of the spikelets into clear-cut ranks as in the case of ears 
of many North American varieties. Straight rows in this 
case are probably similar to the rows seen in young in- 
florescences of Pennisetum (Weatherwax, 19). 
Pairs of Rows. Lines of demarcation between pairs 
of rows, commonly seen in ears of North American va- 
rieties, usually separate one rank of paired spikelets from 
the adjoining rank of paired spikelets. In the Guarany 
maize the lines of demarcation separate the two spikelets 
of the same pair and a pair of rows thus represents spike- 
lets from two adjacent ranks of spikelets intermeshing 
with each other like the teeth of gears. This is illustrated 
in Plate X. 
Compaction of the Inflorescence. Since the 
chief, if not the only real, difference between the upper 
and lower regions of these ears is one of elongation, it 
follows that one of the important characteristics of the 
normal ear of maize lies in the fact that it is a strongly 
compacted inflorescence. In the ears of Guarany pod corn 
there is a strong correlation between the amount of com- 
paction and other characteristics. As the ear becomes 
more compacted, the internodes become shorter, the 
rachis becomes thicker and the number of rows of grain 
increases. These associated changes are illustrated by the 
three specimens shown in Plate X. 
The correlation between condensation of spikelets on 
the lateral branches of the tassel and the number of rows 
on the ear which Anderson (1) has reported may repre- 
sent one manifestation of the relationship between com- 
paction and number of rows. But since the correlation 
which he observed is characteristic of North American 
maize and apparently does not hold for South American 
varieties (1), it is more likely that condensation of spike- 
lets is correlated with the number of spirals of the under- 
[ 54 | 
