2. Linkage of 4-row ears. Some years ago, I obtained results suggesting that a gene for the 4-row type of ear is in chromosome 6 well to the right of Pl. Four-row cultures were, therefore, crossed with 8-row translocation 6-10a. Y y and Pl pl were also involved. Backcross progenies were grown last summer. There was marked deficiency of 4-row plants as has been observed frequently before in dealing with this character. From a total of 295 plants of the backcross, the following per cents of recombination were found.

Y-Pl 29.5 Y--4-row 41.7
Pl-T 34.2 Pl--4-row 44.7
Y-T 49.5 T--4-row 51.2

From these results it is clear that, if a gene for the 4-row condition is in chromosome 6, its locus is to be sought to the left of Y rather than to the right of Pl.

R. A. Emerson