that we should expect to find the most Tripsacoid maize, 
maize with the largest number of chromosome knobs, in 
the general region where teosinte occurs most abundantly 
as a plant growing in the wild, the region where it pre- 
sumably originated from the hybridization of maize and 
Tripsacum. We might, however, also have a reasonable 
expectation of finding in this same general region non- 
Tripsacoid varieties, descendants of the pure maize which 
had been introduced from South America and which had 
been the only type grown before the hybridization with 
Tripsacum occurred. 
Since western Guatemala is the only region so far dis- 
covered where teosinte grows in profusion in a wild state, 
since it is a region where ‘Tripsacum is common, and 
finally since it is a region of numerous mountains and 
valleys—natural barriers which would enable varieties 
once established to maintain themselves indefinitely ina 
relative state of genic stability 
it appeared to be the 
most promising region for beginning an investigation of 
this problem. 
At our instigation Dr. F. W. McBryde, Department 
of Geography, Ohio State University, who spent more 
than a year in Guatemala and southern Mexico as Na- 
tional Research Council Fellow, has made comprehensive 
collections of maize varieties in these regions. His collec- 
tion from western Guatemala was especially complete in- 
cluding 818 ears from thirty-eight localities in thirteen 
Departments. We are also indebted to Dr. McBryde for 
various data on the corn varieties and the localities where 
they were collected. 
Even acursory study of this collection demonstrates at 
once the great diversity of maize in western Guatemala. 
Here, in an area less than half the size of the state of 
Iowa, are found probably more distinct types of corn 
than occur in the entire United States. 
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