Gregor Mendel published his results from his experiments on simultaneous inheritance of pea plant phenotypes in 1866 (Mendel, 1866). He examined 556 plants and classi?ed them according to their form (wrinkled or round) and color (green or yellow). The expected rates are to a 9:3:3:1 ratio.

Class Round/yellow Round/green Wrinkled/yellow Wrinkled/green Obs 315 108 101 32 Exp 312.75 104.25 104.25 34.75