may be conveniently designated as coarse and fibrous. 
There is a highly significant relationship between knob 
number and the nature of the seminal root system. The 
relationship is closer than the data in Table LI indicate, 
since varieties with intermediate knob numbers tend to 
have intermediate root systems, a fact which is not re- 
vealed when only two categories with respect to each 
characteristic are utilized. 
Pubescence of sheaths 
Many of the Guatemalan varieties exhibit highly pu- 
bescent leaf-sheaths and this characteristic is almost 
universal in the maize varieties of the central plateau of 
Mexico. We have encountered no South American va- 
rieties with knobless chromosomes in which this character 
occurs, and since at least one species of Tripsacum, 7‘ 
pilosum Seribn. & Merr., is highly pubescent we might 
infer that this character, when it occurs in maize, has been 
derived from Tripsacum. Dr. Cutler, on the basis of his 
extensive observations and collections in Mexico and 
Guatemala, is of the opinion, however, that pubescence 
is a maize character and that at least part of the pubes- 
cence in Tripsacum is the result of the introgression of 
maize into 'Tripsacum. There is no doubt that some spe- 
cies of 'Tripsacum are heterozygous for pubescence. The 
senior author has found near Guadalajara, Mexico, pu- 
bescent and glabrous plants, apparently of the same spe- 
cies, growing in the same colony. 
But, whatever may have been its origin in Tripsa- 
cum, pubescence, in Guatemalan maize, is undoubtedly 
a character derived from maize. The teosinte of San 
Antonio Huista is glabrous, and apparently the Tripsa- 
cum which grows in this area is also glabrous, for Kemp- 
ton and Popenoe (9) describe it as ‘‘probably 7. laaum,”’ 
a species, which so far as we know, is always glabrous. 
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