7. Summary(#br)1. A description is given of the inheritance and effects in Tropaeolum majus of three new genes ( N, M, T ), of the genes K and L , and of a factor causing abnormal ratios for the gene B .(#br)2. The results of two-factor segregations are tabulated.(#br)3. The physiology of two forms of genetic doubleness is discussed.(#br)4. An account is given of the biochemical work of Miss Scott Moncrieff and Mr Price on the flower-colours.(#br)5. The interactions of the gene C and the grouping of genes in pairs are considered. There is some evidence that Tropaeolum majus is a tetraploid.