IOWA ACADEMY OF SCIENCES. 
253 
Average number of bacteria per c.c. in manhole and tank. 
MONTH 
Manhole. 
Tank. 
August, 1899 
2, 392, 600 
8.815.000 
6,064, 800 
4 , 537. 333 
816,333 
848.000 
345, 533 
132, 125 
2. 121.000 
I, 021, coo 
1, 318, xoo 
3,908,700 
403,118 
1,181.533 
', 358.300 
3. 245. 000 
4.941.000 
3.014.000 
848.000 
726. 000 
233,810 
xi2, 500 
1,392,800 
783, 3 oo 
i, 39 i, 3 oo 
4 , 578,333 
215.700 
383,733 
September, 1899 
October, 1899 
November, 1899 
December, 1899 
January, 1900 
February, 1900 
March, 1900 * 
April, 1900 
Mav, 1900 
J une, 1900 
July, 1900 
A ugnst, 1900 4 
September, 1900 
BACTERIOLOGICAL ANALYSIS OF THE COLLEGE SEWAGE FROM 
SEPT. 1, 1899, TO SEPT. 1, 1900. 
The college sewage system is a combination of several 
systems combined into one. It combines the system of 
the septic tank with that of intermittent filtration. For a 
very excellent and (20) detailed description, see the article 
in Centralblatt No. 15, on the Iowa State College Sewage 
D’sposal Plant, by Drs. Pammel, Weems, and Professor 
Marston, and Contribution No. I of the Iowa State Col- 
lege (19). 
Bacteriological analysis have been made of the effluent 
each day, while once each week samples have been 
taken from the manhole and the tank, as well as the efflu- 
ent, of which both bacterological and chemical analyses 
have been made. The chemical analyses have been under 
the direction of Dr. Weems, who has from time to time 
published some very interesting results, but as it is my 
intention to deal with the bacteriological side only, no 
chemical results will be given, only as they may serve to 
elucidate some point in connection with the bacteriological 
•analyses. 
In making the cultures, petri dishes of a standard size 
have been used. The dilution method has been employed 
with the manhole and tank samples, it having been found 
on trial that without dilution it was practically impossible 
