THE ANCESTOR OF CORN—MANGELSDORF 503 
to be borne near the slender tip of the stalk. (2) The higher the 
position, the more likely is the ear to have both male and female 
flowers. (3) The higher the position, the shorter the lateral branch 
or “shank” upon which the ear is borne. The shorter the branch, 
the fewer the joints from which the husks arise, the fewer the husks, 
and the less completely the ear is enclosed. Thus an ear borne im- 
mediately below the tassel is enclosed while the young seeds are 
developing, but as these mature the husks flare open, allowing the 
ear to disperse its seeds. In short, a simple change in position deter- 
mined by a single gene change can provide a mechanism for dispersal 
of the seeds borne on the ear as well as those borne on the fragile 
branches of the tassel. 
These facts seem to answer several of the most puzzling questions 
involved in previous attempts to explain corn’s evolution: How could 
wild corn have survived the handicap of an ear incapable of dispers- 
ing its seeds? And if wild corn had no ears, how could the ear of 
modern corn, its most important organ, have come into existence? 
The position of the ear has an effect on still another characteristic 
illustrated in figure 8, the length of the streamers or leaf blades 
which in many varieties terminate the outer husks. The higher the 
ear, the more likely are the leaf blades to be short or absent. This 
may explain the absence of leaf blades in prehistoric husks found 
both in Bat Cave [5] and in La Perra Cave [8]. 
MODERN AND PRIMITIVE CORN COMPARED 
The most primitive ear we have so far obtained by combining 
popcorn and pod corn is shown in plate 3, figure 3, in comparison 
with an ear of modern dent corn and with the most primitive cob, 
dated at 4,445-+180 years, from La Perra Cave, which was excavated 
by Richard MacNeish of the National Museum of Canada. 
In weight and number of kernels our reconstruction is much closer 
to the prehistoric La Perra specimen than to the ear of modern dent 
corn. The modern ear weighs 317 grams. The ear of pod-popcorn 
weighs 1.99 grams. However, only 24 of its 38 female flowers de- 
veloped kernels. Had all done so, it would weigh 2.47 grams, assum- 
ing the additional kernels to have the same average weight, 0.034 
gram, as those which are present. The La Perra specimen weighs 
only 0.52 gram, but it lacks both the 48 kernels, which it once bore, 
and a male spike. Without its kernels and its male spike, the recon- 
structed ancestral form weighs 0.87 gram, only slightly more than 
the prehistoric specimen. 
Although we have not yet completely reconstructed wild corn, or 
duplicated exactly the most primitive specimens from either Bat Cave 
or La Perra Cave—the glumes of the pod-popcorns are still too 
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