Among our syphilitic patients all the living children of 100 families have been examined, Wassermann tests made and the family history studied. In these 100 families there were 331 pregnancies. Of these 100 (30.2 per cent.) were abortions, 31 (9.3 per cent.) still births and 200 (60.4 per cent.) living births. Of the 200 living births 35 children died early and 4 died late, and 161 remained alive and were examined. Of these, 12 are now dead. Of the 35 who died early, 5 gave an undoubted history of syphilis and a number gave suspicious histories. Of the four who died late, one was an idiot. Of the 161 examined, 107 were clinically positive and had positive Wassermann tests. Five were clinically positive and had negative Wassermann reactions. Sixteen, who showed no evidence of syphilis, gave positive Wassermann reactions. Thirty-three, who gave no clinical proof of syphilis, gave a negative Wassermann reaction. Of the five who were clinically positive but gave negative Wassermann reactions, one was a young infant who had snuffles and a large spleen. The mother and sister both gave a positive history and a positive Wassermann reaction. Shortly after beginning treatment the baby developed a syphilitic rash. The baby was removed from the hospital and a second Wassermann was not done. The second case was a nursing baby. The mother had active syphilis and was taking treatment. The baby had an active process in the nose. The third case was a 7-year-old girl who had a markedly sunken nose and who for that reason was the starting point for investigating that family. Both the mother and younger brother gave a positive Wassermann. The fourth case was a 4-year-old girl whose mother and younger sister were both positive and the patient had a general rash which was thought to be syphilitic. The fifth case was a 3-year-old boy with a positive history, and who had had some treatment. His mother and younger brother both had syphilis. A negative Wassermann reaction is obtained in the presence of active syphilis only under certain definite conditions. As had been noted in cases not of this series, very young babies, even with undoubted active syphilis, not infrequently give a negative Wassermann. It has also been noted that even small amounts of mercury tend to cause a positive blood to react negatively. H. Boas[54] states that of fifty-seven babies of syphilitic mothers giving negative Wassermann reactions at birth, thirteen during a three months’ period of observation developed syphilitic manifestations and a positive Wassermann, and two others showed syphilitic changes at necropsy, having had no manifestations during life. Footnote 54: Quoted by Haberman: Jour. Am. Med. Assn., 1915, lxiv, 1146. LATENT SYPHILIS