Furthermore there is a highly significant relationship be- 
tween knob numbers and pubescence, pubescence being 
associated with low-knob numbers, smoothness with high 
numbers. The relationship is so strong and clear-cut that 
it allows us to make the prediction that knobless varieties 
of maize with pubescent leaf-sheaths will be discovered 
in South America when a thorough search is made. 
Hairy sheath in maize has been reported as a simple 
Mendelian dominant by ‘Tavear (21). It may behave this 
way in certain cultures, when, for example, knobless pu- 
bescent stocks are crossed with knobless glabrous stocks. 
Among the Guatemalan varieties, however, its presence 
or absence is related to the number of knobs. All varie- 
ties with three knobs or less were strongly pubescent, all 
varieties with five knobs or less were pubescent to some 
degree. Among varieties with eight knobs or less only 
four in ninety-four were glabrous. In contrast, among 
varieties with twelve knobs or more only one in twenty- 
nine was pubescent and all varieties with thirteen knobs 
or more were glabrous. In this particular population a 
minimum of six knobs and usually eight or nine knobs 
are required to suppress pubescence, while the presence 
of twelve or more practically eliminates pubescence. 
Pubescence, if it does not prove to be too widely dis- 
tributed among South American varieties, may enable 
us to determine the region from which the Andean types 
of maize were introduced into Central America, for all 
of the Andean types so far discovered in this region are 
pubescent. 
Smut infection 
The planting at Forest Hills was made on a piece of 
land which had been heavily manured. As a consequence 
infection with smut, Ustilago Zeae (Beckm.) Ung., was 
extremely severe. The data in Table II show that there 
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