Presumptive Test for Bacillus Coli 



295 



Dry the precipitated salts first on the water bath and then in an oven kept at 100" 

 C. Powder in a mortar and keep in a tightly stoppered, wide mouth glass bottle. 

 Purify if necessary, by redissolving in a small quantity of warm alcohol and again pn-- 

 cipitating with a large excess of ether. 



The author's experiments with bile agar suggested the use oi bile 

 itself with i per cent of lactose as a liquid to rc-i)lace Smith solution, 

 thus making a much more effective medium which would be cheaper 

 and easier to prepare than the latter solution. In the following experi- 

 ments the results with the new bile lactose medium is compared with 

 plain Smith solution, Smith .solution containing .sodium taurochi.late, 

 and the same solution containing sodium glycocholate. 



It is evident that the presence of either or both of the bile .sali.>, 

 favors the growth of B. coli in Smith solution by inhibiting the growth 

 of other bacteria. A proper medium, may, therefore, be made by 

 adding to Smith solution 9 per cent of Platner's crystallized bile 



TABLE 3. 



Test on Sewage 



Total Gas 



.\fter Absorption 



% Carbonic Add 



Teal for B. coli 



Smith solution- 

 o. I c.c. ... 

 1.0 .... 



10 

 Smith 



10 

 Smith 



o 

 I 



10 



Bile 



o 



I 



10 



and taurocholate 



I c.c 



o 



and glycocholate — 



I c.c. 

 o 

 o 



lactose 

 I c.c. 

 o 

 o 



12 

 12 

 17 



S2 

 43 

 6S 



33 

 26 



47 



25 

 3S 

 27 



33 

 27 

 40 



33 

 18 

 3» 



18 

 35 

 19 



37 

 37 

 38 



30 

 JI 

 34 



28 

 JO 



o 

 o 

 o 



+ 

 + 

 + 



+ 



+ 



