THE GENUS STREPTOCOCCUS 151 



nor immunization experiments showed constant group 

 reactions, altho the cultures exhibited marked individual 

 variations. 



Fischer (1904) made a careful review of the literature of 

 this subject, and carried out a considerable series of experi- 

 ments on the agglutination of various strains of streptococci. 

 Like the observer just cited, he found that each strain 

 showed a specific reaction with the serum of the animal 

 into which it had been injected, a somewhat less sharp 

 reaction with other strains, and no agglutination with still 

 others. The forms showing close similarity in aggluti- 

 nation were not, however, those most closely related in 

 origin and pathogenicity. Kerner (1905), after exhaustive 

 investigations, came to the conclusion that serum reactions 

 among the streptococci were so erratic as to be valueless 

 in systematic work. Nedrigailow (1906) has recently 

 reviewed the evidence for constant specific types in scarlet 

 fever and smallpox, and concludes, by analogy with the 

 serum reactions of other pathogenic streptococci, that the 

 special properties of the streptococci in these diseases 

 are only temporarily acquired characters, developed in 

 response to their peculiar environment. 



The hemolytic power possessed by the pathogenic 

 streptococci is another of the subtle properties developed 

 in direct response to the biochemical conditions of their 

 host. Schottmuller (1903) used this character as a 

 differential test, noting that, besides a zoogloea-forming 

 organism (D. involutus), two types of streptococci may be 



