PRESUMPTIVE TEST FOR BACILLUS COLI 299 



This restraining action is selective. It favors the increase of B. 

 coli, retards the growth of certain streptococci, and actually kills off 

 the majority of species which grow at 37 C. 



The effect is due to the cholic acid radical and is, therefore, com- 

 mon to both of the bile salts. 



Advantage may be taken of the selective action of the bile salts in 

 the determination of B. coli in water by planting various amounts of 

 the water to be tested in bile lactose solution. The results are much 

 more accurate than those obtained by the methods at present em- 

 ployed. 



BIBLIOGRAPHY. 



1. MACCONKEY. The Thompson Yates Laboratory Reports, 3, Part I, p. 41. 



2. MACCONKEY. Ibid., Part II, p. 151. 



3. MACCONKEY. Ibid., 4, Part II, p. 151. 



4. JORDAN, RUSSELL AND ZEIT. Jour. Infect. Dis., 1904, i, p. 682. 



5. ROBIN. Eng. News, 1905, 54, p. 160. 



6. SMITH. Thirteenth Annual Report of the State Board of Health of New York, 



1892, p. 712. 



7. SMITH. The Wilder Quarter-Century Book, p. 187. 



8. SMITH. Centralbl. f. Bakt., 18, p. 494. 



9. PRESCOTT AND BAKER. Jour. Infect. Dis., 1904, i, p. 193. 

 10. IRONS. Rep. and Papers Am. Pub. Health Assoc., 26, p. 311. 



