All sample and dilution bottles shall be shaken vigorously 25 times
before samples are removed for plating. Plating shall be done
immediately after the dilutions are made. One cc. of the sample or
dilution shall be used for plating and shall be placed in the Petri
dish, first. Ten cc. of liquefied medium at a temperature of 40° C.
shall be added to the 1 cc. of water in the Petri dish. The cover of the
Petri dish shall be lifted just enough for the introduction of the
pipette or culture medium, and the lips of all test-tubes or flasks used
for pouring the medium shall be flamed. In making litmus-lactose-agar
plates, 1 cc. of sterile litmus or azolitmin solution shall be added to
each 10 cc. of culture medium either in the Petri dish or before pouring
into the Petri dish. The medium and sample in the Petri dish shall be
thoroughly mixed and uniformly spread over the bottom of the Petri dish
by tilting or rotating the dish. All plates shall be solidified as
rapidly as possible after pouring and gelatin plates shall be placed
immediately in the 20° C. incubator and the agar plates in the 37° C.
incubator. Endo plates shall be made by placing one loopful of the
material to be tested on the surface of the plate and distributing the
material with a sterile loop or glass rod.