a1 National Institute for Research in Dairying, Shinfield, Reading
a2 Courtauld Institute of Biochemistry, Middlesex Hospital, London, W.1
1. Four species of Medicago, six species of Trifolium and fourteen grass species, all frequently found in British dairy pastures, have been tested for oestrogenic activity by the mouse uterine weight method. Activity was detected in four, four and six species respectively.
2. It is probable that the quantity of oestrogen present in British pasture plants is insufficient to affect milk composition in cows at pasture. Some further experiments with cows are, however, suggested which might elucidate this.
(Received February 04 1959)