74 MAUD MASON OBST 



These experiences led to communications with other bacteri- 

 ologists,^ all of whom expressed dissatisfaction with bile media. 

 Prof. Edwin 0. Jordan, University of Chicago, has stated, ''Bile 

 from different animals varies in composition, and this is probably- 

 one reason for the variable results obtained when this substance 

 is added to culture media. Dried bile and bile salts have been 

 used by various observers. In my own experience bile salts, 

 like fresh bile, inhibited B. coli to some extent." Previous to 

 the time when he made this statement, Jordan determined the 

 ''degree of inhibition" of B. coli by bile and reported that from 

 one-third to one-half of the vital cells of B. coli were thus in- 

 hibited (Jordan, 1913). He stated also that there was no 

 evidence that these cells were more attenuated or in any way 

 less vigorous biologically than the others. 



A resume of the literature was then made, with regard to the 

 origin of the use of bile as a medium. It was found that Jack- 

 son (1906) had experienced the difficulty of having B. coli 

 inhibited by other organisms when he used glucose or lactose 

 bouillon as recommended by Theobald Smith (1893, 1895). 

 Jackson, therefore, experimented with MacConkey's bile salt 

 agar, "Platner's Crystallized Bile," which consisted of a mix- 

 ture of the two bile salts, and finally with his own medium which 

 he made by adding 1 per cent lactose to fresh ox-bile, and which 

 gave satisfactory results in his work. 



Sawin (1907) corroborated Jackson in his recoromendation of 

 the use of lactose bile and regarded it as a satisfactory and deli- 

 cate indicator of minor sewage pollutions of springs and wells. 



When the necessity of finding a substitute for bile was rec- 

 ognized, dried bile was considered. This substance, being 

 obtained from liquid bile, varies in composition approximately 

 in the same manner as the original material. Biochemical 

 laboratories overcome these variations to some extent by drying 

 bile from large quantities of mixed liquid biles, but this pre- 

 caution does not produce an entirely satisfactory product. 



» Dr. F. L. Rector, Great Bear Spring Co., New York, N. Y. ; Dr. W. W. Browne, 

 College of the City of New York; Prof. S. C. Prescott, Massachusetts Institute of 

 Technology; Prof. Earle B. Phelps, Hygienic Laboratory, Treasury Departmeot. 



