been in obvious contact with teosinte; (b) chromosomes 
with tripsacoid effects extracted from races of maize far 
removed from contact with teosinte. 
Evidence in the first category is provided by the studies 
of Roberts et al (46), on races of maize of Colombia, es- 
pecially the race called Chococefio which they describe 
as follows: 
Chococefio is one of the most unusual races of this hemisphere, both 
in its characteristics and in the primitive way in which it is grown. 
Its culture is largely confined to the humid coastal region of western 
Colombia, where rainfall sometimes exceeds 400 inches annually. The 
maize is grown without cultivation. The fields are prepared by cutting 
down the small trees and brush. The seed, which is broadcast and 
not covered, germinates on the surface of the soil. The plants grow 
up through the branches of the cut vegetation. 
To succeed under these primitive conditions the maize must have un- 
usual characteristics. Chococefio is highly tripsacoid. It has tough, 
slender stalks with tillers, narrow, drooping leaves and pendulous 
tassel branches. It has the general aspect of certain segregates from 
maize-teosinte or maize-Tripsacum hybrids. Since teosinte does not 
occur in this region, and Tripsacum is common, it has been assumed 
that Chococefio is the product of the hybridization of maize and Trip- 
sacum. 
Roberts et al also report that in the Chocé region, from 
which this peculiar race derives its name, plants of maize 
and 'Tripsacum often grow together in the same field and 
flower at the same time. In a preliminary experiment, 
varieties of Tripsacum collected in Colombia were crossed 
with a number of different races of maize, and hybrid 
seeds, some of them capable of germinating without em- 
bryo culture, were produced in all crosses. 
All the evidence is consistent with the conclusion that 
maize and ‘Tripsacum have hybridized in Colombia to 
produce, not teosinte, but a highly tripsacoid race of 
maize which, in its vegetative characters, at least, shows 
some resemblance to teosinte. 
Even more tripsacoid, at least in characteristics of the 
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