“…These results are obviously highly satisfactory. 7 3.Diphtheria antitoxin (Figure 1) One month after the third injection 84.6 per cent of 123 infants tested had a " protective " titer of diphtheria antitoxin, only 20 per cent had antitoxin levels of more than 1.0 unit per ml., and 15 per cent had less than the minimum antitoxin titer tested for. After booster dose, however, with one exception, all patients developed " protective " antitoxin titers and the percentage of those with high antibody levels had risen from 20 per cent to 50 per cent.…”