By x-raying seedlings previous to plumule development 2 plants showing different mutations for cancerous degeneration were obtained. One (group A) produced forms with indefinite color and form defects (v. F. D.), which possess a homozygous recessive gene ca, for cancerous development, and another complex, GKDl, in the heterozygous condition, which contains the gene K for extreme cancerous disturbance, and the genes G (veined) and Dl (dark leaf). The latter 2 types occasionally become isolated in non-cancerous plants, probably through chromosomal disturbances. Heterozygous GKDl gkdl plants (without ca) are characterized by thin white lines in the corolla (m. spr). Progenies from selfing totalling 2641 individuals contain about 26% normal, 66% Dl, and 8% G, and in both of the latter classes a small proportion of m. spr. plants occurred. Backcrosses with the normal strain segregated into Dl and G when GKdl GKdl was the ovulate parent, but the segregates were not carried through the pollen. The genes G K, and Dl do not form a linkage group. The 2d plant (group B) contained the mutation cancroidea, discussed in earlier papers. This apparently involves a non-visible chromosomal disturbance. || ABSTRACT AUTHORS: G. L. Stebbins, Jr