le. Should
any drops of the inoculum be forced out, they will fall on the filter
paper, which should be immediately burned.

1. Have the animal firmly held by an assistant. The selected ear is
grasped at its root and stretched forward toward the operator.

2. Shave the posterior border of the dorsum of the ear.

3. Disinfect the skin over the vein, rubbing it vigourously with
cotton-wool soaked in lysol. The friction will make the vein more
conspicuous. Wash the lysol off with ether and allow the latter to
evaporate.

4. Direct the assistant to compress the vein at the root of the ear.
This will cause its peripheral portion to swell up and increase in
calibre.

5. Hold the syringe as one would a pen and thrust the point of the
needle through the skin and the wall of the vein till it enters the
lumen of the vein (Fig. 189). Now press it onward in the direction of
the blood stream--i. e., toward the body of the animal.

6. Direct the assistant to cease compressing the root of the ear, and
_slowly_ inject the inoculum. (If the fluid is being forced into the
subcutaneous tissue, a condition which is at once indicated by the
swelling that occurs, the injection must be stopped and another attempt
made at a spot closer to the root of the ear or at some point on the
corresponding vein on the opposite ear.)

7. Withdraw the needle and press a pledget of cotton-wool over the
puncture to ensure closure of the aperture in the vein wall.

8. Label, etc.

[Illustration: FIG. 189.--Intravenous inoculation.]

~9. Inhalation.~--

(a) _Fluid Inoculum._--(_Anaesthetic, none._)

1. Place the animal in a closed metal box.

2. Through a hole in one side introduce the nozzle of some simple
spraying apparatus, such as is used for nasal medicaments.

3. Fill the reservoir of the instrument (previously sterilised) with the
fluid inoculum, and having attached the bellows, spray the inoculum into
the interior of the box.

4. On the completion of the spraying, open the box, spray the animal
thoroughly with a 10 per cent. solution of formaldehyde (to destroy any
of the virus that may be adhering to fur or feathers).

5. Transfer the animal to its cage.

6. Label, etc.

7. Thoroughly disinfect the inhalation chamber.

(b) _Fluid or Powdered Inoculum._--_Anaesthetic, A. C. E._

1. Anaesthetise the animal and secure it firmly to the operating table.

[Illustration: FIG. 190.--Gag for rabbits.]

2. Prop open the mouth by mea