In 1903 Kruse 2 pointed out the close cultural similarity of 

 groups two and three and suggested that the oval bacillus was 

 the result of rapid growth of the streptococcus in the process 

 of division. In 1906 Heinemann 3 published the results of a care- 

 ful comparison of bacillus acidi lactici with pathogenic, sewage 

 and water streptococci. He showed that there was no constant 

 differences in cultural characteristics or in their action on milk 

 and contends that bacillus acidi lactici is non-existent, the 

 organisms formerly classed as such being rapidly developing 

 strains of streptococcus lacticus. 



Concerning the resemblance of streptococcus lacticus to the 

 streptococcus pyogenes, Paul G. Heinemann says : "Streptococcus 

 lacticus agrees in morphological, cultural and coagulative prop- 

 erties with pathogenic, fecal and sewage streptococci." 4 Miller 

 makes the following statement in this regard: "In view of the 

 facts presented the assumption seems justified that the strep- 

 tococcus pyogenes and the streptococcus lacticus, the common 

 organisms of lactic-acid fermentation, are indistinguishable by 

 our present methods." 5 



The strains of milk streptococci, commonly classed as strep- 

 tococcus lacticus, are culturally similar to streptococcus pyo- 

 genes. So far as is known at the present time the only essential 

 difference between these milk streptococci and the streptococcus 

 pyogenes is the difference in pathogenicity. It might well be 

 that these are but attenuated forms of the pathogenic germ and 

 it has been one of the chief efforts in this investigation to de- 

 velop virulency in a number of strains of this class. 



FREQUENCY OP OCCURRENCE OF, MILK STREPTOCOCCI. 



Two methods of investigation were utilized to throw light on 

 this question. First, direct examination of cover-glass spreads 

 of milk stained with Lofflers rnethylene blue. This would give 

 some idea of the number of streptococci as a class, but would 

 not enable one to draw any conclusions as to the number of any 

 particular variety. 



By the stain method streptococci were demonstrated in 



