Kaiisax Academii of Science. 



105 



SOME EXPERIMENTS WITH BACILLUS COLI 

 COMMUNIS (ESCHERICH). 



FKA.N K V . (i. AliKKI.ll S. 



IN OUR WORK with water analysis we have frequently 

 observed that the water of the hydrants, cisterns, and some- 

 times that of wells, will give positive results at a certain time, 

 and after a few days it will be negative or nearly so. This 

 led us to attempt an experiment to test the matter somewhat 

 more under control, and to see whether B. coli would behave 

 that way then. 



We took two liters of tap water and placed it in an ordinary 

 Erlenmyer flask and kept it in a dark, cool room of a temper- 

 ature from 13.2 C. to perhaps 20.0 C. We placed in this water 

 1 cc. of a broth culture of B. coli recently isolated from sewage. 

 After stirring the water in the flask well we inoculated a 

 fermentation tube of medium size with 1 cc. of this water and 

 placed it and a duplicate in a 40" oven. We started also dupli- 

 cate tests of B. coli (1 loopful), and of tap water (1 cc.) at 

 the same time, December 29, 1915. 



The tap water proved free from B. coli. The B. coli from 

 the broth direct gave 57 percent of gas. By January 8 the 

 water gave entirely negative tests, and it gave these uni- 

 formly thereafter until the 11th, when we stopped the tests. 

 We have represented the results graphically, where they can 

 be seen more perfectly. (Fig. 1.) 



ri<;i"RK 1. — S|)('cial lest nf linriUiis Coli r inn mini is. 



