(figs. 4,5,6) and Harinoso de Ocho (figs. 7,8,9) as well 
as their hybrid product, probably the Pima-Papago race, 
or Maiz Blando (figs. 10, 11, 12). 
As Maiz de Ocho moved northward and eastward from 
the Southwest, it would have encountered colder soils 
and shorter growing seasons. As a result, natural selec- 
tion, especially during germination, would have increased 
the frequency of the hard, flinty kernels and early ma- 
turing kernels. At the same time, natural selection would 
have filtered out any residual adaptation to the growing 
conditions which are found in the North and Northeast. 
Such germplasm might have been carried over through 
the poorly adapted Harinoso de Ocho in Sonora from the 
introduced highland race Cabuya of Colombia. Thus, 
during its northward migration from the Southwest we 
would have had the well-known substitution of latitude 
for altitude adaptation resulting in this reassertion of the 
original South American heritage. 
This new eight-rowed race had certain advantages over 
the indigenous Chapalote race in that its larger and softer 
kernels were easier to grind for flour. When the prob- 
lem of adaptability was overcome by hybridization with 
indigenous maize, the new superior type of grain must 
have spread rapidly, probably through trade and migra- 
tion. The hybrid, called Maiz Blando de Sonora by Well- 
hausen et al. (1952), remained in Mexico. It has floury 
kernels approaching those of Harinoso de Ocho in size 
and a twelve-rowed ear approaching that of Chapalote. 
Just to the north, the counterpart of this hybrid is called 
Pima-Papago after the Indians who cultivated it (An- 
derson and Cutler, 1942). Teosinte introgression seems 
also to have played a role in the spread of this hybrid, 
especially in the Fremont area of Utah, where the kernels 
become strongly dented and the glumes indurated (Plate 
XXIV). The close similarities among the races Maiz 
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