differences between modern cultivated corn and the orig- 
inal pod corn, states (30): 
It may be contended that these deficiencies of pod corn are due to 
characteristics of cultivated corn which have been superimposed upon 
its original nature by recent hybridization, but there is a question as 
to how much liberty of this sort we may take with the plant and still 
call it pod corn or talk about its characteristics as being primitive. 
It is true that when we proposed the pod-corn theory 
we had in mind a restrained form of pod corn controlled 
by the 7’ gene on chromosome 4 in combination with 
a complex of modifying factors. Since then, as the result 
of intensive studies of pod corn, stimulated and guided 
by this part of our theory, we have discovered not only 
lower alleles at this locus but also modifying and inhib- 
iting factors. Various combinations of these alleles and 
modifying and inhibiting factors can produce a gamut 
of types ranging from those in which the glumes are 
scarcely longer than those of modern varieties of sweet 
corn to those in which the glumes are several inches in 
length. In this wide range, where does normal corn end 
and pod corn begin’ We have weak forms of the geno- 
type Tutu whose glumes are much less conspicuous than 
those found in monstrous forms of the genotype tutu". 
Is one of these pod corn and the other not and which is 
the pod corn? 
Until specimens matching prehistoric cobs are synthe- 
sized by methods other than the one which we have suc- 
cessfully employed—that of combining alleles at the 7'w 
locus with inhibiting and modifying factors—we shall 
continue to assume that these prehistoric specimens pos- 
sessing relatively long glumes and slender rachises are 
torms of pod corn. 
Pop Corn 1n Livinc VARIETIES 
The conclusion that changes at the 7 locus on chrom- 
osome 4 represent an important factor in the evolution 
[ 347 ] 
