knob groups is very small and is not significant. There is 
a highly significant difference, however, between knob 
numbers and regularity of rows. The population had 
originally been divided into three groups on the basis of 
this characteristic, the first in which the rows were so in- 
distinct that their number was difficult to determine; the 
second in which the rows were irregular but still readily 
discernible; the third in which the rows were distinct 
and straight. For purposes of computation, the first two 
groups were combined. In spite of this loss of refinement 
there is a highly significant relationship with knob num- 
ber. ‘The Chi square computed from a fourfold table is 
51.4, the highest value encountered in any of the rela- 
tionships studied. It was probably this character, more 
than any other, which was unconciously taken into con- 
sideration in classifying some of the ears as ‘‘Andean,”’ 
for it is a fact that ears of the Andean region usually ex- 
hibit decidedly irregular rows of grain. 
Firmness of the cob 
Associated with a cylindrical ear and straight rows of 
grain is a hard, stiff cob holding the grains so firmly that 
they do not yield when pressure is applied with the 
thumb. In ears of many Andean varieties the kernels 
are easily pushed into the cob. Dr. Hugh C. Cutler who 
has travelled extensively in Guatemala tells us that the 
Indians are familiar with this characteristic and that in 
certain regions they discriminate against ears in which 
the kernels yield to pressure. 
There is a relationship between this characteristic and 
knob number. When Chi square is computed from a four- 
fold table, the relationship does not appear to be signifi- 
cant, but when the ears are divided into three categories 
instead of two on the basis of firmness of the cob, a sig- 
nificant relationship can be shown. 
[ 228 ] 
