BACTEEIOLOGY OF SEWAGE 241 



Bacteriology of the Sewage Filters Themselves. Before 

 leaving the subject of sewage bacteriology, brief 

 reference must be made to the importance of bacteri- 

 ological studies in relation to the processes of sewage 

 purification which bring about the removal of the 

 organic matter itself. Nothing is more necessary to the 

 development of the present art of sewage disposal 

 than knowledge of the micro-organisms concerned and 

 of the conditions which favor their activity; but such 

 knowledge is woefully deficient. Something is known 

 of the nitrifying organisms long ago discovered by 

 Winogradsky. More recent work, like that of Schultz- 

 Schultzenstein (1903), Boullanger and Massol (1903) 

 and Calmette (1905), has cleared up many points 

 concerning these forms; but much remains to be done. 

 In regard to the reducing action of bacteria in the 

 septic tank and contact bed we are almost wholly in 

 the dark. Septic tanks work well with some sewages 

 and badly with others; and the presence or absence 

 of the right bacteria is probably largely responsible 

 for the different results. In some cases, as at 

 Plainfield, N. J., the seeding of a tank with cesspool 

 contents has produced a material improvement in 

 septic action. 



Knowledge of the kinds of bacteria involved would 

 make it possible to substitute scientific control for 

 such empiricism and might well lead to improved 

 methods of a more intensive character than are yet 

 available. The work already done upon a laboratory 

 scale furnishes promise of such results. The student 



