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 sources it was almost 

 constantly present in 1 c.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 difiiculties 

 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 w^as frequently 

 found in waters of a suspicious 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 



