6. Take up the required dose of inoculum into a sterilised pipette. Insert the point of the pipette into the open end of the catheter and allow the fluid to run down into the stomach. Remove the pipette and drop it into a jar of lysol. 7. With another sterile pipette run one cubic centimetre of sterile saline solution through the catheter to wash out the last traces of the inoculum. 8. Withdraw the catheter. 9. Label, etc. _B. Rats and Mice (Mark's Method)._ 1. Secure the animal in the vertical position. (a) _Rat._--Take a pair of catch sinus forceps about 22 cm. in length and seize the animal by the loose skin of the head as far forward as possible--fix the forceps, and holding the instrument vertically upward, transfer to the left hand of an assistant who secures the animal's tail between the fingers grasping the handle of the forceps. (See Fig. 191.) [Illustration: FIG. 191.--Intragastric inoculation of rat.] (b) _Mouse._--An assistant grasps the loose skin between the ears as far forwards as possible between the forefinger and thumb of the left hand. He now grasps the tail with the right hand, draws the mouse straight and passes the tail between the fourth and little fingers of the left hand and secures it there. 2. The assistant takes a closed pair of thin-bladed forceps in his right hand, passes the ends into the animal's mouth, then allows the blades to separate. This opens the animal's jaw and serves as a gag. 3. Moisten the sterilised oesophageal tube with sterile water. (This tube is of silk rubber, 6.5 cm. in length, with the distal end rounded, the proximal end mounted in a syringe needle head, which fits the nozzles of the two sterile syringes to be used.) 4. Grasp the tube about its middle and pass it into the animal's mouth, downwards and a little to one side or the other until its length is lost in the digestive tract and mouth. Gentle guidance is alone necessary. Do not use any force. 5. Take up the required dose of inoculum into the syringe; insert the nozzle of the syringe into the needle-mount, and force the piston down. 6. Steadying the needle-mount with the left hand, detach the syringe. 7. Draw up some sterile water in the second (sterile) syringe, and inserting its nozzle into the needle-mount force a few drops of water through the tube to wash it out. 8. With one quick upward movement remove the tube from the animal's mouth. 9. Label, etc. One other method of inoculation remains to be described, which does not require operative interference. ~11. Feeding.~-- 1. _Fluid Inoculum._--Small pieces of sterilised bread or sop (sterilised in the steamer at 100° C.) are soaked in the fluid inoculum and offered to the animals in a sterile Petri dish or capsule. 2. _Solid Inoculum._--Small pieces of tissue are placed in sterile vessels and offered to the animals. FOOTNOTES: [12] This table is made by Messrs. Down Bros., St. Thomas's Street, London, S. E.