study is rarely seen. It must be recognized further that 
a collection of plants is rarely a random sample of the 
population. Botanists have more or less innocently prac- 
ticed misrepresentation for many years by selecting spec- 
imens of a convenient size or those which were the most 
attractive, the most nearly perfect or the most unusual, 
even when these were unique in the population they were 
supposed to represent. Thus, in the case of maize, colored 
or freak ears frequently receive more attention than nor- 
mal ones. For example, in a harvest of 8000 ears at San- 
tiago de Chiquitos, Bolivia, only four ears differed from 
the predominating type, yet in a collection representing 
this lot three of the atypical ears were included and only 
four of the major type. 
The present paper is based upon collections made and 
studied in South America and checked by growing plants 
in the same or similar localities; and upon collections at 
the Botanical Museum of Harvard University, the Es- 
cola Superior de Agricultura Luiz Queiroz in Piracicaba, 
Brazil, the Instituto Agronomico of Campinas, Brazil, 
the Missouri Botanical Garden, the Pioneer Hi-Bred 
Corn Company, and the Universidad Autonoma Simon 
Bolivar at Cochabamba, Bolivia. Through the kindness 
of the directors and staff of the Escola Superior de 
Agricultura and the Universidad Simon Bolivar, it was 
possible to grow and study native maize in their experi- 
mental fields. 
The valleys of Peru and Bolivia have long been sup- 
posed to possess the greatest diversity of maize types and 
for this reason much emphasis has been laid upon this 
center, while little attention has been paid to the maize 
of the eastern Andean slopes and the adjacent lowlands. 
It is true that the highland areas do have a large number 
of visibly different types, but one must consider also the 
invisible variation, that which is recessive and masked by 
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