Most genes are lined up on chromosomes like pearls on a string. However, a certain class of genes differ by being highly mobile; and the mecha- they are termed transposons. Their properties of transposition will be described in this book. nism is the rule, irregularities like a spot on a Where uniformity plain-coloured surface strike the eye. Thus the phenomenon of has long been a source of fascina- variegation among organisms In plants, variegation is most easily recognised as irregulari- tion. in pigment patterns on leaves, flowers and seeds, but other ties as leaf or flower form might also...