Comparison of the genomes of Cow, Sorghum and maize: 
The suggestion made by Anderson (1945) that maize 
originated in southeast Asia as an amphidiploid of a hy- 
brid between species of Coix and Sorghum possessing a 
diploid chromosome number of 10, though rejected on 
a number of grounds (Mangelsdorf and Oliver, 1951; 
Chaganti, 1965), makes interesting a comparison of the 
morphology of the chromosomes of C. aquatica and spe- 
cies of Sorghum with a diploid chromosome number of 
10 and those of maize. Pachytene chromosome mor- 
phology has been reported by other investigators in two 
species of Sorghum with a diploid chromosome number 
of 10: viz., S. intrans (Garber, 1947) and S. purpureo- 
sericeum (Reddi, 1958). The chromosomes of JS. intrans 
are uniformly dark staining, and the centromeres are 
hard to locate in them. Three pairs are of one length; 
the remaining two are shorter and participate in nucleolus 
organization. The chromosomes of S. purpureo-sericeum 
ure in the same size range as those of maize and possess 
dark staining chromomeres in the proximal regions of 
both arms, making the centromeres easy to locate. 
Neither species possess knobs. The genome of C. aqua- 
tica, at pachytene, is about 1.7 times longer than that of 
maize (data from this study compared to measurements 
of maize chromosomes at pachytene given in the publi- 
‘ation of Rhoades, 1955), and the chromosomes them- 
selves are quite dissimilar in morphology to those of 
maize. Chromosomes of C. aquatica show differentially 
stained eu- and heteropyecnotic regions. ‘They are also 
devoid of knobs. Maize chromosomes do not exhibit 
similar differential staining, and they possess knobs. 
Morphological comparisons, thus, do not reveal common 
features between the genomes of C. aquatica, S. intrans, 
and S. purpureo-sericeum on the one hand and maize on 
the other. This observation by itself, in the absence of 
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