It has been shown (Holmes, Stanier, Semambo and Jones, 1951) that the concentration of y-globulin in the serum of apparently healthy adult Africans is considerably higher than that of Europeans. It is also known (Longsworth, Curtis and Pembroke, 1945) that, in white infants, the level of y-globulin of the serum of umbilical cord blood is higher than that of the maternal blood taken on the day o...