STREPTOCOCCUS PYOGENES 365 



cultures, each from a different individual. These indi- 

 viduals came from- nearly all parts of the country and 

 therefore fairly represented conditions to be found through- 

 out the population in general. The physical conditions 

 of the persons from whom the cultures were obtained were 

 sufficiently diverse to x indicate the comprehensive nature 

 of the investigation. They were: 



Throat cultures: 



Healthy carriers 80 



Acute bronchitis 60 



Measles 9 



Sore-throat . . . .... 30 



Pneumonia: 



Sputum 20 



Autopsy 21 



Empyema -. > ., . . .- . 67 



Gunshot wounds 4 



Renal infections . : . . . . . ... -. . . 1 



Total 292 



By selecting at random from the 292 cultures three that 

 were characteristic in their gross peculiarities and immun- 

 izing animals from them, it was found: (1) That in their 

 agglutinating reactions these cultures were identical; and (2) 

 that by the same test 139 other strains, or 47 per cent, of the 

 whole number, proved to be like them, while the remainder, 

 153 strains, failed in their agglutinating reactions with that 

 serum and were therefore regarded as different. Animals 

 were then immunized from one member of this negative 

 group and of the 153 strains in that group 54, or 19 per 

 cent., of the whole number agglutinated with the serum 

 from this immunized animal. Again a culture of those that 

 failed to agglutinate in the second test was chosen and a 

 third animal rendered immune from it. With the serum 

 from that animal 79 members of the group, or 27 per cent., 

 of all the cultures reacted positively. 



