79 
cerned with obtaining additional data on second generation plants 
of a large number of different hybrids involving various combina- 
tions of smut resistance. At least five different groups of hybrids 
were grown. 
t. In the first group, one variety resistant to both loose and 
covered smut was crossed with another variety which is susceptible 
to both smuts. Three different hybrids involving this type of 
combination were made. In every case, Markton was the resistant 
variety, being crossed with the susceptible varieties Canadian, Early 
Champion and Victor. These latter varieties usually give 100 
per cent. infection with both loose and covered smut, while Mark- 
ton quite regularly gives negative results, although occasionally an 
infected plant may be observed. 
2. A second group of hybrids involves the combination in which 
one parent 1s resistant to both smuts, while the other parent is 
susceptible to the loose, but resistant to the covered. The second 
generation plants of a hybrid between Early Gothland and Mark- 
ton were studied. 
3. The third type of cross was concerned with the case where 
one parent is resistant to both smuts, while the other is susceptible 
to the covered, but resistant to the loose. This is the reciprocal of 
the preceding type of cross. Again, Markton was used as the 
resistant variety, while Monarch was the other parent. 
The fourth type of hybrids involves a parent susceptible to 
both smuts, while the other one is susceptible to the loose smut, 
but resistant to the covered. Two hybrids of this type were stud- 
ied, one between Orientalis and Victor, and the other between 
Scottish Chief and Victor. The Victor variety is entirely suscepti- 
ble to both smuts, while Orientalis and Scottish Chief are suscepti- 
ble to loose smut, but resistant to the covered. 
5. The final group of hybrids includes crosses between one 
‘ariety susceptible to loose smut, while the other is susceptible to 
the covered. The second generation progenies of six different 
—" 
combinations of this type were studied. In every case, Monarch, 
a variety highly susceptible to the covered smut, and extremely 
resistant to the loose smut, was crossed with the following varieties : 
Early Gothland, Rossman, Danish, Danish Island, Orientalis, and 
Scottish Chief. The last named varieties show extreme suscep- 
