ve steam through the mixture.

4. Emulsify Naehrstoff-Heyden (albumose) 7.5 grammes in 200 c.c. cold
distilled water and add to melted agar.

5. Adjust weight of medium mass to the calculated figure for one litre
(1020 grammes) by addition of distilled water at 100 deg. C.

6. Clarify with white of egg and filter.

7. 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.

~Bile Salt Broth--Double Strength.~--

1. Weigh out Witte's peptone, 40 grammes, and emulsify with 300 c.c.
distilled water previously warmed to 60 deg. C.

2. Wash the peptone emulsion into a litre flask with 600 c.c. distilled
water.

3. Weigh out sodium taurocholate, 10 grammes, and glucose, 10 grammes;
dissolve in 100 c.c. distilled water and add to the peptone emulsion in
the flask.

4. Heat in the steamer at 100 deg. C. for twenty minutes.

5. Filter through Swedish filter paper into a sterile flask.

6. Add sterile neutral litmus solution sufficient to colour the medium
to a deep purple.

7. Fill into small Erlenmeyer flasks in quantities of 25 c.c.

8. Sterilise as for nutrient bouillon.

_Media for the Study of Plant Bacteria._

~Beetroot.~-- }
~Carrot.~-- } are prepared tubes and sterilised in a manner
~Turnip.~-- } precisely similar to that described for potato.
~Parsnip.~-- }

~Hay Infusion.~--

1. Weigh out dried hay, 10 grammes, chop it up into fine particles and
place in a flask.

2. Add 1000 c.c. distilled water, heated to 70 deg. C.; close the flask
with a solid rubber stopper.

3. Macerate in a water-bath at 60 deg. C. for three hours.

4. Replace the stopper by a cotton-wool plug, and heat in the steamer at
100 deg. C. for one hour.

5. Filter through Swedish filter paper.

6. Tube, and sterilise as for nutrient bouillon.

~Haricot Bouillon.~--(_For cultivation of bacteria from tubercles of
Legumes._)

1. Measure out 1000 c.c. distilled water into a 2-litre flask.

2. Weigh out 250 grammes haricot beans and add to the water in the
flask.

3. Weigh out 10 grammes sodium chloride and add to the contents of the
flask.

4. Add 1 c.c. of a 1 per cent. solution of sodium bicarbonate.

5. Place in the steamer at 100 deg. C. for thirty minutes.

6. Filter.

7. Weigh out 20 grammes saccharose and add to the filtrate.

8. Tube, and sterilise as for nutrient bouillon.

~Haricot Agar.~--

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