Plants from 200 ears of this collection were grown in 
duplicate plantings at New Haven, Connecticut,’ and 
Forest Hills, Massachusetts, in the summer of 1941. The 
remaining 118 ears were omitted partly because of limi- 
tations of time and space but mainly because they ap- 
peared to be duplicates or near-duplicates of those selected 
for planting from the same locality. The great majority 
of the varieties were tall-growing, vigorous and late in 
maturity. In spite of an unusually favorable season and 
absence of early frost, not all varieties reached a stage 
where material for cytological studies could be collected 
and only 162 were examined cytologically. 'To this ex- 
tent our sampling of Guatemalan maize is not completely 
random because the more Tripsacoid varieties, those with 
largest numbers of chromosome knobs, are among the 
later maturing ones. 
Again, because of the limitations of time, knob number 
was determined on only one plant in each variety. This 
admittedly is not an adequate sample for establishing the 
average knob number of a variety. The primary goal in 
this case, however, was to sample the region rather than 
the variety. In considering relationships, discussed later, 
between knob numbers and other characteristics, it should 
be borne in mind that significant relationship can be 
shown in spite of rather than because of inadequate sam- 
pling of varieties. Had the average knob numbers for 
each variety been more precisely determined, even more 
significant relationship could probably have been shown. 
No attempt was made to identify each chromosome on 
which a knob was borne nor to determine the position of 
each knob but in examining the preparations all of the 
eighteen knob positions which Longley (14) has described 
3 We are indebted to Dr. D. F. Jones and other members of the 
staff of the Connecticut Agricultural Experiment Station for invaluable 
assistance in connection with the studies made at New Haven. 
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