sterile graduated pipette introduce a suitable small
quantity of sterile bouillon (or sterile normal saline solution) into
the culture tube.

[Illustration: FIG. 174.--Arrangement of pressure injection apparatus.]

2. With a sterile platinum loop or spatula scrape the bacterial growth
off the surface of the medium, and emulsify it with the bouillon. It
then becomes to all intents and purposes a fluid inoculum.

3. Pour the emulsion into a sterile capsule and fill the syringe
therefrom.

(c) _Toxins._--Prepared by previously described methods (_vide_ page
318), are manipulated in a similar manner to cultivations in fluid
media.

(d) _Pathological Products._--Fluid secretions, excretions, etc., such
as serous exudation, pus, blood, etc., are treated as fluid
cultivations; but if the material is very thick or viscous, a small
quantity of sterile bouillon or normal saline solution may be used to
dilute it, and thorough incorporation effected by the help of a sterile
platinum rod.

Solid tissues, such as spleen, lymph glands, etc., may be divided into
small pieces by sterile instruments and rubbed up in a sterilised agate
mortar (using an agate pestle), with a small quantity of sterile
bouillon, and the syringe filled from the resulting emulsion.

[Illustration: FIG. 175.--Holding rabbit for shaving.]

If it is desired to inoculate tissue _en masse_, remove from the
material a small cube of 1 or 2 mm. and introduce it into a wound made
by sterile instruments in a suitable situation, and occlude the wound by
means of Michel's steel clips and a sealed dressing.

~Method of Securing Animals During Inoculation.~--

For the majority of inoculations, especially when no anaesthetic is
administered, it is customary to employ an assistant to hold the animal
(see Fig. 175).

If working single handed Voge's holder for guinea-pigs, is a useful
piece of apparatus the method of using which is readily seen from the
accompanying figures (Figs. 176, 177).

The instrument itself consists of a hollow copper cylinder, one end of
which is turned over a ring of stout copper wire, and from this open end
a slot is cut extending about half way along one side of the cylinder.
The opposite end is closed by a "pull-off" cap and is perforated around
its edge by a row of ventilating holes, which correspond with holes cut
in the rim of the cap. In the event of the animal resisting attempts to
remove it from the holder backwards, this cap is