52 
Although both parental varieties are resistant to the covered 
smut, out of a total of 182 inoculated second generation plants, 
9 (4.9 per cent.) were found to be infected. There were 180 
third generation progenies inoculated and 67 of these contained 
infected plants. In nearly all cases, however, the percentage of 
infection was low, the highest obtained being 70.5. 
Hybrid 85 is a cross between Black Mesdag and Danish Island, 
the latter being susceptible to the loose smut, while the former is 
— 
resistant. ‘There were 120 third generation progenies inoculated 
and 34 were resistant, 51 segregating, and 35 susceptible. These 
results are in line with those obtained in the second generation, 
when 118 plants were inoculated and 34 (28.8 per cent.) infected. 
The data also harmonize with such a hybrid as 81, referred to 
above. 
Danish Island, on the other hand, shows a moderate suscepti- 
_— 
bility to the covered smut in contrast to the resistance of Black 
Mesdag. Of 131 second generation plants inoculated with this 
smut, 10 (7.6 per cent.) were infected. During the past year 
there were 60 third generation progenies grown and 31 were clas- 
sified as resistant, 25 as segregating, and 4 susceptible, two of the 
latter giving 100 per cent. infection. 
Hybrid 86 is a cross between Monarch Selection and Gothland, 
both varieties being fully susceptible to the loose smut and resistant 
to the covered. In the second generation 163 plants were inocu- 
lated with the loose smut and 152 (93.2 per cent.) were infected. 
There were 90 third generation progenies inoculated with this smut 
and a large number of them contained 100 per cent. infected plants, 
very few individuals in any progeny being found which showed no 
infection. Thus the high susceptibility of the two parental varie- 
ties is evident in both the second and third generations. 
In the second generation 166 plants were inoculated with the 
covered smut and none was infected. A series of 90 third gen- 
eration progenies was inoculated with this smut and not a single 
smutted plant was observed. Thus the complete resistance of the 
parental varieties to this smut appears in both the second and third 
generations. 
Experiments with the Fourth Generation of Oat Hybrids —A 
arge number of fourth generation progenies of various hybric 
— 
fla 
S 
