86 ESSENTIALS OF BACTERIOLOGY 



Intraperitoneal Injection. This is used with guinea-pigs 

 mostly. The abdominal wall is pinched up through its entire 

 thickness, and the needle of the syringe thrust directly through, 

 so that it appears on the other side, then the fold let go, the 

 needle withdrawn just far enough so as to be within the cavity. 



Inoculation in the Eye. The anterior chamber and the 

 cornea are the two places used. The rabbit is fixed upon a 

 board, the eyelids held apart and head held still by an assistant. 

 A small cut is made in the cornea, a few drops of cocain having 

 first been introduced in the eye. The material is passed 

 through the opening with a small forceps, and with a few strokes 

 of a spoon it is pushed in the anterior chamber. 



For the cornea a few scratches made in the corneal tissue 

 will suffice; the material is then gently rubbed in. 



Inoculation of the Cerebral Membranes. The skin and 

 aponeurosis cut through where the skull is the thinnest. Then 

 the bone carefully trephined, and the dura exposed. In rabies 

 inoculation, the syringe containing the hydrophobic virus pierces 

 the dura and arachnoid, and the virus is discharged beneath the 

 latter. 



Intratracheal. The bacteria can be introduced directly 

 into the trachea, thus coming in contact with the lungs. 



Intraduodenal. Cholera germs are injected into the intes- 

 tines after they have been exposed, by carefully opening the 

 abdomen. This is done in order to avoid the action of the 

 gastric juice. 



Celloidin sacs of small size are sometimes used to introduce 

 living cultures of bacteria into the bodies of animals without 

 their coming into direct contact with the tissues. 



Obtaining Material from Infected Animals. The animal 

 should be skinned, or the hairs plucked out, before it is washed 

 at least the portion where the incision is to be made. Then 

 the entire body is washed in sublimate. Two sets of instru- 

 ments are required one for coarser and one for finer work: 

 the one sterilized in the flame; the other, to prevent being 

 damaged, heated in a hot-air oven. 



The animal, the mouse, for example, is stretched upon a 



