isa highly significant negative relationship between knob 
number and percentage of plants infected with smut. 
Since Tripsacum has never been reported as a host for this 
organism and is apparently not susceptible to this disease, 
the relationship between knob number and resistance to 
smut is presumably due to the genes for resistance intro- 
duced from Tripsacum with the knobs. 
Here, as in the case of altitude and pubescence, the 
low-knob group is comparatively uniform. All varieties 
with six knobs or less were infected by smut, every plant 
in some cases being severely infected. Varieties com- 
pletely free of smut are encountered only among those 
with seven knobs or more. However, among varieties 
with as many as twelve knobs or more, are several which 
are strongly susceptible to smut; while Florida teosinte, 
with even more knobs than the most Tripsacoid maize, 
exhibits marked susceptibility under certain conditions. 
The relationship between knob number and smut resist- 
ance is obviously not a simple one. 
Lodging 
At both New Haven and Forest Hills many varieties 
were completely lodged. The stalks of some of these were 
so brittle that they snapped at the slightest tension ; other 
varieties stood erect throughout the entire season despite 
a severe storm. These differences are strongly associated 
with knob number, the percentage of lodged plants de- 
creasing progressively as the number of knobs increases. 
Here again, however, the low-knob group is reasonably 
uniform. Among varieties with six knobs or less only 
two had all of their plants erect at the end of the season, 
while about half of the varieties in this group had all 
plants prostrate and tangled. 
Differences in lodging are associated with the internal 
structure of the stalk. Varieties with tender, brittle stalks 
[ 234 | 
