44 
the seedlings had emerged in the constant temperature tank. Many 
of the seedlings, particularly in the sucrose series, were lost on 
account of the growth of a fungus (Cephalothecnun roseum) im 
the sand cultures, a condition which had not occurred in 1935. 
Nevertheless, the data were found to be in agreement with those 
previously secured. 
Vhree of the four varieties used are susceptible and show typical 
smut infection. The fourth variety, leterita, is seldom typically 
smutted. Infection of Feterita is characterized by blasting of the 
heads and a meager formation of smut balls. Infection for all 
four varieties tested was highest when the seeds had been germi- 
nated at 10 per cent. moisture. This was true for all temperatures 
and for both the water and sugar series. At 10 per cent. moisture, 
temperatures of 15 to 17.5 were most conducive to high infection 
in both the water and sugar series except for the variety [eterita, 
which was most heavily infected at 27.5 to 30. At low tempera- 
tures, infections for all varieties tested were usually slightly greater 
in the water series than in the sugar series. At high temperatures, 
shehtly greater infections occurred in the sugar series as compared 
with the water series, while at the intermediate temperatures, in- 
fections were greatest in the sugar series when the moisture content 
was low but in the water series when the moisture content was 
high. The results indicate that these three environal factors are 
inter-related and limit one another. These results are particularly 
important in the study of inheritance of resistance in hybrids. It 
has been noted that in the hybrid Feterita x Sumac Sorgo, seed- 
ling environment influences the interaction between a factor for 
resistance brought in by I*eterita and a factor for susceptibility 
brought in by Sumac Sorgo. Under one set of environal con- 
ditions the Feterita factor is epistatic to the Sumac Sorgo factor, 
while under another set of conditions the reverse is true, 
We are indebted to the courtesy of Director HI. B. Knapp and 
his associates, State Institute of Apphed Agriculture on Long 
Island, Farmingdale, L. [.. for land and facilities for conducting 
extensive experiments with the sorghum smuts. 
