77 



TABLE XL. INCIDENCE OF AEROGENES TYPES AMONG COLON BACILLI 

 ISOLATED FROM SOIL AND GRAINS. 



*Differentiation based on gas ratio. 



Incidence of the Coli and Aerogenes Sections in Water and 

 Milk. There is, at present, comparatively little information available as 

 to the relative abundance, of the coli and aerogenes subgroups in various 

 types of water. Rogers, in a study of 137 strains isolated from a stream, 

 found 66 percent were of the high ratio and aerogenes-cloacae and 33 percent 

 of the low ratio coli type. Greenfield and Skorup found the ratio just 

 the reverse. Among 405 colon strains, isolated from surface and ground 

 waters in Kansas, 70 percent were of the low ratio V. P. negative type and 

 30 percent of the high ratio V. P. positive type. Houston, Winslow and 

 Cohen, and Wood obtained similar findings to that of Greenfield. That 

 is, they also found a preponderance of the coli subgroup in water; while 

 Stokes, in a study of 528 cultures from water of Maryland, and Mac- 

 Conkey, among 49 strains from ponds, rain waters, and roof washings, ob- 

 tained a preponderance of the so-called non-fecal or high ratio aerogenes 

 and cloacae strains. Clemesha, in India, and Boles, in the Canal Zone, 

 point out that the Bact. coli is in excess immediately after pollution but 

 that later the Bact. aerogenes are the prevailing forms. 



Although there is no agreement as to the relative incidence of these two 

 groups in water, it is apparent that the aerogenes section is proportionately 

 much more common than in feces and much less frequent than in soil. The 

 author thinks it is a reasonable assumption that the strains in water repre- 

 sent the resultant of sewage pollution, soil contamination, and proximity 

 of pollution. 



The colon group isolated from milk is about evenly divided between 

 aerogenes and coli types. Wood, MacConkey, Orr, Rogers and Stokes 



