9] 
Hull-less were inoculated with four races, to all of which Hull-less 
was susceptible. The data for the hybrid plants, inoculated with 
race 1 of the loose smut, indicate a two factor relation for the 
inheritance of resistance, while a three factor difference is indi- 
cated for the hybrids when inoculated with races 1 and 7 of the 
covered smut. The progenies inoculated with race 12 of loose 
smut differ markedly from these results. There is a high per- 
centage of infected second generation plants, and in the third 
generation there is a great excess of segregating and susceptible 
progenies over the resistant ones. Second and third generations 
of the hybrids between Navarro and Black Mesdag were grown, 
and five distinct factors for inheritance of resistance to two races 
of covered smut are indicated, and three factors for one race of 
loose smut. The results are particularly interesting because 
Black Mesdag is susceptible to both races of covered smut, but 
fully resistant to the loose smut, Navarro being resistant to al 
these races. In the hybrid between Navarro and Gothland, the 
latter being susceptible to race 1 of loose smut, the results ind1- 
cate that inheritance of the resistant quality depends upon two 
— 
factors. 
The Effect of Smut Infection on Seedlings of Resistant 
and Susceptible Oat Varieties 
Miss Jeanne P. Walther, research assistant, carried out a serics 
of experiments in order to determine the effect of inoculation on 
the growth of resistant and susceptible varieties of oats. Many 
varieties, inoculated with different races of loose and covered 
smut, were grown. In general, a reduced emergence rate of the 
inoculated seedlings as compared with the non-inoculated was 
noted. Varieties inoculated with races of covered smut to which 
they were susceptible showed only a slight reduction in growth, 
but when they were inoculated with races to which they were 
resistant there was a decided retardation. Similar results were 
observed in the case of varieties in their reaction to the loose 
smut. Some varieties susceptible to both loose and covered 
smut races showed retarded growth when inoculated. On the 
other hand, they appeared to be somewhat stimulated when in- 
oculated with races of smut to which they were resistant. 
