 
one specialized race on a group of hybrids may be totally different 
from the reaction of another specialized race. 
Cultural Characteristics of the Oat Smuts 
Mr. L. Gordon Utter has continued his studies on the character- 
istics of both loose and covered smuts of oats when grown on 
artificial media in flasks. Cultures of several of the specialized 
races of each of the smut species have been grown, and observa- 
tions made both on the variations and similarities shown by 
successive transfers. These observations have covered sets of 
flasks within a single race, as well as sets between several races 
and even the smut species. 
The cultures have been derived from the resting spores (chlamy- 
dospores) which constitute the black, dust-like mass replacing the 
oat floral parts, and also from the conidia which are produced by 
the germination of the chlamydospores. Observations on four 
races of the loose smut and six races of the covered smut have been 
made on cultures from chlamydospores, cultures from single 
conidia, and cultures from combinations of single conidia. The 
cultures have been continued by successive transfers over a 
period of a few months to four years. 
The results with the chlamydospore cultures indicate that cer- 
tain sets of cultures of individual races may show uniformity, 
while others show considerable variation. The range of varia- 
tion within an individual race may be as great, or greater, than 
that between different races. Some of the cultures of particular 
races have shown very similar characteristics. 
One race each from the loose and covered smut, represented by 
numerous conidial cultures, both singly and in combination, 
showed many sets to be of similar characteristics. However, 
there were cases of decided dissimilarity within sets of single 
