DOUBLE SUGAR A GAR 207 



6. Weigh out 



Lactose 5 grammes 



and add to the medium in the flask. 



7. Adjust reaction to + 15 and filter if necessary. 



8. Measure out 



Brilliant green, i per thousand aqueous solution. 20 c.c. 

 and mix thoroughly with the fluid agar. 



9. Measure out and add to the medium 



Picric acid, i per cent, aqueous solution .... 20 c.c. 



10. Tube and sterilise as for nutrient agar. 

 China Green Agar (Werbitski) . 



1. Liquefy and measure out into a sterile flask 



Nutrient agar 1000 c.c. 



2. Adjust the reaction accurately to +13 and filter. 



3. Measure out and mix thoroughly with the fluid agar 

 China green 0.2 per cent, aqueous solution. . . 15 c.c. 



4. Tube and sterilise as for nutrient agar. 



Malachite Green Agar (Loeffler). 



1. Liquefy and measure out into a sterile flask 



Nutrient agar 1000 c.c. 



2. Weigh out 



Dextrose 10 grammes. 



and dissolve in nutrient agar. 



3. Adjust the reaction to +3, and filter. 



4. Measure out and mix thoroughly in the fluid agar 



Malachite green, o.i per cent, aqueous solution. .16 c.c. 

 for "weak" medium. 



40. To the filtered agar add 



Malachite green, 2 per cent, aqueous solution . . .25 c.c. 

 for " strong " medium. 



5. Tube and sterilise as for nutrient agar. 

 Double Sugar Agar (Russell). 



1. Liquefy and measure out into a sterile flask 



Nutrient agar 1000 c.c. 



2. Add 100 c.c. litmus solution to the fluid agar. 



3. Weigh out and dissolve in the fluid agar. 



Lactose 10 grammes 



Dextrose 10 grammes. 



