In 1923, we succeeded in producing experimental scarlet fever with an apparently pure culture of a hemolytic streptococcus isolated from a case of scarlet fever.1 The Berkefeld V filtrate of this culture did not produce scarlet fever in a person who later developed the disease on inoculation with the unfiltered culture.In the series of inoculation experiments in which scarlet fever was produced, only two of the ten volunteers acquired the disease. These ten volunteers were young adults who said that they had not had scarlet fever. They were all inoculated with the same culture. Intracutaneous tests were made in sixty-five con¬ valescents from scarlet fever; sixteen persons with a history of scarlet fever, and seventy-two with no his¬ tory of scarlet fever. The convalescent scarlet fever patients were from 2'to 35 years of age; thirty were male, and thirty-five female. The tests were made from the seventh to the thirty-third day of the disease.The persons with a history of scarlet fever were from 3 to 47 years of age. They had had scarlet fever from six months to thirty-seven years before the tests were made ; nine were female, and seven were male.The persons with no history of scarlet fever ranged in age from 12 months to 33 years; thirty-four were male and thirty-eight were female.

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