DANIEL D. JACKSON 



TABLE 4. Continued. 



In the investigation of the relative efficiency of the Smith and lac- 

 tose bile solutions, 275 badly contaminated waters were examined, of 

 which 65 per cent gave improper results with the use of the Smith 

 solution while only 10 per cent of overgrowths were found when lac- 

 tose bile was used. The total amount of gas produced and the per- 

 centage of absorption is generally greater when lactose bile is used. 

 The gas usually forms somewhat more slowly in the lactose bile, and 

 while the second day's results are preferable to those obtained by 

 the Smith solution, still better tests are obtained by incubating three 

 days. 



CONCLUSIONS. 



The bile salts, and especially their acids, exert a strong restraining 

 action on most species of bacteria which grow at blood heat. 



