The transfer of antibodies from the mother to the newborn infant during gestation gives the infant protection against a number of diseases, provided that the mother has a sufficient supply of the antibodies in question. This has been shown in numerous investigations.A comprehensive review of this topic is given by Vahlquist 1952 (52), and the reader is referred to this work. The results of the earlier investigations will be briefly summarized. Diphtheria and tetanus antitoxins, streptococcal erythrogenic antitoxin, antistreptolysin, antistaphylolysin, pertussis agglutinins, typhoid H agglutinins, measles, poliomyelitis, influenza and mumps virus antibodies, toxoplasma antibodies and univalent R h antibodies are dstected in the cord blood in about equal titre as in the blood of the mother. Diphtheria antitoxins, however, often appear in a higher titre in the cord blood than in the maternal (4). Typhoid H agglutinin titres frequently were lower in the cord blood (48, 44).Some antibodies on the other hand cannot be detected in the cord blood or are found in much lower titre. Among these are coli agglutinins, typhoid 0 agglutinins, isoagglutinins, bivalent R h agglutinins and some reagins. During the last years further studies on prenatal antibody transmission have been carried out. As for diphtheria antitoxin it was shown by Murray et al. (28), that antistuphylolysin titres in the cord blood usually ar0 higher than in the mother's blood. This was the case in 40 out of 56 pairs of sera,. The same phenomenon was observed in the case of antistreptolysin (29) in 41 out of 46 pairs of sera. Tunevall (51) demonstrated that the antipnezcmolysin concentration in the cord blood was equal or lower than that in the corresponding maternal blood (70 cases studied).Cashman (6) confirmed, that pertussis agglutinins are present in the cord blood and, again, the cord blood level was above that of the mother in 10 out of 18 instances. Tunevall (50) studied complement-fixing antibodies against Hemophilus influenzae in 7 0 cases. The titres were predominantly considerably lower in the cord blood.Bacteriostatic activity against Escherichia coli, type 0 55, was demonstrated by Dancis & Kunz (8) in sera of full-term infants at birth (15 samples) and in two thirds of the sera of premature infants (16 samples). This finding was confirmed by Yeivin et al. (58). Neter et al. (30) examined agglutinins against E . coli, types 0 111, 55 and 26, in 26 instances, using the hemagglutination test. They found that these agglutinins were either not transferred to the newborn or were transferred in a low titre. This