as for nutrient agar.

~Brilliant Green Bile Salt Agar (Fawcus).~--

1. Weigh out agar 20 grammes and emulsify in 100 c.c. cold distilled
water.

2. Wash the emulsion into a "tared" 2-litre flask with 500 c.c.
distilled water.

3. Dissolve the agar by bubbling live steam through the flask.

4. Cool, clarify with egg and filter.

5. Weigh out

Sodium taurocholate 5 grammes
Peptone 20 grammes

and add to the medium in the flask.

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, 1 per thousand aqueous solution 20 c.c.

and mix thoroughly with the fluid agar.

9. Measure out and add to the medium

Picric acid, 1 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, 0.1 per cent. aqueous solution 16 c.c.
for ~"weak"~ medium.

_4a._ 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.

4. Render the reaction of the medium neutral to litmus paper by the
cautious addition of normal caustic soda.

5. Tube in quantities of 10 c.c. and sterilise in the steamer at 100
deg. C. for twenty minutes on each of three successive days.

6. Store for use in a cool dark place.

_B. Diphtheriae._

~Glycerine Blood-serum.~--

1. Prepare blood-serum as described, page