84 



Recently Hinman reported the relative incidence of these two groups 

 in the water supply of Iowa City which is both filtered and chlorinated. In 

 the raw water, out of 220 positively confirmed tests, aerogenes forms were 

 present in 35 or 16 percent. In the treated water only 11 samples were 

 confirmed for the colon group but of these 4 (36%) were Bact. aerogenes. 



H. E. Jordan in a report on the Indianapolis water supply notes a 

 seasonal variation in the relative resistance of these forms to chlorination 

 which he found to be particularly effective against the coli section during 

 the summer. 



TABLE XLVII. THE VIABILITY OF CAPSULATED AND NON-CAPSULATED 



LACTOSE-FERMENTING ORGANISMS IN BOILED HARD WATER. 



(After Wood 1919) 



The evidence as to the effect of filtration and chlorination, particularly 

 when followed by storage, on the relative prevalence of the coli and aero- 

 genes types is meager and somewhat conflicting. Further observations on 

 this phase are needed and would be of value. Clemesha states that the 

 aerogenes group, for a while at least, multiplies in water. It would be in- 



