IV and V. All of the evidence combined points to two 
conclusions with respect to the rdle of teosinte in the 
origin and evolution of maize: (1) Maize did not originate 
from teosinte; (2) The course of evolution of maize in 
its later stages has been strongly affected by an intro- 
gression of teosinte germplasm. If it should ever be es- 
tablished beyond a reasonable doubt that teosinte is a 
hybrid of maize and Tripsacum, then a third important 
conclusion would be possible; namely that the hybridi- 
zation between maize and Tripsacum which produced 
teosinte must have occurred not later than 500 B.C. 
and perhaps considerably earlier. 
EvoLutTiIoNn OF KERNEL SIZE 
The primitive people who grew the maize whose re- 
mains were found in Bat Cave were evidently extremely 
efficient in their corn-shelling operations. Not a single 
cob among the 766 recovered from the digging bore even 
one normal kernel. However, a total of 125 loose ker- 
nels, all reasonably well-preserved, were uncovered in 
the refuse and some of these were found in each of the 
six layers. The kernels in each of the two lower strata 
are small and corneous, and were undoubtedly capable of 
popping. Thus, the primitive maize of Bat Cave was, as 
Sturtevant (1894) supposed primitive corn to be, both a 
pod corn and a pop corn. 
The kernels, like the cobs, show a progressive increase 
in mean size from stratum to stratum. ‘They were meas- 
ured in three dimensions and, since the calipers used 
registered in thousandths of an inch, these units were also 
used in computing the mean as well as the maximum and 
minimum dimensions which are set forth in Table I. 
It is apparent from the data in Table I that, while there 
is little change in the mean thickness of the kernels from 
stratum to stratum, there is a noticeable if somewhat 
[ 229 | 
