and are not known to be the bearers of any specific genes. 
Annual teosinte has 20 chromosomes, the same as corn, 
and perennial teosinte 40; some varieties of teosinte also 
have B-chromosomes. The lowest somatic number yet 
reported for Tripsacum is 36, but forms with 72 have long 
been known, and others with 45, 54, 90 and 108 have 
been reported by Farquharson (13). All writers on the 
subject have thus far continued to designate the 36- 
chromosome form of 'Tripsacum as diploid, but most of 
them, in doing so, probably recognize the possibility 
that it may be tetraploid. 
As to chromosome length and arm ratio, a majority 
of the corn varieties are essentially similar to one another 
and may be designated for convenience as “‘normal.”’ 
The normal type is described and diagramed by Rhoades 
(39). Numerous aberrants are also known, some of them 
resulting from recent structural changes and others being 
of unknown origin. In these characteristics, the chromo- 
somes of teosinte are usually similar to those of corn, but 
there are conflicting reports on this question (82). Long- 
ley (20) found that the synapsed pachytene homologues 
of an F; corn-teosinte hybrid were not significantly dif- 
ferent from each other, and Randolph (82) accepts Long- 
ley’s results as justification for a final conclusion. How- 
ever, Brown (6), working with hybrids of an entirely 
different plant, Gossypium, showed that paired pachy- 
tene chromosomes of different genom groups are equal 
in length, despite differential size at metaphase, thus 
casting some doubt on the decisiveness of Longley’s re- 
sults even before Randolph’s paper was published. The 
chromosomes of Tripsacum are so different from those 
of corn or teosinte in size and arm ratio as to defy a brief 
comparison. In general, they are much shorter and show 
many differences in arm ratio. 
The number of chromosome knobs varies in corn, teo- 
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