1. Sterility Studies: T1-5-6-7. Mr. Constancio Lazaro has continued his study of this stock in Uruguay. He has identified the chromosomes involved in a series of semisterile plants derived from the cross: (.)8 × Normal. Of these, 16 are T1-5 translocations, 6 are 1+5 or 7 (not 6) while only one is T6+(?). In addition to the derived semisterile lines, another derived type with about 65% pollen abortion and a ring of 6 chromosomes attached to the nucleolus was found here at Minnesota. Intercrosses are growing in the greenhouse to determine which chromosome pair has been lost from the ring of 8 chromosomes. Linkage tests with the (.)8 showed the following percentages of recombination: f - 22%; bm2 - 50%; y - 16%; v5 - 9%; bm - 8%; gl - 5%; ra - 3%. Recombination values and gene order in one T (1) ? -5 stock derived from the (.)8 are: bm 30 Pr 8.7 T; ys-T - 2%.