58 
been inoculated with this smut. The results indicate that Feterita 
and Dwarf Yellow Milo contain the same factor or factors for re- 
sistance to the loose smut. 
Influence of Environal Factors on Sorghum Smut Infection— 
A large number of experiments were carried out with the covered 
smut in order to determine the influence of environal factors on 
infection. One of the difficulties in thoroughly studying the in- 
heritance of smut resistance is the variation which occurs in the 
infection of so-called susceptible parental varieties. The present 
experiments involved temperature ranges from 15 to 30° C, 
variations in the moisture content of the sand from 10 to 15 per 
cent. of the water holding capacity, and the comparison of water 
and 2 per cent. sucrose solution. The sand reaction was approx- 
imately neutral. 
Throughout the series the highest infections of the varieties 
tested were obtained usually at the 10 per cent. moisture at. all 
the different temperatures, and for both the water and sucrose 
series. At the lower temperatures the infections obtained in the 
water series were usually higher than those obtained in the sucrose 
series. At the medium temperatures the infections were higher in 
the sucrose series at the lower moisture percentages, and in the 
water series at the higher moisture. At the high temperatures the 
percentages of infection were generally higher in the sucrose se- 
ries throughout. The occurrence of characteristic blasted plants 
of Feterita follows the behavior of the typical susceptible varieties, 
except that the highest percentages of infection were obtained at 
the high temperatures, while the highest infections of the sus- 
ceptible varieties were obtained at lower temperatures. Further, 
the sucrose solution was more conducive to high infection in 
eterita than water, except at the lowest temperatures. 
The results indicate clearly that the number of infected plants 
of a susceptible variety, inoculated with the covered smut, may 
vary from 0 to 94.1 per cent., depending upon the environal con- 
ditions provided during the germination period. 
We are again indebted to the courtesy of Director H. B. Knapp 
and his associates, State Institute of Applied Agriculture on Long 
Island, Farmingdale, L. [., for land and facilities for conducting 
these extensive experiments with the sorghum smuts. Approxi- 
