IOWA ACADEMY OF SCIENCES. 



247 



into nitrates. This being the case the question at once 

 arises, why would not the system of intermittent filtration 

 and of the septic tank work well together. Experience has 

 taught that they do and it is to a system of this kind that 

 the remainder of this paper will be devoted, taking as a 

 basis the sewage system of the Iowa State College. Great 

 credit is due Prof. Marston, who introduced this system in 

 Iowa. 



TABULATED BACTERIOLOGICAL RESULTS. 



