112 



G. Brilliant Green Lactose Bile (Muer and Harris). The com- 

 position of the medium used is as follows: 



Distilled water 1,000 grams 



Ox gall (dried) 50 grams 



Peptone 10 grams 



Lactose 10 grams 



Brilliant-green 0.1 grams 



Directions for Preparation 



1. Heat 1 liter of distilled water in double boiler until water in outer 

 vessel boils. 



2. Add 50 grams of dried ox gall and 10 grams of peptone, stirring 

 until all ingredients are dissolved. 



3. Continue boiling for one hour. 



4. Remove from flame and add 10 grams of powdered lactose. 



5. Filter through cotton flannel until clear. 



6. To each liter of the filtrate add 10 c. c. of a 1 percent solution of 

 brilliant-green. 



7. Tube and sterilize in autoclave for 15 minutes at 15 pounds pres- 

 sure. 



IV. MEDIA FOR DIRECT ISOLATION OR CONFIRMATION OF 

 PRESUMPTIVE TEST. 



A. Litmus Lactose Agar. (Wurtz Agar). (Standard Methods 

 A. P. H. A., 1920). 



Litmus-lactose-agar shall be prepared in the same manner as nutrient 

 agar with the addition of 1 percent of lactose just before sterilization. The 

 reaction shall be a faint pink with phenol red, or, if on titration with 

 phenolphthalein the reaction is not already between neutral and +1, adjust 

 to neutral. One c. c. of sterilized litmus or azolitmin solution shall be 

 added to each 10 c. c. of the medium just before it is poured into the 

 petri dish, or the mixture may be made in the dish itself. 



B. Fuchsin Sulphite (Endo) Agar. Endo agar consists of 

 nutrient lactose agar containing basic fuchsin decolorized with sodium 

 sulphite as an indicator. Many modifications have been described. Those 

 more commonly employed and method of use are listed below: 



(a). Endo's Medium (Standard Methods A. P. H. A., 1920) 



1. Add 5 grams of beef extract, 10 grams of peptone and 30 grams of 

 agar dried for one-half hour at 105 C. before weighing, to 1,100 c. c. of dis- 

 tilled water. Boil on a water bath until all the agar is dissolved and then 

 make up the loss by evaporation. 



2. Cool the mixture to 45 C. in a cold water bath, then warm to 

 65 C. in the same bath without stirring. 



3. Make up lost weight, titrate, and if the reaction is not already 

 between neutral and +1, adjust to neutral. 



4. Filter through cloth and cotton until clear. 



5. Distribute 100 c. c. or larger known quantities in flasks large 

 enough to hold the other ingredients which are to be added later. 



