240 BACTERIOLOGICAL EXAMINATION OF MATERIAL 



rabbit, is held head downward to permit the intestines to pass ante- 

 riorly as far as possible. The needle is first introduced somewhat 

 obliquely through the abdominal skin posteriorly, then directly into 

 a fold of the abdominal wall pinched between the fingers. The needle 

 should be pressed in until resistance to its passage has ceased. Unless 

 the precaution is taken to dip the point of the needle in sterile vase- 

 line, some of the contents will be introduced into the cutaneous or 

 subcutaneous tissues as well as the peritoneal cavity. The u Plitchens" 

 syringe with its side-arm containing salt solution to rinse the entire 

 charge from the needle before withdrawal from the animal is highly 

 recommended for this purpose. 



Intracerebral injections are made either through the optic foramen, 

 or through the dura after trephining the skull. 



Intratracheal injections are occasionally made, but more commonly 

 the material is introduced deep into the bronchi through a flexible 

 rubber cannula. The animal should be anesthetized for this operation. 



White mice and rats are usually inoculated in the loose subcutaneous 

 tissue at the base of the tail. The needle should pass somewhat 

 obliquely to avoid the spinal cord. 



Care of Animals. Guinea-pigs and rabbits are very susceptible to 

 "snuffles" and frequently perish from contagious pneumonia and 

 other epizootics of the respiratory tract. 1 The first symptoms are 

 usually nasal discharge and a mucopurulent exudation from the eyes. 

 Such animals should be killed at once and their cages thoroughly 

 sterilized. Animals in adjacent cages should be quarantined. 



Inoculated animals are best kept in separate cages apart from the 

 healthy stock. If they become moribund it is better to chloroform 

 them and perform the autopsy at once; fresh, uncontaminated cul- 

 tures may be obtained only at this time. If animals are permitted 

 to die, frequently several hours intervene before an autopsy is per- 

 formed, and postmortem bacterial invasion of the tissues and blood 

 stream is usually a disturbing factor. Infected material is obtained 

 from animals with the same precautions and technic as those for a 

 human autopsy. 



1 Theobald Smith, Jour. Med. Research, xxix, 291, for discussion. 



