AS early as 1926 Dohrn et al. 1 discovered the œstrogenic activity of plant material. It was only in 1944 that Bennets2 described disorders in sheep originating from œstrogens in pasture with a high content of subterranean clover (var. Dwalganup). Bartlett et al. 3 suggested that in Britain œstrogens in pasture might raise milk yield and non-fatty solids in the milk of cows.