AGf~ICULTURAL RESEARCH, PUSA.

CULTIVATION OF lIfICRO-ORGANISlI18 125
an all-glass syringe of 15 c.c. capacity. The syringe is of the
three-piece type, but without the nozzle, and thc plunger is
hollow, as the head of liquid will not lift a solid glass pistoIl.
The barrel is graduated to 15 c.e. by 0'5 e.e., and the numbers
are engraved so as to be readable when the syringe is vertical.
'l'he syringe is connected to the stopcock by means of a metal
screw fitting. A clamp on a swivel mount securcs the lower
end of the syringe. The amount of fluid delivered is determined
by the adjustable screw. A very thin film of liquid paraffin well
rubbed on the surface of the plunger and barrel will make for
smoother working. The action of the filler is simple. 'rhe head
of medium in the funnel forces up the plunger until it is stopped
by the adjuHtablc screw. The handle of the stopcock is then
turned and the syringe empties itself under the weight of
the plunger. Air bubbles in the syringe are removed by fIrst
filling the apparatus and then turning the syringe by means
of the swivel mount. This brings the nozzle of the syringe
uppermost, and when the plunger is pressed home the ail'
passes through the rubber tube and liquid in the funnel. If a
smoothly working syringe is used, very little head of pressure is
necessary, and the height need not be greater than 18 inches.
Once set, thc accuracy of the filler is much greater than that
of an ordinary pipette, while media can be tubed with greater
rapidity. It works equally well with melted agar m gelatin,
provided that fresh hot supplies are available, and the syringe
and stopcock are washed out immediately after use.
When tubing agar or broth with the filler, the medium is
run into clean but not sterilised test-tubes. These are then
plugged with cotton-wool and sterilised in the steamer 01' in
the autoclavc as indicated under the description of thc various
merlia.
Alternatively the agar or broth is distributed into small
bottles (p. 120), the rap is screwed tightly on, and the whole
container suitably steriliscd.
Depending on the method of inoculation to be used,
solid media are solidified in tubes as follows :-
(a) Upright, for "puncture" or "stab" culiU1·e.­
The test-tube or small screw-capped bottle
is half filled with the medium (about 12 c.c.)
which is allowed to solidify in the upright
position. It is inoculated by plunging a
long straight wire (vide p. 128), charged with
the material, vertically down the centre of
the tube. This method is used for anaerobic