78 



recorded 17.5, 29, 39, 47, and 69.4 percent respectively of the aerogenes 

 group in milk. 



TABLE XLI. INCIDENCE OF AEROGENES TYPES AMONG COLON BACILLI 

 ISOLATED FROM WATER AND MILK 



*GUucose fermenters, lactose reaction not recorded. 



The observations as to the incidence and distribution of the colon 

 group in nature may be summed up as follows: 



The evidence indicates that lactose fermenting bacteria capable of 

 growing aerobically are widely distributed in nature and that they con- 

 stitute two distinct groups; a low ratio V. P. negative subgroup, which was 

 previously described as the coli section, is characteristic of the intestinal 

 tract of man and animals and relatively infrequent in localities not recently 

 polluted with human or animal intestinal material; and a high ratio V.-P. 

 positive group, termed the aerogenes section, which is very rare in the in- 

 testinal discharges of man and animals, but constitutes the predominating type 

 in soil and on grains. In water and milk the proportion of coli and aero- 

 genes strains naturally varies, the predominating type depending to a con- 

 siderable extent on the source of contamination. 



Correlation of the Sanitary Survey and the Incidence of Coli 

 and Aerogenes Types in Water. If, as has been intimated in the fore- 

 going discussion, the coli and aerogenes sections are so characteristically 



