PAPERS ON WATER SUPPLY 



81 



Nitrogen free water was used for the temperature tests. The 

 constants for air are very good but those for nitrogen and 

 hydrogen are variable but always less than for air showing a 

 slower death rate. No reason for this variation was found. 



Only a small amount of work was done with B. typhosus. 

 The results obtained were very erratic. The technic was the 

 same as was used for B. Coli. 



It was impossible to obtain good, uniform constants within 

 each set of counts. The averages of different sets were so far 

 apart that no comparison was possible. One possible explana- 

 tion is that the stock cultures were kept at 20° and the 

 agar plate which was used to furnish the suspension was incu- 

 bated at 37° for 12 hours. This sudden change may 

 have weakened some cells to such an extent that uniformity 

 was destroyed. 



In general, the B. typhosus results was similar to those of 

 Whipple and Mayer 1 and Ruediger 2 . 



The death rate was higher in nitrogen than in air and the 

 rate increased with a rise in temperature. 



CONCLUSIONS 



Cultures can be kept uniform for several weeks by daily 

 transfers and by keeping them at the same temperature. 



In pure, natural water and in redistilled water B coli and 

 B. typhosus die from starvation in the gradual regular manner 

 observed in other causes of death. 



Within the limits of temperature studied, 8° to 37°. 

 the rate of death increased with a rise in temperature. 



The death is similar to a chemical reaction and follows the 

 monomolecular law. 



The presence of mineral matter has no apparent effect on 

 the organisms. 



The presence of oxygen under starvation conditions seems 

 to be harmful to B. coli and beneficial to B. typhosus. 



This work was carried on under the direction of Doctor 

 Otto Rahn of the Bacteriology Department of the University 

 of Illinois and was done in the laboratories of the Illinois State 

 Water Survey. 



1. Whipple and Mayer. Public Health Reports, Vo. 32; Part 2, 74, 1905. 



2. Ruediger. Am. J. Pub. Health, 1, 6, 411, 1911. 



