166 MICROBIOLOGY 



it is usually easy to pass a needle directly into one of the 

 superficial ear veins. With large animals the jugular vein is 

 selected. 



4. Intraorbital. Into the anterior chamber of the eye by 

 means of a small hypodermic needle. 



5. Into the ~body cavities. The peritoneal and less often 

 the pleural cavities are used for bacterial injection. The hy- 

 podermic needle is usually employed, less often a glass tube 

 drawn out to a fine point. The needle or the pointed glass 

 tube is gently pushed through the abdominal wall, moved 

 about to ensure its freedom from the intestines, and the fluid 

 injected. The hypodermic needle should be inserted perpen- 

 dicular to the abdominal wall. 



6. By inhalation. This method consists in compelling ani- 

 mals to inhale infected spray or dust. 



7. Into the trachea. This consists in inoculating either 

 directly into the lumen of the trachea by means of a hypoder- 

 mic needle or by making an incision into the trachea and then 

 introducing the material. 



8. By ingestion. This consists in feeding animals the 

 infected material. 



9. Subdural. This consists in injecting the material be- 

 neath the dura. In most instances it is necessary to trephine 

 the skull, removing the button of bone, or to bore a hole 

 through the skull by means of a small sharp instrument such 

 as an awl, when by use of the needle the substance may be 

 injected. With rabbits it is possible to introduce a hypoder- 

 mic needle back of the ear through the skull into the dura 

 without trephining. This method is used most largely in the 

 inoculation for rabies. 



10. Intramuscular. This is the injection of the sus- 

 pected material or culture into the muscle. 



In making inoculations it is important that the instru- 

 ments be sterilized and the field of operation properly dis- 

 infected. 



The use of anesthetics. If an anesthetic is given ether 

 is safer for small animals than chloroform. Local anes- 



