358 EXPERIMENTAL INOCULATION OF ANIMALS 



2. Dip the tube, with its coating of collodion, alter- 

 nately into a beaker of alcohol and one of water. This 

 loosens the collodion and allows it to be peeled off in 

 the shape of a small test-tube. 



3. Take a 20 cm. length of glass tubing, of about 

 the diameter of the test-tube used in forming the 

 sac, and insert one end into the open mouth of 

 the sac. 



4. Suspend the glass tube with attached sac, inside 

 a larger test-tube, by packing cotton-wool in the mouth 

 of the test-tube around the glass tubing, and place in the 

 incubator at 37 C. for twenty-four hours. When 

 removed from the incubator, the sac will be firmly 

 adherent to the extremity of the glass tubing. 



5. Plug the open end of the glass tubing with cotton- 

 wool, and sterilise the test-tube and its contents in the 

 steam steriliser oven. 



To use the sac, remove the plug from the glass tubing, 

 partly fill the sac with cultivation to be inoculated, by 

 means of a sterile capillary pipette, and replug the 

 tubing. When the abdominal cavity has been opened, 

 remove the tubing and attached sac from the protecting 

 test-tube, close the sac by tying a sterilised silk thread 

 tightly around it a little below the end of the glass 

 tubing, and separate it from the tubing by cutting 

 through the collodion above the ligature, and the sac 

 is ready for insertion in the peritoneal cavity. 



B. Celloidin Sacs (Harris). 

 Materials Required. 



Quill glass tubing. 



Gelatine capsules such as pharmacists prepare for the exhibition 

 of bulky powders. 



Various grades of celloidin, thick and thin, in wide-mouthed 

 bottles. 



1. Take a piece of quill glass tubing some 4 cm. long 

 by 5 mm. diameter ; heat one end in the bunsen flame. 



2. Thrust the heated end of the tube just through 



