11 



shaking, iM cubic centimeters of this culture were poured on a 

 piece of bread and fed to the rabbits. No injurious influence 

 could be detected in either case. 



A causal relationship between these bacteria and summer 

 diarrhea of children has been suggested. It has not been estab- 

 lished that they are the agents in the milk which bring about 

 this disturbance and it does not seem probable in consideration 

 of the experiments just mentioned. It may be that they, in 

 conjunction with other nonpathogenic bacteria, are detrimental 

 at this time because of the increased fermentative action on the 

 intestinal contents. 



CONCLUSIONS. 



1. The strains of milk streptococci commonly classed as 

 streptococcus lacticus are indistinguishable culturally from 

 streptococcus pyogenes. 



2. The streptococci of this class comprise a large per cent of 

 all streptococci present in milk from normal healthy udders. 



'J. Streptococcus lacticus does not acquire pathogenicity in the 

 bodies of guinea pigs and rabbits w r hen retained there for a 

 period of seven days. 



4. Streptococcus lacticus does not exert hemolytic action on 

 blood agar. 



5. Streptococci exactly similar to streptococcus lacticus are 

 present in the throats of nearly all healthy individuals. 



6. Streptococcus lacticus fed in large quantities to rahbits 

 produces no ill effects. 



7. Streptoccus lacticus in milk from healthy udders is not a 

 source of danger to man. 



8. Streptococci from diseased udders are often pathogenic. 



