in a Colombian Tripsacum believed to be a form of 7" 
australe. 
We have through repeated backcrossing to inbred 
A158 extracted from Maiz Amargo achromosome which 
has almost the same effects upon the lignification of the 
pistillate glumes as chromosome 4 of teosinte. Other 
examples of extracted tripsacoid chromosomes are de- 
scribed below. 
EXTRACTION oF TRIPSACOID CHROMOSOMES 
FROM LATIN-AMERICAN VARIETIES 
Chromosomes having effects similar to teosinte chro- 
mosomes have been extracted through repeated back- 
crossing to the inbred A158 from the living varieties of 
maize of various countries of this hemisphere (31). Mod- 
ified strains of A158 containing these extracted chromo- 
somes are virtually indistinguishable from those produced 
by introducing chromosomes directly from teosinte. 
Furthermore, these extracted chromosomes, like the 
chromosomes from teosinte, are mutagenic when incor- 
porated into A158 and, more significant still, some of 
the mutations produced are genetically identical with 
those produced by teosinte chromosomes. Chromosomes 
with tripsacoid effects have now been extracted from 
varieties of corn from Mexico, Honduras, Nicaragua, 
Cuba, Venezuela, Brazil, Paraguay, Bolivia and Argen- 
tina. Those extracted from varieties from Mexico, Hon- 
duras and Nicaragua can be attributed to teosinte intro- 
gression. Those from Cuba and Venezuela may also be 
the product of teosinte introgression, for, although there 
is no teosinte in these countries, there has been some in- 
troduction of Mexican and Central American maize 
varieties. But the tripsacoid chromosomes from Brazil, 
Paraguay, Bolivia and Argentina come not only from 
countries where teosinte is unknown but from races of 
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