3. But for cob length, the expanding variation proceeds 
up one level higher. 
6. The same type of parabolic relationship between 
teosinte introgression and cob-length which was found in 
a previous study of cobs from Richards Cave in Arizona 
was also found in the Cebollita Cave cobs. The interpre- 
tation of this type of relationship is that the long Trip- 
sacoid cobs are the vigorous products of heterozygous 
teosinte germplasm, while their short counterparts show 
the detrimental effects of homozygous teosinte germ- 
plasm. 
7. In the final evolutionary products from Levels 2 
and 1 at Cebollita, there is almost complete recovery from 
the detrimental effects of teosinte introgression and many 
of the cobs are larger and probably more productive than 
the original Chapalote maize. Some of these superior 
cobs resemble those of the present day maize from the 
Southwest. 
ACKNOWLEDGMENT 
During the course of the investigation and preparation 
of the manuscript, many helpful suggestions were made 
by Professor Paul C. Mangelsdorf of Harvard University. 
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