ing into the triploid hybrid) as extra bivalents in the 
triploid hybrid (Maguire, 1964). Thus, the behavior of 
Tripsacum chromosomes in the triploid hybrid may be 
taken to represent the intragenomic affinities within the 
Tripsacum genom. In ‘Table VI, the mean per cell of 
chiasmatic and side-by-side association found at meta- 
anaphase in haploid maize, a haploid genom of 'Tripsa- 
cum (in the triploid hybrid) and the Fy maize-Tripsacum 
hybrid are presented (also see Plate NLVITI). 
Taste VI. Mean per cell of chiasmatic and side-by-side associations 
and their range (in parenthesis) in haploid maize, a haploid genom 
of Tripsacum and the F, maize-Tripsacum hybrid. The rest of the 
chromosomes occurred as unpaired univalents or end-to-end associa- 
tions of various kinds and frequencies. It is assumed (Person, 1955: 
Riley and Chapman, 1957) that the later type of associations do not 
imply homologies or homeologies. 
Mean per cell Mean percell Mean percell Remainder 
of chiasmatic of chiasmatic — of s—s assns. of 
trivalents bivalents chromosomes 
Haploid maize 0.00 0.06 0.28 9.32 
(0 to 1) (0 to 2) 
Haploid genom 0.06 0.20 0.20 17507 
of ‘Tripsacum (0 to 1) (0 to 1) (0 to 1) 
Haploid maize plus 0.06 0.26 0.48 27.34 
haploid genom of 
Tripsacum 
F, maize-Tripsacum 0.00 2.28 0.69 22.04 
hybrid (0 to 4) (0 to 4) (0 to 2) 
The above data clearly demonstrate that the mean 
synapsis is higher in the Fy hybrid of maize and 'Tripsa- 
cum compared to the pairing in the parents individually 
or together and hence most of it must be allosyndetic. 
In this connection, it 1s of interest to refer to certain ob- 
servations on chromosome exchanges in maize-Tripsacum 
hybrids made by Maguire (1964) in a study of chromo- 
some pairing in the backcross progenies of maize-Tripsa- 
cum hybrids. Maguire studied two triploid hybrids, one 
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