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 sterile water running from an aspirator jar; deposit the oyster inside the sterile glass dish. Repeat the process with each of the remaining oysters. 2. Before proceeding further, cleanse the hands thoroughly with clean nail brush, soap and water, then plunge them in lysol 2 per cent. solution, and finally in sterile water. 3. Spread a sterile towel on the bench. 4. Remove one of the oysters from the sterile glass dish and place it, resting on its convex shell, on the towel. Turn a corner of the sterile towel over the upper flat shell to give a firmer grip to the left hand, which holds the shell in position. 5. With the sterile oyster knife (in the right hand) open the shell and separate the body of the oyster from the inner surface of the upper flat shell. Bend back and separate the flat shell, leaving the body of the oyster in and attached to the concave shell. Avoid spilling any of the liquor. (Some dexterity in opening oysters should be acquired before undertaking these experiments).