bes; upon glucose agar and in litmus
milk.

5. Test the subsequent growth against the serum of an experimental
animal inoculated against M. melitensis to determine its
agglutinability.

6. If apparently M. melitensis, inoculate growth from a nutrose agar
culture after three days incubation intracranially into the guinea-pig.

ICE CREAM.

~Collection of the Sample.~--

1. Remove the sample from the drum in the ladle or spoon with which the
vendor retails the ice cream, and place it at once in a sterile copper
capsule, similar to that employed for earth samples (_vide_ page 471).

2. Pack for transmission in the ice-box.

3. On arrival at the laboratory place the copper capsules containing the
ice cream in the incubator at 20 deg. C. for fifteen minutes--that is,
until at least some of the ice cream has become liquid.

~Qualitative and Quantitative Examination.~--Treat the fluid ice cream as
milk and conduct the examination in precisely the same manner as
described for milk (_vide_ page 443).

EXAMINATION OF CREAM AND BUTTER.

~Collection of the Sample.~--Collect, store, and transmit samples to the
laboratory, precisely as is done in the case of ice cream.

~Quantitative.~--

_Apparatus Required_:

Sterile test-tube.
Sterilised spatula.
Water-bath regulated at 42 deg. C.
Case of sterile plates.
Case of sterile graduated pipettes, 1 c.c. (in hundredths).
Tubes of gelatine-agar (+10 reaction).
Plate-levelling stand, with its water chamber filled with water at
42 deg. C.

METHOD.--

1. Transfer a few grammes of the sample to a sterile test-tube by means
of the sterilised spatula.

2. Place the tube in the water-bath at 42 deg. C. until the contents are
liquid.

3. Liquefy eight tubes of gelatine-agar and place them in the water-bath
at 42 deg. C, and cool down to that temperature.

4. Inoculate the gelatine-agar tubes with the following quantities of
the sample by the help of a sterile pipette graduated to hundredths of a
cubic centimetre--viz.,

To tube No. 1 add 1 c.c. liquefied butter.
2 add 0.5 c.c. liquefied butter.
3 add 0.3 c.c. liquefied butter.
4 add 0.2 c.c. liquefied butter.
5 add 0.1 c.c. liquefied butter.
6 add 0.05 c.c. liquefied butter.
7 add 0.03 c.c. liquefied butter.
8 add 0.02 c.c. liquefied butter.
9