370 SOME PROBLEMS IN WATER BACTERIOLOGY 



posed of, organisms of the paratyphoid-typhoid-dysentery groups will also have dis- 

 appeared. From a scientific standpoint such conclusions are not entirely satisfactory. 

 The earlier studies on the viability of the typhoid bacillus in water, of which those of 

 Frost' and Jordan, Russell, and Zeit^ may be mentioned, have been generally accept- 

 ed. However, considerable advance has been made in laboratory technique for the iso- 

 lation of these organisms, and the time appears to be ripe for further investigations. 

 The viability of Bad. coli and Bact. typhosum in stored feces has recently been 

 studied by Jordan.^ At room temperature or lower these organisms have been found 

 to survive for considerable periods. For example, typhoid bacilli were recovered from 

 stools of typhoid carriers after fifty-two days' storage at room temperature. Such 

 studies have a direct bearing on the pollution of ground-water supplies from privies. 

 The viability of the typhoid bacillus in the various methods for sewage treatment, in- 

 cluding septic and Imhofif tanks, trickling filters and activated sludge tanks, and 

 chlorination, has not been accurately determined. Courmont and Rochaix^ have re- 

 ported the survival of organisms of the paratyphoid-typhoid group in effluents from 

 the activated sludge process. The whole subject, however, needs further investiga- 

 tion. 



' Frost, W. D.: /. Infect. Dls., i, 599. 1904. 



^Jordan, E. O., Russell, H. L., and Zeit, F. R.: ibid., p. 641. 1904. 



3 Jordan, E. O.: ibid., 38, 306. 1926. 



•I Courmont, R., and Rochaix, A.: Rev. d'hyg., 44, 907. 1922. 



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