from grain production and into the production of strong 
lignification of the cob and stalk tissues. But even so, 
such an expenditure on development of a stiff stalk may 
be necessary to keep the ears erect and away from cer- 
tain vermin. 
The effect of teosinte introgression on cob length is 
not always detrimental. The longest, as well as the short- 
est, intact cobs were the most Tripsacoid (fig. 8). Those 
of intermediate length tended to resemble the original 
maize in having soft glumes. 
The same type of parabolic curvilinear correlation be- 
tween teosinte introgression and cob-length was also 
found with the cobs from Richards Cave in Arizona 
(Galinat ef a/., 1956). In this previous study the para- 
bolic curvilinear correlation, based on 488 intact cobs, 
had a value of 0.859, which was highly significant. The 
nature of the curve was explained by assuming that the 
long Tripsacoid cobs are the vigorous products of hetero- 
zy gous teosinte germplasm, while their short counterparts 
are the detrimental effects of homozygous teosinte germ- 
plasm. This explanation may be applied equally well to 
the cobs from Cebollita Cave. The repetition of the so- 
called ‘tmaize-teosinte heterosis’” at another site, indi- 
cates that this apparent counterpart of modern hybrid 
maize may have become widespread at the time just prior 
to 1200 A.D). in the Southwest. The blending of teosinte 
germplasm into maize would continue if its presence pro- 
vided any selective advantage such as that resulting from 
maize-teosinte heterosis. Under such conditions, the dis- 
tribution of Tripsacoid maize might become many gener- 
ations and hundreds of miles removed trom teosinte itself. 
Level 3 Maize 
Level 8 marks the start of a progressive reduction in 
teosinte contamination or at least a modification of its 
[17+ | 
