PATHOGENIC BACTERIA IN RIVERS 3-43 
a separate publication. Table XX XIII is taken from that paper. It will 
be seen from this table that there is a steady decrease in the chlorine 
content of the water and also in the bacteria content. The rise in the 
count at Wesley City may be explained by the fact that at Peoria large 
amounts of distillery slops and animal refuse were dumped into the 
river. These would have a greater effect on the bacteria count than on 
the chlorine. Dissolved oxygen studies have been carried out by the 
Illinois State Water Survey, some of the data of which are presented 
in Fig. 65. From these data, it will be seen that there is evident puri- 
fication in the Illinois River. 
Pathogenic Bacteria in River Water. There are many data available 
in the literature but in looking it over one is impressed with the diversity 
of opinion. Much of this disagreement may probably be explained by the 
different conditions under which each of the investigators worked. It is 
evident that the factors in the environment influence, to a certain extent, 
the longevity of bacteria in nature. These factors will not be taken up 
here, but those who are interested will find discussions in texts on water 
bacteriology. From the evidence which was presented in the Illinois River 
case, we know that the typhoid bacilli die rather rapidly in nature. Prob- 
ably after three or four weeks the water which contained them would be 
safe. Jordan, Russell and Zeit (1904) studied this question in both pure 
and polluted waters and their data are taken as the bases upon which 
our present knowledge rests. They suspended the bacteria in collodion 
sacs in both pure and polluted waters. In pure Lake Michigan water, 
the bacilli did not die out until after a week, but three days seemed 
to be the limit for the polluted Chicago Drainage Canal water. In 
1906 Russell and Fuller confirmed these results using pure Lake Men- 
dota water and sewage as the substrates. In this experiment the bacilli 
lived for about ten days in Lake Mendota water and three days in sew- 
age. Houston has studied this question in England. He points out 
that 1 c.c. samples were used by the American workers in most of the 
cases, and from these small samples conclusions were drawn with regard 
to the longevity of B. typhi. When no organisms were found in 1 c.c. 
samples, it was stated that the organism had died out. Probably 
American bacteriologists have been too much accustomed to use small 
amounts of water in analytical work. Houston carried on experiments 
using Thames, Lee and New River waters, using 100 c.c. quantities of 
the water as the maximum amounts examined. For 100 c.c. quantities 
in eighteen experiments, it required nine weeks for the total disappear- 
ance of B. typhi. Ninety-nine per cent of them disappeared in one week 
under laboratory conditions of the experiment. The above data of 
