Summary o 1. Instances of Protracted Infection in Scarlet Fever:— o 1 & 2. Hospital cases: no recent contact with other acute cases. 3. Do.: contact with other acute cases. 4. Do.: hospital conditions unknown. 5. Do.: no recent contact with other acute cases. 6. Do.: recrudescent infection due to a catarrh. 7 & 8. Home-treated cases. 2. Alternative Explanations of these Cases:— o 9, 10, 11 & 12. Prolonged latent microbism or “missed” cases. 13. Relapse after release from isolation, with “return” cases. 3. Instances of Protracted Infection in Diphtheria:— o Case group 14. Duration of infection over 100 days. Case group 15. Mixed infection of scarlet fever and diphtheria. Case group 16. Duration of infection probably 160 days. Case group 17. Duration of infection 81 days. Case group 18. Infection in otorrhœa. Case group 19. Infection in otorrhœa 52 days after onset of illness. Case group 20. Infection in otorrhœa 43 days after onset of illness. 4. Points suggested by the previous cases:— o (1) Recurrent infection is relatively infrequent. (2) It is oftenest associated with rhinorrhœa and otorrhœa, but not always. (3) Accurate records of such cases are most desirable. (4) Post-isolation medical supervision of patients is required. (5) The complication with which recurrent infection is most often associated, is commonly already present when the patient is first isolated. (6) Is the morbid mucous membrane of the patient a storer of other patients' infection, or an incubator of self-produced infection? (7) Dormant infection is sometimes rendered active after long intervals by catarrhs, etc. (8) There is a close analogy between the phenomena of recurrent infection in diphtheria and scarlet fever. 5. Considerations as to Protracted Infection. History of this in Diphtheria, Greenhow, Gresswell. 6. Likelihood that the same explanation of Protracted Infection holds good for both Diseases. 7. Are “Return” Cases a Hospital Phenomenon? 8. Unsatisfactory Nature of the Statistical Evidence. 9. Causation of Septic discharges in Scarlet Fever and Diphtheria. 10. Bearing of Relapses on the Problem. 11. Analogy of Influenza and other Infectious Diseases. 12. Bearing on the Problem of the old belief in the Infectivity of the late Desquamation of Scarlet Fever.