238 BACTERIOLOGY. 



thumb outside, the vein is usually clearly seen and en- 

 tered with ease, if a small sharp needle is held almost 

 parallel with the ear surface and gently pushed into it. 

 When no holder is present, the rabbit can be held by an 

 assistant seizing the forelegs in one hand and the hind 

 in another and holding the rabbit head downward. 



4. Into the anterior chamber of the eye. 



5. Into the body cavities. The peritoneal and less 

 often the pleural cavities are used for bacterial injec- 

 tion. The hypodermatic needle is usually employed, 

 less often a glass tube drawn out to a fine point. The 

 needle or the pointed glass tube are gently pushed 

 through the abdominal wall, moved about to insure its 

 freedom from the intestines, and the fluid injected. 



6. By inhalation. This method is carried out by 

 forcing the animal to inhale an infected spray or dust. 



7. By the trachea. This method is carried out by 

 making an incision in the trachea and then inoculating 

 the mucous membrane or injected substances into the 

 trachea and bronchi. 



8. Through the intestinal tract by swallowing. 



' In these injections guinea-pigs are held, as a rule, 

 by an assistant grasping in one hand the forelegs and 

 in the other the hindlegs. 



Rabbits can be held in the same manner, or better 

 placed in some holder. 



Mice, which are usually inoculated subcutaneously at 

 the root of the tail, are best placed in a mouse holder, 

 but can be inoculated by grasping the tail in a pair of 

 forceps, and then, while allowing the mouse to hang 

 head downward in a jar, a glass plate is pushed across 

 the top until only space for its tail is left. 



All these methods must be carried out with the 



