5. Tests for inversions in populations of corn from Central and South America. Inasmuch as inversions exist in different geographical races of many plant and animal species, it was deemed desirable to ascertain if this was true for maize. Through the generosity of P. C. Mangelsdorf F1 seed of crosses between 65 Central and South American strains and a North American line were obtained. Two North American lines were used; one was homozygous for Tu while the other was a Pr tester. The great majority of the crosses were made using the Pr tester. Sporocytes from the F1 plants were taken and held until a pollen sample was examined. If aborted pollen was present, the P.M.C. were then examined. In none of the F1 families involving the Pr tester was there any indication of structural differences. The homozygous Tu strain was used in five crosses. In one of the F1 families only normal plants were found; in two of them half of the plants had about 20% aborted pollen due to a paracentric inversion, in two more families all of the plants possessed some aborted pollen -‑ again due to a paracentric inversion. It seems certain that the Tu stock was segregating for an inversion.


M. M. Rhoades