d excretions, solid
tissues).

~The Preparation of the Inoculum.~--

(a) _Cultivations in Fluid Media._--

1. Flame the plug of the culture tube.

2. Remove the plug and flame the mouth of the tube.

3. Slightly raise the lid of a sterile capsule, insert the mouth of the
culture tube into the aperture and pour some of the cultivation into the
capsule.

4. Remove the mouth of the culture tube from the capsule, replace the
lid of the latter, flame the mouth of the tube, and replug.

5. Remove the syringe from the steriliser, squirt out the water from its
interior, and allow to cool.

6. Raise the lid of the capsule sufficiently to admit the needle of the
syringe and draw the required amount of the cultivation into the barrel
of the syringe.

(Or, remove a definite measured quantity of the cultivation directly
from the tube or flask by means of a sterile graduated pipette,
discharge the measured amount into a sterile capsule, and fill into the
syringe; or take up the required quantity of the cultivation directly
into the graduated syringe from the tube or flask.)

[Illustration: FIG. 173.--Conical separatory funnel, fitted for
injection of fluid cultivations.]

If it is necessary to introduce a large bulk of fluid into the animal,
the cultivation should be transferred with aseptic precautions, to a
sterile separatory funnel, preferably of the shape shown in figure 173,
and graduated if necessary. This is supported on a retort stand and
raised sufficiently above the level of the animal to be injected, so as
to secure a good "fall." A piece of sterilised rubber tubing of suitable
length, fitted with an injection needle and provided with a screw clamp,
is now attached to the nozzle of the funnel and the operation completed
according to the requirements of the particular case.

This method is quite satisfactory when the injection is made into the
pleural or abdominal cavities or directly into a vein but if the
injection has to be made into the subcutaneous tissue the "fall" may not
be sufficient to force the fluid in. In this case it will be necessary
to transfer the culture to a sterile wash-bottle and fasten a rubber
hand bellows to the air inlet tube (interposing an air filter) and
attach the tubing with the injection needle to the outlet tube (Fig.
174). By careful use sufficient force can be obtained to drive the
injection in.

(b) _Cultivations on Solid Media (e. g., Sloped Agar)._--

1. By means of a