“…The Royal Marsden Hospital, and Institute of Cancer Research* THE A and B antigens of the foetal erythrocytes have been the subject of much published work containing many apparently conflicting results (Kemp, 1928;Moureau, 1935 ;Bornstein and Israel, 1942;Tovey, 1945 ;Formaggio, 1948;Engasser and Witebsky, 1948 ;Witebsky and Engasser, 1949;Seelen, 1954). In addition to the innate biological importance of the evolution of cell antigens in early development, interest has been stimulated by the existence of haemolytic disease of the newborn resulting from maternal sensitization to A and B antigens.…”