corn was easily kept ina fairly pure condition simply by 
growing it in isolated fields. Now, in order to conceal it 
from thieves, it is planted amid the less desirable field 
corn, which has a similar appearance and which flowers 
about the same time. The crop is safeguarded by this 
practice since thieves are unable to distinguish the sugar 
corn in the field, but another result is that one now rarely 
sees ears of sweet corn which do not show contamination 
with other varieties. Similarly, sweet grains are of spo- 
radic occurrence in nearly all the other races of maize in 
Bolivia and Peru. 
Almost the same story can be told of cud/li, a deep 
reddish-purple type, which, like sweet corn, was once 
prized and maintained in a more or less pure state. Now 
it, too, is contaminated with other varieties and has left 
its mark upon them as well. 
METHODS OF COLLECTING AND STUDY 
For reliable studies of the races of maize, their origin, 
spread and present distribution, it is necessary to have 
extensive data. Hasty trips through markets may serve 
to collect an impressive mass of ears and seeds which are 
useful for some studies but fail to tell the whole story. 
In spite of the selection of fairly uniform ears by native 
planters, the amount of variation in their fields is aston- 
ishing to one accustomed only to commercial maize 
plantings in the United States. An ideal collection would 
include some indication of the character of the plant and 
the amount of variation in a typical planting, the tassel, 
and some indication of the genotype of the plant for 
characters may be concealed by dominant alleles, domi- 
nant inhibitors or strong expressions of other genes which 
affect the same parts. Since some of these data can be 
secured only after long study in the field and by growing 
cultures under controlled conditions, ideal material for 
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