352 
Journal of Agricultural Research 
Vol. II, No. s 
the plantings at the Cereal Field Station at Amarillo were on new land both 
in 1907 and 1910. This station was established in 1907 and removed to 
another situation, also at Amarillo, at the latter date. In view of the 
fact that the presence of the organism has proved to be so salient a factor, 
as established by seed 
exchange and inocu¬ 
lation experiments, 
presented later, it 
would seem proper to 
attribute the light in¬ 
fection in 1907 and 
1910 to the relative 
scarcity of the infect¬ 
ive stage of the organ¬ 
ism in the virgin soil. 
The large increase in 
1908 was probably 
due to the proximity 
to the station of an 
old field which grew a 
rather badly smutted 
crop of sorgo each 
year. The decrease 
in 1909 was doubtless 
caused by drought, 
scarcely half of the 
crop being headed. 
The inevitable con¬ 
clusion from these 
experiments is that 
infection commonly 
takes place from some 
other source than 
seed - borne spores. 
This conclusion has 
been supported by 
tests of the effect of 
some of these treat¬ 
ments on the viability 
of the spores. Tables 
II and III present the 
results of these tests. 
They were somewhat 
obscured by the comparatively sparse germination so characteristic of these 
spores and by the development of the contaminations contained in the 
untreated spore material used in seeding check plates. The treatments 
with hot water were carried out, mostly on March 10, 1913, as follows. 
Fig. 6 .—Curves summarizing for different years the percentages of in¬ 
fection in plantings of Red Amber sorgo after modified hot-water 
treatments of all durations of presoaking and treatment, but at various 
temperatures. 
