and Laboratory Methods. 



1689 



over alkaline. But the bouillon must remain neutral or "■"^^^"^vP^^r^^i^ 

 slightly alkaline. If turbidity still exists, cool and add the nlnJtllRint!?* 

 white of an egg. Beat this in thoroughly, boil, and filter 

 into a sterilized Erlenmeyer flask. Pour into each one of 

 the test tubes about 10 c.c. of the bouillon, return the cotton 

 plugs, and stand the tubes in a test-tube basket. When all 

 are charged put the basket in a steam sterilizer and sterilize 

 at the boiling point for twenty minutes on three consecutive 

 days. When cool the tubes are ready for use, and will keep 

 with occasional sterilization for months. 

 Prepare the following acid solution : 



Carbolic acid crystals, - - - 5 grams 

 Hydrochloric acid, C. P. - - 4 grams 



Distilled water, - - - - 100 c. c. 



Test Tube Basket. 



Physician's Steam Sterilizer. 



Physician's Incubator. 



Add one, two, and three drops of this acid solution, respectively, to three 

 of the test tubes of sterilized bouillon. 



Collect the water to be examined in one of the sterile bottles, and as soon as 

 possible put 1 c.c. of the water into each of the three prepared test tubes of 

 bouillon, using one of the sterilized pipettes for measuring. Place the tubes in 

 an incubator at 37° to 38 °C. for thirty-six hours. If the bouillon becomes 

 clouded, it will be due to the growth of the typhoid or colon bacillus, and the 

 water should be classed as dangerous and unusable unless it is thoroughly boiled. 



BACILLUS COLI COMMUNIS. 



This bacillus is a normal inhabitant of the intestinal tract, and is of great 

 interest, as it resembles morphologically the bacillus of typhoid fever. It 

 requires a series of complicated bacteriological procedures to differentiate it 

 from the typhoid bacillus. In water examinations it gives the same' reactions 



