3. It has been shown that chromosome knobs can be 
transferred from teosinte to maize and if knobs are ac- 
cepted as indicators of teosinte introgression there are 
abundant cytological manifestations of such introgres- 
sion. 
4. Both circumstantial and direct evidence show that 
maize can be improved in certain characteristics, includ- 
ing yield, by hybridization with teosinte. 
5. No facts have been discovered to support the sug- 
gestion that tripsacoid characters in maize are the result 
of parallel mutations. On the contrary, the fact that 
several such characters may appear simultaneously points 
to genetic recombination following hybridization. 
New evidence from both prehistoric and living maize 
support the following additional statements: 
6. All recent collections of archaeological maize from 
caves in Mexico, Arizona, New Mexico, Colorado, Texas 
and Oklahoma include specimens which can be closely 
matched by segregates of maize-teosinte hybrids. 
7. Archaeological evidence of teosinte introgression 
is accompanied by increased variability and improvement 
in certain characteristics. 
8. The introgression of teosinte has mutagenic effects, 
some of which appear to be beneficial. 
9. There is some circumstantial evidence of the direct 
introgression of Tripsacum into maize. 
10. Chromosomes having tripsacoid effects have been 
extracted from corn varieties from Mexico, Honduras, 
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