



twenty-six out of thirty-four samples of milk examined. None 

 but distinct chains of from six to eight or more elements were 

 considered. Plate cultures were then made and the isolated 

 streptococci were studied to determine what proportion of them 

 were streptococcus lacticus. 



The following results were obtained in attempts to isolate 

 the germs by the plate method : 



(+ = germ isolated. = germ not isolated.) 



1. + 7. 13. + 



2. 8. + 14. 



3. + 9. 15. + 



4. + 10. + 16. 



5. + 11. 17. + 



6. 12. + 18. 



I was able to isolate streptococci from ten out of eighteen 

 samples of milk, whereas the stained preparations showed a 

 larger proportion than that to be present. Cultural study of 

 these strains indicated that of these ten, seven belonged to the 

 streptococcus lacticus group, while the other three were classed 

 with other varieties. It will be seen that a large per cent of 

 the streptococci occurring in fresh milk belong to this class, 

 which because of their cultural similarity are suspected of being- 

 related to the pathogenic streptococci., 



RELATION OF STREPTOCOCCUS LACTICUS TO STREPTOCOCCUS PYOGENES. 



A careful comparison of various strains of streptococcus 

 lacticus on the ordinary cultrfre media with similar cultures of 

 streptococcus pyogenes afforded no means of differentiation. 

 Their action on dextrose, lactose, maltose, glucose, saccharose 

 galactose, mannit and inulin was studied without determining 

 any constant differential features. 



BLOOD AGAR. 



f 



Beside the ordinary cultures, I had hoped to throw some light 

 on the relation of these germs to the streptococcus pyogenes by 

 the use of blood agar, since it is claimed by many investigators 



