HE existence of several allelomorphs at the S locus has been demonstrated in T Nicotiana spp. (EAST and YARNELL 1929), Veronica syriaca (LEHMANN 1926), Antirrhinum glutinosum ( GRUBER 1932), Trifolium pfatense (WILLIAMS 1939; and WILLIAMS and WILLIAMS 1947), Oenothera organensis (EMERSON 1939, 1940) and Trifolium repens (ATWOOD 1944). In Trifolium pratense, BATEMAN (1947) calculated that the nu...