JOHN F. NORTON 367 



On the other hand, American workers have not generally favored such an index. Cer- 

 tainly, in dealing with chlorinated waters, it would be unfortunate to use a spore- 

 forming organism as indicative of the possible presence of bacteria of the paratyphoid- 

 t^TDhoid-dysentery groups. 



The question of the pathogenicity of strains of Clostridium welchii in water sup- 

 plies was brought to the attention of water bacteriologists as the result of outbreaks 

 of gastro-enteritis in Montclair, New Jersey, in 1918 and 1921.' More recently, at- 

 tempts have been made to establish this organism as the etiological agent in perni- 

 cious anemia. At the present time more information is needed both on the relation of 

 Clostridium welchii to diarrheal disease and the significance of its presence in filtered 

 and chlorinated waters. The possibility of its interference with presumptive "coli" 

 tests has already been discussed. Recently, Wilson and Blair^ have devised a sulphite- 

 iron agar for the detection of sulphite-reducing anaerobic organisms. They claim a 

 good correlation between sulphite reduction and tests for Bact. coli in water. The 

 writer has found the method useful in the study of anaerobes in sewages and sewage 

 effluents, and Greer-' has published investigations using Wilson and Blair's method. 

 How useful this will be in sanitary water examination will depend upon the determi- 

 nation of the sanitary status of Clostridium welchii. 



STREPTOCOCCI 



Prescott and WinsloW have stated that "there seems to be some reason to hope 

 that the streptococci may prove of assistance in the important task of differentiating 

 between human and animal pollution, a task in which all other tests have so far failed." 

 In spite of the enormous literature which has accumulated during the past twenty-five 

 years, and of which the work of Andrewes and Horder^ in England, Clemesha^ in In- 

 dia, and Winslow and Palmer^ and Rogers and Dahlberg^ in this country may be cited 

 as examples, it is still impossible to correlate biochemical characteristics of streptococ- 

 ci with their source to any degree of certainty. At the present time the search for spe- 

 cific fermentative strains in potable waters is unlikely to reward the water bacteriol- 

 ogist for his effort. Neither can the determination of streptococci (in general) in a 

 water supply be recommended as a satisfactory procedure for routine water analysis. 



THE INTERPRETATION OF RESULTS 



The tendency during the past twenty-five years has been toward more rigid stand- 

 ards for water supplies. From a former requirement of not more than one Bact. coli 

 per I cc. of water, the standard has been increased until, if figured on the former basis, 

 a good water must not contain more than one Bact. coli in 100 cc. The present stand- 

 ards as adopted by an Advisory Committee of the United States Public Health Serv- 



' Eng. News-Rec, 86, 929. 1921. 



= Wilson, W. J., and Blair, E. M. McV.: /. Hyg., 24, iii. 1925. 



3 Greer, F. E.: Am. J. Pub. Health, is, 860. 1925. 



1 Prescott, S. C, and Winslow, C.-E. A.: op. cit. (4th ed.), p. 720. 1924. 



5 Andrewes, F. W., and Horder, T. J.: Lancet, lyi, 708. 1906. 



^ Cited by Prescott, S. C, and Winslow, C.-E. A.: op. cit. (4th ed.), p. 720. 1924. 



7 Winslow, C.-E. A., and Palmer, G. T.: /. Infect. Dis., 7, i. 1910. 



^ Rogers, L. A., and Dahlberg, A. O.: /. Agric. Research, i, 791. 1914. 



