“…The demonstration of the Rh factor in human blood cells (Landsteiner and Wiener, 1940) has led to the elucidation of many previously unexplained haemolytic reactions following the transfusion of apparently compatible blood. Later workers (Levine et al, 1941 ;Boorman et al, 1942;Race et al, 1943) have shown that the antibody responsible for the haemolysis may develop in aii Rh-negative person either as a result of previous transfusions with Rh-positive blood or, in the case of women, as a result of bearing an Rh-positive foetus. In the latter case the infant usually suffers from haemolytic disease of the newborn.…”