e by bacterial
action is indicated by the coagulation of the serum proteids in addition
to the production of an acid reaction.

~Serum Dextrose Water (Hiss).~--

1. Measure out into a litre flask

Serum water (See page 170) 1000 c.c.

2. Weigh out

Dextrose 10 grammes

and dissolve in the serum water.

3. Filter through Swedish filter paper.

4. Measure out and add to the medium

Litmus solution (Kahlbaum) 50 c.c.

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.

Laevulose, galactose, maltose, lactose, etc., can be substituted in
similar amounts for dextrose and the medium completed as above.

~Omeliansky's Nutrient Fluid~ (_For Cellulose Fermenters_).--

1. Weigh out and mix

Potassium phosphate 4.0 grammes
Magnesium sulphate 2.0 grammes
Ammonium sulphate 4.0 grammes
Sodium chloride 0.25 gramme

2. Dissolve in distilled water 4000 c.c.

3. Flask in quantities of 250 c.c.

4. Weigh out and add 5 grammes precipitated chalk to each flask.

5. Sterilise in the steamer at 100 deg. C. for twenty minutes on each of
three successive days.

_Media for the Study of Chromogenic Bacteria._

~Milk Rice (Eisenberg).~--

1. Measure out nutrient bouillon, 70 c.c., and milk, 210 c.c., and mix
thoroughly.

2. Weigh out rice powder, 100 grammes, and rub it up in a mortar with
the milk and broth mixture.

3. Fill the paste into sterile capsules, spreading it out so as to form
a layer about 0.5 cm. thick, over the bottom of each.

4. Heat over a water-bath at 100 deg. C. until the mixture solidifies.

5. Replace the lids of the capsules. Sterilise in the steamer at 100
deg. C. for thirty minutes on each of three consecutive days.

(A solid medium of the colour of _cafe au lait_ is thus produced.)

~Milk Rice (Soyka).~--

1. Measure out nutrient bouillon, 50 c.c., and milk, 150 c.c., and mix
thoroughly.

2. Weigh out rice powder, 100 grammes, and rub it up in a mortar with
the milk and broth mixture.

3. Fill the paste into sterile capsules, to form a layer over the bottom
of each.

4. Replace the lids of the capsules.

5. Sterilise in the steamer at 100 deg. C. for thirty minutes on each of
three consecutive days.

(A pure white, opaque medium is thus formed.)

_Media for the Study of Phosphorescent and Photogenic Bacteria._