It was demonstrated by von Decastello and Sturli,1 Happ2 and others that at birth the blood group of the infant is rarely established. Normally, the agglutinogens appear before the iso-agglutinins and by the end of the first year the blood grouping is usually complete.
The presence of iso-agglutinins in the blood from the umbilical cord raises the question as to their origin, whether they are a product of the biologic activity of the fetus or whether they have been transmitted from the mother by way of the placenta. If the iso-agglutinins find their source in the maternal circulation, observations as to their fate in the blood of the new-born would prove of interest. This consideration involves not alone the problem of placental permeability but the relationship of iso-agglutinins of the cord blood to the later development of blood groups by the infant.
HISTORICAL REVIEW
What constitutes the stimulus