288 Trans. Acad. Sci. of St. Louis. 
(2) Make plate cultures from these tubes on glucose-litmus 
agar (Wurtz) and incubate at 37° C. for two days. 
(3) Transfer to slant agar tubes two characteristic colonies | 
and incubate at 37° C. for one day. 
(4) Using these pure cultures, make glucose-gelatin shake 
cultures and set the tubes aside for ten days at 20° C. 
(5) If no liquefaction takes place and no gas is produced 
in these tubes, using pure culture on agar, make inoculations 
into the following media :— 
(a) Milk, to test coagulation. 
(b) Dunham’s solution, to test for indol. 
(c) Nitrate solution, to test for reduction to nitrites. 
These cultures are incubated for five days at 37° C. or are set. 
aside for ten days at 20° C. and are then observed. 
(6) A pure culture in broth of two days’ growth is exam- 
ined for morphological characteristics. 
The colon bacillus is very widely distributed, and we have 
been able to find it in all the waters collected from the various 
sources. In river water from certain sourcesit was almost 
constantly present in 1c.c. of the sample. Thorough famili - 
arity with methods of technique, and with the cultural charac - 
teristics, contribute much to the success in the identification 
of this organism. 
No methods have as yet been devised for the successful 
isolation and identification of the typhoid bacillus. The 
methods used in the investigation of water furnish results 
which are available for the detection of sewage contamination, 
and by inference we conclude that there is a great possibility 
of the presence of disease germs. Recognizing the difficulties 
of examination and of proving the presence of pathogenic 
organisms, Victor C. Vaughan (1904) has resorted to biologic 
or animal tests as a means of obtaining information on the 
toxicogenic germs found in drinking-water. While not being 
able to identify the typhoid bacillus, he has, however, isolated 
an organism of the B. venenosus group which was frequently 
found in waters of asuspicious character, and which was fatal 
to guinea pigs. It seems to me that these biological or 
animal tests are of great value, and that a further study 
