7. A study has been in progress for several years to determine whether the marked differences between Euchlaena and Zea are genic and whether the genes which differentiate the two genera can be located on definite chromosomes. Four chromosomes have been studied, using marker genes from corn, and it has been found that the V-Pl genes are definitely linked with genes for number of tassel branches, B-lg₁ genes are linked with genes for height of stalk, number of tillers, number of leaves, number of ears, and number of tassel branches. Waxy gene is linked with genes for number of tillers, number of leaves, and number of ovules per ear. su₁Tu genes are linked with genes for height of stalk, number of leaves, number of ears, number of tassel branches, length of ear, number of rows of ovules and number of ovules. So far as the results go they indicate that the genes which differentiate Zea and Euchlaena are scattered at random over all the chromosomes.

P. C. Mangelsdorf and R. G. Reeves