into two Texas inbred strains, 4R8 and 127C. Some of 
the modified strains of 4R3 showed significantly greater 
tolerance to heat than the controls but were not appre- 
ciably changed with respect to yielding ability of their 
hybrids. Similar modification of 127C, however, increased 
the yielding ability of its hybrids quite significantly. 
Reeves concluded that some inbreds can be improved 
by the addition of teosinte genes but others can not. He 
postulated that, so far as yield is concerned, 4R8 already 
has the optimum assortment of teosinte genes. He might 
have added that 4R8 is actually one of the most tripsa- 
coid inbreds in the United States. 
The contention that the tripsacoid characters found in 
maize varieties can be attributed to parallel mutations 
rather than to admixture with teosinte has no foundation 
in the evidence now available. It merely substitutes an 
untestable hypothesis for the well-established fact that 
maize and teosinte are hybridizing today and have prob- 
ably been doing so for almost 2000 years as the evidence 
from prehistoric corn shows. 
ARCHAEOLOGICAL EVIDENCE OF 
'TEOSINTE INTROGRESSION 
Virtually all of the archaeological maize from Mexico 
and North America which has been studied recently in- 
cludes specimens which are highly tripsacoid and which 
are quite similar in their general appearance and certain 
botanical characteristics to modern ears derived from ex- 
perimental maize-teosinte hybrids. This is especially true 
with respect to the induration and lignification of the 
glumes which are known from genetic studies to be 
among the most common and conspicuous effects of the 
introduction of teosinte germplasm into maize. Man- 
gelsdorf, for example (28), has shown that the genes for 
indurated glumes occur on at least four chromosomes of 
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