53 
tion families were grown, some individuals of each being in- 
oculated with loose smut and other individuals with covered smut. 
By far the larger number of these gave more or less similar re- 
sults with the two smuts; a progeny resistant to one smut was 
resistant to the other, and a progeny susceptible to one was sus- 
ceptible to the other. There were, however, 47 progenies which 
gave dissimilar results. In some cases, the progenies showed re- 
sistance to one smut, while containing a few individuals suscep- 
tible to the other, while in other cases, most of the individuals 
proved to be susceptible to one, but only a few individuals were 
susceptible to the other. Additional plants of many of these pro- 
genies were grown during the past year in order to determine 
whether they actually differed in their resistance to the two smuts, 
or whether the data previously obtained were due to accidental 
variations in the experiments. In such experiments the number 
of plants grown is necessarily small. On retesting, practically all 
of the progenies gave results which indicated that these families 
were like the others in their inheritance of resistance or sus- 
ceptibility to both smuts, and that the variations previously re- 
corded were due to environal factors. 
Seeds from a number of third generation plants were selected 
for growing in the fourth hybrid generation. Practically all of 
these were chosen on the basis of having shown resistance in both 
the second and third generations. They also possessed various 
combinations of the morphological characters of the two parents, 
Hull-less and Black Mesdag. The results indicate quite clearly 
that the resistance shown in the second and third generations 
is carried out in the fourth. 
The two hybrids between Silvermine and Black Mesdag were 
continued in the second and third generation; 29 additional sec- 
ond generation plants were inoculated with the loose smut, 8 (27.5 
per cent.) being infected; 26 additional plants were inoculated 
with covered smut and 7 (26.9 per cent.) were infected. Among 
the third generation progenies the different types of resistant, 
segregating and susceptible families were secured. Since only 
a few of these progenies were grown, the data obtained were 
not in very close harmony with the interpretation that resistance 
and susceptibility are dependent upon a single factor difference. 
