ss so.

2. Inoculate rats, mice, and guinea-pigs subcutaneously into deep
pockets, and intraperitoneally with various quantities of the bouillon
extract, and observe the result.

3. Filter some of the extract through a Chamberland candle and incubate
the filtrate to determine the presence of soluble toxins.

4. If any of the animals succumb to either of these methods of
inoculation, make careful post-mortem examinations and endeavour to
isolate the pathogenic organisms.

THE EXAMINATION OF OYSTERS AND OTHER SHELLFISH.

On opening the shell of an oyster a certain amount of fluid termed
"liquor" is found to be present. This varies in amount from a drop to
many cubic centimetres (0.1 c.c. to 10 c.c.)--in the latter case the
bulk of the fluid is probably the last quantum of water ingested by the
bivalve before closing its shell. In order to obtain a working average
of the bacteriological flora of a sample, ten oysters should be taken
and the body, gastric juice and liquor should be thoroughly mixed before
examination. The examination, as in dealing with other food stuffs, is
directed to the search for members of the Coli-typhoid group, sewage
streptococci and perhaps also B. enteritidis sporogenes.

_Apparatus Required_:

Two hard nail brushes.

Liquid soap.

Sterile water in aspirator jar with delivery nozzle
controlled by a spring clip.

Sterile oyster knives.

Sterile glass dish, with cover, sufficiently large to
accommodate ten oysters.

Sterile forceps.

Sterile scissors.

Sterile towels or large gauze pads.

Sterile graduated cylinders 1000 c.c. capacity, with either
the lid or the bottom of a sterile Petri dish inverted over
the open mouth as a cover.

Glass rods.

Corrosive sublimate solution, 1 per mille.

Bile salt broth tubes.

Litmus milk tubes.

Surface plates of nutrose agar.

Case of sterile pipettes, 1 c.c. (in tenths of a c.c.)

Case of sterile pipettes, 10 c.c. (in tenths of a c.c.)

Case of sterile glass capsules.

Erlenmeyer flasks, 250 c.c. capacity.

Double strength bile salt broth.

METHOD.--

1. Thoroughly clean the outside of the oyster shells by scrubbing each
in turn with liquid soap and nail brush under a tap of running water.
Then, holding an oyster shell in a pair of sterile forceps wash every
part of the outside of the shell with a stream of