STREPTOCOCCUS PYOGENES. 491 



Is Protection Afforded by the Same Serum Against All 

 Varieties of Streptococci? 



We have tested the protective value of one serum 

 against five streptococci. First, the streptococcus given 

 us by Marmorek, which was obtained from a case of 

 angina complicating scarlet fever. Its virulence is now 

 such, after having passed through hundreds of rabbits, 

 that 0.000001 c.c. is the average fatal dose. Second, 

 a streptococcus obtained from a case of erysipelas in 

 England. Its virulence is 0.00001 c.c. on the average. 

 Third, a streptococcus obtained from a case of cellu- 

 litis a few weeks ago, its virulence being about 6 c.c. 

 Fourth, a streptococcus sent me by Theobald Smith. 

 Its virulence is such that 0.1 c.c. is the average fatal 

 dose. Fifth, another culture sent me by Smith, which 

 grew in short chains and was obtained from milk; its 

 virulence was similar to No. 4. 



Against the first three streptococci derived from three 

 different varieties of infection existing in three different 

 countries the serum produced in the horse by the strep- 

 tococcus from England had nearly the same value. 

 Against the latter two streptococci, as well as against 

 a pneumococcus, which in ordinary cultures looks like 

 a streptococcus, the serum had no effect. 



The results published by others must also be taken 

 to prove that a serum which protects from infection 

 with one streptococcus may fail against others; but, 

 taking all together, they indicate that the majority of 

 streptococci met with in practice will be influenced by 

 the same serum. Many more streptococci, however, 

 must be obtained from human infections and tested 

 before we can be certain of this. Those obtained from 



