is difficult to regard as constituting the primitive form 
of modern corn. No archaeological specimens of papy- 
rescent corn have been reported. 
As was pointed out in the first paper in this series, 
Weatherwax (41), in discussing one aspect of the pod- 
corn theory, apparently confused papyrescent maize and 
a weak form of pod corn, half-tunicate. His illustration 
(Fig. 51) of half-tunicate maize is almost certainly a 
photograph of papyrescent maize. 
THe Corn Grass THEORY 
Singleton (35) has suggested that the ancestral form 
of modern corn is ‘‘corn grass.”’ This anomalous type, 
the product of a single dominant gene, produces numer- 
ous tillers and small ‘‘ears’’ with a high proportion of 
single spikelets. Many of the kernels are partly enclosed 
in bracts, but the majority of these are not glumes but 
spathes. 
He also suggested that, if a plant of corn grass were 
found in nature, it would not be recognized as maize and 
would almost certainly be regarded as a different species 
if not a different genus. This may be true, and it illus- 
trates how the maize plant can be drastically changed by 
a single gene mutation. If corn grass were the ancestral 
form, a mutation at a single locus could have transformed 
it from a wild, almost useless, plant to the unique cereal 
which maize is today. 
Although corn grass has some of the characteristics 
which we might expect to find in an ancestral form — 
for example, a freely-tillering habit —it lacks others, 
such as the regular development of prominent glumes. 
At the other extreme, it has characters which are not 
demanded of a hypothetical ancestor. One of these, single 
spikelets (9), represents a condition more specialized in- 
stead of more primitive than the paired spikelets of mod- 
[ 430 | 
