STREPTOCOCCUS PYOGENES 367 



The study of bronchopneumonias though small in num- 

 ber he thinks indicates a special virulence of streptococci 

 of Group I in this disease. 



In his sore-throat and tonsillitis cases the members of 

 Group III predominate and it is of special interest to note 

 that these cases all came from one hospital ward and prob- 

 ably therefore had a common origin. 



These studies further show that the specificity of this 

 grouping is not limited to the agglutinating reactions of 

 the members of the groups but is still further demonstrated 

 by the fact that in vitro the streptococci of one group are 

 killed by its homologous immune serum, while such serum is 

 without germicidal action on the members of the other groups. 



By analogous proceedures Tunnicliffe 1 has shown that 

 according to their specific serologic reactions the strepto- 

 cocci accountable for the angina of scarlet fever and those 

 present in typical cases of erysipelas represent distinct 

 varieties of the hemolytic group of streptococci. 



The bearing of all this on efforts to produce serum for 

 the treatment and prevention of streptococcus infections is 

 evident. 



We can no longer expect the serum from an animal immun- 

 ized from any strain of streptococcus taken at random from 

 whatever source to be effective. It may be, but if so it is 

 only by chance. Serum A may be expected to be effective 

 when used against infection caused by streptococcus of A 

 group, but not those of Group B and vice versa. 



Antistreptococcus Serum. Certain animals - - notably 

 horses and asses as well as some smaller animals, may be 

 rendered immune from Streptococcus pyogenes. In vary- 



1 Jour. Am. Med. Assn., 1920, No. 20, vol. Ixxv, p. 1339. 



