44 MEDICAL BACTERIOLOGY 



reaction. Best results are obtained where the medium is neutral or just slightly 

 alkaline to litmus paper. Add exactly 3 cc. fuchsin solution and 30 cc. sodium 

 sulphite solution (or, the sod. sulph. being hygroscopic, you may add instead of 

 30 cc. of the 10 per cent, sol., 3 cc. of sat. liquid usually found in even tightly 

 stoppered bottles). 



The resulting mixture is quite red when hot but loses its color on cooling. 

 After tubing, sterilize for 20 minutes each day, for 3 days, in Arnold steam 

 sterilizer. 



Loeffler's Malachite-green Agar Medium. 



1. Meat infusion bouillon, 500 cc. 



2. Distilled water, 500. cc. 



3. Neutralize. 



4. Normal hydrochloric acid sol., 7.5 cc. 



5. Shredded agar, 30 Gm. 



6. Boil until agar'dissolves, then neutralize with normal sodium hydrate, 



7. Add normal sodium carbonate sol., 5 cc. 



8. Place in steam sterilizer for 2 hours; then, add 



9. 10 per cent, aqueous sol. nutrose, 100 cc. 



10- Sterilize in steam sterilizer 15 minutes each day for 2 days. 

 When ready to use, liquefy and add between 2 cc. and 3 cc. of a 2 per cent, 

 aqueous sol. of malachite green (Hochst 120) to each 10 cc. of medium. 



Conradi and Drigalski's Medium. 



Minced beef, 750 Gm. 



Water, 1000 cc. 



Put in shallow dish, in ice box, over night. Skim off fat, boil for i hour, 

 filter, add water to bring volume to 1000 cc. 

 .Add- 



Peptone (Witte's), 10 Gm. 



Nutrose. 10 Gm. 



Calcium chloride, 5 Gm. 



boil; add 30 Gm. of agar, boil until agar is dissolved; make faintly alkaline to 

 litmus paper; autoclave for i hour; filter through paper and autoclave for % 

 hour. 

 Add 



Litmus solution (Kahlbaum) 150 cc. 



Lactose 15 Gm. 



Sterilize in Arnold steam sterilizer for ^ hour. 

 Add- 

 Hot, sterile, o.i per cent, solution of crystal violet (B. Hochst), 10 cc. 



This medium favors growth of the typhoid bacillus and inhibits the colon. 

 On it typhoid colonies are transparent, blue-white, and cause no change in 

 color of medium. Colon colonies are red and opaque and the medium imme- 

 diately surrounding them is turned from blue to red. 



