This vest uses an unusual technique called 'shadow knitting'. In it the colour work is done in stripes - two rows Colour A (green) followed by two rows Colour B (white). The stitch work is a combination of stocking stitch and garter stitch; thus every right side row is a knit row, as it the case for both stocking stitch and garter stitch. The trick to this technique comes on the wrong side rows. If a stitch there is purled (stocking stitch), it looks knit on the right side and tends to be recessive. If it is knit, however (garter stitch), it looks purled on the right side and tends to be dominant. The dominant ridges are particularly striking when viewed at an angle, as they then 'hide' the recessive stocking stitch strips. So, for the wrong side green rows the grassy areas are knit (green dominant), and the sheep-y areas are purled (green recessive). For the wrong side white rows the grassy areas are purled (white recessive) and the sheep-y area are knit (white dominant).