56 
conidial cultures as well as between the various sets. Combina- 
tions of single conidial cultures from the two smut species indi- 
cated an analogous situation. 
Data have been accumulated on 235 chlamydospore and conid- 
ial cultures from 11 races of loose smut, and 244 similar cultures 
of 6 races of the covered smut, which have been grown over a 
period of from two months to four years. Careful notes have 
been taken on the color and topographical characteristics of these 
various cultures. Several races of the loose smut showed that 
successive transferring from the original culture, carried through 
one to five culture generations, generally resulted in continuous 
variations. Certain exceptions, however, were noted. Although 
these variations were definite, it was observed that the color and 
topographic characteristics of all the culture sets were confined 
within a given range. 
Culture lines developed from individual spores of a single race 
tended to exhibit variations both in color and topographic 
characteristics. When comparisons were made between other 
individual lines of the same race, or between those of various 
races, it was found that considerable overlapping of the salient 
characteristics occurred. 
Similar examinations of the cultures of covered smut were 
made, with results paralleling those previously noted. In general, 
somewhat less variation was observed in the cultures of covered 
smut as compared with those of the loose smut. 
Sorghum Smuts 
Miss D. Elizabeth Marcy has continued her studies on the in- 
heritance of resistance of various sorghum hybrids to the covered 
smut of sorghum. In previous years, infection of susceptible 
varieties has been somewhat uncertain, and during the past year 
some experiments were carried out in order to find, if possible, 
more effective environal conditions for infection. Asa result of 
modifying the moisture relations of the sand in which the seed 
was planted, a much higher percentage of infection of susceptible 
varieties was secured. Six varieties which have been classified 
as susceptible gave between 79.2 and 100 per cent. infection, 
much. higher than had been obtained in other years. 
