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._--_Anæsthetic, A. C. E._ 1. Anæsthetise the animal and secure it firmly to the operating table. [Illustration: FIG. 190.--Gag for rabbits.] 2. Prop open the mouth by means of some form of gag; seize the tongue with a pair of forceps and draw it forward. The most convenient form of gag for the rabbit or cat is that shown in Fig. 190. It is simply a strip of hard wood shaped at the middle and provided with a square orifice through which a tracheal or oesophageal tube can be passed. 3. Pass a previously sterilised glass tube (17 cm. long, 0.5 cm. diameter, with its terminal 2 cm. slightly curved) down through the larynx into the trachea. 4. Connect the straight portion of a ~Y~-shaped piece of tubing to the upper end of the sterilised tube and couple one branch of the ~Y~ to a separatory funnel containing the fluid inoculum, or insufflator containing the powdered inoculum, and the other to a hand bellows. 5. Allow the fluid inoculum to run into the lungs by gravity, or blow in the powdered inoculum by means of a rubber-ball bellows. 6. Remove the intratracheal tube; release the animal from the table. 7. Label, etc. As an alternative method in the case of fairly large animals, such as rabbits, etc., a sterile piece of glass tubing of suitable diameter may be passed through the larynx down the trachea almost to its bifurcation. Fluid cultivations may then be literally poured into the lungs, or cultivations, dried and powdered, may be blown into the lung by the aid of a small hand bellows or even a teat pipette. ~10. Intragastric Inoculation.~--_Fluid or semi-fluid inoculum. (Anæsthetic none.)_ The method of performing the operation is varied slightly according to the size of the experimental animal. _A. Monkey, Rabbit, Guinea-pig._ 1. Secure the animal to the operating table ventral surface uppermost. 2. Prop the mouth open with a gag; draw the tongue forward with forceps. 3. Sterilise a soft rubber catheter (No. 10 or 8 English scale, or No. 18 or 15 French) and lubricate it with sterile glycerine. 4. Pass it to the back of the pharynx, keeping the end in the middle line. 5. Gently assist the progress of the catheter down the oesophagus until it passes the cardiac orifice of the stomach. Do not use any force.