9. A fairly large coupling F2 of C Sh/c sh and I Sh/C sh has been produced (9053 grains in the first and 7226 in the second case) to see whether there is any significant difference between the recombination values. All the data from the individual ears as well as the totals form a homogeneous sample around the common mean of 5.1%. A backcross for C Sh/c sh gave 4.3% in 6648. The difference between all F2's and the backcrosses is just over twice the error. Experiments will be made to test reciprocal backcrosses.