D0 
tion of hybrids between Fulghum and Black Mesdag. The va- 
riety Fulghum is extensively grown in the southern United States, 
and is particularly susceptible to a definite specialized race of 
Ustilago avenae. On the other hand, where the variety has been 
grown in the southern Spring Oat Section, for example, Kansas 
and Missouri, it has shown a high degree of resistance to loose 
smut. The most interesting data on the hybrids between Fulghum 
and Black Mesdag were obtained with the so-called Fulghum Race 
of loose smut. The variety Black Mesdag is highly resistant to 
it, as well as to the other known races of loose smut. In the ex- 
periments carried out, a total of 401 second generation plants were 
inoculated, of which 78 (19.4 per cent.) were infected. ‘The re- 
sults suggest that resistance is dominant and susceptibility is re- 
cessive and segregation occurs on the basis of a three to one ratio. 
The hybrids are of special interest because of the possibility of 
securing a Fulghum type of plant, combined with a high degree 
of resistance to the Fulghum Race of smut. The Black Mesdag 
parent proved to be completely resistant, while the Fulghum parent 
gave nearly 100 per cent. infection. 
It must be emphasized that in all of these studies, definite 
known races of both loose and covered smut have been used. 
In all cases, except with the hybrid Fulghum < Black Mesdag, 
so-called Missouri Races of both loose and covered smut were 
used for inoculating the plants. It 1s just as important to utilize 
pure specialized races of the parasite as it is pure lines of the 
host. 
One of the hybrids between Hull-less and Black Mesdag has 
been grown through the sixth and seventh generations. Only a 
few progenies in the later generations have been grown, and 
these have been descended from selections which show particular 
combinations of morphological characters, as well as resistance in 
the second and third generations. ‘These selections have continued 
to show, year after year, complete resistance to both loose and 
covered smut. During the past year, in the later generations, 
the selections have been tested with all of the races of smut which 
we now have in culture. In every case they proved completely 
resistant, running parallel to their, resistant parent, Black Mesdag. 
