3. A dominant gene (Dt) interacts with a1 to give dotted aleurone. Dt does not interact with a2, c or r. Seeds of a1p a1 A2 C R Dt constitution have a pale purple background on which appear the more intense dots. The ratio of the number of dots on seeds of a1 a1 a1p A2 C R Dt Dt dt genotype to the number of dots on seeds of a1 a1 a1 A2 C R Dt Dt dt constitution is 2 : 3, while the ratio for seeds of a1 a1p a1p A2 C R Dt dt dt to seeds of a1 a1 a1 A2 C R Dt dt dt constitution is 1 : 3.8. These ratios suggest that the dosage of a1 affects the number or else that a1P has an inhibitory effect which is proportional to the dosage of a1p. Dt is not linked but is independent of a1, a2, c, r, su and lg.