14 
BULLETIN 1239, U. S. DEPARTMENT OF AGRICULTURE. 
bunt free; in fact, no wheat had been grown in the immediate local- 
ity for several years, and other sowings in surrounding ground 
proved it to be free from bunt. Figures 1, 2, and 3 show the loca- 
tion and thickness of the infested soil strata. The approximate lo- 
cation of the branching node is shown by a composite diagrammatic 
sketch of the root system of each plant. From these figures and Table 
12 it will be seen that the location of the origin of the tillers with 
SERIES I 
ABC 
Fig. 1.— Location and thickness of strata of bunt-iufested soil in iin 
experiment to determine the possible relation to infection of the dis- 
tance between seed and stratum of smutted soil. (.Vertical scale, 
each space = one-fourth of an inch.) 
reference to the infested stratum is of considerable significance and 
indicates that direct infection of the tillers does not occur, as little 
or no infection is shown where they originate below the infested 
area. The results also show that the percentage of bunt produced 
is more closely correlated with the total depth of seeding, or the 
depth of soil above the infested stratum, than it is with the distance 
between the seed and the infested stratum, for the reason that depth 
controls the length of the subsurface internode. 
