Since many years different workers have tried to distinguish between strains of streptococci by means of agglutination, but so far uniform results have not been obtained. In 1902 F. Meyer! made experiments with the serum of animals immunized with streptococci from articular rheumatism, and he found that while nearly all the strains of streptococci of human origin which he examined were agglutinated by the serum, the strains from rheumatism and angina were agglutinated most readily while those

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... om scarlet fever and suppurative processes were agglutinated in only slight degree if at all. On the basis of this result Meyer would classify streptococci into two groups; those from the pharynx, and those which are found in suppurative processes. Moser and von Pirquet" found that the serum of horses immunized with streptococci from scarlet fever would agglutinate such streptococci in high dilutions. Salge and Hasenknof" observed that serum from patients recovering from scarlet fever would agglutinate streptococci from scarlet fever specifically, and had no effect on streptococci from other sources. These results seemed to indicate that the streptococci of scarlet fever were of a class by themselves. jogichess,' however, asserted that the agglutination. of streptococci by scarlet fever serum was not specific. From extensive study of agglutination of streptococci by the serum of scarlet fever patients, Weaver" concludes as follows: "Of streptococci cultivated from cases of scarlatina, some are agglutinated by almost all scarlatinal serum, but at dilutions varying from 1: 160 to 1: 4000; others are agglutinated by the same sera with less constancy and at lower dilution, and many are not agglutinated at all. The agglutination reaction between the streptococci cultivated from cases of scarlatina and the serum from the cases of scarlet fever, is in no