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 toa 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 
