296 



Daniel D. Jackson 



prepared as previously described, or by using the author's bile lactose 

 medium. 



This latter medium is to be preferred when fresh bile can be 

 obtained, as it appears to be somewhat more effective and is cheaper 

 and easier to prepare. Several brands of inspissated bile were tried 

 but they were all very acid and even when neutralized were not effec- 

 tive. The bile lactose medium is prepared in the following manner: 



Fresh ox bile from the slaughter house is poured into flasks and sterilized 20 min- 

 utes under 15 pounds pressure. When ready for use the bile is fi,ltered and i per cent 

 lactose is added. It is then poured into Smith tubes and again sterilized. If the bile 

 is fresh the acidity will be from zero to 5 by Fuller's scale, and within these limits 

 there is no interference with the results. 



A large number of tests for B. coli were carried on to determine 

 the relative efficiency of bile media as compared with Smith's solu- 

 tion, and also to show the selective action of the bile salts. Some of 

 the most conclusive results are given in Tables 3 and 4. 



TABI.E 4- 

 Comparison of Results Obtained in the Test for B. Coli with Smith Solution and with 



Lactose Bile. 



Solution No. i containing pure 



culture B. Coli — 



Total gas 



After absorption 



Per cent carbonic acid 



Test for B. Coli 



Solution No. 2 containing pure 



culture B. Coli — 



Total gas 



After absorption 



Per cent carbonic acid 



Test for B. Coli 



Pond water, slightly contami- 

 nated — 



Total gas 



After absorption 



Per cent carbonic acid 



Test for B. Coli 



Pond water , contaminated — 



Total gas 



After absorption 



Per cent carbonic acid 



Test for B. Coli 



New York Bay water, contami- 

 nated. No. I — 



Total gas 



After absorption 



Per cent carbonic acid 



Test for B. Coli 



New York Bay water, contaroi 



nated, No. 2 — 



Total gas 



After absorption 



Per cent carbonic acid 



Test for B. Coli 



Smith Solution 



o. I c.c. 



36 

 22 

 38 



-I- 



30 

 20 



33 



25 

 18 

 28 



26 

 20 



23 

 o 



37 



23 



40 



27 

 19 

 30 



-f 



17 



40 

 25 

 28 



60 



45 

 25 



36 

 24 

 33 



72 

 40 



44 

 + 



13 



Bile Lactose 



32 

 20 

 37 



+ 



49 



33 

 33 



43 

 22 

 49 



29 

 16 



45 



-I- 



I C.C. 



46 



28 



39 



6s 

 45 

 26 



-I- 



o 

 o 

 o 

 o 



41 



23 



44 



35 

 19 

 46 



35 

 22 



37 



+ 



10 C.c. 



45 

 27 

 40 



53 

 26 



34 



+ 



33 

 21 

 36 



52 

 29 

 45 



57 

 32 

 44 



44 

 25 

 43 

 -I- 



